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 thoughts on “We’re All Out Of Africa

  1. 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?

  2. 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!”

  3. 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”

  4. 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 😉

  5. “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?

  6. 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…

  7. 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.

  8. 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.

  9. 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!

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