Out of Africa: The origin of Homo Sapiens (Us!)

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1 Out of Africa: The origin of Homo Sapiens (Us!) Our History from the DNA Record and other methods Robin Clegg

2 Genetics, DNA A Detective Story Involving. Fossils, skulls and skeletons - new extraction of DNA from them Earth s changing climate Ice Ages, resulting sea Levels» The scientific consensus is: all non-african modern humans came recently from Africa, with single genetic lineages identifiable from one maternal and one paternal line. But - new - some mixing of H.Sapiens with other hominids, e.g. Neanderthals and Denisovans.

3 Darwin was asked, which ape is your grandfather?

4 Wrong! Man not directly descended from modern apes, but both are from common ancestors, million years ago. Chimps are the closest to humans.

5 Major progress in the last 30 years Understanding of the genome Fast analysis of human and animal genomes and even Neanderthals Extraction of DNA from hominid remains, e.g. inside teeth, bones Put together knowledge of genetic timelines, fossils, plus information about climate and environment over the past million years to tell a story

6 Million years ago Event (13,700 Big Bang Universe expands) 4,500 The Earth forms First evidence of life 530 Fish develop 475 Life on land - plants 200 Mammals 3.0 Human-like apes ca 0.2 ca 0.06 Homo sapiens in Africa A group leave E.Africa -> non- African humans If Earth history were 24hrs, then life moves onto land at 21h 30, mammals appear at 23h 00, hominids at 58 secs before midnight, and homo sapiens in the last 4 seconds.

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8 Some clarifications Hominids/hominins or humans the different humantype species. Includes homo neanderthal, homo erectus, etc Homo sapiens modern humans, the only hominid left now Example: Lucy skeleton, Ethiopia, 3.2 Million years old Oldest human Well, australopithicus* afarensis a human-like ape upright,bipedal * southern ape

9 More clarifications- Last common ancestor (LCA) a key concept:

10 Most recent Common Ancestor Maternal Eve and Paternal Adam ca 150,00 yrs ago

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12 The DNA Molecule

13 Mammal Cell: 1,2-Nucleus 9-Mitochondria 14-Cell membrane

14 Humans have 23 pairs of chromosomes- 22 plus XX (female) or XY (male)

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16 Mitochondrial Eve Is the most recent common ancestor woman to whom all living non-african humans can trace their origins through maternal links Lived in Africa, ,000 yrs ago before the Sapiens exodus Y-Chromosome Adam The most recent common ancestor man to whom all living non-african humans can trace their origins through paternal links Lived in Africa, ,000 yrs ago. They don t need to have ever met!

17 The various hominids

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22 CLIMATE: Middle Paleolithic sites ( kyrs ago) red dots. Some present deserts were fertile in that climate.

23 Evolution of Brain Sizes

24 Skulls of modern H.Sapiens (L) and Homo Neanderthal (R)

25 Important factors in homo development (not just brain size) Better use of stone tools Manipulation of fire Intake of energy*, especially protein Development of speech Communication and social awareness skills, co-operation * needed, as our brains are 2-3% of our weight but use 25% of energy needs even at rest

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28 L3 These ALL come from L3

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30 Two Major Models of Dispersal Out of Africa - Single main exodus of Sapiens from East Africa, around 60-80,000 yrs ago is the one that has begotten all non-africans - previous exodus, e.g. Sapiens fossils in Israel 120,000 yrs old etc died out - Explains Adam and Eve Multi-Regional Model - Several earlier waves of migration from Africa, ,000 yrs ago - Evolution and development in each region - Explains why fossils in China have face shapes like modern Chinese (this is controversial) Expert Chris Stringer supports Out of Africa but with some interbreeding between Sapiens and hominids already in their regions

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32 Charts from Oppenheimer (2004)

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38 Lake Toba, Sumatra from Space Volcano eruption 74,000 ago

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51 Genetic Groups from mt-dna Record L3 is the origin of non-african modern humans

52 Sapiens interbreeds with Neanderthals and Denisovans

53 Homo Sapiens and Britain Oldest human remains in UK ,000 yrs [H.Heidelberg] Britain populated intermittently since then [Ice] Oldest sapiens 30-40,000 yrs (Gower, Devon) Cro-Magnon is early sapiens, arrived in Europe at 40,000 yrs No human remains between 30,000 and 15,000 yrs [Ice] English Channel - separation from Europe, 8,000 yrs Appearance of farming 6,500 yrs [farming spread, not farmers] DNA continuous linkage with ancient Europeans; invading Angles, Saxons, Jutes, and Viking not a huge genetic influence?

54 Britain joined at various times to Europe- this example 50,000 years ago

55 What have we learned? Part 1 Sources- skulls, bones; DNA methodologies; tracking mitochondrial and Y- chromosome DNA mutations. Rough ideas of climate, sea-level. Majority view is that all non-african modern humans came from one genetic line that left East Africa around 60-80,000 years ago; arrived in Europe 40,000 yrs ago; all other hominids are extinct More genetic diversity in Africa than the entire rest of the planet! The exodus very recent compared with age of primates, life on Earth, etc Only a rough understanding of evolution primates -> hominids -> Sapiens Sapiens mixed with Neanderthals and Denisovans in certain regions Early hominids were in Britain 800,000 yrs ago; then intermittently

56 What have we learned? Part 2 What s Developing Improved techniques for using DNA from the other chromosomes in the cell nucleus ( nuclear or autosomal DNA) More remains get discovered with surprises Better linkage of climate/sea-level history with hominid history Still uncertain about the Exodus and the mixing/gene flow between different homind groups, ,000 yrs ago

57 Further Sources Print Stephen Oppenheimer, Out of Eden, 2004 concentrates on the mtdna and Y- DNA results. Chris Stringer Origin of Our Species 2011 and Homo Britannicus 2007 (plenty on fossils) Brian Sykes, Blood of the Isles, 2006 Robin McKie, Face of Britain 2006 New Scientist, magazines etc Websites Bradshaw Foundation Wikipedia - many entries, some point to recent review articles (eg by Stringer) ** Exhibition in London Natural History Museum New Exhibition, Human Evolution and Prof Chris Stringer homepage