04 | 2020 MAX PLANCK Research

2020 2020 CELLULAR BIOLOGY IRON RESEARCH GRAVITATIONAL PHYSICS |

04 DNA origami Energy revolution in the blast furnace A big fish is making big waves

ONE WAY OR ANOTHER 2 Max PlanckResearch ·4 | 2020 N (and large!) differences all (and all differences large!) patterns and shapes. Every- shapes. and patterns the more exciting. This field of more field exciting.the This research combines disciplines range of different sizes, colors, colors, of sizes, different range birds’ eggs have incredible birds’ an eggs is so, and to explain the small small the to explain so, and is another, as that and same the is nature. However,nature. makes this diversity plays a key role in and astronomy.and attempts to find out why toattempts find this no one one egg knows that such as biology,such as anthropology ot all eggs are the same: the are eggs ot all

PHOTO: SCIENCE PHOTO LIBRARY/FRANS LANTING, MINT IMAGES EDITORIAL

Dear reader,

Most people would probably say that one egg is just like another. However, only eggs from industrially farmed, hybrid chickens show that degree of similarity. Nature is characterized by diversity – a wealth of variety that astonishes, fascinates, and some­ times even confuses us. In our standardized world, we are surrounded by millions of identical objects. Understanding diversity, recognizing its value, and looking beyond differences to see what things have in common is anything but trivial.

Diversity has challenged scientists since time immemorial, as the “Focus” section in this issue shows. One classic example is the biological identification of species. If you try to identify plants just from the appearance of their leaves, for example, you can easily make a mistake. Even closely related plants can have very different 3 leaves in some cases. Genetic analysis is now helping to uncover the secret of leaf shapes.

And diversity is not just unique to nature; humans too have developed a variety of cultures that impact our perception and actions in different ways. However, until recently, psychological research has paid very little attention to this phenomenon. Comparative cultural studies are now attempting to document diversity and identify uniquely human traits that transcend all peculiarities.

Science has also created a system that classifies the multiplicity of form beyond our planet. In the 1920s, Edwin Hubble did pioneering work in the field of astronomy by classifying galaxies in space according to specific criteria. Today, researchers are exploring the role played by dark matter in various types of systems in the Milky Way.

We trust you will find plenty of interesting material among the many topics we cover in this issue, and hope you will enjoy reading it!

Your editorial team

Max Planck Research · 4 | 2020 Different leaf shapes are are shapes Different leaf 38 38 to the environment. environment. the to adaptation clever a of evidence

ADJUSTED Viola Priesemann loves riding, riding, loves Priesemann Viola 48 48 but moment, at the she has almost no time for no her time ponies. almost

IN HARNESS IN 66 38 Max PlanckResearch Steel from the eco-friendly forge eco-friendly Steel the from 66 66 can be produced with lower produced be with CO can emission levels. levels. emission ·4

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2020 ECONOMIC 2

Gravitational waves from black 74 74 holes are regularly getting caught getting regularly holes are up in the detectors’ network. detectors’ the up in

CAPTURED 48 74

PHOTOS: ADOBESTOCK (LEFT TOP); JULIA STEINIGEWEG (RIGHT TOP); PICTURE ALLIANCE/RUPERT OBERHÄUSER (LEFT BOTTOM); N. FISCHER, H. PFEIFFER, A. BUONANNO/MPI FOR GRAVITATIONAL PHYSICS, SIMULATING EXTREME SPACETIMES (SXS) COLLABORATION (RIGHT BOTTOM) CONTENT

03 | EDITORIAL 48 | VISIT TO Viola Priesemann 06 | ON LOCATION An infectious interest in the coronavirus A nesting box in the Westerholz forest near Landsberg am Lech KNOWLEDGE FROM 56 | DNA origami 08 | IN BRIEF What is life? How did it emerge? To find out, researchers are following an ambitious plan. 18 | VIEWPOINT They aim to create artificial cells and, by so doing, to discover what is essential for life. A custodian in the time of corona 60 | Caution – toxic green! The fight against COVID-19 appears to be taking place mainly at national level, Not everything that is green in nature is good. while the World Health Organization, the Some plants produce toxins that can make us WHO, has kept away from the public eye and sick – or even kill us. Which behaviors protect has repeatedly been the subject of criticism. children from dangerous plants? 66 | Energy revolution in the blast FOCUS furnace One way or another It’s impossible to imagine modern life without metals. How can they be produced and used 5 24 | We cultured humans in a more sustainable way? The ideas being developed could completely revolutionize the In many ways, our thoughts and actions are industry. influenced by our social background. That’s why people’s behavior varies so widely between 74 | A big fish is making big waves different countries throughout the world. We cannot ultimately determine what it is that Astronomers have detected a black hole with makes us human until we are aware of what we a mass that is 85 times that of our sun – and have in common and what our differences are. which in fact ought not to exist. What’s the reason for this? 30 | Midwife of the galactic zoo 78 | Forests change the climate Stars cluster in galaxies of dramatically different shapes and sizes. There are elliptical, Scientists are in dispute as to whether forests spheroidal, lenticular and spiral star systems, can best protect the climate if they are managed and occasionally even star systems without any sustainably or left undisturbed. clear form at all. Why is this so? And what role does dark matter play? 86 | POST FROM ... 38 | Diversity in the leafy forest Ghana Lanceolate, ovate, elliptical, entire, serrated, and uni- or multi-pinnate – there are numerous names to describe the variety of leaf morphol- 88 | COMMUNITY NEWS ogy. Researchers have been examining the reasons behind this diversity. They have 90 | FIVE QUESTIONS already found one central regulatory element. On the use of artificial intelligence in pharmaceutical research 46 | INFOGRAPHIC

Black holes – space-time traps 91 | PUBLISHER’S INFORMATION

Max Planck Research · 4 | 2020 A SMART HOME IN A SUN LIT FOREST

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Max Planck Research · 4 | 2020 ON LOCATION

The big double “00” is misleading. That sign on a door in the hotel corridor traditionally means “restroom”. But the inhabitants of this dwelling certainly aren’t likely to get 7 much rest. They’re glad instead to have found such a comfor­ table and safe home for their new family. These blue tits have moved into a “Smart Nest Box” in Westerholz, a mixed woodland region in southern Germany. This state-of-the-art nest box was designed by the Max Planck Institute for Ornithology. The blue tit chicks have hatched and want to be fed – quite a job for their parents! With the aid of the Smart Nest Box, ornithologists can track exactly which birds enter and exit the nest and at what time. An RFID data logger system records the presence and identity of the

PHOTO: JULIUS KRAMER JULIUS PHOTO: parents, 24 hours a day, seven days a week. The birds carry tiny implanted transponders, allowing them to be individually identified. Coupled with a clock and two infrared light barriers, the system compiles an accurate activity profile for each of the breeding birds.

While blue tit pairs usually jointly rear their young, both part­ ners may engage in additional sexual interactions. In recent years, it has become clear that this is far more common in blue tits than previously thought. What is the evolutionary advantage of rearing such “illegitimate” offspring? Thanks to the Smart Nest Box, the researchers have discovered that these chicks hatch earlier and are stronger than their half-si­ blings. In addition, nests containing only chicks from a cuck­ olded partner are rare, and in some of these cases, the social partner was found to be infertile. “Extramarital” copulation may, therefore, represent a kind of insurance against infertility.

Max Planck Research · 4 | 2020 8

GRAPHIC: MPI FOR MOLECULAR BIOMEDICINE/HENRIK RENNER, JAN BRUDER (red: young neurons). whole Bottom: organoid microscope. Top: under the organoids midbrain VOLKER SPRINGEL VOLKER AKHTAR ASIFA Max Planck Society since July since 2020. Planck Society Max of held Vice President post the also of the has “dosage compensation”. as known Akhtar Asifa also regulation, of chromosome understanding scientific to the her and contribution regulation gene of epigenetic work mechanisms biological on the her cell The award recognizes Prizes. Leibniz Foundation’s Research awarded one of German the Freiburg Epigenetics and in to be is Immunobiology of Planck Institute of Max the The Director early, almost uniform universe. an have could from emerged cosmos structured how diversely the things, other amongst to explain, help developed can He has that new methods astrophysics. of numerical work field the his in honored for being is Springel physics Garching. in for Planck Institute Astro- of Max the Director awarded to be is to the Prize Leibniz Another AWARD-WINNING ventional cell cultures. This organoid pro This ventional cultures. cell Biomedicine Muenster, in techno- and the Sometimes, hundredsSometimes, of of thousands active production of organ-like tissues, known as production known as of tissues, organ-like tion has now biotion it has licensed to American the company Planck transfer logy Max Innova Planck Max the Institute for Molecular tissue’s the conditions. mimic ture These lopment of new future. therapeutics the in Organoids are generated are Organoids when precursor ORGANOIDS FROM A MACHINE duction process was developedduction was process by at a team cul special in aggregates tissue dimensional cells derivedcells form from body three- cells characteristic properties better than con than better properties characteristic organoids, to promises accelerate deve- the However, automated the therapeutic. one suming, costly experiments experiments to identify costly suming, just havesubstances time-con tested to in be

Max PlanckResearch IN BRIEF IN ·4 | 2020 ------

StemoniX aims to use these automatically these to use StemoniX aims partners only developpartners most safest, the effec which of brain the producespart dopa the tive active substances for treating diseases tive active for diseases substances treating organoids aday. brain to 20,000 compa- In resemblethat midbrain – the human the litates automatic the generation of organoids tech company StemoniX. faci- The process in aday;in moreover, considerably vary these rison, manual processes only allow for processes manual the rison, generation of acouple of hundred organoids generated organoids to guarantee that its that generated organoids to guarantee mine-producing neurons that are the first to to first the mine-producing are neurons that die in patientsdie Parkinson’s in with Re disease. and are thereforeand are unsuitable for testing. drug such Parkinson’s. as it use to generate can searchers and test up

PHOTO: HEIDELBERG INSTITUTE FOR PHOTO: WOLFRAM SCHEIBLE FOR MPG THEORETICAL STUDIES (HITS) The scientific journal Nature has now Nature has journal The scientific The Nature Index deter is Germany FIRST NATURE INDEX FOR FOR INDEX GERMANY Munich rank fourth and fifth. fourth Munich rank However, of alack diversity and slow ad published its own evaluation of scien prolific research record going forward. forward. going record research prolific lowed by Helmholtz As the and Leibniz topthe Nature positions Index the in are Germany, In journals. scientific tigious achievements for Germany tific in the facilities – the Max Planck Max –the Society,facilities fol first time. The report states that Ger The time. that states report first held non-university by three research rections could Germany’s challenge rections research as keys as to country’sresearch the success. nal cites strong, steady scientific fun- cites strong,nal steady scientific mined by numbermined the counting of arti its one position as many maintaining is ding and long-termding investment basic in cles published pres by institution in an aptation di to contemporary research of world’s the The jour giants. research sociations – while two universities the sociations in www.mpg.de/15969879 - - -

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PHOTO: WABENO/ISTOCK FACTS FACING Five “long the after years of summer mi this paper,this given that global the they argue tion, Integration and Exclusion” has pu- blished its research report. The researchers blished report. The its researchers research have made eight recommendations based not only quite but regrettable dan actually globalization and demographic shifts, it and demographic is globalization shifts, 2015,gration” in Planck Max Society’s the challenges associated with climate change, change, climate with associated challenges a position policy. paper on migration In in them and summarized findings on their scientific initiative “Challenges of Migra

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fleeing on foot through the Balkans to central to central Balkans the on foot through fleeing A long of way: 2015 fall the saw people many legal framework and increasing the the increasing and framework legal tion policy by should guided be instead the European Union, European the it to important is facts. Atfacts. level, national the researchers the involvement of local authorities. Within Within authorities. local of involvement and asylum. migration Migra irregular human rights.human gerous for about discussions current migration to revolvemigration around primarily and to shape a policy that is in accord with with accord in and is to shape apolicy that overcome asylum regarding impasse the suggest standardizing the fragmented fragmented the standardizing suggest been struggling to agree on a joint course of on ajoint course to agree struggling been action for their asylum policy. asylum for their action Max PlanckResearch www.mpg.de/16169506 www.mpg.de/16169506 ·4 | 2020 -

VALLEY With this backing, MunichWith this Quan A quantum computer,A quantum tap-proof FOR MUNICH MUNICH FOR vide start-up financing to the tune of tune to the vide start-up financing years, the State of Bavaria will pro State the years, of will Bavaria University of Munich), President GREEN LIGHT LIGHT GREEN Minister Hubert Aiwanger, Minis President Söder, Markus Minister Munich) light gave for green the the Planck (Max So Stratmann Martin € 120 some of be million, which will Hofmann (TechnicalHofmann University of Bernd Huber (Ludwig Maximilian

Sciences and Humanities),Sciences Presi tum Valleytum intends also to apply for of intent.laration Over next the two ter Sibler, Bernd President Thomas used to setused up a technology park. funding from the federal the from governfunding hofer-Gesellschaft), President O. Höllmann (Bavarian AcademyO. (Bavarian of Höllmann research initiative by a dec research signing QUANTUM QUANTUM nich Quantum Valley.nich Quantum Bavarian nology just are some that of goals the ment, €2billion which making is dent Reimund Neugebauer (Fraun Neugebauer Reimund dent elementsdamental of tech quantum quantum technologies as part of its part technologiesquantum as ciety), and President F. Thomas communication methods, andcommunication fun available for development the of stimulus package forstimulus package future. the Mu in pursuing be will scientists BRIEF www.mpg.de/16258573 IN ------

9 10 “North polar spur”. polar “North cloud This was A RISK CALCULATOR FOR COVID-19 AN AN Viewed together, the northern and and northern the together, Viewed Way occupies that The enormous amount of re energy A computer now can used be program Astronomers have made a remarkable have remarkable a made Astronomers MILKY WAY MILKY THE IN HOURGLASS HOURGLASS Max Planck in Max Institute for Chemistry fected with the coronavirus Sars- coronavirus the fected with from an outburst from a supermassive supermassive a outburst from an from particles in an enclosed space. an The in particles to determine the risk of becoming in ofto determine risk the becoming period ofperiod intensive formation or star CoV-2 following to aerosol exposure thought to have by created the been in a shape reminiscent of an hourglass. of hourglass. an ashape reminiscent in long known of asimilar planethe of Milky the northern sky,northern the known as black hole at center the of galaxy. the model developed by at the researchers gas bubblesgas could have come from a most of southern the discovery in the first comprehensive first the discovery in quired toquired power formation the of these cloud structure in the the in structure cloud emerge from the center of the galaxy emerge center from the of galaxy the explosion of (supernova). a massive star sky. have Scientists southern structures both appear to appear both southern structures structure of below hot gas structure eRositascope –ahuge circular sky map produced by X-ray the tele

www.mpg.de/16140198

- - - viduals as well. cal viduals as also The algorithm Mainz uses parameters such as the size such size the parameters as uses Mainz the risk of not risk infection, the only for every culates howculates much reduced is risk the one in the room butone room indi the in for specific order in activity to estimate and their of number the room, the of people it, in (yellow), which extend extend (yellow), which Gas from the galaxy: galaxy: the from Gas center of the Milky center of Milky the diagram shows the diagram bubbles observed observed bubbles newly discovered further from the the from further eRosita bubbles bubbles eRosita than the Fermi the than Way space into this schematic schematic this light years light light years light ~ 50,000 ~ 35,000 before. Max PlanckResearch

IN BRIEF IN

·4 | 2020 - - - website. when or people when masks wear the publicly available on Institute’s the infected by larger droplets transmitted by dropletsinfected larger transmitted of risk becoming the assess it cannot room is regularly ventilated. regularly is room However, over is The algorithm ashort distance.

Fermi bubbles Fermi www.mpg.de/16015780 Galactic center Galactic eRosita bubbleseRosita

GRAPHIC: GCO BASED ON DATA FROM THE MPI FOR EXTRATERRESTRIAL PHYSICS PHOTO: SHUTTERSTOCK veloped an explanatory model which which model explanatory an veloped BUILDING BLOCKS FOR Human Cognitive and Brain Sci Cognitive and Brain Human SOCIAL UNDERSTANDING Based on previous studies, research studies, previous on Based ableBeing to feel empathy and adopt pending on the situation. In the case pending on situation. the case the In those responsiblethose for or face speech the otherthe person’s point of view en not clear what these skills constitute. not skills what clear these by processing fear – cooperates with with by –cooperates fear processing many individual factors that vary demany individual vary factors that can recognize critical situations – e.g. critical recognize can ences and otherences institutions have de Planck aters Max the Institute for other specialized regions, such regions, as other specialized of empathy, network that aprimary mind. their However,on in it still is ables to us understand what going is shows that both skills are made up are ofshows skills both that - - - - - vated for each specific situation. situation. specific for each vated pressions or speech melody. speech or pressions the ability to understand facial ex abilitythe to understand facial the individual’sthe competence as social limit not does necessarily two skills of a lack that one or other the of these have perspective.in Analyses shown empathy require both lar and ashift acti are too, regions additional brain recognition. When changing per changing When recognition. become the active the network. core become Here future the and imagine past the ber Complex problems particu social in cific sub-factor such affected, is as cific a whole. It only may that one be spe spectives, the regions used to remem used regions the spectives, the levelsthe of a hormone produced in the brains brains the produced in Measuring sociability: surrounded by many surrounded of zebrafish indicate indicate zebrafish of www.mpg.de/16024611 Max PlanckResearch whether or not an an not or whether others of itsothers kind. individual fish is is fish individual IN BRIEF IN ·4 | 2020 ------

A deep understanding: our ability ability our understanding: A deep factors. These can vary depending vary can These factors. to empathize with other people other with to empathize depends on numerous individual on the situation. on the with others ofwith levels the its species, of IN FISH FISH IN BRAINS DISTANCING DISTANCING Planck Institute for Brain Research Research for Brain Institute Planck SOCIAL SOCIAL Social isolation can have isolation effects can dire Social www.mpg.de/16105035/1202 produced in its brain. If a zebrafish produced its a zebrafish If in brain. played included activity in changes ternational research team that in that team research ternational lateral line organ, a band of sensory of aband sensory organ, line lateral parathyroid hormone within this rise environment: social the more the genethe for “parathyroid hormone 2” by of zebrafish tion on brains the has investigated of effects has the isola kept isolation a tank in placed in is ronment, more the hormone pth2 is neurohormone controlled is by the (pth2). like a barometer acts of This measuring the activity of thousands activity the measuring members pre- are of that its species cells that react to mechanical stimuli stimuli to mechanical react that cells cludes Max the from scientists on both humans and animals. An in An and animals. humans on both and are used by the fish to sense the the to sense by used and fish are the a short According time. to re the of genes. The few dis that genes swimming movementsswimming of kin. their searchers, the production of this this of production the searchers, individualsent an in zebrafish’s envi-

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GRAPHIC: MPI FOR BRAIN RESEARCH/ J. KUHL 11 IN BRIEF

Blackcaps take various routes to their wintering grounds when they migrate in the fall.

PORTRAIT FLEXIBLE OF AN FLIGHT EXOPLANET PATHS Astronomers discover the vast major- Like many other migratory birds,

ity of the planets orbiting distant blackcaps fly south in the fall, cover- GRAPHIC: GCO stars with the help of sophisticated ing thousands of kilometers to reach methods. These exoplanets do not their wintering grounds. Birds living appear in images, but reveal them- in the eastern regions of central Eu- selves indirectly. One of the most rope migrate toward the southeast, popular methods of discovery is the while those that live further west mi- measurement of radial velocity. Be- grate toward the southwest. Cross- cause a planet pulls at its much breeding experiments have shown brighter parent star like a dog on a that parent birds pass on the direc- leash pulls at its master or mistress, tion of migration to their offspring. the star “sidesteps”, i.e. makes peri- Researchers at the Max Planck Insti- odic movements at a specific velocity. tute for Evolutionary Biology in These cause minute shifts in the Ploen have now tracked the flight spectral lines, enabling conclusions paths of 100 wild blackcaps and dis- 12 to be drawn regarding the planet’s ex- covered that birds living in the zone istence. A team of researchers from between the western and eastern the Max Planck Institutesß for Astro- groups choose an “intermediate nomy and Extraterrestrial Physics route”. They fly directly south, suc- has now succeeded in making the cessfully crossing the Alps, the Me- first direct observations of an diterranean and in some cases the exoplanet previously discovered Sahara, before returning to their using this method. They viewed the breeding grounds in the spring. The faint light from the planet ß (Beta) “migratory divide” in which both Pictoris c, some 63 light years from groups of birds mingle is, at 30 kilo- Earth, using the GRAVITY instru- meters, surprisingly narrow. It runs ment, which combines the four large in a north-south direction through telescopes at the European Southern Europe, spanning the distance be- Observatory to form a single super tween Berlin and Prague. The results telescope with a diameter of also show that blackcaps that spend 130 meters. the winter in Britain – a behavior that www.mpg.de/15473085 has been observed more and more of- ten since the 1960s – come from all over Europe. These birds probably benefit from the increasingly mild winters and the food provided in British gardens. www.mpg.de/15987699 DUST DISK b Strange worlds: this c schematic image shows the Beta Pictoris ß Pictoris system with the two planets b and c embedded in a dust disk. This image was created DUST DISK using actual observation

IMAGE: AXEL QUETZ / MPIA GRAPHICS DEPARTMENT data.

