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Earth Science

"Out of Africa" Theory Called Into Question By Originator 169

Posted by timothy
from the oh-great-now-you-tell-me dept.
Amiga Trombone writes "Christopher Stringer is one of the world's foremost paleoanthropologists. He is a founder and most powerful advocate of the leading theory concerning our evolution: Recent African Origin or 'Out of Africa.' He now calls the theory into question: 'I'm thinking a lot about species concepts as applied to humans, about the "Out of Africa" model, and also looking back into Africa itself. I think the idea that modern humans originated in Africa is still a sound concept. Behaviorally and physically, we began our story there, but I've come around to thinking that it wasn't a simple origin. Twenty years ago, I would have argued that our species evolved in one place, maybe in East Africa or South Africa. There was a period of time in just one place where a small population of humans became modern, physically and behaviourally. Isolated and perhaps stressed by climate change, this drove a rapid and punctuational origin for our species. Now I don't think it was that simple, either within or outside of Africa.'"
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"Out of Africa" Theory Called Into Question By Originator

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  • by Anonymous Coward

    I don't care what they say. It was a good movie.

  • by excelsior_gr (969383) on Monday September 17, 2012 @04:34PM (#41366939)

    From TFA:

    But we're having to re-evaluate [the Out-of-Africa model] now because genetic data suggest that the modern humans who came out of Africa about 60,000 years ago probably interbred with Neanderthals, first of all, and then some of them later on interbred with another group of people called the Denisovans, over in south eastern Asia.

    Nice to see some theory re-evaluation in practice. It is the only way to reach the truth.

    • by pr0t0 (216378) on Monday September 17, 2012 @04:54PM (#41367215)

      This is why science is awesome. The very same guy that advocated the "Out of Africa" theory, circled back in the face of more evidence and is re-evaluating. He's not so prideful to say he was possibly wrong, or partially wrong, or mostly right but needing a few tweaks. He has no reason to feel shame, as generally no scientist should as long as they are doing good work. I applaud Mr. Stringer.

      There was a line in the movie "Chain Reaction" where the lead scientist says, "We learned something very important today. We learned another way this doesn't work." or something to that effect. That is also what makes science awesome. Learning what doesn't work is almost as important as learning what does.

      Every time I see something like this, I get that "What am I doing with my life?" feeling and start thinking I need to get out of my particular field of IT and start contributing to the body of human knowledge. Computational Materials Science, here I come!

      • Re: (Score:1, Offtopic)

        by Bigby (659157)

        Although completely unrelated, but a similar circle-back: Roe in Roe v Wade.

        • Re: (Score:3, Insightful)

          by Anonymous Coward

          Although completely unrelated, but a similar circle-back: Roe in Roe v Wade.

          Um... no. Not at all. The complete opposite, in fact.

          The case of Norma McCorvey [wikipedia.org] (AKA "Jane Roe" of Roe v Wade), is clearly not one of rational reflection upon the discovery of new evidence. From her own words, it is painfully obvious that her radical change of heart was due to a series of emotional appeals impressed upon her while she was in a highly vulnerable psychological state. In desperation, she found religion (after growing up in a non-practicing family, some sources claiming she was actually an athe

      • by foma84 (2079302)
        The catch is: if it's so well worth your praise, it's not so common (among scientists).

        Scientists (not this case) can prove some of the most oscuratist, closed-minded dicks. Sigh.
      • by evilviper (135110)

        <blockquote>
        This is why science is awesome. The very same guy that advocated the "Out of Africa" theory, circled back in the face of more evidence and is re-evaluating.

        You've missed the down-side to this... The old theory was wrong... Any decision making or thought-processes based on it are invalidated... All the school-children taught this theory as a fact have been indoctrinated with misinformation. There's no reason to believe the new theory isn't going to be invalidated down the road.

        • This is why science is awesome. The very same guy that advocated the "Out of Africa" theory, circled back in the face of more evidence and is re-evaluating.

          You've missed the down-side to this... The old theory was wrong... Any decision making or thought-processes based on it are invalidated... All the school-children taught this theory as a fact have been indoctrinated with misinformation. There's no reason to believe the new theory isn't going to be invalidated down the road. It's perpetually a "best guess" getting passed off as fact, no matter how incomplete the evidence.

          Yes, and the whole point is that we should be intelligent enough to accept that we might have to re-evaluate our understanding of the world in the face of new evidence, and that any information presented to us may not be 100 % accurate. Does that help?

