Sex and the Single Neanderthal: Inter-Species Breeding in the Upper Palaeolithic?

There’s been some coverage of a recent announcement by Svante Pääbo of the Max Planck Institute, who opines that Neanderthals andneanderthal615 anatomically modern humans had sexual encounters as they co-habited in Upper Palaeolithic Eurasia from around 42,000 bp to 24,500 bp. The main article is over at the London Times, from which this is an excerpt:

Paabo recently told a conference at the Cold Spring Harbor Laboratory near New York that he was now sure the two species had had sex — but a question remained about how “productive” it had been.  “What I’m really interested in is, did we have children back then and did those children contribute to our variation today?” he said.

“I’m sure that they had sex, but did it give offspring that contributed to us? We will be able to answer quite rigorously with the new [Neanderthal genome] sequence.”  Such an answer might ease the controversy over recent contradictory discoveries regarding Neanderthals. Some fossils seem to have both modern human and Neanderthal features, suggesting that the two species interbred. Yet DNA scans have shown that Neanderthal genes were very different from those of modern man.

Pääbo is reported to be at the point of publishing his analysis of the Neanderthal genome, and it seems clear that he has gleaned something from the data that has prompted this latest assertion; previous research has been interpreted as indicating that if the two species did interbreed it was at a very low level, apparently evidenced by the almost complete lack of a Neanderthal presence in our own genome today.

Gene Expression comments thus:

The way Paabo is couching it, what he has found then seems likely to be evidence that humans who had just expanded Out of Africa contributed to the genomes of Neandertals. In other words, modern human introgression into Neandertals. Of course if the gene flow was from modern human to Neandertals exclusively, then it would be an evolutionary dead end since that lineage went extinct.

In any case, for several decades some fossil-based paleoanthropologists have been claiming that there are “intermediate” individuals in the record which indicate modern human-Neandertal hybridization. Most prominently Erik Trinkaus. If Paabo’s finding becomes more solid, then it seems time to update the probabilities on these sorts of claims based purely on morphology.

The story is taken up at Ad Hominin, where the following opinion is expressed:

Today, most researchers acknowledge that some sexual encounters could have occurred between Neandertals and modern humans. The more interesting question is how common were these encounters and did they leave their mark on the modern gene pool. Undoubtedly, modern humans and Neandertals would have recognised each other as fellow humans but this does not mean that they would have acted humanely to each another.

Countless social and psychological studies have shown humans to have a very strong “us versus them” mentality, that no doubt also existed in our ancestors. It is unlikely that modern humans and Neandertals had an easy relationship. Most sexual encounters that took place between the two were likely opportunistic and probably involved enslavement and rape.

Of course we have absolutely no evidence regarding the circumstances under which these liaisons may have taken place, and I imagine the last sentence of the quote above is obliquely referring to the way in which the indigenous Indian populations of the Americas were almost wiped from the face of the Earth by the tide of white Europeans, who staged one of the most brutal and violent land-grabs in recorded history, as they claimed other peoples’ territories for their own, killing thousands in the process.

However, Upper Palaeolithic Europe was a very different place to the Americas of a few centuries ago, with no centralised governments, mobilised armies, or even slavery, as suggested above. I’m not even sure what the duties of a putative slave in the UP would actually be, or how such a state of affairs could even be enforced. The sheer numbers of humans involved in the theft of native peoples’ lands far eclipsed the populations of Ice Age Europe, so although there might have been competition for land and resources, it would have been on a far smaller scale than in modern times.

Moreover, the technological and cultural gap between Neanderthals and incoming moderns was comparatively narrow, as opined by Professor Chris Stringer of the Natural History Museum in London:

“It’s possible that Neanderthals and humans were genetically incompatible, so they could have interbred but their children would have been less fertile,” said Stringer.  This phenomenon is seen in many other species such as when lions breed with tigers and horses breed with zebras.  “I used to believe Neanderthals were primitive,” said Stringer, “but in the last 10,000-15,000 years before they died out, around 30,000 years ago, Neanderthals were giving their dead complex burials and making tools and jewellery, such as pierced beads, like modern humans.”

The popular notion of inter-species sex, as apparent in the previously quoted post, was that brutish Neanderthal men had their wicked way with anatomically modern women by dragging them behind the nearest bush, reinforcing the old stereotype of rapacious cavemen that has so blighted the way in which our archaic ancestors have been viewed for nigh on 150 years.

