North America's First Tool Users?

Selections from the RESEARCH HIGHLIGHTS scientific literature

ASTRONOMY An embarrassment of planets M. R. WATERS A system predicted to contain as many as seven planets orbiting a Sun-like star has been discovered 39 parsecs from the Sun — the most populous extrasolar planetary system found so far. The planets orbit HD 10180 near the southern constellation Hydrus. Christophe Lovis at the University of Geneva in Switzerland and his team used a spectrograph at the European Southern Observatory in Chile to look for a characteristic stellar ‘wobble’ caused by planets tugging on their parent star. Their results suggest that five planets of a similar mass to ARCHAEOLOGY Neptune orbit at distances of 0.06–1.4 times the Earth–Sun distance. A possible sixth North America’s first tool users? planet, with a mass similar to that of Saturn, has an orbital The Clovis people who lived in North America that the artefacts, including ancient tools period of about 6 years. about 13,200 years ago have long been thought (pictured), existed before the Clovis people came The seventh prospective to be the continent’s first tool-using humans. to dominate the landscape. A few of the tools planet could have a mass just But the discovery of older human artefacts at a have similarities to Clovis ones, but are simpler 1.4 times that of Earth, making site in Texas is challenging this idea. and still distinct. The authors suggest that a it the smallest extrasolar planet In sediments dating from between 13,200 and different sort of people was using tools in North found so far. But with an 15,500 years ago, Michael Waters of Texas A&M America before the Clovis people. orbital distance equivalent to University in College Station and his team found Science 331, 1599–1603 (2011) just 2% of Earth’s, it is likely to 15,528 stone artefacts that seem to have been For a longer story on this research, see be a scorched world. undisturbed by soil movement. This suggests go.nature.com/2sijzo Astron. Astrophys. 528, A112 (2011) in the Netherlands and his high number of the molecules, CANCER IMMUNOLOGY CHEMISTRY co-workers have produced the bonds form and the vesicles a vesicle — a water-filled spontaneously take shape; Hide no more, Vesicles form compartment bounded by conversely, when bonds break, tumour with pH shift a bilayer membrane — that the vesicles eventually collapse forms and collapses in (pictured). The stability of Deadly pancreatic tumours Lipid bilayers, which make up response to changes in pH. the bonds is also affected by evade attack by the immune cell membranes, can change The system comprises a the solution’s pH, with vesicles system by developing a stroma shape in response to external solution containing a molecule forming at a pH of more than — a shell of connective tissue stimuli. To reproduce this with two ‘tails’, each of which 7, and dissociating completely enmeshed with white blood behaviour in a synthetic can form reversible covalent when pH falls below 4. cells that suppress the immune system, Jan van Esch at Delft bonds with another molecule. These reversible vesicles response. Robert Vonderheide

WILEY-VCH University of Technology When there is a sufficiently might be useful for applications at the University of that require controlled Pennsylvania in Philadelphia encapsulation and delivery. and his team now report a Angew. Chem. Int. Edn way to reverse this immune doi:10.1002/anie.201007401 suppression. (2011) The authors studied

