June 5, 2011

Some quick prehistory news

P. boisei reconstruction
Quickly some archaeological or otherwise prehistorical news, mostly (but not only) from Stone Pages' newsletter ArchaeoNews.

Paranthropus sp. were patrilocal: enamel analysis finds that females were much more mobile than males in this hominin genus > SD.

Autism was maybe selected for in scattered hunter-gatherer populations > SD.

The effective population size of the first Native Americans was maybe of just 70 > Daily Mail [update: it seems to be on <a href=http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0030193 >a 2005 paper</a>, not really new].

Geometric rock art and "rock gongs" in Northern Sudan (Wadi Abu Dom) may be 5000 years old > Live Science, UPI.  

Newly found Australian skull might date to as much as  25,000 years ago > ABC.

Barrows (tumuli) excavated in Dorset (England) before the sea destroys them > BBC.

Large dolmen tomb discovered at Srikakulam (Andrah Pradesh, India) > Times of India.

14 comments:

  1. Have you read the Daily Mail article you link to? It's awful. It was written by someone with no understanding of the subject, and who apparently can't even use Wikipedia properly.

    Have you got a link to the paper, or to a discussion of it? Thanks.

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  2. I must agree with Clingram: that article is just horrid. Did Hey actually calculate that the first Native Americans arrived 12,000 to 14,000 bp or did he merely assume that figure for his calculations? That article explicitly states the former and thus seems to support "Clovis First", which is damned odd considering that an ever increasing amount of data seems to point in the opposite direction.

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  3. I was in doubt about including it but I never pay too much thought to these "quick news links" entries, so well...

    I do not have link to the paper, sorry. Consider it just another opinion... I do myself.

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  4. After a quick search, the paper seems to be Jody Hey 2005 at PLoS Biology.

    I have some qualm about the quality of the articles on PLoS Biology, Balaresque's paper was also published in this magazine, when most population genetic papers are not.

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  5. Thanks for the link. I didn't realize it was so old. That might explain his assumptions about Clovis. I wonder why the Mail has turned it up now.

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  6. I can't think of anywhere else to bring this to your attention, but it is sort of prehistroy news. Perhaps you could make a new thread. It deals with gene flow and the disconnect between mtDNA and aDNA in elephants:

    http://johnhawks.net/weblog/reviews/genomics/non-human/elephant-paleogenomics-forest-rohland-2010.html

    Quote:

    "There are many parallels here between hominin population dynamics and the elephants. Also, as I pointed out in 2006, the elephant situation helps to clarify how we should consider genetic samples from living great apes".

    And:

    "Forest and savanna elephants may deserve a species rank, but we might equally say that the mammoth-Asian elephant divergence doesn't merit the genus rank it has historically been given. As reconstructed in the paper, the forest-savanna elephant and Asian elephant-mammoth divergences both fall within ranges from 2.5 to 5.5 million years. Some widely-recognized mammalian genera (e.g., Homo) are younger, but most mammalian divergences in this range of times are recognized below the genus rank. Should mammoths be put into Elephas? That would probably be a better recognition of the adaptive radiation of Eurasian elephants".

    And:

    "'A long period of gene flow' would reflect a very gradual speciation event, which might argue that the two resultant species should be classified in the same genus. Or...it might suggest that the ecological differentiation actually commenced much earlier in time than the modal estimate, with later hybridization. Mammoths and Asian elephants, by contrast, seem to have a cleaner separation even though the genetic relationships are almost equally close".

    So again we are faced with a very indistinct separation between species. And, what's more, one that goes back only as far as the various human species do.

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  7. I read the original paper and I can't agree with even the conclusions of the authors: forest and savannah elephans seem almost totally distinct, even if they overlap at some localities.

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  8. "forest and savannah elephans seem almost totally distinct, even if they overlap at some localities".

    They share several relatively recent mtDNA lines though. Their separation has by no means been total.

    "I can't agree with even the conclusions of the authors"

    Because it goes against everything you believe. I see absolutely no problem with the authors' conclusions.

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  9. "Their separation has by no means been total".

    Naturally it is not total. Yes. Is that the big deal about this paper: that different species can share genes? We knew that already.

    Or am I missing something?

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  10. "different species can share genes? We knew that already. Or am I missing something?"

    Presumably different 'species' of human beings could also exchange genes, and presumably did so. But the paper also shows that mtDNA is not necessarily closely associated with aDNA. Same for humans, would be my guess.

    "forest and savannah elephans seem almost totally distinct"

    Not so distinct. Not everyone agrees that there are two species even. A 1955 book on mammals I got when I was in primary school (but it is by no means a child's book) dismisses the idea of a separate species in the African forests. So the gap between species is by no means well-defined.

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  11. The curious thing is that mtDNA and autosomal DNA, in elephants too are in most cases closely associated. That is what the data in that paper says (and spare me the literature).

    "Not everyone agrees that there are two species even".

    That's a terminology problem that would be for a biology congress to solve. I follow mainstream terminology. Being a matter of mere words, it's not really that important.

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  12. "spare me the literature"

    I know exactly why you want me to do that. It's because the literature contradicts this comment:

    "The curious thing is that mtDNA and autosomal DNA, in elephants too are in most cases closely associated. That is what the data in that paper says"

    Partly. But it is often very different:

    "What Enk and colleagues show is that the two Columbian mammoths both have mtDNA sequences that belong to a single, relatively young clade that is present in woolly mammoths in Alaska and Yukon. The simplest explanation is that the Columbian and woolly mammoths of North America were exchanging genes".

    So the mtDNA of Columbian mammoths is a subset of woolly mammoth, but the aDNA is obviously different, or the following wouldn't be the case:

    "The Columbian mammoth is seen by pretty much everybody as a separate species (Mammuthus columbi) from woolly mammoths (Mammuthus primigenius), and paleontologists have thought that they diverged 1-2 million years ago".

    And:

    "We also find that savanna and forest elephants, which some have argued are the same species, are as or more divergent in the nuclear genome as mammoths and Asian elephants, which are considered to be distinct genera"

    So the two 'species' have different aDNA. Yet:

    "The deepest mtDNA clade in the African elephants defines two haplogroups, both of which are shared by the forest and savanna populations. Based on large samples of mtDNA alone, the two populations have been recently exchanging genes".

    So agin we have a contradiction between aDNA and mtDNA. And the two mtDNA clades do not split the two 'species'.

    Back to a comment from a few days ago:

    "Is that the big deal about this paper: that different species can share genes? We knew that already".

    So why this earlier comment:

    "I read the original paper and I can't agree with even the conclusions of the authors"

    But now it seems that you accept the conclusions.

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  13. You do not understand nor want to try understanding: only heated discussion fits you, right?

    When I said I did not accept the conclusions were about the claim that there was a substantial difference between mtDNA and nDNA: in most cases they are the same so the exceptions are anecdotal and the normal to expect among closely related species in close contact.

    If we exchanged genes with H. erectus, why would not elephants do the same?!

    But the key point is that this exchange is minor, not massive, much less up to the point of blurrying the species distinction.

    Are you happy now? Bet you are not.

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  14. "only heated discussion fits you, right?"

    You are the only one I have heated discussions with. Your attitude annoys me, and I'm noted as being easy-going.

    ReplyDelete

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