Daily Data Dump – Monday

By Razib Khan | October 11, 2010 11:42 am

Good morning WWW.

Richard Dawkins publicized the “We Are All Africans” t-shirt on Bill Maher’s show, which resulted in a major backlog of orders. The shirt is factually true. But the “Out of Africa” model is not as clean or simple as it would have been 10 years ago. Ironically Dawkins himself tipped his hand as to the complexity of his own thinking in The Ancestor’s Tale by promoting Alan Templeton’s “Out of Africa again and again” hypothesis. Dawkins in the past has shown a keen skepticism of deriving ought from is, so I’m a touch confused by this current tack, though the maxim on the t-shirt is quite fashionable in our age.

Deep ancestors of human DNA compatible with structured African population. Dienekes reviews a paper which came out this summer. This is going to make me sound stupid, but did I review the paper? [confused it with another paper, no, this just came out] I’ll have to look. There have been models like this around for years, but the discovery that there’s non-trivial Neandertal admixture in non-African populations using the retrieved Neandertal genome should shift our priors a bit in terms of evaluating these papers.


Number of Competitive House Races Doubles from Recent Years. “When I noted this on Twitter on Friday, I got a few sarcastic replies: what good is a forecast if it tells you that essentially anything can happen?” This is the same attitude that conservatives had in 2008. Denial ain’t pretty, but it’s inevitable. Humans are natural born skeptics…when it suits them.

Honour killings: Saved from India’s caste system by the Love Commandos. “A spate of brutal killings in northern India has spurred a group of volunteers to set up a helpline to rescue couples whose lives are in danger because they want to marry across caste lines.” I would be curious to see if fine-grained analysis of genetic data could show past rates of intermarriage across castes in local regions. My bet is that intercaste marriage rates were higher in the past, and that “traditional” norms are enforced much more efficiently in the modern age where communication is more efficient and information flows more freely.

Association analyses of 249,796 individuals reveal 18 new loci associated with body mass index. More than 400 authors. It takes a village. Seriously.

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  • http://mengbomin.wordpress.com/ Meng Bomin

    If you go far enough back, you might be able to make a case for a “We Are All Laurasians.” t-shirt.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    sagan famously observed that we are the stuff of stars.

  • onur

    Neanderthals too are ultimately from Africa.

    What is important here is to not confuse the common African ancestors of modern humans with today’s Africans. Like all other places, Africa has changed much genetically and morphologically. Also recent genetic research indicates that out-of-Africa humans were genetically quite different from most Africans.

  • Chris T

    “We are all Big Bangers”

  • Insightful

    Razib, I would love to see you and Dienekes debate the Neanderthal admixture theory. Dienekes believes (as the authors of that study have also stressed) that the evidence for 1-4% Neandertal introgression into Eurasians has an alternative explanation consistent with the previous (Multple Archaic Populations in Africa) model. I might add that geneticist Spencer Wells still insists there is no evidence for Neanderthal admixture after the supposed findings by Paabo and team came to light, but that’s a debate you can take up with Dr. Wells, too. The theory is still controversial, however, I personally have an open mind so I don’t support one side over the other…

  • onur

    Razib, I would love to see you and Dienekes debate the Neanderthal admixture theory.

    On Bloggingheads preferably.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    the appropriate interlocutor for dienekes would be john hawks. i lean toward hawks’ model, but my confidence is modest at best. i don’t know the fossil and archaeological record well enough to bring to bear those data to differentiate between the plausible genetic models, though i trust john.

  • MK

    Peter Frost mentioned that phrase has been gaining in popularity:

    “In the same interview, Stringer went on to say that our species is so young that differences among humans can only be skin-deep:

    Since so little time has passed since they [modern humans] decamped from Africa, dispersing to the far regions of the world — 100,000 years being a mere paleontological moment — ”only slight differences, if any, in intellect and innate behavior are likely to have evolved between modern human populations.” We are ”all Africans under our skin.”

    Uh, 100,000 years is not a mere paleontological moment. A population can undergo significant physical and genetic change in as little as eight generations. In fact, many animal species go back only to the last ice age (25,000-10,000 BP). Evolutionary change is due primarily to the intensity of natural selection and only secondarily to the passage of time. Indeed, the faster such change has occurred, the more important it must be, since it is being driven by intense natural selection and not by adaptively neutral processes like genetic drift or founder effects.