Max Planck Research · 4 | 2020 IN BRIEF

TEETH WITH LARGE FAMILY PREDETER- OR NO CHILDREN MINED A study of female academics in the demics who only wanted two chil- U.S. conducted by Natalie Nitsche dren. The time of their first marriage BREAKING from the Max Planck Institute for also influenced the number of chil- Demographic Research and one of dren, a finding that also applies to POINTS her colleagues has found surprising men. Men who do not embark on correlations between the desire for their first long-term relationship be- Biting down on a cherry stone can children expressed in younger years, fore the age of 35 are less likely to be- have severe consequences. At worst, a their level of education, the time of come fathers, even though they are tooth breaks and a visit to the dentist their first marriage, and the number able to procreate until a more ad- becomes unavoidable. For the Port of children to whom they had given vanced age than women. Another Jackson bullhead shark, on the other birth by the age of 43. Female aca- finding: female academics who want hand, splintering teeth are perfectly demics who originally wanted to have a lot of children and who become normal, as a team led by Shahrouz at least three children were more mothers at a relatively young age had Amini at the Max Planck Institute of likely to remain childless than less more children than other groups in Colloids and Interfaces in Potsdam educated women who expressed the the study. discovered. The researchers can now same desire – and than female aca- www.mpg.de/0420202en explain why the shark’s teeth stay sharp: its tooth enamel consists of in- The decreased ner and outer layers, both made of ap- use of transport atite. In the outer layer, which covers as a result of the the sides of the teeth, all the apatite coronavirus bundles run parallel to the tooth sur- pandemic was the face. This means there are predeter- main factor that caused global mined breaking points between the CO2 emissions to bundles. In the inner layer, which fall by seven surfaces at the tip of the tooth, the ap- percent. atite bundles are stacked crosswise so 13 that the material does not splinter. ß The tip of the tooth is gradually ground down but remains sharp, be-

cause the enamel on the sides of the GOMEZ/UNSPLASH RICARDO PHOTO: tooth is constantly breaking off. This knowledge could serve as an inspira- tion for new types of material. www.mpg.de/16060198

CORONAVIRUS IS REDUCING

CO2 EMISSIONS The coronavirus pandemic has emissions from fossil fuel combus-

caused a record decline in fossil CO2 tion and changes in land use such as emissions. In 2020, global green- the deforestation of rainforests, house gas emissions from coal, oil amounted to approx. 39 billion tons. and gas combustion were down 2.4 This means that the atmospheric A conveyor belt of billion tons compared to 2019. At concentration of CO2 did not rise as teeth: the Port seven percent, this is the sharpest sharply as in previous years, which – Jackson bullhead drop since the early days of industri- with a few exceptions – saw green- shark has several alization. These findings were pu- house gas emissions increase every rows of teeth that are constantly blished by the Global Carbon Project, year. If the Paris Climate Agree- being renewed. in which scientists from the Max ment’s goal of limiting global war- The red coloration Planck Institute for Biogeochemistry ming to 1.5 degrees Celsius is to be comes from sea in Jena are involved. The decline in achieved, global emissions of CO2 PHOTO: MPI COLLOIDS OF AND INTERFACES/NATURE COMMUNICATIONS 2020 urchins, one of the emissions was particularly marked in must be reduced by one to two billion shark’s most the transport sector. The total tons a year by 2050. common prey. www.mpg.de/16175501(in German) CO2 emissions for 2020, i.e. the

Max Planck Research · 4 | 2020 14 THAN ONCETHAN THOUGHT ANIMALS EVOLVED ANIMALS A longstanding controversyA longstanding sur MORE RECENTLY Planck Institute for Biogeochemistry Earth now to have appears Earth re been fat molecules found in stones dating dating stones in found molecules fat these fossilized molecules, which fossilized re these life. evidenceliest Chemi of animal in Jena have discovered that fossilized rounding the origins of animal life on of animal rounding origins the back 635back not are ear the years million ganisms, are more are likelyganisms, to have cal experiments havecal shown that evolved molecules of from precursor semble steroids the of sponge-like or solved. at Max Researchers the ------when there is a prize to be won, this could won, to be this a prize when is there years ago.years The researchers’ latest work resolves also dichotomy the that Earth’s history, significantly they are fore oxygen the content oceans the in tion only began around 560tion only million began began to rise some 540 million years years some million 540 to rise began gical processes. In terms of terms the In processes. gical currently believed that animal evolu believedcurrently animal that result the of as geolo- algae common evolution life. of animal ago, for even vital was the though this life it forms, so is older animal than animals appear to appear have developedanimals be If aperson’sIf only pupils slightly dilate

be a sign of depression. asign be www.mpg.de/16048936 Max PlanckResearch Dickinsonia. tives of genustives the ago with representa with ago IN BRIEF IN 560 million years years 560 million evolving some some evolving animal life began believed that that believed currently currently animal: it is animal: The oldest oldest The ·4 | 2020 - -

ILLUSTRATION: HENNING BRUER

- The researchers measured the study the The measured researchers weaker the dilation response of their ofweaker response their dilation the vealed that the more the vealed that severe pa the to mea ver, difficult is lethargy this IN THE EYE Using a special set-up,Using aspecial they were able DEPRESSION DEPRESSION DETECTING Institute of Munich Psychiatry in People depression it with often find

pupils of healthy subjects to dilate. positive may par This expectation. pupils. The researchers assume that that assume researchers The pupils. preci great with pupils participants’ tients depression with whose pupils factors, such pupil as logical Pa size. it mayture, possible become to clas frequently lethargy the explain tially nervousthe system of patients with the depression, of symptoms tients’ second; by per 250to take images astudy in ticipating were offered the pupilsthe to dilate. Test subjects par to six seconds.to six The measurements re hard to motivate themselves. Howe- themselves. motivate to hard have advantage taken of that fact the groups to measurable bio according more precisely medication. targeted money, the incentive an causes that do not react as stronglydo as not would react form a depression unable is to activate as comparison, wecomparison, onlyevery blink four amount of asmall to win chance even of areward possibility the causes observed in these patients. these fu the observed in In strongly even when given they are a subgroup and with could treated be diagnostic in psychiatric diseases sify sion extremely and at an high speed. Planck atsure. Max the Researchers www.mpg.de/16073488 ------

PHOTO: KALEA JERIELLE/UNSPLASH IN BRIEF

NO FALSE SENSE FROM MPIFROM FOR CHEMISTRY

OF SECURITY GRAPHIC: GCO BASED ON DATA During the COVID-19 pandemic, both politicians and the general po- 5 10 15 20 25 30 35 pulation are having to come to terms with the fact that scientific know- Estimated percentage of COVID-19 deaths caused ledge invariably comes with a degree by man-made air pollution. of uncertainty. But should the public be explicitly informed about this? Re- searchers at the Max Planck Institute MORE COVID-19 DEATHS for Human Development and the Charité University Hospital in Berlin DUE TO AIR POLLUTION have now looked into this question. During a representative study, they Air pollution appears to increase the combustion. It was found that 15 per- presented the test subjects with four risk of dying of COVID-19. This con- cent of COVID-19 deaths worldwide different scenarios, placing varying clusion was drawn by an international were caused by this pollutant. In Ger- degrees of emphasis on the uncer- team that included scientists from the many, the figure is no less than 26 tainty of the predictions. In the sce- Max Planck Institute for Chemistry percent. It appears that particulate nario that emphasized the element of in Mainz. The researchers calculated matter makes it easier for the virus to uncertainty most strongly, they com- the percentage of COVID-19 deaths infect cells in the lungs, and it also municated the from-to figures, e.g. that could have been prevented if damages the blood vessels in a man- the estimated number of persons cur- there was no man-made particulate ner similar to Sars-CoV-2. 15 rently infected, the estimated number matter in the air, e.g. from fossil fuel www.mpg.de/15952279 of deaths, or the estimated R number. They also stressed that “the diffe- rences observed [could] be caused by random fluctuation or be the first signs of a second wave of coronavirus infection.” In contrast, the scenario that paid the least amount of atten- tion to the uncertainty provided spe- cific figures and stressed that their development “leaves no doubt that a HIGH-SPEED MODEL second wave of infection has already begun.” Each of the scenarios ended FOR THE FIGHT AGAINST with an appeal to comply with protec- tive measures. In response to the CORONAVIRUS question of which scenario would be best suited for informing the public Before treatments for the coronavirus bred genetically modified mice that about the progression of the pan- Sars-CoV-2 can be tested in human carry a human variant of the ACE2 demic, more than half of the partici- clinical trials, they have to be inten- receptor on their cells – thanks to pants cited a preference for formats sively studied in animals. One suit- CRISPR Cas9 genetic scissors and a that conveyed a sense of uncertainty; able model organism for testing treat- technique used in stem cell research. in fact, the majority preferred the ments to be administered to humans The results show that Sars-CoV-2 in- scenario in which the uncertainty is the mouse. However, Sars-CoV-2 fection in these genetically modified was clearest. In contrast, the scenario cannot infect mice, because they have mice causes similar symptoms to that glossed over the scientific uncer- different ACE2 receptors. The virus COVID-19 in humans. These new tainty only convinced 21 percent of cannot bond with these receptors and techniques will now enable resear- the participants. People who take a is therefore unable to penetrate the chers to investigate the effects of critical view of the current measures rodents’ cells. In the record time of antibodies and therapeutics on the also seem more likely to comply with just one month, researchers at the coronavirus, which means they will them if scientific uncertainty is Max Planck Institute for Molecular be able to react more quickly than clearly communicated. Biomedicine in Muenster, working before to the threat of new pathogens. www.mpg.de/0420201en with colleagues in China, have now www.mpg.de/16164102

Max Planck Research · 4 | 2020 16 ARCHIVE OF ANIMAL Warmer, shorter melting winters, ice, Archive” enables to share scientists Behavior “Movebank”Animal plat within these individual these groups,within whereby al MIGRATION IN THE ARCTIC DEMOCRACY AMONG GUINEA FOWL Researchers aroundResearchers world the have Guinea fowl in the East African savannah savannah fowlGuinea African East the in form. The “Arctic Movement Animal pha animals can dominate other dominate group can pha animals that the Arctic is undergoing is Arctic the dra that the Arctic and Subarctic, which Arctic the is live amulti-level in which in social society their knowledgetheir and work together to patterns. migration and their imals hosted on the Max Planckhosted on Max the Institute of now archive data set up online for an Caribou migrate long distances over the course of ayear. over course shown that the Astudy has long distances migrate Caribou groups of 15 between in 60 and more than members and completely monopolize food food monopolize completely and members matic changes that are impacting an impacting are that changes matic populations further south. further populations dividuals interact. There hierarchy aclear is documenting animal movements in in movements animal documenting and increased human activity mean supplies. Planck Max from the Researchers climate change is causing northern caribou to give birth earlier in the spring than than spring the in earlier to give birth caribou northern causing is change climate - - - wolves region. the They in demon from the archive to the from far-re- testify aquatic and 8,000 from more than to out reacting are howfind animals identify significant changes in the in changes identify significant to the present. Three new studies new studies present. Three the to terrestrial animals dating from 1991 golden eagles, bears, caribou, elk, and and elk, caribou, golden bears, eagles, currently contains more than 200 re 200 more than contains currently The Arctic. archive the in changes ecosystem. ecosystem. aching changes in the behavior the in of changes aching strate howstrate to used archive be the can projects movementsearch with data - - When dominant individuals other dominant When chase Institute of Animal Behavior Radolfszell in Institute of Animal birds’ social ranking within their hierarchy. their within ranking birds’ social video and high-resolutionby utilizing GPS members of group the away from aparticu of fowl various groups of guinea on foot and spent several years tracking the movements the spent tracking several years sensors; this enabled to the them determine this sensors;

www.mpg.de/15976863 Max PlanckResearch IN BRIEF IN ·4 | 2020 - -

PHOTO: GEOFFREY REYNAUD/ISTOCK - patch and follow group. the shows This that they abuse power their and monopolize re leadersthe have to bow to majority the if larly rich food patch, excluded the subordi nant group to move on. behavior This ulti nates band together and induce domi the mately to leave forces alpha the the animals sources forsources themselves. THE STONE STONE THE THOUGHT AGE LASTED LASTED AGE The research team has now has discovered team The research techniquesThe earliest employed by Africa, which no there was meant that Africa, Africa 20,000 years longer than was was longer years than 20,000 Africa LONGER THAN THAN LONGER were less extreme than in other parts of other parts in were extreme than less PREVIOUSLY PREVIOUSLY University Diop Anta of in Cheikh Middle Stone Age techniques until Group Planck at Max Insti Leader the fairly isolated due to its proximity to was region the couldfor that be this forests of central Africa. It possibleforests is Africa. of central Senegal. UntilSenegal. now, it assumed was pletely different set of smaller-scale previously result the is This assumed. that climate changes in this region this in changes climate that groups ofthat hunter-gatherers in orlithic Middle Stone Age, such the as stonethat Meso from the tools dating Jena, Niangin and Khady from the tute for Science of the History Human of regions westernmost the in use in the Sahara in the north and rain the north the in Sahara the tools no later than 30,000 years ago. years 30,000 tools no later than hand ax, had been replaced by been had acom ax, hand to make stonehumans tools remained need to make radical changes to tool changes to make radical need making techniques. making modern-day Senegal were still using weremodern-day Senegal still direction of Eleanor Scerri, Research Research of Eleanor Scerri, direction of investigations carried outof investigations under carried the around 11,000 ago. years reason One www.mpg.de/16034177 www.mpg.de/16237767 ------

ILLUSTRATION: HENNING BRUER My neighborhood, the prime numbers

At the Max Planck Institute for Mathematics, Peter Scholze uses geometric methods to study the properties of integers.

With the “perfectoid spaces”, he discovered a new class of geometric The Max Planck Foundation has sup ported structures and problems in number the Max Planck Society for more than theory could be solved. We support ten years by providing targeted funding his research because the intellectual for top-level innovative and cutting-edge adventures and accomplishments research at the more than 80 institutes, of pure mathematics are an in- enabling breakthroughs in frontier science. dispensable base for our life in the As a patron, you can make a crucial 21st century. difference by creating additional scope to keep this research ahead of the curve in the international scientific competition. Join us! ANZEIGE Max-Planck-Foundation Deutsche Bank IBAN DE46 7007 0010 0195 3306 00

www.maxplanckfoundation.org A CUSTODIAN IN THE TIME OF CORONA

The fight against COVID-19 appears to be taking place mainly at a national level, while the World Health Organization (WHO) has repeatedly been the subject of criticism. However, according to Lauren Tonti and Pedro Villarreal, the role of the WHO is often underestimated. They explain from a legal point of view 18 what action the organization is taking during the pandemic, and where there is a need for reform.

A global challenge like the COVID-19 pandemic surpasses any single state’s capacity to cope with its impact, no matter how powerful that state may be. Due to sovereignty considerations, devising and implementing a global response is a task that can only be undertaken through international cooperation. Since fighting a pandemic is a matter of concern for the international community as a whole, wouldn’t it be ideal to have an institu­ tion with both technical know-how and the capacity to act beyond a strictly national purview?

The World Health Organization (WHO) is in a privileged position to act as such an institution. To date, it has played a central role in the COVID-19 pandemic, and has fulfilled a variety of functions stemming from its powers and responsibilities enshrined in a series of international legal instruments. At the same time, the WHO faces criticism of and formal inquiries into its early-stage pandemic management, with questions being asked as to whether something could, and should have been done differently.

Legal research can contribute to addressing a series of questions in this regard. First, the WHO’s functions and powers are enshrined in existing instruments of international law. Identifying the core problems deriving

Max Planck Research · 4 | 2020 VIEW POINT

LAUREN TONTI & PEDRO VILLARREAL

19

Pedro Villarreal is a Senior Research Fellow at the Max ILLUSTRATIONS: SOPHIE KETTERER FOR MPG Planck Institute for Compara- tive Public Law and Interna- tional Law in Heidelberg. He received a university prize for the best work in legal and social sciences for his dissertation at the National Autonomous University of Mexico on the legal aspects of the global response to the H1N1 flu pandemic. Among other topics, Villarreal is currently researching the right Lauren Tonti is a doctoral to health with regards to the researcher at the Max Planck work of the WHO. Institute for Social Law and Social Policy in Munich. She completed her Masters in Public Health at Harvard University. Previously, she studied law at Case Western Reserve University in the U.S. and the Université Paris-Dauphine. The focus of her research is health law, particularly legal issues surrounding telemedicine.

Max Planck Research · 4 | 2020 from the legal framework is necessary in order to adjust the international community’s expectations as to what the WHO can and should do. After the first step, legal research can also help address several normative questions: What should the organization do differently? Which of these actions requires legal reforms? And more generally, how can the interna­ tional community better prepare for the next pandemic? With these ques­ tions in mind, we can explore the roles that the WHO has played during the COVID-19 pandemic based on its existing capacities. These roles include: architect, sentry, counselor, educator, coordinator, and champion of equity – and are probably more numerous than many people realize.

The WHO has long acted as the architect of preparedness. In 2005, the World Health Assembly, the governing forum of the WHO, approved the International Health Regulations, the main legal instrument to be applied in global health emergencies. These regulations are designed to prevent, contain and respond to the international spread of contagious disease, while at the same time avoiding unnecessary interference with interna­ tional travel and trade. The main goal is to minimize the global conse­ quences of contagion regarding both the impact on human health and the disruptive nature of containment measures adopted by individual states. To achieve these aims, the International Health Regulations contain com­ 20 mitments for both the WHO and the Member States. In particular, these commitments include states’ obligations to notify the WHO of events occurring in their territories that may constitute a public health emergency of international concern. Notification must occur A WARNING – within 24 hours of assessing the events. AT LEAST FOR Furthermore, the World Health Organization assumes the role of a global sentry. The WHO may investigate potential public health THOSE COUN- emergencies of international concern through the collection of data on communicable disease outbreaks provided either by TRIES THAT TAKE states or non-official sources. At the beginning of 2020, the NOTE OF THIS WHO worked with China to investigate and assess the danger posed by a novel coronavirus. The WHO is also responsible for INFORMATION sounding the global alarm, based on available epidemiological information relating to a public health event. The WHO initially identified the burgeoning global crisis as a public health emer­ gency of international concern in its declaration of SARS-CoV-19 (the virus that causes COVID-19) on January 30, 2020. The WHO later declared COVID-19 a pandemic on March 11, 2020. These alerts gave countries an initial warning of the looming pandemic, at least to those who paid attention.

The WHO also acts as an adviser and teacher. The WHO’s role in pan­ demic preparedness and response consists of more than just legal obliga­

Max Planck Research · 4 | 2020 VIEW POINT

tions. Even though it cannot issue orders to its Member States in the same way that national health authorities can issue directives to their own popu­ lations, both the Constitution of the WHO and the International Health Regulations direct the WHO to issue guidelines on the best measures for disease control. Through this function, the organization deploys its decades-long expertise as the authority on matters of global health. In this capacity, the WHO counterbalances the rampant ALTHOUGH THE “infodemic” that is currently raging. By offering guidance and educational materials to both national authorities and the general RECOMMENDA- public, the WHO can offset the spread of disinformation by TIONS ARE NOT sharing the best available, factual information. BINDING, THEY ARE In accordance with its mandate, the WHO has issued technical guidance on a wide range of COVID-19-related topics, from clini­ INCORPORATED cal care to therapeutics and from diagnostics to travel guidelines. While these are based on non-mandatory recommendations for INTO NATIONAL states, they are nevertheless often referenced in national health REGULATIONS authorities’ decisions. As the scientific community learned more about the novel virus, the WHO either updated COVID-19 recommendations accordingly (e.g. regarding face-mask usage) or even superseded them (e.g. by discouraging travel restrictions). Several factors may have induced the mixed reception of the WHO’s 21 guidance, including an initial lack of information on a new pathogen, a lack of scientific community consensus, or perhaps even an inadequate the WHO assessment of the numerous factors involved in healthcare service provision. The accuracy of the WHO’s guidelines may be heavily contested and controversial. It is a testament to the weight of such recommendations, since faulty guidance may have adverse consequences when implemented.

The WHO also acts as a coordinator. With personal protective equipment and other necessary medical equipment in short supply, the WHO part­ nered with other agencies to establish and coordinate the COVID-19 Supply Chain System, through which parties can request diagnostic, biomedical and other vital medical supplies for expedited delivery. As a centralized organ of global health governance, the WHO has assumed a coordinating role in both fundraising and COVID research. The WHO established a special fund to raise the sums needed for critical response efforts. The fund has distributed hundreds of millions of dollars for vaccine development and commodity procurement, among other allocations. The WHO also coordinates the acceleration of research. The WHO partnered with other organizations to launch the Access to COVID-19 Tools (ACT) Accelerator, a global collaboration between public and private stakehol- ders aimed at accelerating development, production and equitable access to COVID-19 tests, treatments, and vaccines.

Max Planck Research · 4 | 2020 Finally, the WHO is committed to equity. Countering states’ default ten­ dency to prioritize their own populations, the WHO has championed a more equitable global distribution of multiple COVID-19 medical resources during the pandemic. In the competition for the allocation of such scarce resources, countries with higher financial capacities may stockpile them. By contrast, countries with lower purchasing power are neglected, thus posing the risk of being left last in the supply chain pipe­ line. In a resolution adopted at the World Health Assembly on May 19, 2020, full immunization against COVID-19 was deemed a “global public good.” This framing provides the basis for global programs and strategies aimed at finding the best solutions to the most devastating pandemic in recent history.

One of these programs is COVAX, an ACT Accelerator branch and global initiative aimed at facilitating equitable worldwide access to safe and effective COVID-19 vaccines. While the WHO devised the fair allocation scheme, other bodies (e.g. Gavi, the Vaccines Alliance, a public-pri­ vate-partnership, as well as UNICEF) will undertake the actual vaccine distribution. Based on the goal of simultaneous distribution for a propor­ tion of countries’ populations, the COVAX initiative represents the most equitable mechanism for global allocation of a vaccine against COVID-19 22 to date. Participating states are divided into two major groups: a self-fi­ nanced group, whose members pay per dose received; and a funded group, whose members obtain vaccines through developmental aid instru­ ments (i.e. on a concessional basis).

However, COVAX faces two major limitations. First, the initiative requires an active willingness to participate by both states and pharmaceutical companies. When the first vaccine, developed by Pfizer/Biontech, received regulatory approval in several countries, it was not in the COVAX Initiative’s portfolio. The company joined the Initiative only after the pur­ chase and distribution of its vaccine in multiple high-income countries was well underway. Second, financed states’ vaccine purchases are fully dependent on donations from either international financial institutions or philanthropic non-state actors. It is a reflection of the persistent limits of solidarity when it is most needed.

Just as installing a sprinkler system during a blazing inferno is problematic, so too is implementing preventive measures at the height of a global pandemic. However, the WHO and its Member States can make the best of the momentum triggered by COVID-19 and incorporate the wisdom learned from this experience into reforms for an improved pandemic response.

Max Planck Research · 4 | 2020 VIEW POINT

First, the Member States should use the roadmap provided in the Interna­ tional Health Regulations. This roadmap is fully dependent on states’ adherence to its provisions in order to function properly. When the pan­ demic first struck, only a small group of Member States was complying with the basic requirements of disease surveillance stipulated in the Inter­ national Health Regulations. States should work to improve this, while the WHO can design objective evaluation and feedback mecha­ nisms for International Health Regulations metrics. IN LIGHT OF THE Second, stakeholders at all levels of governance can place CRITICISM, THE best-available evidence at the core of decision-making. Evi­ dence-based decision-making largely depends on information WHO SHOULD sharing. Hence, effective and reliable local, national, and inter- BECOME MORE state surveillance and information sharing systems can prove decisive in battles against future outbreaks. TRANSPARENT Third, states can demonstrate their commitment by dedicating WITH REGARD TO financial resources to public health emergency preparedness.

THE WAY DECI- Fourth, in the face of criticism of its decision-making, the WHO SIONS ARE MADE should work to increase public transparency and cooperation with bodies working on global health security. Both the WHO 23 and the Member States can optimize communication with one another. The WHO should find clearer ways to convey to the world the severity of a health threat, so that states may take necessary precautions. The sometimes inconsistent use of technical terms by the WHO’s officials is not constructive in such an endeavor. For instance, the unclear defini­ tion of a ‘pandemic’ led to mixed messaging from the WHO Director-Gene- ral regarding the exact nature of COVID-19’s spread in early 2020.

Fifth, the WHO can bolster the International Health Regulations by harmo­ nizing them with other global health security instruments. The WHO, in conjunction with the Member States voting in the World Health Assembly, can also embrace necessary reforms to make it a dynamic governance structure in tune with contemporary challenges. In so doing, the WHO can increase confidence in the overall framework. Finally, the WHO and the Member States can strive for consensus regarding the support and mechanisms needed by institutions in order to protect global public health.

Both the WHO and its Member States can learn from COVID-19’s chal­ lenges to protect populations from subsequent pandemics. These bodies and their leaders should treat pandemics as seriously as other security threats, and mobilize global governance infrastructure in order to prevent and prepare for public health emergencies.

Max Planck Research · 4 | 2020 FOCUS

ONE WAY OR ANOTHER 24 | We cultured humans WE 30 | Midwife of the galactic zoo 38 | Diversity in the leafy forest CULTURED HUMANS

24 ILLUSTRATION: REGINA MARIA MÖLLER, BILD-KUNST VG BONN. WWW.REGINAMOELLER.NET

Max Planck Research · 4 | 2020 FOCUS

WE CULTURED HUMANS

TEXT: STEFANIE REINBERGER

25

In many ways, our thoughts and actions are influenced by our social background, which is why people’s behavior varies so widely between different countries throughout the world. The psychologist Daniel Haun, Director at the Max Planck Institute for Evolutionary Anthropology in Leipzig, has made cultural diversity a focal topic of his research. His theory is that we cannot ultimately determine what it is that makes us human until we are aware of what we have in common and what our differences are.