    • Genuine question.

      I wonder why the one-origin theory is so prevalent in science. I never really understood it at university. I get that so much of our DNA is similar.

      human origin - we must have been formed at one location.
      first organism - must have been created once and then multiplied and diversified.

      I never understood why it had to be a single origin. Couldn't a particular evolution or event happen at multiple locations or multiple stages of merging?

      • Couldn't a particular evolution or event happen at multiple locations or multiple stages of merging?

        Heh, I don't have any hard data, and this is not my field, but Asimov pondered on that question (Foundation series). The chances of life (or evolutionary events) sprouting in many locations simultaneously must be very thin. It seems plausible, but it is still science fiction and not science. Maybe an expert can enlighten us...

        • It isn't science fiction. We know very little about the origin of life and until we have better evidence about the actual mechanism the single vs. multiple origin debate is largely subjective. I am not an expert.
        • by meglon (1001833)
          Not an expert, but what you're talking about is basically convergent evolution i believe; multiple instances of evolution with the a similar end product. If they were able to interbreed, i'd think that would be a knock against the idea.... it would seem, perhaps, a better premise would simply be an earlier migration of a common ancestor predating what we have physical evidence for.

          As for Asimov's suggesting multiple evolutionary events being unlikely, i don't think i'd agree given what we now know (beyon
      • There are ways to determine (with a certain degree of accuracy) whether something was a case of parallel unrelated evolution, or comes from the same root. Due to the way DNA works [wikipedia.org], there are different ways to encode the same information. If two species encode the sequence in the same exact sequence, or nearly so, it is highly unlikely that it had just accidentally came up to be that way separately from both of them.

      • by 1u3hr (530656)

        I never understood why it had to be a single origin. Couldn't a particular evolution or event happen at multiple locations or multiple stages of merging?

        A single evolutionary change could arise in different places. But after a while, there would be a whole lot of other changes too. The odds of them ALL being the same are impossible. So you won't get identical creatures arising in different places. Similarl though is quite possible. And whether they are able to interbreed, to be considered the same species, depends on how far diverged they are from a common ancestor.

        Obviously the parents don't have to be identical genetically to crossbreed. but the more di

        • Not quite correct, there is an optimal distance. Too close and the population exhibits low genetic diversity and a tendency to genetic diseases, it takes a great deal of divergence, much more than is present in modern Humans, before there are fertility problems.
          • by 1u3hr (530656)

            , it takes a great deal of divergence, much more than is present in modern Humans, before there are fertility problems.

            Well, we aren't talking about "modern humans". We're all the same species and interfertile, having wiped out our near relatives.

      • The core argument for single origin is the loss of diversity as one radiates away from the origin area. Part of the problem with this argument is that addition of diversity at very low rates is statistically indistinguishable from ordinary rates of mutation. What is apparent now is that the out of Africa population swept up other groups of genus homo but at such small rates of mixing that the statistical change was small, even though there were several identifiable EPT in the mix. We are still "out of Afri
    • The theoretical interbreeding of Homo Sapiens with Homo Neanderthalensis (in the Middle East) was a separate and non sequential event with the theoretical Homo Denisova interbreeding (in Asia) with a different (later) branch of Homo Sapiens.

    • I had posited this idea back in my High school Genetics class in a report I wrote about Human evolution. I Discussed the Multi-regional theory and the out of Africa theory and to me, the Multi-regional theory was absurd on its face and the Out of Africa theory had a much better model but could not, IMO explain how the different human populations evolved to physically adapt to their environments so quickly. I used inter-breeding as a mode to allow for out of Africa but also account for the adaptations each h

      • but could not, IMO explain how the different human populations evolved to physically adapt to their environments so quickly.

        Evolution of the (mostly) superficial adaptations that distinguish human populations happens faster than might seem intuitive.

        As a general rule, human populations evolve a skin color appropriate to their latitude. We can date some migrations as far back as the neolithic period, and when you look at those populations and their current skin color you come up with maybe only a few thousand years for full adaptation.

    • by hairyfeet (841228)

      Exactly and more importantly its nice to see that we aren't getting a billion "that's racist!" for daring to say that man as we know it didn't just come from Africa.

      Science doesn't have a damned thing to do with race, it has to do with evidence, and as we find more and more fossils I'd say its pretty obvious that there were probably a dozen, maybe more "offshoots" and those ended up either breeding into the other groups or dying out.