    I can forgive journalists for not knowing the above. I find it harder to forgive Chris Stringer, who is fully aware of how fast natural selection can operate. There is no point in winning a debate if you inflict a lot of collateral damage in the process.

    Clearly, there has been collateral damage. The catch phrase “We are all Africans” has taken on a life of its own, with almost 100,000 Google hits. In the last French election, Ségolène Royal cited the latest findings in paleontology when she proclaimed, “Nous sommes tous des Africains!” This cute expression is even appearing in high school textbooks.

    And we’ll probably see it in newspaper headlines when the Neanderthal genome is finally published.”

    http://evoandproud.blogspot.com/2010/04/cheap-shots-and-collateral-damage.html

  • gcochran

    Be fair. There is no reason to think that Chris Stringer knows much about natural selection.

  • Chris Stringer

    Thanks so much Greg, you clearly know so much more about all of this than I do. Actually my views have evolved too, as will be apparent from my book on modern human origins, out early in 2011..

  • outeast

    The catch phrase “We are all Africans” has taken on a life of its own, with almost 100,000 Google hits.

    Well, even setting aside the notorious inaccuracy of ghitcounts there are going to be a lot of false positives in there. There’s a book, “We Are All Africans”, which ‘challenges the teachings of the Judeo-Christian-Islamic religions from an African perspective’; there are discussions of how ‘To the outside world, we are all “Africans”’; there’s a festival of African theatre called ‘We Are All Africans’; and so on. Just saying that as a datapoint that’s little better than a gut feeling.

  • dave chamberlin

    Thinking like a vapid reality TV producer I sure would like to see a series of debates by scientists who not only disagree on some science issue of the day but flat out don’t like each other. The name of the show could be “Somebody is Wrong.”
    Well it won’t happen, but I can dream.

  • vnv

    What if the discussion segments of “Somebody is Wrong” were interspersed with American Gladiator-style combat segments between the scientists?

  • vnv

    On second thought, it would distract from the scientific part of the discussion, which would probably just degenerate into trash talking due to the adrenaline rush of the upcoming physical confrontation. For maximum fireworks you probably want to keep the stakes of pride purely intellectual.

    But what if the segments (discussion and combat) were filmed separately, say a day or several days apart?

  • miko

    I don’t get what’s wrong with it… is the argument that it should say “We are all descendants of people who lived in what is now called Africa”? Anyway, it seems like a fairly benign expression of human unity.

    MK, I agree that humans have encountered strong selective pressures in the last 100,000 years (pathogens and diet being the big guns), but we also have a fairly pitiful effective population size, which makes drift a major force. Another consideration when making comparisons to other animals is generation time. Most animals have a generation time at least one order of magnitude shorter than humans.

    Point being, I don’t think it’s wrong to characterize 100,000 years as short on an evolutionary time scale for humans. But it’s a stupid argument, because anyone can pick what they mean by terms like “short” and “significant.” But I also agree with Stringer that subtle cognitive or behavioral differences are unlikely to have been targets of selection, particularly relative to the deathfest that is selection by pathogens (though any trait could get dragged along through linkage/drift).

    Re: your comments about racism on your blog. It is ad hominem to accuse someone of racism when criticizing their scientific theories about race only if racism was not a motivating factor in their formulation or promotion of those theories. I don’t know about the particular example, but it’s not like evolutionary theorizing driven by racism (implicit or explicit) is a historical rarity, whereas kitten microwaving does not suggest a particular stance on human evolution.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    I don’t get what’s wrong with it… is the argument that it should say “We are all descendants of people who lived in what is now called Africa”? Anyway, it seems like a fairly benign expression of human unity.

    for me the back-story to the multiregionalist vs. out-of-africa arguments in the late 20th century is that proponents of *both* sometimes tried to portray the other as somehow more insidious. e.g., multiregionalists would accuse out-of-africa proponents of positing a genocide as birthing human (“replacement”), while out-of-africa proponents would imply that multiregionalists of giving succor to racists. this was done mostly in the public domain. but once these ideas take root then changes in the science come to imply changes in norms in people’s minds (i still am confused as to why it should matter that out-of-africa with total replacement may imply genocide).

    the moral and ethical precepts which we hold to be true shouldn’t be contingent on a particular phylogenetic model. especially in a field in tumult.