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A person who works harder ultimately gets to rake in more of a well-deserved reward. That’s only fair, isn’t it? “You have to ask That’s how children as young as three see it – at least in our part of the world. They apportion rewards accor- yourself what validity ding to effort, and prefer to share with other playmates who have been more actively involved. This has been studies have that focus confirmed time and again by experiments. If you think that the result of these studies is all too logical, you solely on U.S. college probably come from Germany, or you at least live in an industrial society. However, what might seem perfectly students.” natural to us does not necessarily apply to people else- where in the world. DANIEL HAUN Culture influences our perception and actions. And ­everything that we now know indicates that the ­distinct, diverse culture of Homo sapiens is unique compared to those of other species. But what enables the children of the same age in Germany. Instead, they people to develop such broad cultural diversity in the shared the reward about evenly, with the more success- first place? What are the foundations of human cogni- ful child getting one block more. However, the re- tion that make us stand out from other species and searchers were astonished by the approach taken by the make us human? These are the big questions that the third group: Kenyan children from the Samburu peo- Director of the Max Planck Institute for Evolutionary ple, a society with a strict age-based hierarchy. “The Anthropology in Leipzig, Daniel Haun, has been children chose a wide range of different distribution ­investigating, and which he has been studying since models, up to and including one version in which the setting up the Department of Comparative Psychology more successful angler was left with practically not- there in 2019. hing,” Daniel Haun, who was involved in the study, ex- plains. “We were completely unable to relate to the 26 principles behind this approach.” One important con- Our culture determines clusion was that our concept of fairness is also influ- what we regard as being fair enced by our culture. Another example that is almost even more striking is the “In different cultures, people have very different attitudes Müller-Lyer Illusion, a well-known optical illusion. towards social relations, social emotions, color, num- The illusion consists of lines that have arrows in the bers and space,” he explains. “It’s remarkable when form of open angles at each end. Some of the tips point you meet groups of people who see things that you inwards and others outwards. Depending on how they don’t, who notice things that you are unable to notice are arranged, we unfailingly perceive the lines as being

yourself, or who regularly do things that you wouldn’t longer or shorter – although in fact, they are all of equal GRAPHIC: GCO FIBONACCI/WIKIPEDIA FROM 3.0) BY-SA (CC do.” In one study, a research team from several Max Planck Institutes and the University of Jena observed just how differently people behave in certain situations. They asked children aged 4 to 11 to fish for toy blocks in a fishing game. In each case, two children fished for the blocks from two different containers. The ma- gnetic blocks of one child had been manipulated, ma- king it impossible to pull out some of the “fish”. After- wards, the two children received small prizes accor- ding to the total number of blocks they had both caught, and were asked to share the reward between them. As Partial illusion: in the expected, the German children strictly apportioned western world in the prizes according to performance, with each child particular, humans getting the same share of the reward as the number of incorrectly perceive the fish they had caught. There was no discussion. lines between the arrows as being of different Young members of the ≠Akhoe Hai//om, an egalitarian lengths. People from other cultures in other community of hunter-gatherers in Namibia, also di- parts of the world are not vided up the rewards according to the number of fish deceived by this optical caught. However, they did so in a far less clear way than illusion at all.

Max Planck Research · 4 | 2020 FOCUS PHOTO: ANTHROPOLOGY DANIEL FOR EVOLUTIONARY HAUN/MPI

A long way from western norms: a girl from the ≠Akhoe Hai//om people in Namibia 27 takes part in a psychological study.

length. However, this visual phenomenon doesn’t work to develop cultural diversity in the first place, we have everywhere in the world. As Haun explains: “It already to understand the relevant fundamental development emerged back in the 1960s that there are societies in processes from which cultural variation arises. We different parts of the world where people perceive the compare these with the development of other species lines to be of equal length when they are (truly) of equal and look for reasons why our unique human cultural length – but it’s impossible for us to see it.” Both examp- evolution was made possible.” les underline the fact that the way in which our cogni- tive abilities are expressed depends strongly on the en- Here, it’s not enough simply to compare people from dif- vironment in which we live – particularly our society ferent cultures. The age of the test subjects, or the de- and its culture. “You then have to ask yourself what mographic composition of the population, also plays a general validity psychological experiments have that role. “Age is a very important factor for social learning,” are conducted only with psychology students from the says Haun. What he means by this is a form of learning U.S. as subjects, or developmental psychology studies in which we observe the way in which other people do that observe only European babies and young infants,” certain things. This approach is used in all human cul- says Haun. At any rate, it is not always possible to make tures. generalized statements about human perception and thought processes at this level. But do children orient themselves to others in the same way all over the world? And what criteria do they use However, Haun is not interested in challenging the psy- when choosing role models? Haun investigated this chological research that has been conducted to date. question alongside an international team. The study For him, cultural differences are a primary key to an- involved children from seven different cultural groups, swering the questions that he is examining in his re- from Germany, Brazil and Indonesia, as well as the search. “In order to comprehend what enables people BaAka people in the Central African Republic, the

Max Planck Research · 4 | 2020 FOCUS PHOTO: KINDER-UNI JENA

On an educational mission: for Daniel Haun, it is important to raise awareness of the diversity among humans, as well as to point 28 out our special characteristics. He also presents this topic at the Kinder-Uni (children’s university) in Jena.

“We’re running

≠Akhoe Hai//om in Namibia, the Samburu in Kenya out of time: and the Bemba in Zambia. The study was centered around a simple dispenser – a box with three different globalization is colored tubes. If you put a ball in one of the tubes, a small toy falls out at the bottom. Children aged be- blurring the tween 4 and 14 were then allowed to watch videos in which children of the same age showed them how the differences box works. In each case, three children demonstrated how to work the box using one and the same tube. between cultures.” Then, one other child demonstrated the procedure on another tube three times in succession. The result was always the same: the dispenser ejected one toy for DANIEL HAUN every ball thrown in. Then, the children who watched the videos were each given a ball and had just one attempt at also getting a reward. overall, across all cultures, the degree to which the children were inclined to adopt the majority approach The extent to which the children based their actions on changed proportionately depending on their age,” what they had seen in the film varied very widely Haun explains. Overall, both the youngest and oldest ­depending on their cultural background. However, children in all groups most frequently emulated the be- there were also some fascinating things that they had havior of the three role models instead of following the in common: “Although the cultural variation was high repeated demonstration given by the individual child.

Max Planck Research · 4 | 2020 FOCUS

“Results like these show us how important it is not only and Machine Learning are important topics for psy- to observe individual children in different ­situations or chologists. The aim is to use both in the future to auto- performing certain tasks,” Haun continues. “In fact, matically evaluate psychological studies in order to be we need long-term development studies, from birth able to study larger numbers of test subjects – perhaps until they reach adulthood.” In this way, he says, reli- even in their normal everyday lives, away from per- able data can be obtained that make it possible to reach forming tasks in a study environment. A large number a conclusion as to which cultural factors ­influence of test subjects is crucial in order to ultimately under- which developmental processes – and for which deve- stand the connection between individual development, lopmental processes there are no variations at all. social environment and geographical surroundings among humans and apes. And all this ultimately not only applies to studies about humans. To find out which cognitive abilities and ways Despite all the challenges, Daniel Haun’s team continues of behaving are uniquely human, we also need to draw to work to make contacts and establish research units comparisons between ourselves and our closest rela- in different parts of the world that will remain firmly tives, chimpanzees and other apes. Here, too, behavior connected to his Department over a long period of varies between different groups. “This is not so clearly time. This is an important prerequisite for being able evident as it is for humans, and the extent of the varia- to work continuously with specific cultural groups. For tion also depends strongly on the composition of the the scientists in Leipzig, it is also important to work population,” Haun explains. “However, there is no closely in cooperation with people who are native to the doubt that not all chimpanzees are the same, and we various study sites, because as locals they are familiar have to take a much closer look before comparing the with the language, culture and ways of behavior in their behavior and cognitive abilities of non-human pri- home countries. “Cooperation with the people on the mates with those of humans.” ground is essential for the success of this project. That’s the only way that we can ensure that studies are Haun’s research project involves countless behavioral culturally appropriate and are interculturally compa- studies, observations in a wide range of different hu- rable.” man cultures and in various groups of apes – with the largest possible number of test subjects 29 and ideally over long periods of time. It The aim is not to be judgmental is quite clear that no single research ca- reer will be able to cover all this work. The team is also involved in the Many Primates project, a SUMMARY And there’s one more problem: “We’re scientific consortium researching apes, in order to cre- running out of time,” says Haun. “The ate a stable network of zoos and rescue centers. “The The culture in which we live increase in globalization is blurring the time when individual groups conducted their own re- not only determines our values and preferences, but also the differences between cultures, while at search has passed. Science is a team sport now. For our fundamental characteristics of the same time, non-human primates are research area in particular, it is essential that we colla- our being, such as our concept dying out because their habitats are be- borate with other researchers,” Haun explains. With of what is fair and our visual ing lost.” The lower the degree of vari- this in mind, he also plans to invite other psychology perception. ability on the planet, the more difficult it research groups in the future, to examine their areas of will become to filter out similarities that study together with his team with a focus on compara- Using psychological tests in different cultures and among go beyond cultural background – the es- tive cultural psychology. “As Max Planck researchers, different ages, researchers are sence of what it means to be human. we have a particular responsibility to create added working to document what “Perhaps two or three generations of re- value for the scientific community,” he says. makes us different from each searchers will be able to move this proj- other, and what we have in ect forward. After that, it may be too He also takes responsibility for another aspect of his work. common. late.” One thing is very important for him: “When we inves- Comparisons with the way tigate cognitive differences between individual cul- apes behave are also required The corona crisis isn’t improving the si- tures, we must never judge them in the process.” In the in order to filter out what is tuation. “Field research is almost impos- past, a lot of information has been misused for political specifically human. sible under the current conditions,” purposes. For Haun, one thing is clear: cognitive abili- Haun says. It’s quite clear that the pre- ties in humans are expressed in different ways. They sent situation is hard for him to bear – can be fascinatingly diverse, surprising, and some- when there are so many exciting cultures times entirely incomprehensible from our own per- out there in the world and so many interesting issues spective – but they are always determined by the influ- that he wants to explore. Even so, the Max Planck Di- ences and demands of the individual living environ- rector has plenty to keep him occupied. He is using the ment. Here, there is no such thing as better or worse. time to establish new methods. Artificial Intelligence www.mpg.de/podcasts/vielfalt (in German)

Max Planck Research · 4 | 2020 FOCUS

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A miniature milky way: approximately 40 million light-years away, UGC 5340 is classified as a dwarf galaxy. Dwarf galaxies exist in a variety of forms – elliptical, spheroidal, spiral, or irregular – and originate in small halos of dark matter. Dwarf galaxies contain the oldest known stars.

Max Planck Research · 4 | 2020 FOCUS

MIDWIFE OF THE GALACTIC ZOO

TEXT: THOMAS BÜHRKE

31 IMAGE: NASA, TEAM & LEGUS ESA

Stars cluster in galaxies of dramatically different shapes and sizes: elliptical galaxies, spheroidal galaxies, lenticular galaxies, spiral galaxies, and occasionally even irregular galaxies. Nadine Neumayer at the Max Planck Institute for Astronomy in Heidelberg and Ralf Bender at the Max Planck Institute for Extraterrestrial Physics in Garching investigate the reasons for this diversity. They have already identified one crucial factor: dark matter.

Max Planck Research · 4 | 2020 FOCUS

Nature has bestowed an overwhelming diversity upon our planet. The sheer resourcefulness of the plant and animal world is seemingly inexhaustible. When scien- tists first started to explore this diversity, their first step was always to systematize it. Hence, the Swedish naturalist Carl von Linné established the principles of modern botany and zoology in the 18th century by clas- sifying organisms.

In the last century, astronomers have likewise discovered that galaxies can come in an array of shapes and sizes. In this case, it was Edwin Hubble in the mid-1920s who systematized them. The “Hubble tuning fork dia- gram” classified elliptical galaxies according to their ellipticity. The series of elliptical galaxies along the di- PHOTO: PETER FRIEDRICH agram branches off into two arms: spiral galaxies with a compact bulge along the upper branch and galaxies with a central bar on the lower branch. From left to right, Hubble classified the galaxies as early and late types, although he didn’t necessarily regard this as a chronological evolution.

The idea of an evolutionary relationship between the two 32 basic forms emerged later: “When I first started my re- search in the mid-1980s, many people were convinced that giant elliptical galaxies form when two spirals col- lide and merge,” says Ralf Bender, who has been Di- rector at the Max Planck Institute for Extraterrestrial Physics in Garching since 2002. Present-day astrono- mers do indeed observe such collisions in the universe, and computer simulations confirm the theory pro- Pursuing the evolution of galaxies: posed at the time. Ralf Bender studies the formation and evolution of galaxies. Bender is a Director of the Max Planck Institute for Extraterrestrial Physics and observes Collision with the ancient, luminous star clusters, which are thought to be the forerunners of today’s Andromeda Galaxy giant ellipticals.

In several billion years, our Milky Way will likewise col- lide with the Andromeda Galaxy, currently about 2.5 million light years away, and swirl into an elliptical gal- axy. “However, this process can only have created the small and medium-sized ellipticals, not the very large ones,” says Bender. Bender and his team have long been especially focused on determining the age of gal- axies, and their work has cast doubt on the existing model. Just how do you go about determining the age of a galaxy? The current theory is that the Big Bang only produced light elements, almost exclusively hy- “The size and density drogen and helium. The heavier elements first had to bake in the hot interior of stars in fusion reactions of the halos were key.” known as “stellar nucleosynthesis” and they were then released in stellar explosions. They dispersed in space and formed the raw material for the next generation of RALF BENDER

Max Planck Research · 4 | 2020 IMAGES: ESO (LEFT); ESA/HUBBLE & NASA (RIGHT) Surprising kinship: spiral galaxies (left) have long been recognized by astronomers as a conventional galaxy aconventional galaxy as by astronomers (left) have recognized long galaxies been spiral kinship: Surprising that globular clusters (right) also belong to this family – as the core regions of galaxies. former dwarf regions core clusters (right) the globular –as that family belong to this also shape; viewed from outside, our Milky Way is similar in appearance. What is new, is What however, appearance. Way in outside, viewed shape; from Milky our similar is realization the is With this in mind, Ralf Bender observed luminous ellip Ralf mind, in With this lion years. After this early vigorouslion this After years. baby star boom, discovered that these giant galaxies formed about two galaxies giant discovered these that five billion years old. One theoretical analysis suggests old. suggests years billion analysis five theoretical One back into whenfar past, the universe the just was under tical galaxies we today, see galaxies tical therefore, primarily contain and now then from ious elements and galaxies the in to us. other reach In words, were scientists the looking whose years billion light nine taken had galaxies tical evolution of cosmic course the laterthe in it born was to generation. The more heavy elements contains, astar ellipticals, which contain up to a trillion stars. Bender stars. which upellipticals, contain to atrillion forerunners of the are today’s galaxies these that giant births declined and soon ceased altogether. ceased and declined soon births The ellip Big the after years Bang,billion majority the of their and, younger from our the perspective, it is. and his colleagues measured the abundance the of var the measured colleagues and his stars having been born within a period of aperiod just one within bil born having been stars generation from progressed development This stars. Max PlanckResearch FOCUS ·4 | 2020 - - - - Spiral galaxies like our Milky Way like our Milky Spiral galaxies have developed quite Scientists had long had Scientists doubted whether such huge accumu Germany, have discovered that a disk-shaped galaxy Max PlanckMax Institute for Astronomy Heidelberg, in Furthermore, even the largest known spiral galaxies Furthermore, galaxies even known spiral largest the lations of stars could havelations of stars formed early the universe, in didn’t galaxies liptical evolve of predecessors from the however, conceivable they were that by created the stars. for homes differently. They have developed over a longer period from today’s but apes, from more evolved el hominids, the spirals we today,” spirals see the Bender. Ralf explains “It is, “In muchtical. way didn’t same the humans that evolve of time, and new stars continueof and new them. time, to stars form within older They retirement stars. could as regarded be but Scientists this. recent at discoveries the confirm merging of very large and dense star clusters.” of and densemerging star very large are notare massive enough to merge ellip and form agiant - - - 33 FOCUS GRAPHIC: NASA, ESA, M. KORNMESSER

34

Cosmic tuning fork: the astronomer Edwin Hubble was the first to classify galaxies based on their form – from spheroidal to elliptical (top), spiral (top right), and barred spirals (bottom right). However, this scheme does not represent an evolutionary sequence for galaxies.

had already reached the impressive mass of 70 billion solar masses a mere 1.5 billion years after the Big Bang. This puts it in the size range of our Milky Way. And an international team recently used the Atacama Large Millimeter/submillimeter Array (ALMA) operated by the European Southern Observatory (ESO) to discover approximately one hundred large, highly evolved ga­ laxies dating from one to one-and-a-half billion years after the Big Bang. All these observations are forcing cosmologists to reconsider their models. The standard theory is that initially the universe was solely com- “We’ve identified three posed of a large number of small star accumulations, which then collided, merged, and slowly grew. This populations of different “hierarchical” scenario would mean that large galaxies could only exist in a later phase of the universe. But ages.” this has been definitively disproved. What then deter- mines which galaxy types arise? Dark matter is the an- swer. NADINE NEUMAYER

Max Planck Research · 4 | 2020 FOCUS

Andromeda Galaxy and a few other stellar systems, it Dark matter is matter forms the Local Group, whose collective average den- that only interacts with sity is very low.” Large, dense halos, on the other hand, formed regions like the Coma cluster, with its two giant “ordinary” matter through elliptical galaxies. gravitation While Ralf Bender focuses on the most massive galaxies, Nadine Neumayer, who heads a Lise Meitner group at After the Big Bang 13.8 billion years ago, the primordial the Max Planck Institute for Astronomy, is investigat- gas consisting mainly of hydrogen and helium on the ing smaller “dwarf” galaxies. For a long time, these one hand, and dark matter on the other, formed a fairly were regarded as the “gray mice” of the universe. They evenly distributed nebula. Researchers still don’t know can also be ellipsoidal, spheroidal, spiral, and irregular exactly what dark matter is, but at present everything in form, but because of their dimness, only the closest points to the existence of an unknown form of elemen- ones can be observed. At present, researchers know of tary particle that makes itself felt solely 24 dwarf galaxies orbiting our through its gravitational effects. Most Milky Way. notably, its particles exert no repulsive electrical forces on each other. This SUMMARY Their formation is consistent with was crucial at the beginning of the uni- the dark matter scenario: large gala­ verse; gravity tended to condense this Recent observations and xies were formed in the large halos, mixture of matter into large clumps. computer simulations while in contrast only small However, the hydrogen and helium increasingly support the amounts of matter flowed into the atomic nuclei were electrically charged scenario that large clouds small ones, subsequently condens- (halos) of dark matter and repelled each other. This pre- existed after the Big Bang ing to form stars. Depending on the vented the hot gas from compressing. that acted as gravity traps, density of the halos, small ones col- Dark matter particles, on the other within which galaxies of all lided into large ones and dispersed 35 hand, exert no electrical forces and sizes formed. or remained as satellites. “Because clumped together to form huge clouds the flow of matter into these small Huge elliptical galaxies also and long filaments. Termed “dark mat- formed relatively soon after halos dwindled very quickly, the ter halos” by astronomers, these acted the Big Bang. supply for new stars likewise dimin- like gravity traps, sucking in the nor- ished,” Neumayer says. “That’s mal gas particles. The particles accu- Dwarf galaxies can plunge why we tend to find the oldest stars mulated like marbles in a trough and through large galaxies, in dwarf galaxies, as evidenced by condensed into the first stars and gal- stripping the dwarfs of their their elemental abundance.” outer, lightly bound stars. axies. What remains is a compact globular cluster, similar to The connection between dwarf ga­ “The size and density of these halos, as that at the center of our laxies and globular clusters is a new well as their distribution, were critical Milky Way. discovery. The latter also orbit large in determining the diversity of galaxy galaxies; some 150 of these clusters types,” says Ralf Bender. The denser a are currently known to orbit the halo was, the faster it collapsed, and the Milky Way. However, they are not faster it dragged the gas with it. If, in this turbulent ini- considered to be galaxies. They were once believed to tial phase, several halos merged together, huge galaxies be the oldest objects in the universe, in which no stars could form, rapidly leading to the generation of a huge have formed for a long time. But this picture is chan­ number of stars. This was how elliptical galaxies ging. One case in point is a dwarf galaxy in the constel- formed soon after the Big Bang. Today, we see the stars lation Sagittarius. in these galaxies orbiting around the center on all pos- sible trajectories. Spiral galaxies, on the other hand, Discovered only in the 1990s, this dwarf galaxy in Sagit- take many billions of years to form and maintain their tarius is located outside the plane of the disk of our uniform structure. “Spiral galaxies need time in isola- Milky Way. Astronomers at the Max Planck Institute tion without suffering major collisions,” says Bender. in Heidelberg have recently discovered that it pos- sesses a long tail of stars. This developed because the Hence, spiral galaxies were formed in halos that were so dwarf galaxy’s orbit around the Milky Way is nearly widely dispersed that they didn’t impinge on each perpendicular to the plane of the disk. Over the past other. “You can still see this in our Milky Way today,” billions of years, it has crossed the disk several times, says the Max Planck researcher. “Together with the “stripping” stars from its outer region and leaving only

Max Planck Research · 4 | 2020 FOCUS

those bound more tightly within its central region. Es- Neumayer has measured the elemental abundance of pecially significant is the fact that the core of the Sag- the stars in this cluster and has deduced that most were ittarius dwarf galaxy is a globular cluster. The cluster’s formed more than eight billion years ago. However, it former designation, Messier 54, is indicative that it was also contains a young generation, which was formed discovered more than 200 years ago, but the dwarf ga­ approximately one billion years ago within a compara- laxy surrounding it remained unidentified. tively short period of time.

In a departure from the previous standard explanation for Nadine Neumayer is investigating whether this cluster globular clusters, a recent analysis of the elemental represents a merger of high-mass globular clusters that abundances within Messier 54 revealed its eventful have gravitated towards the center and subsequently history. “We have identified three stellar populations formed additional stars. This research also sheds light of different ages, approximately 2.2, 4.3, and 12.2 bil- on how supermassive black holes formed. The latest lion years old,” says Nadine Neumayer. These ages, in research undertaken by the Heidelberg astronomers combination with the calculated stellar orbits, have reveals that black holes containing up to ten billion so- yielded the following explanation. The oldest of these lar masses existed as early as one to two billion years stars formed less than two billion years after the Big after the Big Bang. One of the most interesting ques- Bang. The younger stars may have formed when the tions in cosmology today is how these giants were able dwarf galaxy crossed the plane of the Milky Way, to grow so rapidly to this gigantic size and what influ- during which it accumulated gas from which the new ence they had on the evolution of galaxies. One hy- stars formed. After further passages through the pothesis is that, early on, intermediate-mass black Milky Way, the dwarf galaxy will eventually shed its entire mantle, leaving only the globular cluster. “We suspect this is very similar to what happened to the globular cluster Omega Centauri,” Neumayer says. Our galaxy’s largest globular cluster, Omega Centauri has a mass of 3.5 million suns and can also look back on 36 a complex evolutionary history, and also recently re- vealed a tail of barely visible stripped-off stars.

Invisible giant in the center of a dense star cluster

The question whether all globular clusters are in fact cores of former dwarf galaxies is at present impossible to answer. But they are definitely a source of surprises, as was demonstrated just a few years ago. An interna- tional team that included Nadine Neumayer observed a dwarf galaxy located near the center of the large ellip- tical galaxy Messier 60. This ultra-compact system contains more than a hundred million stars, all within a relatively small volume measuring 160 light-years in diameter. At its center, however, the researchers dis- covered a black hole of 21 million solar masses. No other galaxy contains a central object that accounts for such a large fraction of its total mass. “Interestingly, we find a similar mass ratio at the center of the Milky Way,” says the Max Planck astronomer.

At the center of our galaxy resides a black hole of around four million solar masses. Reinhard Genzel of the Max Research in the library: Planck Institute for Extraterrestrial Physics and An- Nadine Neumayer (right) drea Ghez from the U.S. were awarded this year’s No- heads a Lise Meitner Group at the Max Planck Institute for bel Prize in Physics for their detailed analysis of this Astronomy. Together with her black hole. This dark giant resides in the middle of an team, she studies dwarf ultra-compact star cluster of 25 million stars. Nadine galaxies and star clusters.