      So while there indeed may have been a primitive ancestor in Africa all th

  • by Baby Duck (176251) on Monday September 17, 2012 @04:35PM (#41366953) Homepage

    The problem with pinpointing human origins is we keep digging where 1) human remains are close to the surface, making them easy to dig up, with yearly rains washing away more and more making it even easier, and 2) the conditions for fossilization are highly salient. We very well could have come from environs where fossilization processes are nearly impossible, leaving no trace of our ancestors.

    We also like to dig where early humans leave behind stone tools. We don't dig where humans uses wood tools, because they fossilize way less often. It's hard to study what's not left behind! However, it's probable more humans used wood tools earlier and longer.

    • Pretty sure the actual problem is that there is no 'pinpoint' of human origins.

    • We have plenty of remains dug out that long predate any evidence of stone tools.

    • Re: (Score:3, Informative)

      by nowsharing (2732637)
      Your points are either incorrect or untestable:

      The problem with pinpointing human origins is we keep digging where 1) human remains are close to the surface, making them easy to dig up, with yearly rains washing away more and more making it even easier,

      See the cave sites in France. Actually, see cave sites across the world, where excavation involves chipping rock away to find the remains. It's nearer to sculpting and excavation. That's hardly easy, nowhere near the surface, and is standard practice in paleo excavations.

      2) the conditions for fossilization are highly salient. We very well could have come from environs where fossilization processes are nearly impossible, leaving no trace of our ancestors.

      The burden of proof is on you for this point. You need to give the reasons why you think humans were present in a specific area, and yet their remains (bone, stone, etc) are not present. You ma

      • The bamboo assertion hasn't been proven, but there is work to test it. For example see West and Louys " Differentiating bamboo from stone tool cut marks in the zoo-archaeological record, with a discussion on the use of bamboo knives"
    • A three for of outright errors in the above post:

      First to the outright factual error: wood and stone tools are used by our near primate relatives, so wood as tools as nothing to say about human origins. Zero. By the time their are humans, stone tools are in the toolkit.

      Second to the appeal to "absence of evidence is evidence" fallacy: one doesn't have to find anything from the point of origin to start to find where it is, in a manner similar to triangulation. Each find presents data, and when a rate of

  • by i kan reed (749298)

    Reality is more complex than humans just appearing in one location in Africa? That doesn't really question ANYTHING about the theory, but instead just suggests a refinement. This is essentially a non-story that only acts as fuel for dumb creationists who don't read more than a headline.

    • Re: (Score:3, Funny)

      by Anonymous Coward

      And on the third day, god created the Remington bolt action rifle, so that man could fight the dinosaurs. And the homosexuals.

      Amen.

      My guess is that Slashdot editors evolved from a completely different species of proto-human with limited cognitive capacity due to their thick brows and heavy, bony skull plates, which constrained the growth of their brains. This explains many things about their inability to create a useful headline, or edit a summary properly - it's like "infinite monkeys on infinite typewri

      • by ddd0004 (1984672)

        You wouldn't happen to operate a church do you? Because this sounds AWESOME. Especially, if you offer a large over-salted popcorn and 50 ounces of soda with every collection plate contribution over 15 dollars. 3-D glasses would be a nice touch too.

    • Yeah, the summary is very misleading. The Great Reexamination started in the moment when we started sequencing DNA and finding the most recent hominids. Does anyone actually doubt the very fact that higher primates evolved in Africa? If not, then the headline is an attempt at being sensational.
      • Headlines and summaries have a finite length; it's a little difficult to express a complex idea in one paragraph. If you're really interested in getting the full story, RTFA.

      • Does anyone actually doubt the very fact that higher primates evolved in Africa? If not, then the headline is an attempt at being sensational.

        IIRC there was recently some noise about some of the apes evolving outside Africa. Presumably because their ancestors migrated out earlier.

    • by russotto (537200) on Monday September 17, 2012 @09:15PM (#41370049) Journal

      Reality is more complex than humans just appearing in one location in Africa? That doesn't really question ANYTHING about the theory, but instead just suggests a refinement.

      There are multiple theories that really are different

      1) H. Sapiens evolved in Africa, travelled from there, overtaking and outcompeting (or outright killing) previous hominids who earlier left Africa.

      2) A mostly-modern H. Sapiens evolved in Africa, travelled from there, and interbred with/absorbed existing hominid populations (by some definitions these were also H. Sapiens) who had earlier left Africa. This one isn't so different, but it is different.