21 patients undergoing BIOPHYSICS chemotherapy for pancreatic Tiny swimmers cancer, and added an COMMUNITY The most viewed antibody that stimulates trapped by lasers CHOICE papers in science a protein called CD40 to their treatment regimen. Large, self-propelling STEM CELLS CD40 is known to activate microorganisms can be certain types of immune cell, optically trapped with laser The roots of insulin production including tumour-specific beams, a process previously T cells. Tumours in four of the achieved only for smaller ✪ HIGHLY READ The pancreas harbours a small population patients regressed. motile cells such as sperm and on www.cell.com of insulin-producing stem cells — cells The scientists repeated the Escherichia coli. 19 Feb–21 Mar that might one day be harnessed to replace treatment regime in mice Gregor Thalhammer and damaged cells in people with diabetes. genetically engineered to his colleagues at Innsbruck Whether new insulin-producing β-cells in the adult develop similar pancreatic Medical University in Austria pancreas develop from stem cells has been hotly debated. cancers. About 30% of mouse used two opposing laser Simon Smukler and his colleagues at the University of tumours regressed, with holes beams and a system involving Toronto in Ontario, Canada, now report the isolation of appearing in the stroma. a mirror, prism and lenses to ‘pancreas-derived multipotent precursor cells’ from mouse Surprisingly, the immune cell capture a variety of organisms. and human tissue samples. These cells make insulin and can responsible for killing tumour These included protists such take on various cellular identities, including that of the β-cell. and stroma cells was not the as dinoflagellates and Euglena The authors traced the origin of the mouse precursor cells to T cell but the macrophage. gracilis, which measures, on the embryonic pancreas. Science 331, 1612–1616 (2011) average, 50 micrometres in Transplantation of both mouse and human precursor cells For a longer story on this length. The team’s technique into diabetic mice lowered blood sugar levels and reduced research, see go.nature. avoids creating damaging diabetes-associated weight loss. com/2ZNmhb levels of heat. Euglena was Cell Stem Cell 8, 281–293 (2011) held for 13 minutes without NEUROSCIENCE showing signs of heat stress. The method could be used The authors conclude that into the banks of the Delaware No sleep, to manipulate microbes for wild fish can probably carry River at a site in Pennsylvania better mood imaging, as well as in other seeds up to 5.5 kilometres — looking for prehistoric experiments, the authors say. one of the longest distances changes in soil chemistry and Sleep-deprived people are J. Opt. 13, 044024 (2011) reported for fruit-eating sediment particle size, and for known to have stronger animals — often to habitats ancient plant material. They reactions to negative where the seeds will germinate found increased sediment experiences, but some patients once the flood waters recede. deposits from ad 1100–1600 with depression seem to However, overfishing has — an indicator of elevated M. SMITH/SPL perk up with lack of sleep. To greatly depleted the numbers erosion — as well as signs resolve this paradox, Matthew of larger C. macropomum, that humans had cleared trees Walker at the University of which carry seeds farther than around rivers to farm corn. California, Berkeley, and his their smaller counterparts, and The erosion and flooding team used functional magnetic may be threatening this mode were made worse by the wet resonance imaging to scan of seed dispersal. climate of the Little Ice Age the brains of 14 people who Proc. R. Soc. B doi:10.1098/ in ad 1450–1530. European hadn’t slept for about 36 hours rspb.2011.0155 (2011) settlers later caused further while presenting them with ECOLOGY For a longer story on this ecological changes to the emotionally neutral and research see go.nature.com/ flood plains as a result of their pleasant-looking images. Feasting fish fv4zyd various land-use practices. The volunteers rated a scatter seeds Geology 39, 363–366 (2011) greater proportion of the ARCHAEOLOGY images as ‘pleasant’ than did Massive Amazonian characid CORRECTION people who had maintained fish can carry seeds kilometres Early farmers The highlight ‘Copper a normal sleep routine. The across jungle flood plains, caused floods makes for selectivity’ sleep-deprived individuals potentially making them one (Nature 471, 413; 2011) also showed increased of the most important seed Several hundred years stated that selectivity of activation in brain regions distributors in this habitat. before Europeans settled 90% was achieved using that mediate reward-driven Jill Anderson, now at in North America, small organolithium reagents. behaviour, as well as greater Duke University in Durham, Native American farming In fact, this was achieved connectivity between North Carolina, and her communities were already by using organolithium certain visual and emotional colleagues radio-tracked 24 having a big impact on eastern reagents in combination with processing centres. of the animals (Colossoma flood plains — clearing the copper-based catalysts. The results suggest that macropomum; pictured) land and thus increasing sleep deprivation can enhance during three flood seasons. erosion, runoff and flooding. NATURE.COM reactivity to both positive and They also monitored how Gary Stinchcomb of Baylor For the latest research published by negative stimuli. long captive fish of this species University in Waco, Texas, Nature visit: J. Neurosci. 31, 4466–4474 (2011) retained consumed seeds. and his colleagues dug deep www.nature.com/latestresearch