Max Planck Research · 4 | 2020 Neumayer is pinning her hopes on an instrument called Neumayer called her instrument hopes on pinning is an “Intermediate-mass black holes of this type should black holes ex type “Intermediate-mass of this This mega-telescope will usher anew in for era mega-telescope will science, This MICADO, which will yield hyper-accurate images MICADO, images yield which hyper-accurate will holes existed, comprising perhaps tens of of thousands galaxies of this kind have kind definitively of been this identified. galaxies tions from the Max Planck Max from the Institutetions for Astronomy. Physicstute major for with contribu Extraterrestrial led byPlanck Max the consortium Insti international tremely Telescope. Large It developed being is an in ist at center the of globular clusters,” says Nadine Neu them.” black holes and by sucking upfar, So gas. however, no mayer, “but unable are telescopes our current to detect as well as for Ralf Bender well foras as and Nadine Neumayer. Ralf and will be Earth’s be telescope ESO’s –the and will largest Ex solar masses, and that they grew by they other grew with and that merging masses, solar www.mpg.de/podcasts/vielfalt (in www.mpg.de/podcasts/vielfalt German) Max Planck Research FOCUS ·4 | 2020 - - - - - About 27 of universe percent the gravitation. Researchers are still still are Researchers gravitation. include axions, WIMPS (weakly WIMPS include axions, unable to determine the nature nature the to determine unable types of matter, hot such gas as types Halos are composed of various composed are Halos interacting massive particles), A roughly spherical region in in region A roughly spherical is made up made is of invisible matter (X-ray halos) matter. or dark which a galaxy is embedded. is which agalaxy that only interacts through through only interacts that of this matter. of this Candidates and sterile neutrinos. sterile and DARK MATTER DARK GLOSSARY HALO

PHOTO: JÜRGEN LECHER FOR MPG 37 FOCUS

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Over the course of evolution, plants have developed a wide array of leaf shapes. Every shape is the result of adaptation to the environment, which is why the way that leaves look is no real indication of whether or not plants are related. Even closely related species may have different leaves, in some cases as a way of adapting to different environmental conditions.

Max Planck Research · 4 | 2020 FOCUS

DIVERSITY IN THE LEAFY FOREST

TEXT: TIM SCHRÖDER

39 PHOTO: ADOBESTOCK PHOTO:

Lanceolate, ovate, elliptical, entire, serrated, and uni- or multi-pinnate – there are numerous names to describe the variety of leaf morphol­ ogy. But how does this diversity come about? Miltos Tsiantis from the Max Planck Institute for Plant Breeding Research in Cologne and his team are looking for genes that control leaf growth. They have already found one central regulatory element.

Max Planck Research · 4 | 2020 FOCUS PHOTO: FRANK VINKEN FOR MPG

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In botanical guides, the lists of leaf morphology descrip- the fruit fly for botanists. Thousands of researchers tions can fill several pages. These classifications dis- have analyzed the plant’s genetic material, metabolism, tinguish between simple leaves with continuous leaf and development. Many of its genes are therefore rela- surfaces and outlines, and so-called compound leaves, tively well studied. which feature leaf surfaces consisting of separate units called leaflets. The vast range of morphology is well re- But studying Arabidopsis thaliana alone cannot tell searched, because the shape of a leaf is an important Tsiantis how various leaf forms evolve. For this, he is characteristic for the identification of plants and be- researching its close relative, Cardamine hirsuta, a de- cause leaves are the sites of fixing atmospheric carbon licate plant with white flowers that also belongs to the into sugars in a process known as photosynthesis. But Brassicaceae family and that the Cologne research the origin of different leaf forms and why even leaves of group has used to develop a model system for compa- closely related species can look very different remained rative studies in plant genes. Although the two plants a mystery until quite recently. are closely related, their leaves have different shapes. Those of Arabidopsis thaliana resemble round spinach Together with his team at the Max Planck Institute in Co- leaves, which have a few delicate serrations at the edge. logne, Miltos Tsiantis is analyzing when and where Cardamine hirsuta, on the other hand, has pinnate genes that are important for shape development are leaves (i.e., one leaf is divided into several pinnae or switched on and off as a leaf bud slowly takes shape. leaflets). A larger, roundish leaflet grows at the tip of He’s utilizing modern technologies to do so, including the petiole with small pinnate leaves on delicate stalks advanced microscopy methodologies that allow scien- on the left and right below it. Tsiantis cultivates Car- tists to zoom deep into leaf tissue and computer models damine hirsuta in the greenhouses at the MPI in Co- to grow virtual leaves. “We want to find out which logne, because he needs genetically different individu- genes make leaves of different species look the way they als for his investigations. To achieve this, he and his do. Since flowering plants typically have over twenty team treat the seeds of the plants with the chemical thousand genes, it’s a bit like searching for a needle in a ethyl methanesulfonate. This substance induces point haystack,” says Tsiantis. For many years, he has been mutations (i.e. damage to the genetic material). “This working with Arabidopsis thaliana, which is essentially helps us modify individual genes. However, the muta-

Max Planck Research · 4 | 2020 FOCUS

Exchange of ideas tions occur randomly. We can’t influence where they during the COVID occur,” says Tsiantis. But if one of the treated plants pandemic: Miltos Tsiantis, Angela Hay, develops leaves of a different shape, he and his research Neha Bhatia, team can analytically reverse engineer the process to Ziliang Hu, David pinpoint which genes have mutated and are thus re- Wilson-Sanchez und sponsible for the change in shape. Shanda Liu (from left to right). This is how Tsiantis’s former student, Huw Jenkins, has cultivated thousands of Cardamine hirsuta plants with varying leaf shapes – from curly, parsley-like leaves to elongated ones resembling lavender. Among all the plants, the group discovered one in which the leaves looked familiar – round, with fine indentations at the edges and completely without pinnate leaves. “This Cardamine hirsuta plant looked a bit like an ­Arabidopsis thaliana plant,” says Angela Hay, who also uses Cardamine hirsuta in her studies. A genetic ana- lysis showed that the chemical treatment had altered a DNA segment of Cardamine hirsuta that does not ­occur at all in Arabidopsis thaliana. The researchers had thus discovered a gene that was missing in the sim- ple leaves of Arabidopsis thaliana but that, when it is ­damaged, causes Cardamine hirsuta to develop simpli- fied leaves as well. These results were further con- firmed by using the recent breakthrough technology of genome editing, which allowed the Cologne group to induce targeted mutations in the RCO gene: and again they observed the formation of that same, simple leaf phenotype. That made it clear that this gene con- trols the shape of the leaf. Because the leaves of 41

A

Camelina Arabidopsis Myagrum Lunaria Lepidium Cardamine sativa: thaliana: perfoliatum: annua: virginicum: hirsuta: False flax Thale cress Muskweed Annual Virginian Hairy honesty peppercress bittercress

B Cardamine hirsuta: Hairy bittercress

C Rorippa aquatica: Lake cress

Aquatic form Terrestrial form Ambient temperature Light intensity INDUCES HETEROPHYLLIC IN ALTERATION AMERICAN NORTH LAKE CRESS GRAPHIC: GCO BY NAKAYAMA ET. AL. (2014). REGULATION THE OF GRAPHIC: AL. GENE KNOX-GA MODULE GCO (2014). NAKAYAMA BY ET.

Leaf diversity among crucifers: differently shaped leaves occur not only in different plant species (A) but also in the same plant depending on its age (B). Environmental conditions also influence leaf shape (C).

Max Planck Research · 4 | 2020 42 Max PlanckResearch FOCUS ·4 | 2020 under the microscope. Although microscope. under the divide. This allows the pinnae of pinnae the allows divide. This the bittercress leaves to develop. bittercress the the cells in between continue to between in cells the active (pink)active do not proliferate, cells in which the RCO which the in is gene cells A leaf bud of hairy bittercress bittercress budA leaf of hairy

IMAGES: MILTOS TSIANTIS/MPI FOR PLANT BREEDING RESEARCH FOCUS

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Young leaf bud of a genetically modified thale cress (left). The microscopic image shows the contours of the cells that have been made visible with a fluorescent protein. With the help of a computer, the cells of the same bud can be color-coded (right), and the multiplication of individual cells can be investigated.

Max Planck Research · 4 | 2020 FOCUS

Cardamine hirsuta have a less complex structure with- ancient members of the family have simple leaves. out the gene, the researchers named it “RCO” (Re- When RCO emerged from a gene duplication event duced Complexity). during the course of evolution, species such as Car- damine hirsuta or Arabidopsis lyrata (which is even Tsiantis’s team then conducted a more detailed analysis of more closely related to Arabidopsis thaliana) were able how leaves of Cardamine hirsuta develop. Using fluo- to form deeply indented or compound leaves. The rescent protein labeling, the researchers were able to gene was lost later in the phylogenetic history, so that observe under a microscope that the RCO gene is ac- Arabidopsis thaliana was able to form simple leaves. tive at certain places along the leaf edge – specifically, Since the discovery of the RCO gene, Miltos Tsiantis, in distinct bands at the base of emerging leaflets. The and his team have been studying the regulation of leaf RCO gene inhibits cell growth at these sites, while the growth even more closely. Although cells in between the RCO bands continue to grow. The Tsiantis’s work is basic research, his findings could certainly have practical relevance, for example in agriculture. “In light of climate change, knowledge SUMMARY about the development of different leaf “The RCO gene is one forms could become increasingly im- Developing Cardamine hirsuta as a model system for studying portant and contribute to the environ- plant biology helped the of our most important mentally sustainable cultivation of scientists make new higher-yielding plants,” says Tsiantis. discoveries about how plants discoveries – because When Miltos Tsiantis moved from Ox- develop and diversify. For ford to Cologne in 2013, he was able to example, the ‘RCO gene’ readily acquire state-of-the-art micro- is active in some species and it gives us a clear not others, and it plays a scopes. They make individual cells visi- significant role in determining glimpse of how ble to Neha Bhatia, a post-doctoral sci- the shape of a leaf. entist in the group. With great dexterity, evolution works.” she first removes the mature leaves of RCO is active in the cells the seedlings, and then places the tiny located at regular intervals along the edge of the leaf. It 44 plant under the microscope. This al- prevents those cells from MILTOS TSIANTIS lows her to observe the newly formed growing. leaves which can be as small as a few mi- crometers long. Then she switches on STM is another important bulges created in this way gradually grow into the dis- the screen, focuses the microscope and gene that is active in leaves of tinct leaflets or pinnae. “RCO thus helps the individ- suddenly the cells marked with fluore- some species but not others. STM is active more broadly in ual leaflets to emerge and grow into separate pinnae, scent proteins begin to glow. “We can the leaf than RCO and it instead of producing a continuous leaf surface,” ex- now mark several genes simultaneously allows prolonged proliferation plains Tsiantis. with different colors and see where in of leaf cells. This feature, the leaf they are currently active,” ex- together with the more local Thus, if the RCO gene is a pivotal gene in the evolution of plains Bhatia. growth repressive action of leaf shapes, then an Arabidopsis thaliana with an arti- RCO, allows small bulges at the leaf margin to eventually ficially transferred RCO gene should also develop pin- In the meantime, the researchers have also grow into separate leaflets. nate leaves. And indeed: an Arabidopsis thaliana plant discovered that a previously discovered modified to contain the RCO gene has roundish leaves gene called the STM gene acts together with clearly visible protrusions. Although the plants do with RCO to initiate leaflet formation. not grow pinnate leaves on stems, the resemblance to While RCO inhibits leaf growth, STM Cardamine hirsuta is truly astonishing. “The results of causes cells to continue growing. Nor- these experiments caused some excitement in the sci- mally, cells no longer divide when they specialize. entific community, because it is very rare for a single However, when STM is active, the cells can continue gene to influence the differences between plant species to multiply so that the leaf grows wider at this point. If to such an extent,” says Tsiantis. “Actually, we ex- RCO and STM are active at the same time, broad pected that the minor, respective effects of a large bulges form at the edge of the leaf. “When we activate number of genes would work together to cause evolu- both genes in the Arabidopsis thaliana leaves, the tionary changes in such fundamental traits.” So, to- leaves formed by these genetically modified plants gether with Donovan Bailey from the New Mexico look like those of Cardamine hirsuta,” says Tsiantis. State University, Tsiantis then began studying the This experiment shows that, by having an in-depth phylogeny of Brassicaceae in order to find the origin of understanding of how plants differ from one another the gene. Apparently, the Brassicaceae family did not in their specific characteristics, we might then also use originally possess an RCO gene. Consequently, spe- that understanding to modify the traits of crop plants cies of Brassicaceae that are developmentally similar to as well. However, the shape of a leaf is not determined

Max Planck Research · 4 | 2020 FOCUS

A DEVELOPING LEAF OF THALE CRESS

Growth

Growth inhibition

A growth zone forms a Zones of growth activation As the leaf grows larger, gradient from strong and inhibition alternate more local growth zones (green) to minimal (gray) and lead to bulges along emerge. growth. the edge of the leaf.

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GRAPHIC: GCO AND • RUNIONS BY TSIANTIS – THE SHAPE THINGS OF TO COME, AMERICAN 104 VOL. 2017, JOURNAL OCT. BOTANY, OF by its genes alone. The physical properties of leaf tis- which will form soon after flowering,” the scientist ex- sue also influence the development of the leaf, by plains. The various methods, the wealth of ideas, and means of the mechanical resistance it exerts on grow- the unusual perspectives implemented by Tsiantis and ing cells. Adam Runions, a computer scientist in his team have made important insights into leaf growth Tsiantis’s team, developed a mathematical model that possible. Tsiantis himself considers the RCO gene to takes into account physical interactions within the leaf be one of his most important discoveries, “…because it tissue. This allows him to “program” leaves that grow very clearly illustrates how innovations can arise virtually. “If we suspect, for example, that a gene func- during evolution.” tions in a certain way, we can use our model to test this hypothesis,” says Tsiantis. “In this way, we can iden- Most genes have several functions. For this reason, the tify the basic rules according to which the leaves de- mutations of one gene can trigger a wide variety of velop.” changes in a plant’s form and function. A mutation can improve one function and impair another. Experts re- But why do plants have such dissimilar leaves in the first fer to this as “pleiotropy”. “Just imagine: a bird deve- place? To answer this question, the Tsiantis team stu- lops wings that can help it fly better. But if the genetic dies different Cardamine hirsuta plants from Europe modifications responsible for this improvement also and other parts of the globe to learn how the local en- change the bird’s color and thus make it less attractive vironment may affect the shape of a plant’s leaves. “For to potential mates, that change in wing shape will most instance, we have observed that plants that grow in re- likely not be successful,” explains Tsiantis. RCO on gions where they can produce flowers quickly and re- the other hand is a gene that is hardly pleiotropic at all. produce rapidly also produce more leaflets more It largely controls the shape of a plant’s leaves, but quickly. This strategy may support a more efficient as- otherwise has few other functions. “The example of similation of carbon and consequently a better supply RCO lets us not only reveal the secret of leaf diversity, of nutrients for the next generation. Conversely, in are- but also learn how evolution works.” For example, the as like central Europe or Scandinavia, where plants role of RCO in leaflet separation can be considered bloom late because they have to survive a cold winter, analogous to processes that lead to the separation of they tend to ‘wait’ to attain their maximum leaflet digits on developing limbs. In this case, however, the numbers until just before they flower in spring. Per- separation is primarily driven by programmed cell haps this strategy also ensures the leaves’ ability to death, and not growth inhibition. supply an optimum level of nutrients for the seeds, www.mpg.de/podcasts/vielfalt (in German)

Max Planck Research · 4 | 2020 INFOGRAPHIC BLACK HOLES – SPACE-TIME TRAPS

Ergosphere Ring singularity

Abstract mathematics is being used to determine the structural design of a rotating black hole. It is impossible to imagine a ring singularity with no spatial extension. Easier to envision is the event horizon; it defines the size and limit beyond which there is no return, neither for light nor matter. Everything 46 within the ergosphere has to rotate in sync with the black hole. Event horizon IMAGES GCO; ISTOCK; WEISS; (FROM TOP ESO/L. NASA/CXC/M. CALÇADA/SPACEENGINE.ORG TO BOTTOM)

An incredible thought experiment: compress the Earth to the size of a cherry and you turn it into a black hole.

THEORY In 1783, John Michell first imagined In 1915, Albert Einstein created the mathematical basis for “dark stars”, which do not emit such objects in his general theory of relativity. A year later, light because of their gravitation. Karl Schwarzschild described the geometry of a static black hole.

OBSERVATION In the early 1970s, the first stellar black Groups led by Andrea Ghez (University of hole (Cygnus X-1) was discovered as California, Los Angeles) and Reinhard Genzel part of a binary star system. This was (Max Planck Institute for Extraterrestrial accomplished indirectly with the aid of Physics) had been observing the orbits of stars an X-ray satellite, which registered at the center of our Milky Way since the high-energy radiation from the hot gas 1990s and concluded the existence of a black disk (accretion disk) surrounding the hole of 4.3 million solar masses, for which black hole. they received the 2020 Nobel Prize in Physics.

Max Planck Research · 4 | 2020 INFOGRAPHIC

VARIOUS TYPES

Four types of black holes can be differentiated according to their respective masses:

Primordial black holes Mass: approximately equal to that of the Earth’s moon Origin: Big Bang

Stellar black holes Mass: between 3 and 65 solar masses Origin: Supernova (how heavier black holes of up to 120 solar masses are formed remains unclear)

Supermassive black holes Mass: between a few million and billions of solar masses Moderately heavy 47 Origin: mergers between black holes numerous black holes, Mass: between 120 and each comprising several 100,000 solar masses hundred solar masses; Origin: collisions between collisions between galaxies stellar black holes; mergers or accretions of mass between massive stars or the gathered from surrounding Big Bang space SIMULATING EXTREME STEINHAUSER D. (AIRBORNE PROJECT, SPACETIME HYDRO MAPPING GMBH); EHT COLLABORATION (TOP TO BOTTOM) IMAGES: ISTOCK; NASA, ESA, AND BANOVETZ J. AND MILISAVLJEVIC (PURDUE D. UNIVERSITY); ISTOCK; S. OSSOKINE, PHYSICS); A. BUONANNO (MPI FOR GRAVITATIONAL

In the 1960s, the theory of relativity experienced a renaissance as a result of new observations. Roger Penrose (2020 Nobel Prize in Physics) and Stephen Hawking demonstrated the presence of a singularity of infinite density, as well as an infinite curvature of spacetime within black holes.

The gravitational waves Scientists published the first predicted by Einstein image of a black hole in 2019, were detected for the first which was pieced together from time on September 14th images taken by the Event 2015 and emanated from Horizon Telescope – a network of the merger of two black eight radio observatories scattered holes having 29 and 36 over half the globe – and shows solar masses, respectively. the massive monster at the heart of Galaxy M87.

Max Planck Research · 4 | 2020 AN INFECTIOUS ­INTEREST IN THE CORONAVIRUS

Viola Priesemann’s life has changed a great ral Systems” at the Max Planck Institute for Dy- deal since the corona epidemic first started in namics and Self-Organization in Goettingen had Germany: Priesemann, the head of a research only begun analyzing the spread of the virus and the effectiveness of the countermeasures in the group at the Max Planck Institute for Dynamics past few weeks. But the physicist already rec- and Self-Organization, is now investigating not ognized one fact: the pandemic can only be con- only information processing in the brain, but also trolled over the long term by keeping case how the SARS-CoV-2 virus spreads. And ever numbers low. It’s the only way to avoid excessive collateral damage to public health, society and the since, her daily routine has included consulta­ economy. A lockdown, she realized, would have to 48 tions with policymakers, giving interviews, and reduce case numbers to the point where health appearing on TV. departments can reliably detect and isolate a suffi- cient percentage of cases by means of consistent testing and tracking. If this can be achieved, TEXT: UTA DEFFKE restrictions could be relaxed again. Any local flare-ups could then be quickly identified and ea- sily contained with short, but tough, measures.

That was the conclusion Priesemann arrived at based It was past 11 p.m. on an evening in late March 2020 on her calculations of several alternative scenarios. when Viola Priesemann sat back down at the com- And that’s what she wrote in the draft of her state- puter in her home office in Goettingen. Her usual ment. “I suddenly recognized that my working tasks as a physicist – developing new models, per- group had expertise that was important to society, forming calculations, and fine-tuning new aca- but it was not yet known to others. That’s a really demic papers – were not on her mind. She was fo- strange feeling.” She was certain even then that we cused on a completely different matter: drafting a were going to be dealing with the pandemic for position paper for policymakers written from the many months to come. Her assessment of the bene- point of view of a scientist. The COVID-19 pan- fits of the shortest possible hard lockdown was demic, just a few weeks old at the time, was grip- shared by colleagues in the fields of psychology, ping the world’s attention. Germany had also just social sciences, and economics. She shared and gone into lockdown: events were prohibited, day- discussed her findings with them. Because one care centers, schools and universities were closed, thing was clear to her: her own epidemiological as were most stores, restaurants and cultural insti- findings on the spread of the pandemic were only tutions. Social distancing was the order of the day. one perspective on how the disease would develop. Even the streets of the big cities were filled with an She was particularly impressed by an article in The eerie stillness. Economist on the “90 percent economy”, which ar- gued that a short, sharp restriction would be less But Viola Priesemann’s mind was racing. The head of damaging to the economy than repeated curtail- the Max Planck Research Group “Theory of Neu- ments over months or years. Priesemann coordi-

Max Planck Research · 4 | 2020 VISIT TO

VIOLA PRIESEMANN

49 PHOTO: JULIA STEINIGEWEG

Theorist of the epidemic: Viola Priesemann develops mathematical models of information processing in the brain. She employs similar methods to predict the spread of the coronavirus.

Max Planck Research · 4 | 2020 VISIT TO PHOTO: JULIA STEINIGEWEG

50

A rare chance to find some balance: when she can make the time, Viola Priesemann likes to go horse riding. Right now, however, she has little opportunity to do so.

nated her draft with colleagues at the other major is the theory of information processing in the brain. German research institutions. “It was important To understand her sudden involvement in research and reassuring that we all came to the same con- into COVID-19, you need to trace her career back clusions, each with our own specific approaches,” a few steps. she says, looking back. A first version of the posi- tion paper quickly entered the political realm. For many years, it was far from clear whether Priese- Nonetheless, the message that sprang from the re- mann would follow a scientific career path or not. search institutions largely went unheeded in the With a grandfather who was a classical philologist “orgy of discussions on opening back up,” as Chan- and pedagogue, as well as vice president of the cellor Merkel is said to have called the ongoing de- University of Kiel, her social background certainly bates in the German states. When the paper offi- placed a high value on education. But for a long cially appeared on April 28th, an end to the lock- time it never occurred to Viola that women could down had already been decided. But a second wave also become researchers, inventors, or even profes- was on its way, at the latest in the fall; of that the sors. For example, she remembers a schoolfriend’s researchers were certain. father telling her about his work in speech recogni- tion, the technology involved in translating spoken Over the summer, a modicum of calm returned – at words into written text: “Right now, the methods least in hospitals and health departments. Viola known as ‘deep learning’ are revolutionizing Priesemann continued to work flat out, both on speech recognition, but even back then, I thought the COVID-19 pandemic and on her other scien- it was pretty cool. But at the same time, I was sub- tific pursuits. Her main area of research, after all, consciously aware that this was not anything that I

Max Planck Research · 4 | 2020 VISIT TO

would ever work on.” Because it’s just not some- via the sensory organs is then combined with thing that women do. Studying was still the order pre-existing information stored there – is some- of the day though – in Darmstadt. Physics ap- thing that Viola Priesemann is investigating using pealed to her, because she had always felt an urge mathematical techniques. Another thing that at- to understand the world. “Looking back at it now, tracted her to Wolf Singer’s group at the time was physics was the perfect foundation for what I now its interdisciplinary perspective. Her work in the enjoy doing,” she says. The theory of complex sys- group would involve collaboration with physicists, tems fascinates her the most. How do swarms de- psychologists, biologists, and philosophers. It was velop? Why do zebras have stripes? How do natural clear that the processes in the brain are self-orga- structures form? The underlying premise is dis- nizing, since a network of that size and complexity covering how numerous individual entities are could never be programmed. transformed into a single large one that has its own

“It’s an incredibly dynamic time, especially for us scientists. Because new information is emerging every day.”

unique properties. In her fifth semester, Priese- Such self-organization is governed by local rules of mann happened to notice a new sign on an office learning, which determine the strength of indivi- door: Prof. Barbara Drossel. “That’s when it hit dual synaptic connections. Insights into these pro- 51 me for the first time – wow, a woman can become cesses help us, on the one hand, to better under- a professor too. In theory, so could I.” stand the biological brain, while on the other, they can help in optimizing artificial neural networks. As it turned out, she called her career goals into ques- tion once again during her Erasmus study year. A As she began delving into her diploma thesis, Viola passionate rider from childhood (“Some people Priesemann made an important discovery: if you just seem to have a horse gene.”), she headed off to want to get to grips with a system as complex and Lisbon. It’s a part of the world with a great tradi- large as the brain, you’ll inevitably need to limit tion in classical dressage. Priesemann spent more yourself to examining its individual components. It time on horseback than in the lecture hall. But had long been thought that the big picture could be nonetheless, in the end, she made up her mind: her extrapolated from such components, because the professional future was definitely going to be in brain is a scale-independent system. Just like frac- physics. tals, which are similar in appearance when you zoom in, it shouldn’t matter whether you are ob- She took great care in choosing the subject of her di- serving such a system on a large or a small scale. ploma thesis. It should, she felt, be something that However, on the basis of contradictory data, Prie- was both complex and relevant to everyday life. semann discovered that unlike the system itself, And that’s how she ended up working in the field of the properties of a scale-independent system do theoretical neuroscience with Wolf Singer, Direc- not appear to be scale-independent when only a tor at the Max Planck Institute for Brain Research small subcomponent of that system is viewed. In in Frankfurt/Main. After all, the brain is a com- other words, the properties of the subsystem can’t plex system as well – perhaps the most complex simply be extrapolated to infer the properties of one that we know of. And the fundamental princi- the system as a whole. This insight doesn’t just ap- ple underlying how we think and learn is the for- ply to the brain; it’s a general principle. mation of new structures. Each of the 80 billion neurons interacts with thousands of other neurons A discovery like that gave her self-confidence – and by creating connections known as synapses. How toughened her in scientific debate. After all, a these interactions lead to information processing – young scientist – and a young female scientist to for instance, how information reaching the brain boot – isn’t likely to endear herself by calling esta-

Max Planck Research · 4 | 2020 VISIT TO

NEW CASES PER 1 MILLION INHABITANTS Scenarios of the epidemic: the model developed by Viola Priesemann’s group makes it possible to track the numbers of new infections and forecast future developments based 400 on various assumptions. The sharp reduction in cases over Prognosis New Year is due to reduced testing during this period. The temporary increase in January is partly due to a return to normal testing operations and also to increased personal contacts during the Christmas holidays. 300

brain known as the cortex, which plays an important

200 role in vision and the processing of visual informa- tion. Her work confirmed a general but crucial in- sight into scientific research that she learned from her doctoral supervisor: “Making an observation that fits one’s hypotheses is exciting. But then the real 100 work begins. You have to scrutinize and check your results and be your own most critical reviewer.”