      3) Multiregional. Earlier hominids (not H. Sapiens) leave Africa in multiple expansions. These various groups evolve, run into each other, and interbreed, and continue migrating (including back to Africa). H. Sapiens emerges as a product of this global interbreeding and evolution. This is obviously a very different theory.

      Evidence of modern humans having some Neanderthal and Denisovan DNA casts a lot of doubt on the first theory.

  • by Daetrin (576516) on Monday September 17, 2012 @04:35PM (#41366965)
    Like every other part of science and history, no matter how simple the subject appears at first the more you dig into it the more complex it gets?
    • by timeOday (582209)
      Exactly... this seems to be a matter of degree. What percent of DNA do currently-living humans have in common? What percent of that is common with our "out of Africa" ancestors and was not anywhere else yet at that time? Certainly a little has changed since then, but how much?

      I'm not challenging the usefulness of refining the science, but such refinements are often MUCH smaller than the margin of error of the layman's knowledge of the subject in the first place.

  • by future assassin (639396) on Monday September 17, 2012 @04:36PM (#41366973) Homepage

    on humans and it showed them coming in on space ships.

  • Respect! (Score:5, Insightful)

    by folderol (1965326) on Monday September 17, 2012 @05:00PM (#41367293) Homepage
    For someone to publicly challenge their own theories takes considerable stature.
    • by 517714 (762276)
      Or they are using it as a means of getting back in the spotlight. I don't know which in this case, but usually it is as I have suggested.
  • I hate Biology (Score:1, Informative)

    by chubs (2470996)
    This is one of the reasons I hated Biology as a subject. The best definition I ever got for 'species' was a set of organisms that could interbreed and produce fertile offspring. This guy reminds us "remember, that's not always the case". So, if that's not the definition of species, what is? Poke and prod any Zoology professor long enough and he'll finally say "that's just the way it is, so just memorize it". There's no logical process defined for assigning organisms a place in our taxonomy. The only answer
    • Species is a qualitative, not a quantitative definition. The reason for that is due to the fact that it is a taxonomic category.

      Perhaps some day we can understand enough about genetics and proteomics to reclassify organisms according to their genetic or preteomic drift. That would be quantifiable.

    • You don't need to have a strict definition of species to do science. The notion of species is just an arbitrary category that works reasonably well in most cases you're going to study, but categorization is something you do for your own convenience.

      To give a simple example, you could arbitrarily categorize chemical elements into various groups according to perceived characteristics. Even if you later found out that there is some fuzziness between the groups, it does not make your study of the properties of

    • by tehcyder (746570)
      Shock horror, the real world is messy and hard to define in black and white terms.

      Not everything can be expressed as 1 or 0.
  • by rrohbeck (944847) on Monday September 17, 2012 @05:47PM (#41367899)

    A species is rarely singular, like a line or even like a river. It's more as if there was a continuum, like a flooded plain, and what we see is mainly determined by our own narrow views of organisms (or their remains) in spatial, temporal or cognitive terms. Simple things like the fact that wolves and coyotes are so close genetically that they should be called one species. Or many large cats. Or earlier subspecies of humans.
    Paleontologists only see the world as if it was lit up by small flashbulbs every now and then. Yes we've seen a lot of snapshots but how much is that compared to billions of years of evolution all over the Earth?

    • Humans love to categorize. Square and round things go together. Things with four legs vs things with six legs go together. Same basic principle.

      Of course, in practice, there is a continuum, stretching from specimen to specimen, and also back in time. But sometimes it's convenient to draw lines to limit your area of study.

    • by MaXintosh (159753)
      As a biologist, I'd say you've hit the nail on the head. There's probably no such thing as a species as a discrete entity, and the reason we have about 57 different species concepts is that they're all differing models for categorically explaining a continuous phenomenon that otherwise defies enumeration. But like other models, they're fantastically useful in some respects, and we keep them around for those purposes. When species concepts start to break down, we start talking about things like gene trees, o
      • by rrohbeck (944847)

        I thought about it a little more. The traditional species concept is probably a holdover from a pre-scientific era, basically a biblical concept.
        If God did it, it's a species. If man did it or if it was observable how it came to be then it's not a species. Hence wolf and coyote are different species, while dobermann and chihuahua aren't.

  • look at the data you have and formulate a theory. Collect more data. Modify your theory. SCIENCE!!

Algol-60 surely must be regarded as the most important programming language yet developed. -- T. Cheatham

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