Apes just being apes

A while back I made fun of bonobos and chimpanzees for being kind of losers for looking across at each other on either side of the Congo river for ~1.5 million years the time elapsed since their diversion. I finally ended up reading the paper from last year, Chimpanzee genomic diversity reveals ancient admixture with bonobos, which reported complex population history between these two species. In other words, “they got it on”.

The key was a reasonable sample size of N=40 and high coverage genomes (>20x), to give them the amount of information necessary to have the power to detect admixture. If you aren’t human and have a reasonable size genome, and all mammals do, get to the back of the line. But theĀ Pan‘s turn finally arrived.

The paperĀ primary result is that over past few hundred thousand years there have been reciprocal gene flow events of small, but detectable, magnitude between chimpanzees and bonobos. Naturally, there was some geographic specificity here, in that chimpanzees from far West Africa lack much evidence of this while those from Central Africa have a great deal. The admixture is directly proportional to proximity to b0nobo range.

To obtain the result their initial focus on high-frequency bonobo derived alleles that were at low to moderate frequencies in chimpanzees. There was a notable excess for this class among Central African chimpanzees. And, these alleles seem to have introgressed recently.

I suppose the major takeway is that hominids do it like they do it on the Discovery Channel.

4 thoughts on “Apes just being apes

  1. Humans and the common chimp have some bad behaviors in common – e.g., “Demonic Males: Apes and the Origins of Human Violence”, Dale Peterson and Richard Wrangham (1997).

    Until very recently I understood that the common chimp was closer genetically to humans than the bonobo chimp was to humans. But perhaps this is not the case.

    The paper that made me wonder was “The bonobo genome compared with the chimpanzee and human genomes”, Kay Prufer et al, Nature (2012), but maybe I don’t understand the paper very well.

    Any comments?

  2. Humans split off from proto-chimpanzees before bonobos did. It’s not comparable to gorillas or orangutans where we can definitively say we’re closer to one species on the family tree.

  3. Prufer et al show (figure 3b) the split of humans from the lineage taking place about 4.5Myrs ago, and then bonobos and chimps splitting apart 1Myrs ago.

    And from their analysis: “This showed that 1.6% of the human genome is more closely related to the bonobo genome than to the chimpanzee genome, and that 1.7% of the human genome is more closely related to the chimpanzee than to the bonobo genome”

    It made me question the “we are closer to chimps than bonobos” idea. There are some references to follow up in the paper that might give me some clarity.

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