In 2013, Priesemann returned to theoretical work – 0 moving to the Max Planck Institute for Dynamics NOVEMBER 1ST 2020 DECEMBER 1ST 2020 JANUARY 1ST 2021 and Self-Organization in Goettingen. “I can per- form experimental work. But I love to understand data and to develop theories to explain it.” This she Smoothed reported data from the RKI has done, first as a postdoc and then, soon after, as a Bernstein Fellow and Max Planck Research Group More social contacts from Christmas onwards Leader. “This gave me independence, my own bud- No change in social contacts get and, with an additional research grant, the abili- 52 ty to recruit my first students.” She certainly has a Significantly fewer contacts from December 25th 2020 onwards gift for it. She learned from one of her mentors that working with people who stimulate you and are GRAPHIC: GCO BASED ON RESEARCH THE BY MPI FOR DYNAMICS AND SELF-ORGANIZATION pleasant to be around is important. Her team has now expanded to around twenty researchers. blished theories into question. But for Viola Priese- mann, that insight was the foundation upon which Among their most important findings is a learning rule her further research work was built. She asked her- for how neurons interconnect to form stable and ef- self: how could conclusions drawn from the sub-sys- fective networks that can process any and all types of tem nevertheless be applied to the entire system? information, and how they accomplish this by ad- She developed mathematical techniques to help her justing the strength of their connection. Connection investigate. strengths are not fixed, as was long assumed, but are adapted to the task at hand. Priesemann’s team dis- Nonetheless, with a view toward broadening her ex- covered this when they were working on the “Hu- pertise for the future, she sought a new subject for man Brain Project” with research colleagues from her doctoral thesis at the interface between theory Heidelberg. They constructed artificial neurons and experiment. Priesemann’s dissertation would from semiconductor materials and combined them lead her first to the École Normale Supérieure in to create relatively large networks that could auto- Paris and then to Caltech in California to Gilles nomously learn using the applied rules. Laurent, who she later followed back to the Max Planck Institute for Brain Research when he became When COVID-19 erupted in the spring of 2020, Viola Director there. Above all, this meant years of hard Priesemann’s own synapses immediately went into work as an assistant setting up a laboratory. However, overdrive: “It was just such a good fit,” she asserts. Priesemann has never shied away from technology Brain research and the spread of a virus? In the brain, and hands-on labor, even as a child when she once information propagates as one neuron activates its single-handedly repaired the family toaster because neighbors; similarly, corona virus infections spread she was determined not to get a new one. She was from one person to the next. “In both cases, we can working on more delicate objects in her lab: the make inferences about the big picture (with a high brains of turtles – a good model system for studying level of uncertainty) by observing a small subset: the role of the outer corrugated structure of the drawing conclusions about how the activity of a few

Max Planck Research · 4 | 2020 VISIT TO PHOTO: JULIA STEINIGEWEG

Presenting her findings to other scientists is a regular part of the work of a research group leader. 53 But Viola Priesemann also aims to disseminate her findings about the corona epidemic to politicians and the public – as a physicist, that is a new experience for her.

hundred neurons results in information processing the tensions and contrasts were palpable. After the in the brain and, in much the same way, about how a pandemic, she hopes to revive such salons and dis- comparatively small number of known cases of cuss issues such as the concentration of power, COVID-19 cause the spread of the virus throughout self-organization, and social justice. Scientists have the population.” Fired up by this parallel and moti- had a good understanding of how infectious diseases vated by its relevance to society, Priesemann threw spread since the 1970s, but it was barely active as a herself into the subject. She already had at her dis- field of research when she began exploring it. Never- posal a set of fundamental mathematical tools. These theless, Priesemann was able to introduce new ideas she developed further, adapting them to the new based on her mathematical methods from neurosci- challenge. To quickly find out everything there was ence, enabling her to model much more complex in- to know about viruses, she networked with experts: fluences. “It’s an incredibly dynamic time, especially medical scientists, virologists, and epidemiologists. for us scientists. New information is emerging every She also contacted psychologists, economists and so- day – new figures and new publications. I have spo- cial scientists – first experts in Goettingen and then ken with an incredible number of people, increased all around the world – to attain a holistic view. “I’d the size of my team, engaged in external press rela- always been interested in interdisciplinary dis- tions and written advisory reports. Sometimes I course,” says Priesemann, recalling the salons from don’t even know how I’ve managed it – Monday to her Frankfurt days, where people from all walks of Sunday from six in the morning until midnight,” she cultural, political and business life could meet and says. engage in casual conversation. “Frankfurt at the time was the hotspot of the financial crisis. My part- For Priesemann and everyone else, the corona crisis ner and I discussed the crisis in all its dimensions dominates our lives, with all its restrictions and in- with a large circle of friends from the worlds of phi- securities. However, the virus isn’t having a nega- losophy, sociology, and economics, seeking to com- tive impact on her research activities – despite prehend it.” Living in the banking city of Frankfurt, working from home and having a child in daycare

Max Planck Research · 4 | 2020 VISIT TO

since March. “Our work is purely theoretical. It re- Does Viola Priesemann feel that politicians have ade- quires, above all, the ability to think, free from dis- quately heeded her advice? One thing she’s sure of is tractions and with access to powerful computers – that the chancellor herself must have been quick to which we can fortunately operate from home.” She take note of her publications. That much was evi- can meet up with her team in two video chatrooms, dent from Merkel’s press conferences. Priesemann which are accessible around the clock if needed. One is less certain when it comes to the heads of Germa- is dedicated to research into the COVID-19 pan- ny’s federal states. In truth, Priesemann had been demic, the other to neuroscience issues. It’s a system planning on scaling back her media activities in No- that works really well, she says. Everyone has been vember – the time commitment was enormous, and working fantastically together, scattered as they are she was also about to take the next steps in her scien- across Hamburg, Leipzig, Hanover, Amsterdam, tific career. But as long as the corona pandemic is Lyon, and Granada. In the summer of 2020, small still rampant, and as long as new, politically relevant groups regularly met for extended walks around the findings are still emerging, she’s decided to stay in- grounds of the Institute, which is nestled in a beau- volved. tiful wooded setting. The purpose of these mee- tings was to help develop a new project and to – lit- For example, Priesemann is currently refining her co- erally – walk through the group’s ideas at length. rona model to take into account, among other things, the age structure of the population, its geographic One important finding from the fall of 2020 was that in distribution, and the uncertainties involved. Up to addition to an R score above 1, another tipping point now, the calculations have been based on compara- existed for the epidemic: the capacity of public tively simple assumptions that the distribution of health departments to trace cases. If this capacity infected persons is homogeneous. An expansion of proves insufficient, the virus spreads uncontrolla- the model should help to more accurately estimate bly. “And then the longer we wait to initiate counter- the number of undetected cases and the effective-

54 “The longer we wait to initiate countermeasures, the harder it will become to contain high case numbers again.”

measures, the harder it will become to contain high ness of the measures taken. Priesemann is also ex- case numbers again.” This is the message Viola panding her perspective to take in all of Europe. She Priesemann disseminated in talk shows, radio has coordinated a joint position paper, supported by broadcasts, online media and newspapers through- over 300 colleagues from many countries, which out October 2020, and sometimes even on the front was published in the British journal The Lancet. pages of those newspapers. Nonetheless, the second The paper calls for a reduction in the number of new wave of the pandemic continued to spread. Re- infections to about seven per 100,000 people per searchers were alarmed, but policymakers dithered. week throughout Europe. Viruses are no respecter It took until November 2nd for a “lockdown light” to of borders, after all. be declared. Anne Will, the host of a German TV show, asked Priesemann whether she thought the Now, at the beginning of 2021, it’s impossible to pre- measures that had been taken were sufficient. Prie- dict when the next period of respite from the virus semann measured her words: “We can succeed in will be. Priesemann took a break over Christmas lowering R from 1.4 to 0.7, but to achieve this, we anyway, at least in her public capacity. She likes to need to employ every tool in our toolkit.” And by spend her free time riding – a hobby, it turns out, “tool” she meant all possible measures to contain the that is shared by other female scientists. At a mee- epidemic. She’s aware that science can only provide ting with the president of the University of Frank- data and facts. Deliberating on those facts and ma- furt, she discovered that the president owns two king decisions is the task of politicians: “That’s not horses. She also knows other top female scientists a métier I would venture into.” Four long weeks who ride: “Maybe it’s a sport for strong women,” Vi- later, the politicians finally decided to tighten the ola Priesemann says with a laugh. That bodes well lockdown. Way too late for a carefree Christmas. for her next career leap.

Max Planck Research · 4 | 2020 RESEARCH DOESN’T HAVE TO BE HEAVY.

The Max Planck Society’s magazine is available as an ePaper:

www.mpg.de/mpr-mobile DOWNLOAD THE www.mpg.de/mpresearch EMAGAZINE FOR FREE! DNA ORIGAMI

TEXT: MARA THOMAS

What is life? How did it emerge? And could it possibly look completely different? At Kerstin Göpfrich’s lab at the Max Planck Institute for Medical ­Research in Heidelberg, scientists are working on answers to the really big blocks from nature as possible. Be- Göpfrich’s enthusiasm for her field of re- questions. Her research group’s plan cause these scientists almost exclu- search is so infectious that it comes as is no less ambitious: to create artificial sively use new components that have no surprise that she manages to excite cells and, by so doing, to discover been produced in the laboratory, non-scientists about her field of spe- 56 Göpfrich refers to this approach as cialism as well. Her videos and essays what is essential for life. “de novo synthetic biology.” Propo- about scientific research are both en- nents of this method are attempting to tertaining and informative. She regu- detach their work from the natural larly gives public lectures, presents Even the simplest bacterial cell is so building blocks of life. Are there, for science talks in schools, and founded complex that disentangling the inter- instance, alternatives to cellulose as a the “Ring-a-Scientist” initiative, play of its varied components is hugely material for cell walls? What potential which links up researchers and teach- challenging. It is similarly difficult to ways are there for a cell to generate en- ers to bring science into the classroom determine which of these elements is ergy, and how might it store informa- via videoconferencing. “Dialog with indispensable for the life of the cell tion? the public helps me focus on the ques- and which is merely a biological tions I want to answer through my re- “spandrel” – a by-product of the pro- Components such as the cell membrane, search: what constitutes life, how cess of evolution. “What I cannot cre- nucleus, or the mitochondria can also might it have arisen, and what other ate, I do not understand is a maxim of be simplistically regarded as systems, forms of life are possible.” the physicist Richard Feynman, and respectively, for packaging, informa-

for me it holds true: I can only fully tion storage, and energy production. PHOTO: KATRIN BINNER FOR THE MPG understand something if I can create These researchers are now looking for Well packaged it myself,” says Kerstin Göpfrich. alternatives that can accomplish these This approach is not solely the central tasks as well as, or better than their in fat molecules theme of her own scientific work, but natural counterparts. “Emancipating of an entire field of research: syn- ourselves from nature provides us In recent years, Göpfrich’s team has thetic biology. Some scientists in this with a lot of creative freedom. It al- been working on the cell membrane, field use living cells as a starting point, lows us to overcome hurdles more the structure enveloping cells. Life while others begin with individual quickly,” explains Göpfrich. But in depends on boundaries, at least on a cellular components, which they try any event, laboratory-developed sys- biochemical level. Only by means of to reassemble like pieces of a jigsaw tems like this need to fulfill one con- boundaries can living systems sepa- puzzle. dition: they should eventually enable rate themselves from their environ- the creation of a new type of cell that ment and create the conditions for And other researchers even go one step possesses all the characteristics of life, their survival within. In nature, the further: they plan to design a cell in particular, its ability to reproduce cell membrane consists of a double from scratch, using as few building and evolve. layer of fat molecules called lipids.

Max Planck Research · 4 | 2020 KNOWLEDGE FROM

BIOLOGY & MEDICINE

57

Like paper in traditional origami, DNA can be formed into almost any shape. DNA is a long, thread-like molecule, but the technique can be used to fold it into sheets, tubes, boxes, or, if desired, into a cloverleaf.

Max Planck Research · 4 | 2020 KNOWLEDGE FROM

Scientists already know how to pro- duction is at the very top of their list. duce such envelope structures in “Regardless of who you ask, the an- SUMMARY large quantities. Termed “vesicles”, swer to the question of what consti- they are surrounded by a lipid bilayer To better understand the nature of life, tutes a living cell is usually that it and filled with water, just like natural researchers are seeking to develop must have the ability to divide.” The cells. “They are our basic model of a artificial biological systems. This capacity to reproduce is indeed one of cell,” says Göpfrich. “The aim now is research involves looking for the scientific criteria for life. to fill the vesicles with life.” To ac- completely new ways of recreating complish this, the team is utilizing the properties of cells. It’s a challenge that Göpfrich’s team has tools from a wide variety of disci- Artificial fat vesicles can mimic the already surmounted. They can cause plines. One of these is “microflu- membrane of natural cells. Some can vesicles to divide, for instance with idics”, the targeted maneuvering of even divide and move around. the aid of a pulse of light. The light tiny amounts of liquid onto micro- causes a specific type of molecule in chips the size of a fingernail. This Targeted combinations of DNA the surrounding liquid to decompose molecules autonomously fold into a tool allows scientists to sort vesicles desired shape to form structures and thereby increase the surrounding by size or content, inject them with that can perform different tasks solute concentration. To counterba- substances, and merge two vesicles (DNA origami). Scientists can lance the resulting osmotic disequi- together. The vesicles are stable precisely predict what form multiple librium, water flows out of the vesi- enough that researchers can endow DNA molecules will take. cles. The trick is to make sure the vesi- them with life-like functions. Repro- cles don’t just shrivel but, instead, ac- tually divide. To achieve this, the re- searchers introduce two different types of lipid molecules into the membrane of the vesicle. These mole- cule types have a tendency to segre- gate from each other, and this, to- gether with the shrinking process, causes the vesicle to divide into equal- 58 ly-sized daughter vesicles. There’s a catch, though. The daughter vesicles formed in this way cannot continue to divide using the same method, since they now each consist of only one of the two fat molecule types. The re- searchers therefore allow them to fuse with small globules of fat, each composed of molecules of the other fat type. This allows the daughter vesicles to divide once again.

Cells can assume a wide variety of shapes depending on their type. This is another property that Kerstin Göpfrich has also imbued in her vesi- cles. It requires an artificial cytoskele-

PHOTO: KATRIN BINNER FOR THE MPG ton that, ideally, molds itself in re- sponse to a stimulus from the sur- roundings. To achieve this, the team uses building blocks incorporating a pH-sensitive molecule. These blocks attach themselves to the lipid mem- brane at a high pH, forcing the mem- brane to flatten out locally. “The ma- terial we use to make our cytoskeleton is nothing really unusual; it’s in every one of our cells: DNA,” says Kerstin Göpfrich is fascinated by the idea of constructing a living cell. Göpfrich. The DNA molecule con- She wants to not only make use of prototypes found in nature, tains a pH-sensitive region and a but also to completely redesign individual cellular components. molecular region that can bind to the

Max Planck Research · 4 | 2020 As GöpfrichAs principles the explains, un DNA, that amaterial is general, in They offer awide of researchers range vironment changes. vironment Göpfrich high hopes for has –not only DNA sequence for required aparticu DNA designed be also molecules can DNA multiple origami, DNA mole lar shape. additionlar In to playful struc Along microflu size. with limeter in lipid envelope, enabling it to deform used to construct tunnels, plates, tunnels, to construct used known for along time: “The is secret derlying DNA folding have been four different building molecular formed. Hence, along of DNA strand quired shape.quired The techniquebe can geometric shapes, the technique the shapes, geometric also Göpfrich’s that gies utilizing. is team gami”, to paper, analogous because, can be shaped by shaped be many short DNAcan combine suchcules in away as that chemical interactions between the component: artificial membrane membrane artificial component: puter software, she can calculate the the puter calculate she software, can possibilities for constructing compo pores madepores of DNA to facilitate the the vesiclesthe when en- pH the the in into of asingle her unit. part doc As ture attains an energetically favorable energetically an attains ture substances. signaling of exchange Göpfrich de thesis, already toral had technology one is of key the technolo idics and 3D printing, DNA nano to fold any on and re take almost referreding, also “DNA is to as ori ofence to Japanese paper the fold art block.ing technique, refer This in tures such as smileys, stars and other such stars smileys, as tures boxes, or connectors between compo between connectors or boxes, but aversatile biological build as also blocks of DNA, thymine, bases the nents for and assembling them cells ofnents only amil are millionths that nents for an artificial cell. nents for artificial an makes itmakes possible to produce compo many base pairs as possible as are pairs many base as a carrier of inherited information, acarrier as adenine, cytosine, and guanine. In In and guanine. adenine, cytosine, state,” Göpfrich. explains Using com snippets until the entire DNA entire snippets the until struc signed and signed investigated one such DNA molecule DNA molecule pair bonding ------

Equipped with such structures, artifi Equipped such with structures, IMAGE: YANNIK DREHER/MPI FOR MEDICAL RESEARCH Göpfrich says. But al are researchers creating living systems from scratch,” from systems living creating cial cells could one cells daycial a va perform body. “We’re along way still off from riety of tasks, for ofriety example, tasks, serve as miniaturized helpers human the in miniaturized BIOLOGY &MEDICINE Max PlanckResearch simultaneously shrinks, the vesicle the shrinks, simultaneously starts to divide. Is this amodel for to divide. this Is starts (yellow, it and green) segregate When a vesicle’s fat molecules vesicle’s a molecules fat When ·4 artificial cell division? cell artificial | 2020 - - - At present, science the of building is cells Terms like “artificial life” and “artificial Terms life” and “artificial like “artificial The next big step to is develop a system – constructs made of matter, dead – constructs no we’re searching for artificial systems we’re for searching artificial would allow the artificial cells to au cells would allow artificial the within cells. If we could find asystem we If cells. could find within which, very difficult been to date, has would evo only then to need steer this Göpfrich explains: “As yet, our work Frankenstein; what primarily inte- Nevertheless, it’s we that important DNA of nucleus. cell the Right now, lead to developmentlead the of artificial wayleading and arouse fear. “Syn lution direction. desired the in little more than molecular aggregates aggregates molecular than more little don’t lose sight dimen of ethical the deviate from the originals, we woulddeviate originals, from the different to those in other areas of ma different other areas in to those for encoding information. “In natural for evolution,” Göpfrich. explains It grammed to perform medical tasks,” to perform medical grammed cells that could one that daycells pro be characteristics of even life, and then, characteristics cells, the genetic information is in the the genetic the in is information cells, can be used as a sensor to determine to asensor determine as used be can possess, at most, a small number at most, of a small possess, proving useful in other areas of re proving other areas in useful patent some of her findings. led Göpfrich has to periments. This to accomplish during microscopy ex terials science and nanotechnology. science terials are cells point, artificial issues; at this today cells itsin infancy. Artificial biology,thetic however, not is the in researchers evolve. The tonomously even have met one of prerequisites the that can encode information. They can that that can not only can producethat copies that only in the laboratory.only the in Kerstin As organisms” are often a mis are in used organisms” barely touches sensitive on ethically business of creating monsters ofbusiness like creating ready making discoveries that are are discoveries that ready making rests us are cells. Our research could research Our cells. are us rests nently and replicate themselves need to be able toneed be to store perma data are accurate but that also occasionally but occasionally also accurate are that solute concentrations, something something concentrations, solute example, for vesicles, self-dividing medicine. and in Göpfrich’ssearch sion of our research.” Göpfrich. says www.ring-a-scientist.org ------

59 KNOWLEDGE FROM

CAUTION – TOXIC GREEN!

TEXT: CLAUDIA DOYLE

For humans, plants are a source of food, building material, and medi­ cine. But not everything that is green is good. Some plants pro­ 60 duce toxins that can make us sick – This realization gave her an idea. In by no means a niche topic. “Which or even kill us. Thus, a wariness of western cultures, most food comes plants around me are edible, which plants makes sense from an evolu­ from the supermarket. Only a few ones can kill me, and how can I distin- tionary point of view, especially for people still cultivate their own food or guish one from the other – these are infants and toddlers. Annie Wertz forage for wild plants. But for the crucial questions that have ensured from the Max Planck Institute for greater part of human history, fora- our survival throughout human evo- ging for plants and hunting animals lution,” says Wertz. Humans are curi- Human Development in Berlin is in­ has ensured a sufficient supply of ous by nature, and especially in the vestigating which behaviors protect food. Our ancestors once had exten- first months of life, they have an insa- children from dangerous plants and sive knowledge of which plants were tiable urge to discover and explore how they learn from adults which edible and how to best prepare them. many objects with their mouths. At They passed on this wealth of experi- this age, the tongue has a particularly plants are safe to eat. ence to their descendants. “It would large number of nerve cells. But when have been a deadly endeavor if each it comes to exploring plants, this individual had to find out for them- strategy alone could be fatal; after all, selves which plants can be eaten and quite a few plants are inedible – or As Annie Wertz was jogging through the which ones cannot,” says Wertz. The even deadly – for humans. “Humans mountains in California one day, an psychologist has since left California have always co-existed with plants. unpleasant thought came to her: if she and has been heading the “Naturali- Therefore, strategies that facilitate were to get injured or lost in that mo- stic Social Cognition” research group safe co-existence should have ment, that would be the end of her. at the Max Planck Institute for Hu- emerged during the course of evolu- She would starve to death. But the man Development in Berlin since tion,” says Wertz. then doctoral researcher from the January 2015. There, she researches University of California, Santa Bar- the evolutionary strategies that enable Whether a plant has the potential to be- bara was surrounded by trees, ferns, infants and toddlers to safely learn come your favorite food or your last and grasses. A veritable cornucopia of about plants. meal can’t be deduced from its looks nourishment. But she had no idea alone. White flowers? This could in- which plants were edible and which When Wertz talks about her project at dicate a harmless apple tree or the poi- were poisonous. She had never conferences, she often receives skepti- sonous wood anemone (Anemone learned this life-saving information. cal looks. But her research question is nemorosa). Blue fruit? This applies to

Max Planck Research · 4 | 2020 PHOTO: IMAGO IMAGES/DANITA DELIMONT Max PlanckResearch CULTURE &SOCIETY ·4 | 2020 distinguish between edible between distinguish young age – like this girl in in girl this young –like age the Ecuadorian rain forest. rain Ecuadorian the and poisonous plants at a plants poisonous and From tree to mouth:From tree children learn to learn children 61 KNOWLEDGE FROM PHOTOS: MPI FOR HUMAN DEVELOPMENT 62

Dried fruit from the tree: in this experiment, the child had observed an adult picking orange dried fruit from a real plant and purple fruit from a silvery artificial plant and eating it. Like most of the children in the test, this child reaches for the fruit that comes from the real plant.

