We’re All Out Of Africa

An important scientific finding was reported a couple of weeks back, that has very important implications.

Palaeontologists and molecular biologists have disagreed with each other regarding the origins of modern Homo sapiens. Since 1987, molecular biologists have believed, using DNA evidence, that Homo sapiens evolved in Africa and then spread out to other parts of the world. Paleontologists, on the other hand, said that modern humans evolved separately in different regions of the world, from the earlier Homo erectus.070718-african-origin_170

Until now.

In a recent study in Nature, Andrea Manica of the University of Cambridge and his colleagues show that the skull data and the genetic data actually agree with each other. They studied 4,666 male skulls and 1,579 female ones, drawn from 105 groups of people from all six inhabited continents, and showed that they varied in the same way as human genetic data do.

The Economist reports:

One of the main lines of evidence for the “Out of Africa” hypothesis, as it is usually known, is that the most genetically varied human populations are in that continent—particularly in the south and east of it. The farther you go from Africa, the less genetic variety there is, because in a rapidly dispersing population genetic variety is lost faster by random failures to breed than it is replenished by evolution.

If the “Out of Africa” hypothesis is right, that decreasing variability should be reflected in skull shape—since this is ultimately under genetic control. As far as skulls are concerned, there is one confounding variable: climate. Things such as nostril size vary with temperature and humidity in ways that suggest evolution is at work. Since Dr Manica was looking for effects other than those produced by natural selection, those things had to be eliminated. Which he did.

Using what was left, he estimated the amount of diversity in groups of skulls from different parts of the world using a statistical technique called multiple-regression analysis, and compared the resulting map with a similar map of genetic diversity. The two matched perfectly. There was no room for the influence of local populations of Homo erectus.

Also see National Geographic's report here. Even if there is one notable skeptic of the study, I find this reassuring for two reasons:

First, this is the beauty of science at work. We have two scientific disciplines contradicting each other. And when sufficient data from both streams is analyzed and known influencing factors accounted for, the data from the two independent streams matches almost miraculously. This is the true scientific method at work.

Second, and more important, this finding effectively kills the concept of "race". We have all come from the same place, evolved from the same species. There are no separate origins, and hence no different races of people. Race is a product of the imagination of Homo sapiens, not a natural occurrence.


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9 Comments

  • When I don’t find a com­ment I entered on a post of yours in this blog, I click ‘sub­mit’ again, but invari­ably get a mes­sage that says ‘don’t foc­k­een repeat your­self’. Now you sub­mit TWO posts with the same header and con­tents (I think) and you get away with it.…. how?

  • Reminds me of a sci­en­tist that told the jour­nal­ist, “This skull here is three mil­lion and four years and six months old.” “How can you spec­ify the date so accu­rately?” asked the journo.
    Sci­en­tist: “When I first dis­cov­ered this skull four and a half years back, it was three mil­lion years old!”

  • The notable skep­tic is Fox News? The guys who can take this sen­tence “George Bush lied to the Amer­i­can Pub­lic about the Iraq War” and report it as “The Pres­i­dent kept Amer­ica safe by judi­ciously with­hold­ing infor­ma­tion related to Iraq”

  • So I am an African now?
    Killing the con­cept of race is a good thing, but I am sure it will start a cri­sis of Iden­tity among many. I am already in ;)

  • Race is a prod­uct of the imag­i­na­tion of Homo sapi­ens, not a nat­ural occur­rence.“
    Eh? How did you arrive at that conclusion?

    Race is nat­ural! African ele­phants are dif­fer­ent from Indian. African humans are dif­fer­ent from Indian. I do not under­stand why we are gen­er­ally try­ing to deny the exis­tence of race (or caste for that matter).

    Acknowl­edg­ing races is not wrong. Racism is.
    kay mhan­tos?

  • Ram­bodoc: it was a glitch of using Win­dows Live Writer to edit and repost over an unsta­ble con­nec­tion. Thanks for point­ing it out.

    All: thanks for the com­ments. Past few days have been hec­tic, and am trav­el­ing to Mum­bai today. Will respond to your gra­cious com­ments later. Also, haven’t vis­ited any of your inter­est­ing blogs…

  • Well I think recog­ni­tion or exis­tence of race depends on the time­line that we are look­ing at. If you say that all humans came out of Africa, I can say what about the humans before that. What­ever the­ory you give me I can say “…and before that??”. So it comes down to the The­ory of Begin­ning that you believe:

    [1] Big Bang The­ory — Every­thing started from a point, so no ques­tion of dif­fer­ent races
    [2] Adam & Eve — Every­thing started with this cou­ple, so no ques­tion of dif­fer­ent races (assum­ing both came from the same race)
    [3] Darwin’s The­ory — Ya here the sci­en­tists will have to find out first if Apes have races, then we can pro­ceed further.

  • Hmmm, inter­est­ing. Thank you. I didn’t know there had still been a debate. I thought it was set­tled years ago that human life began in Africa and moved around the rest of the world.

  • Priyank: The con­cept of ‘race’ is so con­tro­ver­sial and has many dif­fer­ent inter­pre­ta­tions, that most sci­en­tists today term it as a fuzzy con­cept that has no use. Regard­ing ele­phants, African and Indian ele­phants belong to two dif­fer­ent species alto­gether, not ‘races’.

    Among the many dif­fer­ent inter­pre­ta­tions of race and racism, I was refer­ring to the one that uses multi-regional ori­gin as a basis for declar­ing race supe­ri­or­ity. Whites descended from Euro­pean ances­tors were deemed supe­rior to blacks descended (sep­a­rately) from Africans, and this jus­ti­fi­ca­tion was used to engage in slav­ery. I’m refer­ring to Brit­tan­ica Encyclopedia’s def­i­n­i­tion and using this sci­en­tific dis­cov­ery to debunk sci­en­tific racism in general.

    Oemar: Since we and most peo­ple are con­cerned about Homo sapi­ens, the the­o­ries related to ‘what before humans’ are sort of out­side the cir­cle of con­cern here. As I’ve described above, the multi-regional the­ory of the ori­gins of Homo sapi­ens have been used in many ways through­out his­tory to pro­mote racism. This dis­cov­ery resolves that debate (and no, it doesn’t resolve debates about the the­o­ries of the begin­ning :-) .

    Sib­bia: Thanks and wel­come to my blog!