    MK, I agree that humans have encountered strong selective pressures in the last 100,000 years (pathogens and diet being the big guns), but we also have a fairly pitiful effective population size, which makes drift a major force. Another consideration when making comparisons to other animals is generation time. Most animals have a generation time at least one order of magnitude shorter than humans.

    two points which go in the other direction

    1) that size has gone up A LOT in the holocene

    2) we as a species have a very wide geographic range

  • gcochran

    Nice to hear from you, Chris. Note that I was defending your honor. Anyhow, it seems to me that you have been insufficiently aware of some points. First, you have often said that even if there was a small amount of admixture with Neanderthals, it was probably evolutionarily insignificant. That is incorrect: even a smidgen of admixture is enough to transmit alleles with a noticeable selective advantage [Haldane 1927] . And we now know that there was more than a smidgen. It also seems that your default assumption is that no Neanderthal alleles would have conferred selective advantages in anatomically modern humans . That is unlikely, considering that we were moving into their territory, territory that they had lived in and adapted to for hundreds of thousands of years.
    Imagine that the inhabitants of Central Africa disappeared because of some disaster and were replaced by Boers, who then spent tens of thousands of years living with premodern technology in that region. After that time, you’d find that the Boer-ancestry population in central Africa had high frequencies of a number of adaptive African alleles – skin color, Duffy negative, etc – the _same_ adaptive alleles that Africans carry today, because Boers have about 5% African ancestry, and thus the founding population would have many copies of those adaptive African alleles. Even while 95% of their neutral genome would stem from Dutch,Huguenots, and Germans.

    Another point: the only useful way of predicting whether sister populations are interfertile is the time depth of separation, not how different they look. Dogs make this clear, I think. Deciding that a group was a morphological species doesn’t tell us whether it was a biological species. I looked, and was unable to find an example of two mammalian sister populations that split as recently as Neanderthals and AMH (less than a million years) and were intersterile. So the odds were overwhelming that they were interfertile – so admixture was almost certain, people being what they are.

    And more: you have several times suggested that Neanderthals may have lost because of bad luck, rather than some kind of biologically-based competitive inferiority. “Modern humans may have had no direct effect on Neanderthal extinction. They actually walked into empty spaces where Neanderthals had already disappeared. ” We now know that’s wrong, since we interbred. But even before we knew that, it was clear that this scenario, although logically possible, was terribly unlikely. When two populations occupy the same niche, the most common outcome is replacement. There can only be one. Think parsimony: did disasters wipe out all the other archaic humans in Eurasia ( India, East Asia, Indonesia) just before anatomically modern humans showed up? The simpler explanation is that anatomically humans out-competed archaics: killed, ate, occasionally screwed them, not necessarily in that order.

  • http://www.kinshipstudies.org German Dziebel

    “Thinking like a vapid reality TV producer I sure would like to see a series of debates by scientists who not only disagree on some science issue of the day but flat out don’t like each other.”

    Great idea, Dave. I’ll take it even further. How about mixed cognitive arts cage fighting? No holds barred: archaeology, genetics, cultural anthropology, kinship studies, paleontology, odontology, sumo – anything goes. I would tap anybody out in the first round with my Out of America theory.

  • Chris Stringer

    Thanks Greg, but I think I’d rather do without your snide comments in my defence in future :-) The quote about moderns walking into empty spaces was actually my summary of Finlayson’s view – mine are more accurately represented here
    http://www.timesonline.co.uk/tol/news/science/eureka/article6904661.ece
    and here
    http://www.timesonline.co.uk/tol/comment/columnists/guest_contributors/article7118688.ece
    and here Evolutionary Anthropology 19:89–91 (2010).

    My new book covers all this, and your recent work, but I do agree with Dienekes on the importance of deep African population substructure to the story..

  • gcochran

    Dienekes is wrong about the Neanderthal interbreeding results being explained by African population substructure, , but there are a lot of indications that there was significant substructure. A lot of this involves work that is not yet published: I look forward to seeing the details. Some of what I hear is remarkable.

  • http://www.kinshipstudies.org German Dziebel

    “I do agree with Dienekes on the importance of deep African population substructure to the story.”

