Evolution of Hominine

The Big History of our Planet – Towards The 6th threshold “Time” Cover: What makes us Human? How different are we from other primates?

A human skeleton

A male Mandrill Our place in nature Taxonomy: classifying living organisms into related groups: Pioneered by Carl Linnaeus (1707-78) Our place in modern taxonomy: we belong to … 1. The superkingdom of Eukaryota (made of eukaryotic cells) 2. The kingdom of animalia (animals, not fungi or plants) 3. The phylum of chordata (animals with backbones) 4. The class of mammalia (mammals) 5. The order of primates (lemurs and monkeys) 6. The family of Hominidae (Humans, chimps, gorillas) 7. The sub-family of Homininae (bipedal apes) 8. The genus, Homo 9. The species, Homo sapiens The ‘Order’ of Primates (Lemurs & Monkeys)

Tarsier: Philippines & Indonesia

Gorillas: at 400 lb. the Galago, or largest living primates ‘bush baby’, Africa

Macaque, N. Africa Madagascar: the ‘Indri’ is regarded in Madagascar as a reincarnated ancestor What features do primates share?

• Mammals – Embryos develop in the womb • Tree-dwelling, so they need: – Dexterous hands (and feet) – Stereoscopic vision – A large brain to process visual information Our closest living relatives: Orang-Utan The ‘family’ of Hominidae, ‘Great Apes’ Large, intelligent primates, with no tails

Gorilla

Chimpanzee Darwin guessed (rightly) that our ancestors evolved in Africa, where our Homo sapiens closest relatives live We are also very different

• How? The 1.6% DNA difference matters! – Includes 30 million ‘point mutations’ – Affecting most of our 30,000 genes • Which difference makes us so strange? – Our history has been utterly different – We have become more powerful than any other species on earth – Why? And How? EVIDENCE OF HUMAN EVOLUTION Four types of evidence on human evolution 1. Archaeology: bones & remains can tell us about physiology & lifeways 2. Primatology: Studies of modern primates can help us understand their social life 3. Genetics: Genetic comparisons show relationships between species 4. Climate Change: Evidence of climate change & its impact 1) Studying bones & Remains: Lucy, about 40% complete Found by Donald Johanson in Ethiopia in 1974

Could you tell if Lucy walked on two legs or four? How?

1) Look where the backbone enters the skull

2) Look how the leg bones join the hip

She was bipedal, but may have preferred climbing Don Johanson introduces Lucy to the press: 1974 Confirmation that Australopithecines were bipedal? Australopithecine footprints: Laetoli, Tanzania

These footprints, left in the still soft lava of a volcano, have been dated to 3.6 million years ago. They were found by Mary Leakey in 1978 A careful 2011 study showed they walked as well as modern humans

What else can we tell about Lucy?

Measurements  – About 3.5 feet tall – Her skull was slightly larger than a chimp’s Modern Dating techniques  – She lived 3.2 million years ago Lucy’s homeland today: Hadar, Ethiopia Hadar, Ethiopia

African Rift Valley Other important sites for human evolution?

Olduvai Gorge

Laetoli footprints How a rift valley is formed The beginning of a divergent plate margin

Rising magma This is how the Atlantic Ocean began driving plates apart Olduvai Gorge: Tanzania The African plate is tearing apart Studying what Hominines left behind • Stone tools give clues about – How hominines thought [planning? foresight? right-handedness?] – What they ate [microscopic studies of edges] – What they ate tells much about how they lived

Oldowan tools, from c. 2.5 million years ago, products of Homo habilis

The sharp chips flaked off them may have been as important as the “axes” 2) 2nd type of evidence: Primatology: Studying modern primates

Can tell us a lot about the abilities and social life of our closest relatives

Tool making? Language? Social competition? Jane Goodall

• Pioneered the study of primates in their natural environments • Began studying chimpanzee communities at Gombe in Tanzania in the 1960s as a student of Louis Leakey Jane Goodall working in Olduvai Gorge Dian Fossey

• Studied gorillas in Rwanda • Wrote “Gorillas in the Mist” • Murdered in 1985, probably by gorilla poachers Studying modern primates

Can tell us much about the social life of our Hominine ancestors

Mother & daughter Orang-Utan A family of gorillas Social learning in primates? Can they learn from each other? To a limited extent: yes Sept 2006: • A troop of chimpanzees learning how to safely cross a road • Dominant adults took up protective positions in front and at the rear 3) Comparing genes can show relationships between organisms • We share 98.4% of our DNA with chimps • In the 1980s, researchers showed it takes c. 5-7 million years for such a difference to evolve • i.e., c. 5-7 million years ago, humans and chimps had a common ancestor The statistical nature of evolutionary change • This conclusion depended on seeing that much genetic change is statistical – Only 3% of our genome produces proteins & is directly subject to natural selection – Some parts may play no role, so they can change randomly – The rest probably controls our bodies indirectly by switching genes on and off • How these ‘non-coding’ genes work is an important new research frontier! Bonobo Chimpanzees Our closest relatives only 10,000 left in the wild Too human for comfort? The smoking chimpanzee

Ai Ai is 27 years old and has been smoking for 16 years since her partner died

Zookeepers in China are helping her kick the habit 4) Climate change • Rapid climatic changes in the last few million years • Favored generalist species • Capable of surviving in rapidly changing climates and environments • Species such as – Humans – Weeds CLIMATE CHANGE OVER 800 Mys

Mark Maslin, Global Warming, p. 44 • We live in a peculiarly cold era • Temperatures have been falling for 100 Mys • Mainly because of changes in plate tectonics, e.g. • Union of Americas  creation of cold water current around Antarctica Falling temperatures Last 100 Mys

Today Cambrian era Pangaea Last 100 Mys CO2 levels: The Last 800,000 Years Data from the European Project for Ice Coring in Antarctica, Epica. • A fairly regular cycle of ice ages • About 100,000 years of ice age • About 10,000 years of warmer, “interglacial” climates Humans Appear

The Anthropocene?

