The Neanderthal-modern human handover

We live in a time of transitions when it comes to Neanderthals. Since the 2010 discovery of strong genomic evidence for Neanderthal ancestry in most humans they’ve been…humanized. This was pretty much inevitable, but, I also think it was right. Neanderthals were a big-brained human species which dominated much of Eurasia for hundreds of thousands of years. Their culture did exhibit a certain stasis, but then so did that of our modern African ancestors ~200,000 years ago.

There has been a recent debate about how far back the divergence between Neanderthals and modern humans goes back. My own views is that it’s probably further back than 500,000 years, perhaps closer to 750,000 years, but that there may have been ancient gene flow between lineages as well.

A new paper is now out which suggests that Neanderthals persisted in southern Spain for 3,000 years after they disappeared elsewhere, Precise dating of the Middle-to-Upper Paleolithic transition in Murcia (Spain) supports late Neandertal persistence in Iberia. Obviously, I can’t evaluate the taphonomy and all that. There have long been debates by paleoanthropologists about this region and its Neanderthal habitation (some earlier dates suggested Neanderthals persisted down to 29,000 years ago in southern Spain, but those seem to be rejected). What I can say is that it is entirely expected that the Neanderthal range as it contracted would exhibit an s-shaped trajectory, with a tail where they persisted as relic populations in areas which they were particularly well adapted to.

As paleoanthropology and genetics progress I’m rather sure that we’ll drill-down on very detailed dynamics of interaction, and local succession and replacement. Though humans leave cultural artifacts behind, as a rule the first and last fossils in paleontology usually underestimate the time span that a species flourished. I wouldn’t be surprised if the same applied to Neanderthals, and some day someone with a suspiciously high Neanderthal ancestral fraction was sequenced or genotyped who lived just before the Last Glacial Maximum.

Also, I should mention for those of you looking for a pre-Christmas gift, my company’s Neanderthal product (which does a functional analysis of a set of characteristics where modern humans segregate ancestral and derived variants from the two lineages) can be had for $29.99, as Helix is discounting the $80.00 kit cost (the same applies to the $39.99 Metabolism product, though if you bought Neanderthal earlier then Metabolism is always$39.99 since Helix has banked your data).

People keep asking us the details of the Helix-Insitome relationship and how it works. So we decided to write a blog post addressing that (it’s very short), How does Helix work?.

P.S. we’re probably the only start-up in the world where regular office conversation occurs about Neanderthals.

4 thoughts on “The Neanderthal-modern human handover

  1. “we’re probably the only start-up in the world where regular office conversation occurs about Neanderthals.” This is also common in political consultancies, although with a less literal meaning.

  2. In your Twitter poll earlier today, was there any difference between the two ways you posed the question about humans/Neanders? Doesn’t “fixation across lineages” more or less mean different species or, at least, different placements in a taxonomy?

  3. The strange part is the convergence of Neanderthal and Sapien cranial capacities at latter stages.

    Pearce’s paper with the cranial capacities of Neanderthal and Anatomically Modern Human AMH through history (kbp KYears before present) provided an interesting comparison, though only with two and a half set of data points,

    76kbp 25kbp present
    Neander 1535.5 1473.8 –
    AMH 1272.0 1473.5 1454.0(EU3avg) 1368.63(Eurasia8avg) 1358.25|(AFR4avg) 1365.17(Pearce12avg)
    diff 263.5 0.4

    Why the AMH while in Africa did not increase the cranial size significant before leaving the continent. Why the size for Neanderthal decreased while that for AMH kept increasing when both more or less were in the same environment (either cold or warm winters) that they even interbred.

    One possible explanation could be that through the interbreeding, AMH got more of the big brain genes from Neanderthal while Neanderthal got the reverse, until they reached the equilibrium at 25Kbp. There would be four possible results for the admixtures. For example an analog of a cross-bred dog with giant head and small body,

    Interesting thing is that at this point the Neanderthal had gone extinct and the size for AMH got in reverse and kept decreasing since then and is currently still decreasing.

    Nature through evolution seemed to prefer the larger head with smaller body version (while the Neanderthal still existed) and the other types simply disappeared.

    The introgressed Neanderthal genes do interfer with the mental state of Sapien like depression, psychiatric diseases and nicotine addiction,

    The nicotine addiction allele rs109033T concerned (EAS 17%) is negatively correlated with IQ proxy (OECD PISA score) for the East Asian, blamed it on the Neanderthal,

    Math = -956.739*rs901033T +654.776; # n=9; Rsq=0.6155; p=0.01229 *

    Only 1% of the European have such allele. The effect is not statistically significant for the European may be because of the small range.

    Strangely the alcohol aversion allele rs971A is also 18% for the EAS and none for the European. As alcohol damages nerve cell connections, Rs971A has the reverse effect,

    Math = +503.18*rs671A +412.369; # n=9; Rsq=0.9468; p=1.036e-05 ***

    The Ashkenazi also were reported to have significant similar alcohol aversion alleles ALDH2*2 though detail data were not available. It was noted that the Ashkenazi immigrants from the hard drinking Russia had less of such allele that those from Eastern Europe. Evolution in action.

    EAS have a fatal combination, for esophageal cancer risk rs971A increases it by 3.7X, together with heavy smoking the risk increases to 130X. Half of the world wide esophageal cancer cases are in China. The price for getting higher IQ. Almost 0% of EUR are exposed to this.

    Strangely the presence of rs971A seems to have negated the effect of rs901033T on IQ, Rsq for the former is 0.9468 while with both variable the AdjRsq is 0.9333, i.e. not worth adding the second variable. If forced into the regression, the coeff for the latter has turn positive. Over-sensitivity to alcohol might also induces over-sensitivity to nicotine.

    Math = +126.816*rs901033T +548.253*rs671A +384.529;
    # n=9; Rsq=0.95; AdjRsq=0.9333; p=0.0001252 ***

    Of cause this is a bit of speculation based only on 9 datapoints.

    To throw more circumstantial correlation to the issue, the correlation of OECD PISA 2012 scores with the introgression percentage data of Neanderthal DNA with Sapien from Sankararaman,

    PisaMath12 = +108.329*NeandPct +355.417; # n=27; Rsq=0.2923; p=0.003593

    There might be something there to be investigated for the brave researchers.

  4. I’d been considering them to be humans, but the introgression deserts around FOXP2 make me think that it could possibly be otherwise. Gray area to be sure.

    Four windows (1:99–112 Mb, 3:78–90 Mb, 7:108–128 Mb, and 13:49–61 Mb) are both Neanderthal and Denisovan ancestry deserts. The desert on chromosome 7 contains the FOXP2 gene, which has been hypothesized to have a role in enabling modern human speech and language [19] and has been identified as a desert in previous maps in Europeans and East Asians. Our finding that this region is also a desert of Denisovan ancestry strengthens the evidence that the modern human version of this gene may be critical for modern human biology [14, 15].

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