Human-on-human sex

By Razib Khan | August 13, 2012 12:27 am

Dienekes tips me off to the fact that the long-awaited Reich lab paper on Neandertal admixture dating has finally been put on arXiv! The date of interbreeding between Neandertals and modern humans:

Comparisons of DNA sequences between Neandertals and present-day humans have shown that Neandertals share more genetic variants with non-Africans than with Africans. This could be due to interbreeding between Neandertals and modern humans when the two groups met subsequent to the emergence of modern humans outside Africa. However, it could also be due to population structure that antedates the origin of Neandertal ancestors in Africa. We measure the extent of linkage disequilibrium (LD) in the genomes of present-day Europeans and find that the last gene flow from Neandertals (or their relatives) into Europeans likely occurred 37,000-86,000 years before the present (BP), and most likely 47,000-65,000 years ago. This supports the recent interbreeding hypothesis, and suggests that interbreeding may have occurred when modern humans carrying Upper Paleolithic technologies encountered Neandertals as they expanded out of Africa.

This isn’t the only group working on the Neandertal genomic admixture story. From reading his blog you probably know that John Hawks is working in this area, but there are other labs too. I’m hoping that the Reich lab pushing their stuff on arXiv will prompt the other groups to also start moving (instead of just presenting preliminary results to a narrow group of researchers).

As for these results, I’m still amazed that LD based methods can work this far into the deep past. Second, it is nice that the low bound estimate can plausibly predate the arrival of anatomically modern humans to Australia. Also, this admixture date is well after anatomical modern humanity, and well before the classical “Great Leap Forward” of behavioral modernity. Though I think that over the next few years we may start to discard the idea of any such punctuated leap.

And again, it’s on arXiv. As they used to say, read the whole thing!

MORE ABOUT: Neandertal

Comments (6)

  1. Sandgroper

    It aways looked likely not to have occurred in Europe, and this gives that some support.

    Good to see them using arXiv – more power to them. I don’t see the point in being gratuitous about it, but I really think we should applaud researchers who do this.

    I’m determined to find a suitable open-access vehicle for my next paper, now.

  2. gcochran

    If there was a later wave into Australia, Neanderthal admixture could have been acquired then. The date of original settlement may not be relevant.

  3. Steve C

    I wouldn’t be surprised if modern human/neanderthal mating corresponded with the first use of alcohol.

  4. Gary B

    I’ve long had the (unsupported) idea that the section of the Bible (in Genesis? I don’t recall) discussing sex between ‘men’ and something different and lesser, that was also described as ‘men’, was about this very thing. It was an attempt to prohibit having sex with the low-life neighbors who weren’t quite ‘men’.

  5. bob

    The admixture makes more sense than any other explanation. It coincides with fossil finds in the middle east that show a 40,000 year overlap of Neanderthals and moderns, and which hint at shared morphology.

    Furthermore, the human bottleneck 70,000 years ago would have taken away most of the variability between northern and southern populations. Neanderthal admixture is the best explanation of the (apparently) reintroduced genetic diversity in non-African populations of moderns.

  6. Tom Bri

    #4 you are thinking about the Nephilim, I believe. Described as ‘sons of God’.
    Later giants were said to be descended from them.


Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

Gene Expression

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


See More


RSS Razib’s Pinboard

Edifying books

Collapse bottom bar