http://youtube.com/watch?v=GOoVjXx0bPk

Scatterlings of Africa Bio380 Human Evolution Genes and GenomesProfessor Mark Pallen, University of Birmingham

Africa: Cradle of Humanity?Charles Darwin: Origin of Species

1859“Light will be thrown on the origin of

man and his history”Charles Darwin: Descent of Man 1871

speculated that humans originated in Africa

“In each great region of the world the living mammals are closely related to the extinct species of the same region. It is, therefore, probable that Africa was formerly inhabited by extinct apes closely allied to the gorilla and chimpanzee; and as these two species are now man's nearest allies, it is somewhat more probable that our early progenitors lived on the African continent than elsewhere.”

The focus moves from AfricaArchaic fossil humans found in

Asia (Java Man 1891, Peking Man 1921) Europe (Neanderthal 1856, Heidelberg 1907,

Piltdown* 1912)Early theories

Multiregionalism (Weidenreich 1930s) H. erectus turned into H. sapiens everywhere, but populations retained local “racial” features”

Long cryptic “pre-sapiens” lineage, separate from archaic forms

Pre-Neanderthal ancestor (based on Tabun, Skhul fossils)

Africa: Cradle of Humanity reduxEarliest hominid fossils found in Africa

(Toumai, Orrorin, Ardipithecus, Australopithecus)

Earliest Homo erectus/ergaster fossils from Africa (~1.9Mya)

But fossils from Georgia and Java dating to ~1.8Mya suggest early spread: “Out of Africa I”

But where and how did Homo sapiens originate?

Coon’s candelabraUS anthropologist Carleton Coon

(1962) posited five separate lineages evolving in parallel from H. erectus“If Africa was the cradle of

mankind, it was only an indifferent Kindergarten. Europe and Asia were our principal schools”

American Loring Brace added “Neanderthaloid phase”

Spectrum hypothesis: blending of modern and archaic characteristics

CapoidNegroidCaucasoidAustraloid

Mongoloid

Dispersal of H. erectus from Africa ~1.9Ma

Competing theories from 1970s onwards

Recent African Origin (RAO) or “Out of Africa”Chris Stringer suggests Homo erectus evolved into

Homo sapiens in Africa, and then only recently (<200 Kya) ventured out of Africa and dispersed around the world, replacing any existing H. erectus or H. neanderthalensis populations (note distinction between OOA1 and OOA2)

Modern Multi-regionalismMilford Wolpoff suggests that Homo erectus evolved

into modern humans in several different locations through out the world, with continuity of gene flow between ancient H. erectus and modern human populations

Stringer 1974: cranial shape suggests Neanderthals are not good ‘ancestors’ - there are better ones, esp. in Africa

How can we test the hypotheses?Predictions....

Fossil Recordmultiregionalism: oldest human fossils could be

anywhereRAO: oldest human fossils will be found in

Africa; cultural universalsGeographical distribution of genetic diversity

multiregionalism: greatest diversity could be anywhere

RAO: greatest diversity will be in AfricaMolecular phylogenetics

multiregionalism: MRCA anywhere; RAO: MRCA in Africa

Fossil Record

Earliest AMH fossils are from AfricaOmo Kibush 1 Ethiopia 195

KyaHerto Ethiopia 154-160 Kya

Oldest AMH fossils outside Africa much youngerSkhul, Qafzeh, Palestine,

80-120 KyaMungo, Australia, 42 KyaTianyuan, China, 38-42 KyaPeștera cu Oase, Romania,

40.5 KyaWhite TD, Asfaw B, DeGusta D, Gilbert H, Richards GD, Suwa G, Howell FC (June

2003). "Pleistocene Homo sapiens from Middle Awash, Ethiopia". Nature 423 (6941): 742–7

McDougall, I.; Brown, F. H.; Fleagle, J. G. (2005), "Stratigraphic placement and age of modern humans from Kibish, Ethiopia", Nature 433 (7027): 733–736

Geographical distribution of diversity

0.29 0.33 0.380.81 0.68 0.73

0.32% 0.33% 0.23%0.035

%0.025% 0.034%

0.11 0.06 0.062.1 1.75 1.10.84 0.90 0.85

Africa Asia Europe

79 RFLPs

30 microsatellites

beta-globin flanking region

Xq13.3

50 autosomal segments

mtDNA control region

43 Y-chr binary markers

From Human Evolutionary Genetics: Origins, Peoples & Disease, p 251Jobling, Hurles, Tyler-Smith

(Cavalli-Sforza and Feldman 2003)

Allozyme polymorphisms in multiple loci

Molecular PhylogeneticsMitochondrial DNA analysis (mtDNA)

Maternally inherited, therefore telling the story from the female side of human history

Y Chromosome analysisInherited down the paternal line,

complementing mtDNABut most recent common ancestor far

more recent than mtDNA and Y chromosomes MRCAsin 15,000 years you will be the ancestor of

everyone or of no one!