    And let’s not forget that one of the earliest criticisms of the out of Africa model was centered precisely around the notion of the structure of the ancestral population. Out of Africa assumes panmictic mating for the ancestral population, but in all “ethnographically” attested examples (e.g., small Amazonian demes) populations are subdivided (See Neel, Estrutura populacional dos amerindios e algumas interpretacoes sobre evolucao humana // Origens, Adaptacoes e Diversidade Biologica do homem nativo da Amazonia. 1991.) In a subdivided population, Fst is high, and the greatest Fst values have been recorded not in Africa but in the New World.

    Notably, those Amerindian populations are sometimes used explicitly as a proxy for an ancestral African population, as in “Indeed, among the current human populations, South American aboriginals [and these are specifically the Surui and Karitiana that have low population sizes - GD] can be considered a reference for microsatellite variation in an ancient African ancestor because their population size is low and might be compared with that estimated for an African ancestor, from one to a few thousand gametes (Rogers and Harpending 1992 ; Rogers 1995 ; Rogers and Jorde 1995; Zhivotovsky et al. 2000), and they have maintained their style of life probably since they arrived in this area (L. L. Cavalli-Sforza, personal communication).” (Zhivotovsky “Estimating Divergence Time with the Use of Microsatellite Genetic Distances,” 2001).

    It’d be interesting to know if variation at the studied loci in South Amerindians is close to a Neanderthal value. Unfortunately, Green et al. 2010 didn’t include an Amerindian sample in their study of “Neanderthal” admixture.

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  • http://www.evoandproud.blogspot.com Peter Frost

    “It is ad hominem to accuse someone of racism when criticizing their scientific theories about race only if racism was not a motivating factor in their formulation or promotion of those theories.”

    You’re misunderstanding the term “ad hominem.” An argument should be judged on its own merits, not on the basis of the arguer’s presumed motives. An argument remains ad hominem even if the motives are proven to be true.

    Oh yeah, some motives are good and some are bad. Is that your point?
    And just what constitutes a ‘good’ motive? When a defense attorney defends an accused person, the underlying motive is not to find out the truth. It’s to get the charges dismissed (and earn a fat lawyer fee). Is that wrong? When people testify in divorce court, should we dismiss their testimony when they seem to be acting out of spite?

  • Richard Sharpe

    MK, I agree that humans have encountered strong selective pressures in the last 100,000 years (pathogens and diet being the big guns),

    So, I guess culture must be sui generis and without effect, then.

    Has there been no selection for traits required to live in large groups of people and deal with capricious governments, deal with the written (and other recorded) means of cultural transmission, and the future time orientation required in these environments?

  • miko

    Peter, someone was saying that he was wrong, and he was wrong because he was deluded by his racist assumptions. Mentioning that he’s racist seems fairly central to this argument, not a tangential attack.

    Has there been no selection for traits required to live in large groups of people and deal with capricious governments, deal with the written (and other recorded) means of cultural transmission, and the future time orientation required in these environments?

    If you’ve got evidence of some, I’d be interested to hear it. Again, my understanding is that when people look for evidence of selection in humans, the things they find are 1) things related to living with pathogens 2) things related to diet 3) artifacts of drifts and meiotic quirks 4) regions of unknown function. Maybe this last category contains some of the things you’re interested in.

    I kind of buy a generalized theory of cultural evolution based on Terence Deacon’s theories on language. It looks like our brains evolved to learn languages, but really languages evolved to be easily acquired by human children. I think our brains are a much bigger constraint and selective force on our cultures than vice versa.

  • http://www.evoandproud.blogspot.com Peter Frost

    “Peter, someone was saying that he was wrong, and he was wrong because he was deluded by his racist assumptions.”

    Sorry, but there are no racist assumptions built into the multiregional model of human evolution (which I incidentally have never supported). Some of its earliest proponents, like Loring Brace, were prominent antiracists a half-century ago, when the social pressures to be antiracist were much weaker.

    Again, please judge an argument on its merits, not on the arguer’s real or alleged motives.

    Your justification (“someone says …”) would guarantee you an ‘E’ on a term paper. Check your sources.

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This blog is about evolution, genetics, genomics and their interstices. Please beware that comments are aggressively moderated. Uncivil or churlish comments will likely get you banned immediately, so make any contribution count!

About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at http://www.razib.com

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