Max Planck Research · 4 | 2020 CULTURE & SOCIETY

both delicious blueberries and the delay does not seem long. However, illustrated using the example of color. poisonous buckthorn. Even mechani- this small window of opportunity Although children avoid green plants, cal defense mechanisms such as could well give parents enough time they readily touch green objects. Be- thorns are found in both edible and to intervene and prevent their child- cause edible plants vary greatly in ap- poisonous plants. Therefore, infants ren from coming into contact with pearance, size, smell, shape, and tex- and toddlers should ideally be wary of the plant. This effect was indepen- ture, the learning process is also com- all plants from birth, so that they do dent of the age of the children. “That plex. When learning to use tools, not accidentally put a poisonous plant surprised me,” says Wertz. “I had ex- children tend to pay more attention to in their mouths. With this thesis, pected that there might be greater shape. But when learning about the Wertz started her postdoctoral posi- differences as children became more edibility of food, they seem to prefer tion in 2009 with Karen Wynn at Yale mobile.” In a second experiment, neither specific shapes nor specific University. To test their theory, she Wertz found out that when it comes to colors. This is only logical if you con- invited parents and their infants to deciding what can serve as a food sider the differences between blue- the laboratory. The infants, aged source, young children distinguish berries, kiwis, and oranges, for exam- eight to 18 months, sat on their par- between plants and artificial objects, ple – although all of them are edible. ents’ laps and were presented with learning through observation that different objects one after the other. you can eat fruits from plants, but not artificial objects. Toddlers aged 18 Distrust These objects were green potted plants, months watched as an adult picked like parsley or basil, as well as artifi- dried fruits attached to a potted plant of vegetables cial plants. There were also novel and put them in their mouth. The man-made objects, which were same procedure was repeated with Despite all their curiosity, many child- matched to the characteristics of the dried fruits that were attached to a sil- ren eventually develop an aversion to plants. “We designed these objects so very artificial plant. The adults then vegetables. Many toddlers push broc- 63 that we could rule out the possibility picked the remaining dried fruits coli florets off their plates in disgust that the infants would simply avoid from a living plant as well as from the or listlessly poke around at their car- any green object or objects with a silvery artificial plant and presented rots. This strong aversion to new plant-like shape,” explains Wertz. Fi- them to the children – most of whom foods is particularly common with nally, natural materials (e.g., shells) chose the fruits that came from the vegetables, and is referred to as food and everyday objects (e.g., spoons) real plant. neophobia. Together with post-doc- were used. In general, the infants toral fellow Camille Rioux, Wertz wanted to touch all the objects. But These first two experiments laid the wanted to test whether it was possible there were big differences in the foundation for Wertz’s research work, to detect the basis for this aversion in speed at which their little hands which she is now expanding upon in infancy. reached out for them. The infants her own research group. She has al- hesitated for only three to five se- ready been able to demonstrate that, To this end, children aged between 7 conds when it came to natural materi- to a certain extent, toddlers can ab- and 15 months were presented with als, everyday objects, and the objects stract information about the edibility plant-based foods at various stages of that were modeled after plants. On of plants. For example, if they ob- processing: whole fruit still on the the other hand, it took about twice as serve that an adult eats an apple from plant, picked fruit, fruit cut into long for the infants to reach out to- an apple tree, they learn that they can strips or slices, and heavily processed, ward the real and artificial plants. eat the apples from other apple trees plant-based foods such as rice wafers. as well. This kind of generalization Control objects were also used, such makes learning about food much as a sponge shaped like a fruit. Once Five seconds more to more efficient. But it is a tremendous again, the infants hesitated longer be- achievement to be able to recognize fore touching plants and the picked intervene an apple tree among a variety of trees. and sliced plant-based foods than Wertz now wants to identify which they did for the heavily processed “With this study, we showed for the first characteristics infants use to catego- foods and the control objects. The in- time that infants are reluctant to rize an object as a plant and to distin- fants also looked for more eye contact touch plants,” says Wertz. This could guish between different types of with their caregivers, possibly to be an evolutionary strategy to protect plants. It does not seem to depend on learn about the correct behavior when young children from poisonous one characteristic alone but rather on dealing with the plant-based foods. plants. At first glance, a five-second the sum of many details. This can be One year after the experiment, the

Max Planck Research · 4 | 2020 KNOWLEDGE FROM

Set up for children: psychologist Annie E. Wertz in the BabyLab.

parents completed a questionnaire about their child’s neophobic beha- viors toward food. It emerged that the children who had hesitated the lon- gest to touch sliced pieces of fruits and vegetables had a more pro- nounced aversion to these foods one year later. Parents with picky toddlers can therefore breathe a sigh of relief. It is not all upbringing – some children seem to be more careful from the very beginning. PHOTO: GESINE BORN FOR MPG

Contact with plants from early infancy

But do these results apply to infants all over the world? Cross-cultural stu- dies are needed to find out. Unlike in the U.S. or Germany, many children in other societies still live in close con- 64 tact with nature and have frequent in- teractions with plants. With the help of an anthropologist from Victoria University of Wellington, Wertz worked with a population of Indige- nous Fijians known as iTaukei. These families live with and from nature, behavior towards plants is deeply an- and most of them also grow their own chored in the brain. Could it be that food. Infants and toddlers in this cul- even primate species related to hu- SUMMARY ture also showed wariness of plants. mans show similar behavior? After all, But there was one major difference. they too face the same challenges Infants and toddlers take much longer to reach for plants than While children from Western socie- when it comes to determining which for other objects. ties typically avoid all plants, iTaukei plants are food and which are deadly. children showed this behavior only Wertz and her post-doctoral fellow By observing adults, they learn with plants they did not know. “These Linda Oña are currently investigating that certain plants or their fruits children have presumably observed this question in five non-human pri- are edible. adults interacting with certain plants mate species. However, Annie Wertz’ Infants and toddlers outside quite often and therefore know that innovative and still growing research industrialized societies who live these plants are safe,” says Wertz. program suggests that learning mech- in close contact with nature Children from Western societies of- anisms have developed through evo- avoid only the plants they do not ten lack this kind of experience. lutionary processes. know.

In a second cross-cultural project, Wertz, Experiments have shown that toddlers who have an aversion in collaboration with anthropologists to fruit and vegetables were also from the University of California, particularly wary of slices Los Angeles, is investigating Indige- of plant-based foods as infants. nous Shuar children in Ecuador. Here too, she would like to find out how the cultural context influences children’s behavior towards plants. The results so far suggest that infants’ avoidance

Max Planck Research · 4 | 2020 “Insight must precede application.” Max Planck One idea, 86 institutes

The Max Planck Society conducts basic research in the natural sciences, life sciences, and human sciences at 86 research institutes.

HUMAN SCIENCES Behavioural Sciences / Cultural Studies / Economics / Humanities / Law / Social Sciences / ...

BIOLOGY AND MEDICINE Behavioural Biology / Cell Biology / Developmental Biology / Ecology / Evolutionary Biology / Immunobiology / Infection Biology / Medicine / Microbiology / Neurobiology / Plant Research / Psychiatry / Structural Biology / ...

CHEMISTRY, PHYSICS, TECHNOLOGY Astronomy / Astrophysics / Chemistry / Climate Research / Complex Systems / Computer Science / Materials Science / Mathematics / Nanoscience / Particle Physics / Plasma Physics / Quantum Physics / Solid State Research / ...

www.mpg.de/institutes KNOWLEDGE FROM

Steel from an eco-friendly forge: in a pilot system in Duisburg, ThyssenKrupp is substituting hydrogen for some of the coal used in iron smelting, thereby

reducing CO2 emissions by up to 19%.

66 PHOTO: PICTURE ALLIANCE/RUPERT OBERHÄUSER ALLIANCE/RUPERT PICTURE PHOTO:

Max Planck Research · 4 | 2020 MATERIALS & TECHNOLOGY

ENERGY REVOLUTION IN THE BLAST FURNACE

TEXT: TIM SCHRÖDER

It’s impossible to imagine modern life without metals, but today’s metal in­ 67 dustry is responsible for a third of all industrial greenhouse gas emissions. Dierk Raabe and Martin Palm, scien­ day, the production of steel, alumi- imperative for the metal industry to tists at the Max-Planck-Institut für num and many other metals is big reduce its CO2 emissions. “There’s Eisenforschung in Duesseldorf, are business – and presents a problem in growing interest in climate-friendly working on a more sustainable way of terms of climate change. Around a production,” says Dierk Raabe. “In producing – and using – metals. Their third of all industrial carbon dioxide the future, industry innovators will ideas could completely revolutionize emissions originate from metal pro- want to advertise these sorts of pro- duction, which also accounts for al- ducts in order to set themselves apart the metal industry. most one-tenth of global energy con- from competitors.” Raabe, a materials sumption. scientist and Director at the Max-Planck-Institut für Eisenfor- There are certain behavioral changes schung in Duesseldorf, is part of a that we can make in order to tackle cli- growing group of experts around the mate change: flying less, traveling by world who are working on more-sus- Everyone knows that extracting and bus or train instead of by car, or limi- tainable forms of metal production forging metal requires heat. Indeed, ting meat consumption. But how can and manufacturing. This will require the production of iron has not funda- we make metal production more cli- the industry to bid farewell to long-es- mentally changed in thousands of mate-friendly? Producing metal re- tablished principles, some of which years: the ore is heated with charcoal quires a lot of heat – that’s unlikely to stretch back thousands of years. or coke, the molten metal is collected change. And it would be hard to make and allowed to solidify, and the mate- do without metal – steel is an essential Steel is largely made up of iron, which is rial is then formed into the desired construction material for buildings, extracted from iron ore in blast fur- shape. This method was already used bridges and industrial facilities, and naces the size of lighthouses. Iron ore 3,500 years ago in Asia Minor when today’s society would be unwilling or is essentially the same thing as pure the Hittites needed iron for their even unable to get rid of cars, ships rust – in other words, iron oxide

swords – although in those days, pro- and aircrafts, which primarily consist (Fe2O3). In order to turn iron oxide duction was limited to a few piles of of metal. Even bicycles are made of into iron, the oxygen must be re- charcoal burning here and there. To- steel or aluminum. That is why it is moved. Even today, this is still

Max Planck Research · 4 | 2020 KNOWLEDGE FROM

achieved by heating the ore with coke sis – as is done with other metals, in- (Fe2O3). Hydrogen would be the best so that – via several intermediate cluding aluminum. This would be a option from a climate protection per- steps – the oxygen from the ore bonds clean undertaking if the necessary spective, provided it was produced with the carbon from the coal. Iron is power were obtained from renewable using electricity from renewable

left behind, and the resulting CO2 es- sources. However, the processes are sources. Following several intermedi- capes. “If we can succeed in establi- still nowhere near sophisticated ate stages, water vapor would then be shing sustainable new methods in this enough and would presumably be in- formed as the exhaust gas instead of area, they will be a powerful tool for capable of producing the huge quanti- carbon dioxide. Before hydrogen can reducing global greenhouse gas emis- ties of steel that are used around the be used to produce pure iron on an in- sions,” says Dierk Raabe. world each year. So at least initially, dustrial scale, however, Dierk Raabe Raabe sees greater potential in replac- and his team still have a few issues to The scientific community is currently ing a proportion of the coal with bio- clarify – such as how the hydrogen discussing various approaches to gas, methane and, above all, hydrogen. can penetrate far enough into the ore green steel production. For example, These substances are also capable of for the iron oxide to react quickly and steel could be produced by electroly- extracting oxygen from iron ore completely. After all, this reaction

68 PHOTO: PICTURE ALLIANCE/JOCHEN TACK

Max Planck Research · 4 | 2020 MATERIALS & TECHNOLOGY

faces an obstacle: the conversion of of wustite so that they fully react with cess,” says Raabe. In the new tech- iron oxide (Fe2O3) to pure iron passes hydrogen,” says Dierk Raabe. His nique, iron oxide is converted into through an intermediate product team is studying the reaction between iron within a plasma state, and the known as wustite (FeO), which has ore and hydrogen at different pres- material it contains is smelted down only one oxygen atom per atom of sures and temperatures with a view to simultaneously. “All in all, hydrogen iron. The problem is that wustite likes identifying the ideal conditions for is going to be a major focus of our to surround itself with a shell of pure, the conversion of wustite into a sort of work over the next 10 to 15 years,” newly formed iron, which is produced permeable nanosponge. “I’m also says Raabe. “With the equipment during the reaction with hydrogen. It currently reading some specialist arti- available here at the Institute, we can takes a long time for the hydrogen, as cles published around 80 years ago by perfectly control iron production well as the released oxygen, to pass Fritz Wüst, the founder of our Insti- with hydrogen and observe it as far through this iron cladding, which can tute,” says Raabe. “He worked in- down as the atomic scale.” This therefore slow down the production of tensely with iron oxide, which is why equipment includes atom probes, iron considerably. “With that in mind, the compound was named after him. which can determine a material’s we’re trying to break down the grains His work provides us with vital infor- composition atom by atom, and trans- mation to this day.” mission electron microscopes, which the researchers can use to inspect the There are other challenges when it ore right down to the electronic level, comes to the reaction between iron as well as equipment usually used to oxide and hydrogen. Gaseous hydro- study the quantum mechanical pro-

gen occurs as a molecule of H2, but it perties of metals and semiconduc- An industry facing is only reactive in the form of an ion – tors. radical change: steel + production – for that is, as H . Accordingly, it must example, at the Tata first be split up (or cleaved) quickly However, switching over to hydrogen Steel iron and steel and without expending a great deal of and green steel will not be without works in IJmuiden, additional energy. “Iron ore always cost, says Christian Vietmeyer, ma- Netherlands – is contains a small proportion of foreign naging director of the Association of indispensable for 69 industrial companies. atoms that, like the iron, are present the Steel and Metal Processing Indus- However, if climate in the form of oxides,” Raabe explains. try (WSM). The association’s mem- goals are to be met, the “We want to find out whether some of bers include companies that process metal industry will need these impurity oxides could act as ca- raw metals, including making auto- to make greater use of talysts to accelerate the splitting of H2 motive parts out of steel. “We strongly energy from renewable molecules.” In that case, the ore itself suspect that the automotive industry sources in the future. would produce reactive H+ ions. “Ac- will be the first to express a clear de- cordingly, we then have to turn our mand for steel with a significantly minds to the issue of catalysis, which smaller carbon footprint. But this isn’t usually the focus of our work,” steel will initially be more expensive.” says Raabe. Steel producers have already called for state subsidies for the green transi- tion, so that German steel production Who will foot the bill can remain competitive in the face of cheaper, conventionally produced for the transition? steel from abroad. “We are very criti- cal of this approach, as it would lead to So hydrogen might not be the most sus- long-term subsidization.” It remains tainable way of producing iron in the unclear, therefore, how the transition long term, because it must first be to green steel production could be fi- converted into its reactive form. Over- nanced. “We take the view that regu- all, the more efficient method would latory policy must seek to achieve this be to use hydrogen plasma. This is the the other way around – by way of cust- most reactive form of hydrogen and is omer demand.” He suggests a re- made up of atoms that have been sep- formed motor vehicle tax as one possi- arated into H+ ions and electrons. bility. Today, cars are taxed according

Formed in the flash of an electric arc, to their CO2 emissions, but Vietmeyer for example, hydrogen plasma reacts says that, in the future, it will be pos- with iron oxide much more vigorously. sible to consider the entire life cycle, “Here, we’re working on a completely including the quantity of greenhouse new alternative to the traditional pro- gases a vehicle had given rise to

Max Planck Research · 4 | 2020 KNOWLEDGE FROM

during its manufacture and the pro- lities can, for example, be achieved by quantities of molybdenum that can duction of the steel used to build it. melting capsules containing liquid seal up fine pores. In other words, in or- Dierk Raabe also recognizes that the plastic ingredients into components der to reduce greenhouse gas emissions development of climate-friendly in order to fill cracks if the need arises. in the metal industry, it also makes methods of iron and steel production “The plastics themselves notice when sense to preserve these products, won’t be enough: “There is a need for damage occurs. Aluminum and iron instead of building them again. a continuous chain from the basic re- haven’t reached that stage yet – there’s search through to a good understand- still a lot of work to do,” says Dierk ing of the steel manufacturing pro- Raabe. That being said, some initial Recycling is to cess.” The transition to lower-carbon or even carbon-neutral production of become simpler iron and steel will require companies to invest large sums of money. “Hasty SUMMARY When it comes to sustainability, alumi- and potentially incorrect decisions num faces similar problems to those could pose a threat to their survival,” Approximately one third of the affecting iron and steel. Aluminum is

says the researcher. world’s industrial CO2 emissions produced in “electrolysis cells” that come from the production of operate at very high temperatures and It is certainly a gargantuan undertaking, metal. Emissions from steel consume large quantities of power, so with global demand for steel standing production could be reduced if at its production is every bit as ener- least part of the required coal at 1.8 billion tons per annum – an al- were replaced with methane, gy-intensive as that of steel. “Alumi- most inconceivable quantity of metal biogas or, above all, hydrogen. num recycling is therefore a key factor, that corresponds to almost twice the because melting down scrap alumi- weight of all cars currently on the In order to use hydrogen to num only requires about 5% of the road. With this in mind, a more sus- produce steel on an industrial energy,” says Dierk Raabe. However, tainable method of steel production scale, Max Planck researchers many industries take a dim view of are working to speed up the would indeed be an important tool chemical reaction. They are also aluminum that contains recycled ma- when it comes to climate protection. investigating the possibility of terial, because it could contain impu- But there are also other aspects to producing steel in a completely rities. In particular, contamination 70 consider, says Raabe. One major issue new process using hydrogen with iron and copper – from screws or is longevity. “It’s estimated that some plasma. cables included in the scrap alumi- 3.5% of global GDP is lost to corro- num, for example – can influence the Improved corrosion protection sion alone – and these huge losses and a higher recycling rate could properties of the aluminum during could be avoided if metals, buildings also help to reduce the carbon processing or when a part is exposed and products were more durable.” and energy footprints of metal to mechanical loads. In the aviation The fact that car bodywork is fully products. industry, for instance, aluminum that galvanized is, he says, a testament to contains recycled material is mostly As iron aluminides are the value of corrosion protection and corrosion-resistant, lightweight ruled out due to safety concerns. has meant that – unlike 30 years ago – and readily recyclable, they “Aluminum alloys have to satisfy 20 or cars are no longer destroyed by rust. represent a sustainable sometimes 30 parameters laid down However, corrosion protection is alternative to steels. By adding by the manufacturers,” says Dierk about more than simply sealing the boron, Max Planck researchers Raabe. “Impurities can change their surfaces of metals, says Raabe. For ex- have also succeeded in properties.” However, many manu- optimizing the alloy for use at ample, many bridges are apparently high temperatures – for example, facturers won’t even use the unmixed now being demolished after standing in turbines. production waste from their own for only a few decades, because we manufacturing process. Nowadays, don’t know how advanced the corro- for example, a laptop housing is milled sion is inside the structures. “There from a block, and more than half of are neither sensors nor pH meters nor the material is lost as chips. It is still voltmeters to give us information on ideas have already been floated. One mostly less expensive for the manu- the material’s condition – it’s like possibility is that, when oxygen enters facturers to buy new aluminum alloy we’re in the Stone Age.” For Raabe, the material as a result of damage, than to process their own scrap. self-monitoring features of this kind solid metal oxides could form in order are indispensable in the modern era. to repair minor defects. Likewise, For some time, Dierk Raabe has been pores in some alloys can seal them- working with his team to conduct a In addition to this measurement technol- selves at high temperatures by means systematic study of how the behavior ogy, another possible solution would of atomic transport processes. Indeed, of aluminum changes in response to be metals with self-rejuvenating or the Duesseldorf researchers have the tiniest recycling-related impuri- self-repair capabilities – which al- been involved in another project, in ties – and is one of the first scientists ready exist in plastics. These capabi- which steel was mixed with small in the world to do so. He is initially fo-

Max Planck Research · 4 | 2020 MATERIALS & TECHNOLOGY

71 PHOTO: FRANK VINKEN FOR MPG

On the hunt for sustainable metallic materials: Martin Palm and Angelika Gedsun produce lightweight, durable and cost-effec- tive iron aluminide alloys in an induction furnace.

Max Planck Research · 4 | 2020 KNOWLEDGE FROM MPI FÜR EISENFORSCHUNG /

Heat-resistant, thanks to GRAPHIC: ANGELIKA GEDSUN nanoparticles: the alloy is prevented from softening at high temperatures by tiny boron-containing deposits at the boundaries between the iron aluminide structures, which are shown in different colors in the microscope image.

72 25 μm

cusing on what he terms the “big in elevator cladding or spare tire wells tively light and could therefore help to problem bears” – iron and copper. in car trunks. improve the sustainability of metal Working in a vacuum, his team depo- products. For a long time, however, sits pure aluminum onto a surface and one factor has stood in the way of a then gradually mixes in iron to pro- Considerable interest major breakthrough: the materials duce an iron gradient within the ma- lose their strength at temperatures terial sample. This allows the re- from industry above 700 degrees Celsius. At the searchers to seamlessly track detailed same time, their low weight means changes in the aluminum’s character- Whereas Dierk Raabe tends to view iron they would be especially suitable for istics as the iron content increases. in aluminum as an impurity, this is turbines in power stations and air- Their objective is clear: in the future, not the case for Martin Palm, head of crafts – because less mass requires it should be possible to mix increasing the “Intermetallic Phases” research less fuel. In the last few years, howe- amounts of scrap aluminum into alu- group at the Max-Planck-Institut für ver, the materials scientist Martin minum alloys without reducing the Eisenforschung. Indeed, Palm sees a Palm and his team have solved the quality of the products. “How dirty bright future for materials that delibe- temperature problem. Specifically, can the child get and still stay healthy? rately combine the two elements. For they have made iron aluminides That’s what we want to find out,” says a number of years, his work has fo- heat-resistant by using sophisticated Raabe. “If we achieve 90% of the de- cused intensively on iron-aluminum methods to penetrate deep into their sired product parameters with recy- alloys, which are seen as a future sub- microstructure. cled aluminum, that will be sufficient stitute for expensive steels with ad- for many applications.” Although mixtures of nickel, chromium or co- If you look at solidified metal under an safety-relevant applications would balt. Iron aluminides are corrosion- electron microscope, you can clearly initially be ruled out, this green alu- and wear-resistant and hence ex- make out light and dark areas along- minum is easily good enough for use tremely durable. They are also rela- side one another – like countries on a

Max Planck Research · 4 | 2020 MATERIALS & TECHNOLOGY

GLOSSARY map. Experts refer to these “coun- compounds, for example, they are not ELECTROLYSIS tries” as metallic phases. They differ ecotoxic. Given the advantages of This is a process in which in terms of their chemical composi- these materials, there is considerable electricity is used to break tion and atomic arrangement, because interest from industry. Martin Palm’s down substances such as water atoms join together in different ways partners therefore include Siemens, or metal oxides into their from one place to another as the alloy Rolls-Royce Deutschland and the constituent parts. Industry solidifies – forming phases that con- company Leistritz Turbinentechnik, produces hydrogen and aluminum electrolytically, but tain more iron or more aluminum, for among others. In Palm’s view, the steel can also be produced in example. This separation into diffe- Duesseldorf researchers can clearly this way. rent phases is what gives iron alu- put their unique expertise regarding minide alloys their strength – at least alloys to good use – after all, this PHASE at low temperatures. “Unfortunately, know-how is almost non-existent in In chemistry, this term refers when they get very hot, the phases industry today. “We have the plant to an area of matter with uniform physical and chemical tend to merge with one another, cau- technology to produce the alloys, but properties. In a material, areas sing the material to soften,” explains above all we have the fundamental with different compositions Martin Palm. However, his team has knowledge about phase transitions – are described as different succeeded in finding ways to sup- in other words, how alloys and their phases. press this merging of phases, inclu- phases change with temperature.” We ding by mixing low concentrations of can therefore look forward to the day PLASMA In the fourth state of matter, boron into the alloy. When the alloy when the first lightweight iron alu- the particles of a gaseous solidifies, the boron forms boride minide turbine goes into operation. substance are entirely or nanoparticles that accumulate at the And, of course, it should ideally run partially ionized – in other phase boundaries like poppy seeds on on environmentally friendly biofuel – words, they take the form of a bread roll. And, as borides are or even hydrogen. This outcome positively charged ions and among the most heat-resistant mate- would represent a big achievement in free electrons. rials, they prevent the iron aluminide terms of sustainability. 73 phases from merging with one an- other at high temperatures. Martin Palm has therefore paved the way for a prosperous future for iron aluminides. “There’s no doubt about it: the indus- try will inevitably turn its attention to iron aluminides in the next few years, because all of the other elements in to- day’s alloys are gradually becoming scarce.” Iron and aluminum are the most common metals on earth and are available in large quantities, whereas reserves of chromium, cobalt and nickel have already shrunk signifi- cantly. These scarcer metals are therefore becoming a plaything for speculators – and their prices are be- coming incalculable. “Even today, iron aluminides would be 20%

cheaper than chromium steel and as PHOTO: FRANK VINKEN FOR MPG much as 80% cheaper than ni- ckel-based alloys,” says Palm. “This trend is set to intensify.”