Mitochondrial EveThe first glimpse

Cann et al 1987analysed mtDNA from 147 individuals

using 12 restriction enzymesconstructed tree and date tree using

mtDNA mutation rate root in Africa; ~200 (140-290) Kya “all these mitochondrial DNAs stem

from one woman who is postulated to have lived about 200,000 years ago, probably in Africa”

“African Eve” Criticisms

18/20 “African” mtDNA samples came from African-Americans

methodology not idealmid-point rooting rather than use of

outgroupMitochondrial Eve was not the only

female of her time!!

http://www.flickr.com/photos/dwysiu/5101682506/sizes/o/in/photostream/

53 individuals, complete mtDNA (minus highly variable region), used 32 “real” Africans

complete separation of African and non-African lineages

three exclusively African branches

African branches deep; others “star-like”

TMRCA for all: 172 KYA TMRCA for main non-

African/African branch 52Kya

Mitochondrial Eve

All non-African lineages derive from two branches, M and N,

from L3 haplogroup

All non-African lineages derive from two branches, M and N,

from L3 haplogroup

X YMaleFemale

X X

Y chromosome is paternally inherited

Europeans Asians Africans

“Y Adam” was also African ~60,000 years ago

But not the only male of his timeand a moving target, shifting forward as Y lines die

out

Y chromosomal data

Y chromosomal data

All non-African lineages derive from

CR haplogroup

All non-African lineages derive from

CR haplogroup

T. Michael Keesey (CC BY 2.0)

The peopling of the world

100-150Kya

60Kya

45Kya

50Kya

15Kya

N D

Beachcomber routeRemote Australia colonised before Europe!

African Exodusmovement of beach-combing people? small group of humans living

in East Africa migrated north east, crossing the Red Sea and went on to populate the rest of the world

today at Gate of Grief Red Sea about 12 miles wide, but 50 Kya was much narrower and sea levels were 70m lower

straits were never completely closed, there may have been islands in between which could be reached using simple rafts.

fresh water springs along coast when sea level lower

shell middens 125Kya in Eritrea indicate the diet of early humans was sea food obtained by beach-combing.

migration speed for the first Eurasians of 0.7 to 4 km per year

rough upper estimate of the number of women who left Africa 60,000 years ago:

~600

Other EvidenceOf Microbes and Man

Human gut bacterium Helicobacter pyloriCauses gastritis, peptic ulcers and gastric

cancerPassed from mother to children (similar to

mtDNA)Little human-to-human horizontal transmission

H. pylori and human evolutionary histories are congruentCan be used to infer human pre-historyHigh mutation rate, so H. pylori DNA

sequences are more informative about the human past than human DNA

(see also Disotell 2003 Genome Biol.)

Other EvidenceOf Lice and Men

Darwin letter to Henry Denny, 1865“Will you excuse me asking you to inform me whether the Chiloe pediculi form a

distinct species or well-marked variety? Is it the case that the Lice differ on different races of man; & can you believe, from any other evidence which you may possess, the statement by Mr Marshall about the Polynesian lice not living on a distinct race of man?”

ConclusionsAnatomically modern humans appeared

first in AfricaGenetic diversity for most loci higher in

AfricaMost phylogenies of individual loci show

root in Africaespecially mitochondrial Eve and Y Adam

Evidence from human DNA, lice and microbes consistent with RAO, but also with some archaic admixture

Current consensus?

100% RAO | RAO+hybridisation | assimilation | multiregionalism | 0% RAO

Old racist view

View from modern genetics

Genetic Residues of Ancient Migrations: An End to Biological

Essentialism and the Reification of Race William M. Richman University

of Toledo

Hdptcar Attribution 2.0 Generic (CC BY 2.0) Dennis Stefani, (c) Mrs. Me, Inc., 2008, made available under a CCBY-

NC-ND licenseHelga's Lobster Stew Attribution 2.0 Generic (CC BY 2.0)

Steve Evans Attribution 2.0 Generic (CC BY 2.0)Publik15 Attribution 2.0 Generic (CC BY 2.0)

We are all no more than 4000 mothers away from Africa

Conclusions

Recommended Viewing & Listening

See also:Genomic Dub Collective Origin of Species in Dub

http://www.infection.bham.ac.uk/BPAG/Dub/Videos/Track9.html

http://bababrinkman.bandcamp.com/track/im-a-african

I’m a African, I’m a African And I know what’s happenin’ I’m a African, I’m a African Archaeologists know what’s happenin’ You a African? You a African? Do you know what’s happenin’? I’m a African, I’m a African Geneticists know what’s happenin’  No I wasn’t born in Ghana but Africa is my mama ‘Cause that’s where my mama got her mitochondria You can try to fight if you wanna, but it’s not gonna change me ‘Cause it’s plain to see, Africans are my people And if it’s not plain to see then your eyes deceive you I’m talkin’ primeval; the DNA in my veins Tells a story that reasonable people find believable But it might even blow your transistors; Africa is the home of our most recent common ancestors Which means human beings are all brothers and sisters So check the massive evidence of Homo erectus And Australopithecus afarensis in the fossil record And then try to tell me that we’re not all connected The fossil record has gaps but no contradictions And it complements the evidence in your chromosomes So I came to let you know about your ancestral home.

Recommended ReadingSee online archiveThe Incredible Human

Journey, Alice RobertsOrigin of our Species,

Chris StringerAnd if you want to buy

a textbook:Human Evolutionary

Genetics, Origins, Peoples and DiseaseJobling, Hurles, Tyler -Smith