Because the population of Europe in the Upper Palaeolithic was probably very low in both modern and archaic communities, contact was likely to have been infrequent – indeed it seems quite possible that members of both species lived entire lifetimes without encountering one another – as Neanderthal numbers began to decline, any encounters would become increasingly rare.

And when moderns and Neanderthals did make primary contact, it could have been under any number of circumstances, some of which may have resulted in violence and death, whilst others might have developed into co-operation, friendship, up to and including, romance and kisses. Yet other encounters might have ended in polite ‘nice-to-meet-you’ handshakes, after which the two species quietly got on with minding their own business, without harbouring any particular feelings for or against their new acquaintances.

As a brief aside, I can’t help but speculate that it might have been easier for Neanderthal women to give birth to inter-species offspring than their AMH counterparts – bearing in mind that Neanderthal babies were more robust, the shape and size of their skulls, even when hybridised, would have made it more difficult for AMH mothers to give birth. A Neanderthal woman who had conceived a child fathered by an AMH male would maybe have found it easier to give birth to the hybridised and possibly smaller baby she was carrying – so should we expect to find that hybridised children conceived by Neanderthal women survived in greater numbers than those conceived by AMH mothers? And how would we then consider the evolutionary social factors that led to relationships between the two species that caused AMH men to bond and breed with Neanderthal women? Such a question may be answered in part from this further quote from Ad Hominin:

The recent announcement by Svante Pääbo that he is sure that Neandertals and modern humans had sex is quite a bold pronouncement coming from a scientist. It raises the question of whether this ascertain is based on some hard evidence they found while sequencing the Neandertal genome. It is possible that if there was some Neandertal genes passed on to the first moderns in Europe, they could have got eliminated from the subsequent gene pool as population sizes fluctuated during the more severe climatic episodes. A more likely scenario is that Pääbo’s team found evidence of modern introgression in the Neandertal genome. In all likelihood the incoming modern humans were more numerous than the Neandertals, thereby absorbing the endemic populations through genetic swamping.

This would seem to reinforce the point that any enforced sex is more likely to have been instigated by incoming AMH males on the female Neanderthal population, if we are to take modern history of human conquest and genocide into account and apply the same mind-set to life 30,000 to 40,000 years ago. But the fact that the both modern and archaic populations may have co-existed in Europe for 10,000-15,000 years at least hints that there was no large-scale or organised species cleansing undertaken by AMH, and it’s quite possible that both they and the Neanderthals behaved a great deal better towards each other than has often been the case in our own recorded histories.

It remains to be seen whether this latest research is able to resolve this question of interbreeding, or whether instead tentative clues will emerge that raise more questions than answers.

See also: Video – Svante Pääbo discussing the Neanderthal Genome Project on YouTube.

15 thoughts on “Sex and the Single Neanderthal: Inter-Species Breeding in the Upper Palaeolithic?

  1. I can see how the word ‘enslavement’ could be interpreted as meaning slavery in the colonial sense. This is not how I intended the word, however. I meant enslavement in the following sense: “cause (someone) to lose their freedom of choice or action”. I do not wish to suggest that Late Pleistocene peoples kept slaves in any systematic or organised way. I simply speculate that males may have opportunistically taken females against their will in order to have sex with them, thereby removing the females’ freedom of sexual choice.

    1. I suppose the next question would be, who was doing the enslaving – AMH, the Neanderthals or both? Or is it even possible that prospective mates were traded between species, selected to create alliances, or chosen for other reasons that might not appear obvious to us tens of millennia later?

      1. maybe it is farfetched to call it enslaving, i took it as a comparison with modern huntergatherer society’s that under foodstress tend to indeed ‘enslave’ persons of other groups, sometimes. indeed in sexual matters a prisoner could be abused without consent. allthough it is not that evident, for example the vikings that habitually robbed woman, as to (in contemporain literature) enslave them (wich was a most common event in exactly the developed cultures describing the vikings) in practice married them so much the load of scandinanvians with dark hair can be retraced to these events.

        the point here being that such mechanism would have much facilitated interbreeding, since as far as we know under circumstances of population stress (wich we may assume the (if) existant influx of ‘new’ humans into europe created) woman are more often kept, then abused in singular events. within tribal structures. so i think its is a good point, although the literal interpretation of enslavement, and humans being ‘property’ may well have only developed with the ascent of monetary systems. in the least those cultures that early on ruled and minted for the surrounds (say greek, babylonian, roman) all share the trait of slavery. in a much ruder and more widely applied form then the , intrinsically romantic, abduction practice that has long been part of marital strategy’s.