There is another characteristic iron alu- minides have that makes them unusu- ally sustainable: they require almost Masterminding a sustainable metal industry: Dierk Raabe sees no other alloying elements and there- the increased recycling of scrap aluminum, for example, fore offer excellent recyclability. as an opportunity to reduce the industry’s carbon footprint. Moreover, unlike certain chromium

Max Planck Research · 4 | 2020 KNOWLEDGE FROM

74 IMAGE: N. FISCHER,IMAGE: N. H. PFEIFFER, PHYSICS, SIMULATING EXTREME FOR A. BUONANNO/MPI GRAVITATIONAL COLLABORATION SPACETIMES (SXS)

Space quakes: collisions of black holes shake the space-time fabric and cause gravitational waves. Albert Einstein predicted this effect in his general theory of relativity and these waves were detected for the very first time a century later in September 2015. The relevant cosmic scenarios are described in numerical simulations such as these.

Max Planck Research · 4 | 2020 PHYSIK & ASTRONOMY

A BIG FISH IS MAKING BIG WAV ES

TEXT: HELMUT HORNUNG

It should not actually exist – a black hole with a mass 85 times that of our sun. But that is precisely what astrono- mers have discovered. Apparently, this heavyweight used to be part of a But what lies behind this cosmic quiver? out in the universe. The signal de- 75 In the ultimate analysis, general rela- tected on September 14th, 2015, for ex- binary star system before it merged tivity is a field theory, according to ample, was caused by two black holes with its equally massive partner. The which the accelerated motion of that merged in a fraction of a second resulting space-time quake unleashed masses within the gravitational field following a turbulent dance of death. gravitational waves that are posing results in disturbances that propagate Each of the objects, which were about at the speed of light. These distur- 1.3 billion light-years from Earth, had many a puzzle for researchers at the bances are referred to as gravitational a mass around 30 times that of the Max Planck Institute for Gravitational waves. It sounds incredible, but they sun. Physics in Potsdam and Hanover. stretch and compress the space through which they pass. Theoreti- By the time this issue of Max Planck cally, they occur when, for example, a Research went to press, scientists had child bounces around on a trampoline. reliably detected 50 gravitational But humans have a small mass and wave events since their initial discov- bounce comparatively slowly, so the ery five years ago. The majority of Gravitational waves are messengers gravitational waves the child causes these events were caused by colliding from the dark universe. Albert Ein- are immeasurably minuscule. black holes, and such discoveries had stein described them in two papers gradually become a matter of routine. published in 1916 and 1918 respec- By contrast, masses out in the universe But something powerful occurred on tively, but temporarily came to doubt are large and there is even a “trampo- May 21st, 2019. Rather than detecting their existence during the 1930s. In line”, i.e. space-time itself, in which a “chirp” in the LIGO (U.S.) and any case, he considered these waves – everything is in constant motion, be- Virgo (Italy) detectors, what the whose existence is predicted by his cause there isn’t a single celestial body astronomers perceived was, as it were, general theory of relativity – to be im- that remains motionless in one place. a plop! It lasted just a tenth of a second measurable. However, they became The Earth creates a bulge in the fabric and reached a maximum frequency of entangled in the scientists’ finely of space-time too as it orbits the Sun, only 60 Hertz – the lowest observed spun web for the first time on Sep- emitting gravitational waves with a so far. tember 14th, 2015, and shook the two power of 200 watts. But even these Advanced LIGO detectors at the waves are too weak to be detected. “Right from the beginning,” says Ales- Hanford and Livingston sites in the However, there are some extremely sandra Buonanno, Director at the U.S. large masses and super high velocities Max Planck Institute for Gravita-

Max Planck Research · 4 | 2020 KNOWLEDGE FROM

tional Physics in Potsdam, “this ex- form when heavy stars reach the end SUMMARY tremely short signal presented a chal- of their lives. When the nuclear fuel in lenge when it came to identifying its the interior is depleted, the stellar gas Astronomers used gravitational wave detectors to observe the origin. But we were able to match the spheres first enter an energy crisis coalescence of the most massive signal to one expected of black-hole phase and then become unstable be- black holes to date. mergers.” Based on the recently ana- fore finally exploding as supernovae, lyzed data, the scientists conclude the leaving behind a lightweight black This event was the first time event involves two true heavyweights hole. At the other end of the weight the scientists had witnessed of around 85 and 65 solar masses, re- range of these gravity traps, scientists the formation of an intermedi- ate-mass black hole. spectively. This event, referred to as suspect the presence of extremely GW190521, also broke another re- heavy stars that, rather than explo- Prior to the merger, one of the two cord: the merger happened about ding as supernovae at the end of their black holes had had a mass equivalent seven billion years ago when the uni- lives, immediately collapse with no to 85 solar masses and – in theory – verse was just half its current age. such fireworks, to form intermedi- should not exist. And because looking into the uni- ate-mass black holes of over 120 solar verse’s past also entails a journey into masses. the distance, the signal is the most distant ever observed.

What’s more, eight solar masses were converted into gravitational energy during that cosmic collision, resulting in the creation of a colossus with 142 times the mass of our home star. “We realized we had witnessed, for the first time, the birth of an intermedi- ate-mass black hole,” says Alessandra 76 Buonanno. Scientists had only ever suspected the existence of such ob- jects, which are heavier than the lighter black holes with masses of up

to 65 times that of the Sun, and less PHOTO: SVEN DÖRING FOR MPG massive than the extremely heavy ones at the centers of galaxies. In short, their masses equate to around 120 to 100,000 solar masses.

All of this sounds very plausible. Yet one of the protagonists involved in the GW190521 event confounds expecta- tions: “According to our understand- ing of how stars age and evolve,” says Frank Ohme, group leader at the Max Light into the dark: Planck Institute for Gravitational Alessandra Buonanno is developing Physics in Hanover, “we would ex- theoretical models to pect to find black holes with masses of identify and interpret either less than 65 solar masses or gravitational-wave greater than 120 solar masses, but signals. The work none in between.” However, this is being carried out by the Director at the precisely the gap into which the black Max Planck Institute hole of 85 solar masses falls. “Either for Gravitational our understanding of stellar evolution Physics is helping to is incomplete, or something funda- decode the secrets of mentally different took place here,” black holes and Ohme concludes. neutron stars and allows conclusions to be drawn about the According to astronomers’ models, black physical properties of holes of up to about 65 solar masses these exotic objects.

Max Planck Research · 4 | 2020 PHYSIK & ASTRONOMY

This gives rise to the mass gap of GW190521 around 65 to 120 solar masses men- tioned by Frank Ohme, in which no stellar black holes ought to exist be- cause, theoretically, those stars from which black holes could form within this range fail to explode as superno- GW150914 vae and therefore do not collapse into black holes. Instead, these stars un- dergo one or more brief episodes of instability, during which they eject GW170608 significant quantities of their matter. Only following this radical weight loss will a star remain, which then GW190814 explodes in a supernova to produce a black hole, but this will have a mass of less than 65 solar masses.

So how was the black hole with 85 solar masses created in the GW190521 event? One possibility is that our

current evolutionary models of stars GRAPHIC: K. FERGUSON, JANI, SHOEMAKER, D. D. TECH, COLLABORATION GEORGIA LAGUNA, MAYA P. are flawed or incomplete, and that certain supernovae may still spawn Heavyweights: this graphic shows a freeze frame from a black holes with masses in excess of numerical relativity simulation of the GW190521 event. About seven billion years ago, two black holes with about 85 and 65 solar 65 solar masses. However, the re- masses had merged – a record! For comparison, the image on the searchers consider this rather un- left shows a schematic representation of the masses involved in likely, as Alessandra Buonanno ex- other gravitational wave events. 77 plains: “My assumption is that this object emerged from an earlier merger of a binary system, probably as the result of a coalescence of two smaller black holes or of two massive stars.” GLOSSARY In fact, according to the general theory of relativity, the signal could be well However, in the final analysis, none GRAVITATIONAL WAVE described as a merger of two black of these scenarios quite fits the DETECTOR holes. Nevertheless, the scientists data. The largest facilities currently are also investigating other potential in operation are LIGO in the explanations for their observation, “We don’t yet know whether the U.S. and Virgo in Italy. Their for example that the signal may be GW190521 event represents an en- working principle involves the result of an interaction between tirely new class of binary black holes, interferometry: laser light travels in two vacuum tubes, or cosmic strings, i.e., hypothetical ob- or just the high-mass end of the arms, arranged at right angles jects that may have formed in the source spectrum we’ve observed so to one another. These arms early universe. Or could it be the re- far,” says Karsten Danzmann, Di- lengthen or shorten whenever sult of a supernova after all? Could rector at the Hanover-based Max a gravitational wave passes GW190521 ultimately be not nearly Planck Institute. “Hopefully, we’ll through the detector, which as distant as it seems, and the event know more once we’ve analyzed all causes the laser light waves to get out of sync, thereby thereby involves less massive black binary black hole mergers seen by altering the intensity of the holes, which in fact merged at a LIGO and Virgo during their third measured light. The LIGO shorter distance from Earth, and observation run (O3).” The scien- sites in Hanford and their waves were subsequently dis- tists certainly have no shortage of Livingston each have arms torted by a gravitational lens? And data to work with. During the O3, that are four kilometers long, finally, could the signal have been which lasted from April 1st, 2019 to while the Virgo site in Tuscany th uses tubes that are three generated by primordial black holes March 27 , 2020, they recorded data kilometers long. that formed in the infancy of the uni- from no fewer than 56 potential verse before the first stars appeared? gravitational wave candidates.

Max Planck Research · 4 | 2020 KNOWLEDGE FROM

A prospect for climate protection: as long as forests grow, they absorb large amounts of the

greenhouse gas CO2.

78 PHOTO: ADOBE STOCK

Max Planck Research · 4 | 2020 ENVIRONMENT & CLIMATE

FORESTS CHANGE THE CLIMATE

TEXT: KLAUS JACOB

Forests can remove large amounts of CO2 from the atmosphere. So far, there is consensus about this throughout the scientific community. Researchers at ETH Zurich led by Jean- Many experts are deliberating the ques- However, there is some dispute about François Bastin have even calculated tion of how the world’s forests must be how forests can best protect the that large-scale afforestation could transformed in order to resist climate 79 climate – whether they should solve the climate problem – at least for change. In this context, they also dis- the next few decades. However, many agree about what kind of forest is the be managed sustainably or left undis­ experts doubt that this is realistic – most favorable for climate mitigation. turbed. Right in the middle of this partly because an area of the size of Is it better to leave a forest alone – as is dispute is Ernst-Detlef Schulze, the U.S. would have to be planted the case in some nature reserves? Or Director Emeritus at the Max Planck with additional trees, at a time when can a forest benefit the climate more if Institute for Biogeochemistry in Jena. suitable areas for afforestation are be- it is managed sustainably? Ernst- coming increasingly scarce as a result Detlef Schulze, Director Emeritus at of climate change and of intensified the Max Planck Institute for Biogeo- competition with food production in chemistry in Jena, has studied the fo- many places. Development is cur- rests in Central Europe together with rently pointing in a different direc- other scientists – and has come to a The fight against climate change can be tion. According to the UN Forest Sta- conclusion that may sound surprising won only with allies – and forests can tus Report for 2020, around 10 mil- at first. Schulze calculates that a be one of them. They are a natural lion hectares of forest are lost every sustainably managed forest makes a counterpart to oil and coal because year – an of area the size of Bavaria much greater contribution to climate

trees assimilate CO2 from the atmo- and Baden-Wuerttemberg combined. mitigation than one that is left undis- sphere, convert it into sugars with the In Brazil, plantation owners are burn- turbed. help of sunlight, and use it to produce ing the Amazon rain forest. They are wood, among other things. On aver- encouraged by a president who be- The reason is that a natural forest helps age, one cubic meter of wood contains lieves that the export of agricultural the climate only if it is growing (i.e., if about 0.3 tons of carbon, which corre- products – not least to Europe – is the mass of its wood – and thus of se-

sponds to about 1 ton of CO2. Thus, more important than climate and en- questered carbon – is increasing). In forests remove huge quantities of vironment. In the U.S., increasingly older forests, where the wood incre- greenhouse gases from the atmo- devastating wildfires are blazing; ment is reduced, the carbon balance sphere. Along with the oceans, forests these are exacerbated by climate has largely reached equilibrium. And are one of the world’s major “carbon change. And in Europe, heat, drought, as soon as trees die and their wood sinks” (to use the experts’ termino- and storms are damaging the forest, rots, the stored carbon is released as

logy) – and for Germany, forests are making it easy for bark beetles and CO2. What’s more: the forest can even the nation’s largest sink. harmful fungi to take hold. become a source of carbon, for exam-

Max Planck Research · 4 | 2020 KNOWLEDGE FROM

ple when drought, windthrow, or Schulze assessed the CO2 flows for relatively low energy input instead of pests, such as the bark beetle, attack German commercial forests (as far as using materials that require more en- the vegetation – as can currently be the data allowed) and concluded that ergy input or from fossil raw materi- seen in the Harz Mountains. A study replacing fossil fuels with wood alone als, such as a house constructed of

by the University of Leeds confirms: saves 1.9–2.2 tons of CO2 per hectare wood instead of concrete or bricks. the capacity of undisturbed tropical of commercial forest per year. How- “We estimate this contribution of the

forests to absorb CO2 has been decli- ever, this applies only if the wood ac- forest to reducing CO2 emissions to be ning since the 1990s. Scientists warn tually replaces oil or coal. If Germany about 2.8 to 4.9 tons per hectare per that the Amazon could even become a were to begin generating 100% of its year,” says Schulze. This contribu-

source of CO2 by the mid-2030s. energy from wind and solar resources, tion is in addition to the replacement this calculation would no longer add of fossil fuels and the increment of However, different rules apply to man- up, even though wood is also a renew- wood volumes. Schulze and his col- aged forests. There is no natural state able resource. leagues have published their results in of equilibrium here because logs are the journal “Biologie in unserer Zeit”. constantly being removed. According But does a managed forest really con- to data from the Federal Ministry of The climate balances tribute more to climate protection Food and Agriculture from 2014, than a natural one? Schulze has also about 11 m3 of wood per hectare grow of different forests calculated that it does. But we must each year in German forests. Most of also bear in mind that true primeval this is used commercially. Only a Not all wood that grows back is har- forests have not existed in Germany small proportion of this wood decays vested. Schulze assumes that only since time immemorial. German fo- on the forest floor, and roughly two- about two thirds of the growth is re- rests have been used and cultivated in thirds of the annual growth serves hu- moved. About one third remains in one way or another since ancient mans in many ways. The wood is pro- the forest. Among other things, the times. cessed into durable products (such as wood volumes of forests grow. Ac- wooden houses or furniture), used in cording to the calculations made by Today’s nature reserves, in which the consumer goods (including paper, Schulze and his team, each hectare forests are left undisturbed, are all 80 cardboard, or tissues), or provides removes 1–2 tons of CO2 from the at- relatively young. They have by no cozy warmth in the form of firewood mosphere every year stored in bio- means reached the stage where the or pellets. Wood that is burned re- mass. On average, the replacement of carbon dioxide balance has reached places fossil fuels. Without firewood, fossil fuels and the increase in wood equilibrium. They are therefore capa-

many homeowners would turn to oil compensates the CO2 emissions or ble of sequestering additional CO2 for

or coal. However, many durable pro- CO2 concentration of around 3.5 tons years or decades to come. These years ducts are also incinerated after use per hectare of forest. In the meantime, are particularly important for climate and thus serve to generate energy. In a group led by Schulze has also quan- mitigation while restructuring of the an article published in early 2020 in tified how much greenhouse gas the energy industry is being driven for- the journal Global Change Biology – atmosphere would be spared if prod- ward. In Germany, about one-third of Bioenergy (GCBB), a team led by ucts were made out of wood requiring the land area is forested, of which around 3% goes unused. But which nature conservation area provides meaningful figures for comparison? A passion for forests: after his retirement, the forest scientist and There are very different kinds of fo- biologist Ernst-Detlef Schulze acquired tracts of forest, which rests: deciduous, coniferous, and he manages with great care. mixed forests: young and old forests, forests growing on sandy soil, lime- stone, or clay; forests in mountainous or flat terrain, forests interspersed with large and small clearings. We should be ascertaining the growth in each forest and calculating its average value. However, we don’t have enough data to accomplish this. In his article in GCBB, Schulze cited forest inven- PHOTO: JACOB KLAUS tories in Hainich National Park in Thuringia from 2000 and 2010 for comparative calculation. At the turn of the millennium, the survey documented a timber inventory

Max Planck Research · 4 | 2020 ENVIRONMENT & CLIMATE

TIMBER GROWTH IN THE HAINICH

A according to Schulze B according to Grossmann I C according to Grossmann II Different perspectives: Schulze’s team considers the 2000 inventory Hainich as an operational unit (A). The fact that the forested area sampled (shaded area) has increased in size between 2000 and 2010 is irrelevant here. The young, thin trees on the new forest plots only lead to a slight reduction in the 2010 timber stock inventory. This results in an increase of only 0.4 m3/ ha/yr. In the 2010 inventory, researchers led by Manfred Grossmann therefore 5,015 ha 363.5 m3/ha 5,015 ha 363.5 m3/ha 5,287 ha 306.0 m3/ha consider either only the areas that were already forested in 2000 (B), for which they

GRAPHIC: GCO 2010 inventory determine a wood increment of 9 m3/ha/yr. Or they factor the areas that were newly forested in 2010 into the 2000 inventory as areas without wood supply (C) and arrive at a wood increment of 6 m3/ha/yr.

81

5,287 ha 367.5 m3/ha 5,015 ha 453.0 m3/ha 5,287 ha 367.5 m3/ha

Timber growth 0,4 m3 9 m3 6 m3 /ha/yr /ha/yr /ha/yr

Operational unit Area with measurements Area without measurements Older forest Younger forest

of 363.5 m3/ha; 10 years later, This calculation sparked fierce criticism, Schulze justifies his approach with the figure was 367.5 m3/ha. Using which led to weeks of heated exchange the fact that the Hainich is an opera- these figures, as published by the in specialist journals and the media. tional unit that must always be con- National Park, as a basis, Schulze The bone of contention was that the sidered as a whole – even if partial are- arrived at an increase of 0.4 m3/ha/yr size of the forest area in the Hainich as grow and shrink in size and the for the unmanaged natural forest. had increased between the first and number of sample points changes.

This corresponds to a CO2 equivalent the second inventory. Thus, the num- “The national forest inventory follows of 0.37 tons – compared with ber of sample points increased from the same procedure. Only then can 3.2–3.5 tons in the commercial forest. 1,200 to 1,421. Where before there had we compare the results,” Schulze ex- Schulze’s conclusion: a sustainably been only bushes, 10 years later, arm- plains. managed forest is about 10 times thick saplings had grown. This young more beneficial to climate protection forest reduced the average timber However, Forest Torsten Welle from than a natural one. The use of wood stock because the figures always re- the Natural Forest Academy in in durable products was not even ferred only to the forested area of the Luebeck thinks this kind of calcula- considered here. National Park as a management unit. tion is wrong: “This is cherry-pi-

Max Planck Research · 4 | 2020 KNOWLEDGE FROM

cking!”. The head of the Hainich Na- the former is still growing and the CO2 applied, sustainably managed forests tional Park, Manfred Grossmann, savings from wood products are not do not contribute 10 times more to

also criticizes the approach. He sug- taken into account. Forestry scientist CO2 storage than unmanaged ones. gests a different calculation: if you and ecologist Henrik Hartmann, a However, they are at least as beneficial consider only the 5,015 ha with 1,200 colleague of Schulze’s at the Max to climate protection. “That, too, measuring points from the second in- Planck Institute in Jena, also believes would be a good argument,” says ventory that were recorded in the first, Schulze has left himself open to criti- Hartmann. However, Schulze and his you get an annual increase of just un- cism with his comparison with the co-authors use only the Hainich Na- der 9 m3; this corresponds to about 9 t corrected reference area. Moreover, tional Park in Thuringia for a direct

of CO2 absorbed from the atmosphere. he thinks Schulze should have looked comparison with commercial forests. And for a reference area of 5,287 ha at additional nature reserves, includ- Schulze justifies this by saying that with 1,421 measurement points (i.e., if ing ones outside Germany. Corre- they wanted to draw up a balance for part of the area is included in the cal- sponding figures for natural parks in Germany and that no further inven- culation as unforested in 2000), it Slovakia are even listed in the paper. tory data of National Parks in Ger- comes to 6 m3/ha. In terms of climate When they are factored in, the average many were available for this purpose. protection, both values mean that the increase in the wood supply of unma- natural forest rates better than the naged forests totals approximately The data from the Slovakian nature re- commercial forest – but only as long as 3 m3/ha/yr. When this calculation is serves were from relatively small ex-

FUNCTIONS AND BENEFITS OF THE FOREST

Versatile green: forests

not only absorb CO2 and counteract climate change, they also store water and provide a habitat for many plants and animals. 82 Furthermore, they provide wood that is

CO2 reservoir processed into paper and furniture, used in construction, and made available as an alternative energy source. People go to the forest to hunt or relax.