9 Coldest phases ….

Last Ice Age From the Vostok Ice Core, Antarctica THE STORY OF HOMININE EVOLUTION The Story of Hominine Evolution • The ‘sub-family’ of Hominines – Bipedal great apes • Appeared about 7 million years ago – What’s the evidence for that date? – Perhaps 30 or more species – All but one now extinct Which survives? The shape of human evolution: a bush with many lost limbs Common ancestors of chimps and humans c. 7 million years ago Hominine line Chimp line Australopithecines Most branches have died out. Humans and Chimps are the Homo habilis only survivors of a large Homo erectus/ergaster evolutionary ‘radiation’.

Neanderthals Chimps & Modern Humans Bonobos Three Main Stages in Hominine Evolution A brief history of hominine evolution since the split from the chimp line, 6-8 Mys ago – We focus on three main groups of species 1. Genus: Australopithecines 2. Species with variants: Homo habilis 3. Species with variants: Homo erectus/ ergaster A) Australopithecines: e.g. Lucy “Australopithecus” is a genus that includes several distinct species. Its members are: •Bipedal •About as tall as chimps •Brains same size as those of chimps •Little evidence of tool use or language •c. 5 million to 1 million years ago Bipedalism: the first major difference from chimps • Bipedalism (not braininess!) is the defining feature of hominines – Walking on two legs as the norm • Why? Not sure – Maybe to enable tool use? • Bipedalism comes before tool use – More efficient travel in savanna lands?

Modern Reconstructions: how accurate?

Bipedal, but otherwise similar to modern apes B) Homo habilis: 1st species of a new genus, ‘Homo’, from c. 2.5 MY ago The genus ‘Homo’ includes us Homo habilis had: • Larger brains (perhaps because they ate more meat or cooked food?) • Made tools (which helped them get meat) • Once thought to be the first ‘humans’ Now thought to be much more ape-like 1964: Louis & Mary Leakey & first finds of Homo habilis Homo habilis Modern Reconstructions Louis Leakey holding a Homo habilis skull 1960s To the right: an Australopithecine skull

• Leakey saw tool use as a unique feature of humans • So classified habilis as the 1st human Damn! Tool Use: No longer seen as key to humanity: many primates use tools

2005: For the first time Gorillas observed using tools in the wild

Efi uses a stick to get across a swamp C) Even closer: Homo erectus/ergaster • From c. 1.9 million years ago • As tall as us • Brains almost as large as ours • Migrations out of Africa • Perhaps use of fire?

Skull of a female Modern Homo reconstructions erectus Homo ergaster: KNM ER 3733 found 1975, Koobi Fora, Kenya c. 1.75 million years old 1.5 M-year old footprints of Homo erectus • Fossilized, found in Kenya, 2009 • They walked almost exactly like us • Which may explain why they travelled further than any earlier hominines Homo erectus/ergaster was a traveller! Why did brains get bigger? • Brains are costly: – 3% of body weight but need 20% of its energy – Large heads make childbirth dangerous • Is cooking the key? Richard Wranghams’s idea – Evidence that Homo erectus used fire – Cooked foods are partially digested – Pre-digestion made it easier to use high energy foods such as meat – Support for this idea from changing dental patterns But even erectus/ergaster didn’t change much They made ‘Acheulian’ stone tools

More skillfully made than the stone tools of Homo habilis, but

Didn’t change much over 1 million years

No sign of major technological innovation What distinguishes us from other hominines? • A = Tool Use • B = Art, religion and culture • C = Language • D = Something else A frustrating conclusion

• Hominines  more like us • But no fundamental breakthrough • A problem: – Evolution can explain why we are so similar to other animals – Can it also explain why we are so different? 1st fossil primates 1st hominines Earliest apes Lucy

Next Timeline The last 7 MYs The Evolution of Primates A TIME-CHECK: Timeline 4: 65 million years How do you get from early primates to the Cassini satellite? Earliest hominines Homo erectus/ergaster

Modern humans

Ardipithecus ramidus

1 Australopithecines extinct

extinct

habilis

Homo habilis

Homo sapiensHomo erectus

Very few

fossils from

hominine migrations to S. Eurasia S. to migrations hominine

Australopithecines

Earliest remains of of remains Earliest hominine bipedal erectus/ergaster Homo 1

Ardipipithecus ramidus Ardipipithecus and Australopithecines & Neanderthals Age Ice Beginninglast of & Neanderthals Homo habilis Homo this period 1

7 6 5 4 3 2 1 0 MILLIONS OF YEARS BEFORE PRESENT DAY Lucy HOW FAST THINGS HAPPENED! Hominine evolution over 7 MYrs FROM GREAT APES TO THE CASSINI SATELLITE All of human history lies between these two arrows Earliest hominines Homo erectus/ergaster