Hunting

Biodiversity

Recovery

Material degradation

Max Planck Research · 4 | 2020 ENVIRONMENT & CLIMATE

perimental plots, not comparable to judge whether protecting forests is the Director Emeritus, who at the be- National Inventories. Therefore, they better for protecting the climate than ginning of his career was on a path to did not take into account all of the using wood for energy. taking a high-up position in the For- changes found in a contiguous forest est Service. As a forest owner, he has area, such as losses resulting from The discussion shows that forest inven- learned not only about the ecological storm or beetle damage. “The only tories and plot studies have their but also the economic and social as- way to do that is to conduct invento- limitations. Timber inventories take pects of forest management. One of ries at the landscape level,” says only the trunk wood into account – his forests surrounds a long-extinct Schulze. The Thuenen Institute of and only from trees that are thicker volcanic cone, and the terrain is fairly Forest Ecosystems, which reports to than seven centimeters in diameter at steep. The 79-year-old clambers up the Ministry of Agriculture and pub- breast height (DBH). But carbon is the 400-meter elevation difference lishes the annual forest condition sur- also in the soil: in the roots, in the soil with the vigor of someone half his age. vey, supports Schulze and his team – litter, in the mineral soil, and in the When you ride along the breakneck albeit with reservations. They believe underground biomass. Critics of the paths with Schulze in his off-road ve- that the Hainich is not representative climate balance drawn by Schulze hicle, you get the impression that he is of a typical German forest because it and his colleagues also argue that the talking about a garden that he lovingly is on limestone terrain. Based on side effects of logging are not taken tends. In one place, he bemoans the these figures alone, it is impossible to into account: to get to the logs, heavy loss of some hundred-year-old machinery must work its way through beeches that were damaged by a late the undergrowth; this can alter the frost and will probably die sometime soil structure. Pierre Ibisch, a profes- in the next year. In another, he has sor at the Eberswalde University for planted a few rowan trees. But these Sustainable Development, also points do not seem to be thriving. Apart out that complete clearance leads to a from individual spruce monocultures, significant increase in temperature the forest, with its abundance of because the sun’s rays can then reach bushes and undergrowth, appears the ground. He says that even thin- wild and rich in biodiversity. No won- ning, which creates more space for us- der it is popular with hikers, espe- Fuel able trees through selective interven- cially because the ancient volcano is tions, leads to warming. German for- the highest elevation in the area. The 83 Building esters therefore describe it as “hot rocks at its summit are an attractive materials cutting”. The consequences: the destination. But these visitors are giv- ground heats up, carbon dioxide es- ing Schulze cause for concern. He has Cellulose capes, and the trees at the edge of the painstakingly built paths in order to new clearing come under stress. be able to harvest wood. But the hi- kers leave their trash behind, and Comparing a natural forest with a ma- mountain bikers recklessly race down naged forest is always risky from a sci- to the valley, frightening the wildlife. entific point of view. This is because He bears the costs, while others are many assumptions have to be made benefiting from his investment and because not all details have been re- dedication. searched yet. In addition, a forest not only protects the climate – it also per- forms a variety of tasks and has envi- Too many deer ronmental advantages. People there- fore seek forests for recreation, hiking, Schulze shows me a photo of a stag in a cycling, and jogging. Forests also clearing on his phone. What would store water and thus prevent flooding. delight any city dweller presents ano- At the height of summer, they lower ther problem for Schulze. There are temperatures through evaporation. simply too many deer. Large preda- Finally, forests provide a habitat tors like bears or wolves, which could for many plant and animal species, help to decimate the population, were including deer, which like to eat wiped out centuries ago. Even though the shoots off young trees in particu- wolves are gradually returning and lar. lynx are back in some forests – inclu- ding Schulze’s – there are too few natu- Schulze, who owns several tracts of fo- ral enemies of the deer. Moreover,

GRAPHIC: GCO, ILLUSTRATIONS: ISTOCK rest, knows all this from experience. when forest owners are primarily con- “I bought the forest because I wanted cerned with hunting, they feed the to manage it in my retirement,” says animals throughout the winter. The Water reservoir

Max Planck Research · 4 | 2020 KNOWLEDGE FROM

animals then continue to gnaw away at the young trees during the rest of the year. Schulze prevents this by putting up fences – a lot of them. But even intensive hunting does not limit the game population – because ani- mals keep migrating into his relatively small forest. But the problem under consideration goes beyond gnawing dear and reckless mountain bikers. The challenge is ultimately how to manage forests in Germany and Eu- rope in the future. Forests are about to reach a turning point. On the one hand, the trees are supposed to have effects on climate change. On the other, climate change is increasingly affecting trees. According to the 2019 German Forest Survey, the crown condition “has never been as bad as in 2019.” Not even a quarter of the trees had a healthy crown. The dry sum- mers are increasingly leaving their mark – with long-term consequences. Pierre Ibisch speaks of the “physio- logical memory” of trees. And there is no sign of climate change letting up;

in fact, temperatures are continuing PHOTO: PICTURE ALLIANCE/IMAGEBROKER | ANDREAS VITTING to rise. Ibisch warns that in the long 84 term, a forest steppe with a high pro- portion of grass could even develop in many places. Even today, storms, bark beetles and fungi are already destroy- ing entire forests. In turn, the large amount of damaged timber causes timber prices to fall. Forest owners are extremely concerned about this – Shaped by humans: in the 15th century, mendicant monks cut a cavity into the oak according to Ibisch, there is even a tree so that travelers could leave alms inside it. Over time, the hole grew, and the sense of panic. Many of them sell off landmark of the Hainich National Park gradually took on its current appearance. the damaged spruce wood to China in order to at least partially mitigate their losses. And they’re cutting down their beech trees while they are still relatively healthy. According to the Thuenen Institute, in 2018, felling in- enthusiasts embrace trees to For example, they could benefit from

creased by 10% compared with the strengthen their souls, and some peo- a CO2 tax levied on the burning of fos- previous year because of the removal ple even express a desire to be buried sil fuels. But if one assumes that a nat- of damaged timber. However, it stabi- under oaks or beeches when they die. ural forest protects the climate better lized again to some extent last year – However, sometimes the love of fo- than a commercial forest, then de- albeit at a high level. rests goes too far: Hartmann learned mands would be made for a policy that environmental activists in Wei- that leads to different measures being The human psyche also plays a role mar have destroyed forestry workers’ implemented. Large swathes of the when it comes to forests, and this can machinery in order to prevent logging. German forests would have to be left

hinder objective discussion. Almost Against this background, a calcula- undisturbed, and a CO2 levy would be everyone instinctively feels at ease tion like the one Schulze presents also demanded from the owners of the and calms down beneath a canopy of carries considerable political signifi- commercial forests every time they oaks and beeches. Germans in parti- cance. His demands are derived from log. However, this would be short- cular have an almost romantic rela- his calculations. He believes that for- sighted; wood cannot be replaced as a tionship with forests. It is the perfect est owners should be rewarded for raw material – especially in light of counterpart to a hectic city life. Forest their sustainable management efforts. the fact that there are plans to increa-

Max Planck Research · 4 | 2020 ENVIRONMENT & CLIMATE

singly use wood as an alternative to building materials that are manufac- tured using a great deal of energy. As Hartmann points out, “How are we supposed to do without forest ma- nagement if we need wood products?” If the logs do not come from Germany, for chemistry they will have to be imported from Si- beria or the tropics. This would most & life sciences certainly be more harmful to the cli- mate because forestry practices in those regions are usually not sustainable. In the From chemists to chemists – worst case scenario, forests make full use of the GDCh there – which store large SUMMARY amounts of carbon – will be network: cut down and will be un- A team led by Ernst-Detlef able to recover and grow  Job market – online and in Schulze has published a study back quickly enough. the Nachrichten aus der Chemie showing that the climate balance of sustainably managed forests  CheMento – The mentoring is significantly better than that Of course, financial inter- program for young chemists ests also play an important of unmanaged forests.  Publications about career paths role, since about half of Other researchers criticize the way Germany’s forests are pri-  Workshops in which the climate balance of vately owned. The list of a natural forest is calculated in this  Job fairs and lectures study. They conclude that the landowners who want to benefits to climate protection from make money from forests these forests are greater. reads like a directory of the old noble families: from It is difficult to quantify all the Thurn and Taxis to Ho- factors that would need to be taken henzollern to Knigge and ADVERT into account in such a comparison. There is still no final verdict on Guttenberg. So far, their which form of forest is more sole source of income is the beneficial to climate protection. sale of wood. That is hard Various interests also play a role enough at the moment. in the discussion. However, according to Hartmann, forcing them to In addition to their effect on the climate, forests fulfill many pay a CO2 levy for each log- functions (e.g., as sources of raw ging operation would not materials, recreational areas, be justifiable. After all, the or water reservoirs). Managed forests have served the ge- and unmanaged forests are neral public in many ways – differently suited for this purpose. However, these functions whether as flood protec- currently have no economic value. tion or as recreational spaces. However, Ibisch points out that funding programs should not be used to create false incen- tives that lead to increased felling. Wood should not replace coal, but what else could be used? No matter how the forests are managing to slow down the increasing global warming, this is not a panacea. Even in the lar- gest forest, the capacity for absorbing carbon dioxide is exhausted. In the long run, there is only one way to combat global warming: by drasti- cally reducing greenhouse gas emis- sions.

Gesellschaft Deutscher Chemiker

Max Planck Research · 4 | 2020 www.gdch.de/karriere PHOTO: ANNA PROSS Sunrise over the tree canopy: the suspension bridge along the treetop trail in the Kakum National Park north of Cape Coast is up to 45 meters high. The researchers chose it as the ideal spot from which to observe nightingales and many other animals.

86 Max Planck scientists collabo­ rate with partners in over ding on their age, the males can have the nightingale.” We often had to 120 countries. Here they write up to 200 different phrases in their leave at four o’clock in the morning to about their personal experi­ repertoires, which they can also com- be at the target location by sunrise, as ences and impressions. bine in any order. They can also adapt the birds are particularly active at Anna Proß of the Max Planck their songs spontaneously to match an dawn. Our chosen destinations were Institute for Ornithology opponent’s vocalizations. In terms of national parks, which are usually fre- this ability, they are similar to hu- quented by tourists. But due to the researched the vocal behavior mans; after all, we have no problem COVID-19 pandemic, the parks were of nightingales in Ghana. with reacting spontaneously in the almost deserted, which meant that we Here, she talks about her course of a conversation. could lie in wait at our leisure. encounters with venomous snakes, her new fondness for Nightingales are one of the migratory If you hang around national parks in or- bird species; they breed in Germany der to see birds at dawn, you’ll see plantains, and she reveals during the spring, for example in other wildlife through your binocu- how ornithologists are making Brandenburg, and then fly to warmer lars as well. For example, in addition the most of the COVID-19 climes, including Ghana, in the fall. to all kinds of colorful birds, we saw pandemic. Having already studied their vocal be- antelopes and monkeys. The ceiling havior during the breeding season, I in one cave was covered with bats, and then wanted to investigate how they we once spotted a group of crocodiles communicate in winter. So I set off for from a safe distance. But the most Accra in early November, accompa- dangerous encounter we had was with My research concerns the question as to nied by the head of my research group, a snake. We were walking through the how communication works and which Daniela Vallentin, and another doc- rainforest when we heard something neuronal processes it involves; to that toral researcher. rustling in the bush. And then we saw end, I study the vocal behavior of it – a Green Mamba, one of the most male nightingales. The male birds at- The early bird catches the worm – to venomous snakes in West Africa – and tempt to out-sing one another, usually paraphrase and apply this proverb to it was just two meters away! But the with the aim of defending their terri- my research stay, it would have to be Mamba seemed to have at least as tories or attracting a female. Depen- worded: “the early researcher hears much respect for us as we had for it,

Max Planck Research · 4 | 2020 POST FROM

GHANA

87

because the snake fled before our At one point we stopped in a remote vil- guide could even react. lage at the edge of a cocoa plantation, where the residents gave us a warm Our research stay was barely affected by welcome and took the opportunity to the COVID-19 pandemic, as we were give us a tour of the plantation. It was traveling in remote locations and harvest time, so we learned how to

avoided large crowds. At our hotels, open the cocoa pods, which are about MPI FOR ORNITHOLOGY

we were often the only guests, which is 30 centimeters long, how to separate PHOTO: DR. SUSANNE SELTMANN/ why the operators focused all their at- the individual beans from the jel- tention on us. One time we were ly-like pulp and how to dry them. Of treated to a traditional drum concert course, we were also allowed to taste while we savored an amazing fish din- them. Anna Proß ner. This encounter is just one example of the 28, studied biology at the All in all, the trip was a culinary revela- amazing hospitality to which we were TU Braunschweig and tion. I was especially fond of plantains, repeatedly treated throughout our neurobiology and behavioral which have a similar consistency to time in Ghana. In addition to its fasci- science at the FU Berlin, where she began her PhD potatoes and – whether they are boiled, nating scenery, dazzling flora and studies under the supervision roasted, or deep-fried – are included fauna and numerous culinary delights, of Daniela Vallentin in in nearly every meal. I’ve already there are lots of other good reasons to March 2018, after which she looked into where I can buy them in visit the country. One thing’s for cer- followed her PhD supervisor Munich and have every intent to in- tain: I’ll be returning to Ghana as to the Max Planck Institute clude them in my own recipes. Apart soon as I possibly can. for Ornithology in Seewiesen in early 2019. The biologist from that, there are many soups and is interested in the vocal stews in Ghana, which are delicious, behavior of nightingales and but often very spicy. For snacks, you studies their underlying can find a huge selection of fresh neuronal processes. fruits all over the place, like pineap- ples, papayas, and coconuts.

Max Planck Research · 4 | 2020 “A RACE WE MUST WIN”

When he took part in the Vendée Globe, 39-year-old Boris Herrmann created a real sailing sensation: on January 28th, the Hamburg native reached the finishing port in Les Sables-d’Olonne, France, after more

than 80 days on the world’s oceans. Many ZEDDA PHOTO: YVAN people were on the edge of their seats when Boris Herrmann collided with a fishing boat shortly before the end of the race – narrowly missing out on a place on the winner’s podium and finishing fifth. And he performed a great service to science. Under full sail: Boris Herrmann regularly sent data on the CO2 content of the sea surface via satellite.

Peter Landschützer from the MPI for Me- How did Boris actually come to take we are also unable to model such strong dy- teorology also followed the race with excite- samples for you? namics satisfactorily. ment: Boris Herrmann regularly sent the climate researcher measurement data on We met in 2018. It was Boris who proposed Did you and Boris keep in touch during the race? the CO2 content of the sea surface via satel- a collaboration to me a short time later. He lite. Peter Landschützer is researching the is passionate about climate research. So the carbon cycle in the ocean and reveals in an words “A race we must win” on his sail not Yes, we connected via WhatsApp from time interview why the solo sailor took the time only stand for his sporting success, but also to time. We had to coordinate so that I could to do this despite lack of sleep during the for his fight against climate change. To- submit everything to the SOCAT database 88 world’s toughest regatta. gether we then developed the idea of carry- in time: when can Boris send the data? How ing the OceanPack – a lightweight sensor much time do I need to look at and check Mr Landschützer, was Boris Herr- that measures CO2 – on Boris’ yacht. the data? We received some compliments mann’s data collection successful? from other scientists about our data. I im- Can you already derive initial findings mediately passed them on to Boris - also as Yes, it all worked out well, although at this from the data? motivation for the last days before he point I don’t have the most recent data yet. reached the finishing line. In the heat of the moment, transmitting One finding that is not new, but which has data wasn’t the top priority for Boris. But I been confirmed by the measurement data, What happens now? have received all data until January 5th, is that the ocean – with a few exceptions –

when Boris had just sailed around Cape has less CO2 than the atmosphere. The It will be weeks, if not months, before the Horn. We have already uploaded 60,000 to ocean therefore absorbs CO2 from the at- first studies of the Vendée Globe data are 80,000 data points to SOCAT, which stands mosphere in most regions. This makes the available. However, the first scientific eva-

for “Surface Ocean CO2 Atlas”. This is the ocean an important factor in our climate luations of Boris’ data from recent years most comprehensive database on the CO2 system. Particularly valuable for us are the have already been incorporated into the content of the surface of the world’s oceans samples Boris took from such remote places global carbon budget. These are estimates

and coastal waters. as the Southern Ocean. There was hardly of CO2 fluxes - on land, in the ocean, in the any data on this before. I was a bit surprised atmosphere.

that the CO2 content in the Southern Ocean fluctuates so much. What do you think: will Boris stay “on board” and continue collecting data What is the reason for this? for climate research?

In the Southern Ocean, different water Well, we have achieved our first big goal, the masses meet: water from the subtropics, but Vendée Globe. We now have to sit down to- also deep water that is driven to the surface gether and plan further steps. Of course, I by the wind. These are separated by strong hope that Boris will continue to collect data fronts, through which Boris sailed. If we for us in the future, for example in other

want to understand CO2 uptake in the ocean, races such as the Ocean Race in 2022. Per- PHOTO: MPI FOR METEOROLOGY we also need to understand how these fronts haps we will also win over other sailors for change dynamically. This confirms that we our research who will be infected by Boris’

need more observations. Because CO2 in enthusiasm. Peter Landschützer the ocean cannot be measured by satellite, Interview: Petra Maaß

Max Planck Research · 4 | 2020 COMMUNITY NEWS

COOPERATION WITH AFRICA

Max Planck researchers have been actively have been created with the cooperation of will also be a special partner group program conducting research in Africa for a long time. Max Planck Institutes. (link to partner group page) and mobility Now the Max Planck Society is exploring to “I myself have been carrying out research grants for African scientists who want to what extent it can better support African sci- in Africa since 1991,” says Bill Hansson, who work temporarily in Germany at an MPI. entists on the ground. The first Africa is now chair of the “Africa Round Table”. “An important aspect must be to provide Round Table (ART) was held on December “Africa has continued to develop as a great re- returning junior scientists with the right 15th, 2020 - initially only virtually due to the search environment and to produce great re- opportunities to develop their careers at pandemic. searchers. And I think what is needed now is home with a view to strengthening Africa’s The MPI for Evolutionary Anthropology that we start engaging in genuinely equitable science and innovation base,” so Bill Hans- maintains field stations for behavioral re- partnerships with African researchers.” son. search on great apes in the Congo and the Africa’s population is young – half of its The bigger challenge, however, will be to Ivory Coast. Teams from the MPI for Ani- billion-plus inhabitants are under 19. And establish a long-term scientific environment mal Behavior are traveling through Kruger even if the young Africa of smartphones and adequate research conditions. How do National Park to record animal movements and solar cells has not yet quite conquered you make a science system work? “While we there with GPS transmitters. The MPI for established politics, it continues to shape should always be willing to learn from best Psycholinguistics is investigating linguistic and develop societies. “We want to open up practice around the world, we should 89 diversity in different regions of Africa. And opportunities,” says Hansson. not simply take our cue from European with H.E.S.S. in Namibia or the Square As a first step, the Max Planck Society institutions like Max Planck or the CNRS,” Kilometre Array (SKA) in South Africa, wants to establish low-threshold measures, Hansson explains. huge measuring instruments for astronomy such as lectures and mentorships. There www.mpg.de/16384579

HIGHER PAY FOR DOCTORAL RESEARCHERS

A new development that has been prepared new regulations is the continuing possibil- As the new PhDnet spokesperson for 2021, over a long period of time has finally come ity of individual recruitment boni. Lea Heckmann, explains, “The new con- to fruition: the Gemeinsame Wissen- The new regulations will apply to all MPIs tract regulations are a great step forward, as schaftskonferenz (GWK) has granted the in Germany, as well as the Netherlands and they will not only ease the financial situa- MPG its approval to apply the DFG’s gold Italy. The Institutes are expected to cover tions of doctoral candidates but also bring standard to doctoral candidates’ remunera- the increased costs for their own doctoral re- greater equality to doctoral researchers’ sal- tion. The novel contract details were pub- searchers from their local budgets, although aries, since they will reduce the section- lished on December 14th, 2020 within the according to Ilka Schießler-Gäbler of the and gender-specific pay gaps – a discrep- Organisationshandbuch (OHB). Department for Human Resources Develop- ancy which was also reflected within the Starting January 1st, 2021, all doctoral re- ment and Opportunities, “current centrally last PhDnet surveys.” The former PhDnet searchers with Max Planck contracts will funded Max Planck Research Groups (Com- spokesperson Lindsey Bultema, was also be remunerated in accordance with the petitive W2 Groups), which are in particular enthusiastic: “We’re very pleased that this DFG funding rates. Both ongoing and new open-topic Max Planck Research Groups, milestone of improvement in the doctoral contracts will be subject to this renewal. If Lise-Meitner Groups, Minerva Max Planck candidates’ situation has now been achieved, signatures of contracts are delayed, for ex- Research Groups, as well as Otto Hahn and we’re thankful to the many generations ample due to the necessity to work from Groups, receive an annual grant of €7,500 of PhDnet steering committees who have home resulting from COVID-19, the regu- per group. The same applies to the current pushed this project forward, as well as to lation and payment will be applied retroac- so-called institute-bound Max Planck Re- the MPG Administrative Headquarters tively. Additionally, Institutes may also de- search Groups. International Max Planck General Administration and the General fine higher base salaries to account for dis- Research Groups will receive single, nonre- Secretary Rüdiger Willems for spearhead- cipline-specific salaries. Untouched by the curring remuneration.” ing this progress.”

Max Planck Research · 4 | 2020 FIVE QUESTIONS

ON THE USE OF ARTIFICIAL INTELLIGENCE IN PHARMACEUTICAL RESEARCH

FOR PETER NUSSBAUMER

Proteins consist of a chain of different amino over time, how their structure is affected but, at this point, I suspect that the costs acids, which can fold into complex three-di- upon binding to other proteins or drugs, nor would exceed the benefits to us. Perhaps the mensional structures. Based on the se- the orientation of side chains. The software algorithm may be made public, thus becom- 90 quence of amino acids, Google subsidiary also does not tell us where and how a mole- ing “open source” software. DeepMind’s AlphaFold software is able to cule binds to a protein, which is particularly predict this 3D structure with high accu- crucial for the development of new drugs. Do you think that DeepMind may racy. move into drug development? What is the current role of artificial Mr. Nussbaumer, will this new intelligence in the development I’m not privy to Google’s plans, but, as I said, software revolutionize the develop- of new drugs? there’s more to developing new drugs than a ment of new drugs? sophisticated program for the 3D analysis of Among other things, the answer to that de- proteins. Even so, I wouldn’t provide our PETER NUSSBAUMER Without a doubt, pends on how one defines artificial intelli- data to the company. In my view, the ques- this program represents a milestone in pro- gence. The computational power of modern tion at this moment is more about whether tein analysis. However, many different re- computers, neural networks and machine DeepMind will eventually offer structural search disciplines contribute to the develop- learning have long been aiding us in phar- analysis as a paid service. So far, research ment of novel drugs. Of course, technical maceutical research. We also refer to this as groups have provided free access to the progress in one field benefits the entire de- “computational chemistry.” Examples of this structural data from their studies. velopment process, yet it is only one piece of include making structural comparisons be- Interview: Harald Rösch ILLUSTRATION: SOPHIE KETTERER FOR MPG the puzzle, so I’m not expecting a revolution. tween known and unknown proteins or the use and evaluation of the vast amount of data How could AlphaFold advance the generated during preclinical research. Com- development of new drugs? putational chemistry is also extremely use- ful for interpreting gene activity patterns We could, for instance, use AlphaFold to ob- and predicting target proteins for drug de- tain a new spatial structure of a protein in- velopment. Artificial intelligence will cer- volved in a specific disease. If it has a struc- tainly become more important going for- tural similarity to another protein whose ward, but we shouldn’t expect miracles from function is already known, we could then it. potentially use that knowledge to infer the Peter Nussbaumer is Managing Director of the Lead Discovery Center Will the LDC be using AlphaFold? role of the disease-related protein. However, in Dortmund (LDC), which is a spin-off we also have to keep in mind what Alpha- of Max Planck Innovation; Fold cannot do; for example, it can neither I don’t know whether DeepMind will make LDC is dedicated to the development predict the ways in which proteins change the software available to us and at what price, of new drugs.

Max Planck Research · 4 | 2020 RESEARCH ESTABLISHMENTS

SCHLESWIG- HOLSTEIN Institute / research center Plön Rostock Sub-institute / external branch Greifswald Other research establishments MECKLENBURG- Associated research organizations VORPOMMERN Hamburg

Bremen The Netherlands BRANDENBURG Nijmegen LOWER SAXONY Berlin Italy Hannover Rome Potsdam Florence Magdeburg Münster USA NORTH RHINE-WESTPHALIA SAXONY-ANHALT Jupiter, Florida Göttingen Bochum Dortmund Mülheim Halle Brazil Manaus Düsseldorf Leipzig SAXONY Cologne HESSE Dresden Luxembourg Bonn Jena Luxembourg Marburg THURINGIA Bad Münstereifel Bad Nauheim RHINELAND PALATINATE Mainz Frankfurt

SAARLAND Kaiserslautern Saarbrücken Erlangen Heidelberg BAVARIA Stuttgart 91 Tübingen Garching BADEN- WÜRTTEMBERG Munich Martinsried Freiburg Seewiesen Konstanz

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Max Planck Research · 4 | 2020