  2. “who opines that Neanderthals and anatomically modern humans had sexual encounters as they co-habited in Upper Palaeolithic Eurasia”.

    I find it incredible that so many so strongly believe that they didn’t.

    “Countless social and psychological studies have shown humans to have a very strong “us versus them” mentality, that no doubt also existed in our ancestors”.

    And that is likely to be the extent of our difference. Simply tribalism. Many today, even seemingly liberal people, seem opposed to what they term ‘miscegenation’.

    “the indigenous Indian populations of the Americas were almost wiped from the face of the Earth by the tide of white Europeans, who staged one of the most brutal and violent land-grabs in recorded history, as they claimed other peoples’ territories for their own”.

    Have a look at what happened to the Tasmanian Aborigines if you think America was bad.

    “It is possible that if there was some Neandertal genes passed on to the first moderns in Europe, they could have got eliminated from the subsequent gene pool as population sizes fluctuated during the more severe climatic episodes”.

    That, in my opinion, is the most likely explanation for the apparent lack of Neandertthal genes’ survival.

  3. I was having the same discussion at Mundo Neandertal (in Spanish) and I’m kind of exhausted about the matter to add anything of relevance at the moment.

    However: Neanderthals were giving their dead complex burials and making tools and jewellery, such as pierced beads.

    This contradicts what I saw Mellars say on TV, mentioning that Neaderthal “imitation” beads were not pierced but tied around a rig.

    I’d like to see the source of that. Maybe he is thinking in the Uluzzian of Italy but that’s the very reason why Hoffecker suspects this culture was made by Homo sapiens and not Neanderthals (no direct fossils exist for this or other transitional cultures).

    A Neanderthal woman who had conceived a child fathered by an AMH male would maybe have found it easier to give birth to the hybridised and possibly smaller baby she was carrying

    Makes some sense. Smaller head at least (Sapiens’ head is higher but not broader nor longer than Neanderthal’s) should make a hybrid birth easier among Neanderthals than among Sapiens.

  4. All this still assumes that neanderthals are not just normal variants of humans. I’ve seen modern people who could have been classified as neanderthals had their skulls had the misfortune to end up in an archeologic dig.

  5. (A)MH these days , as soon as they encountered a different looking kind of human (for an example eg. san) had sex, both voluntarilly (that is to an extend) and forced. it is so that male humans in absence of woman take for man, and that males commonly take for animals if they are closer then man. As such it would be ridiculous to expect no sexual exchange. my personal idea is that the circumstances would be ideal for the event to go moreless unnoticed, most probably neanderthals experienced the newcomers as a threat (rather like native usians, tasmanians or aboriginals did) and one they were not ready to cope with decisively. In that case modern cultures start mimicking exterior characteristics of the newcomers at great speed often. in dress or looks, but more typically in preferential breeding. (wich is why so many africans have white handpalms, and caribeans straight noses). So neanderthalers that made a conscious attempt to breed with (a)mh, would have preferentially opted for minimising the differences in looks. selecting ‘(a)mh looks’ both in their own genetic pool and in the mixed offsprings. it’s allways possible interbreeding was neigh impossible (like eg. with donkey and horse) yet the times they remained seperate doesn’t very well compare to typical cases made, like tiger-lion, or donkey- horse, either of wich were apart for many millions of years and not a few 100000. i am not sure but i know of no mammal species(1) that are remote less then a million year and can’t interbreed.
    (1)or other species

    1. … i took it as a comparison with modern huntergatherer society’s that under foodstress tend to indeed ‘enslave’ persons of other groups

      Totally unheard of to me.

      … for example the vikings that habitually robbed woman

      Vikings were not hunter-gatherers but an Iron Age society (including, of course, farming and animal husbandry).

      I think you are basically wrong, though the fact that “romantic” wife kidnapping happened until recently among Inuits is for real. But these same Inuits don’t seem to have ever interbred with the Tuniit that preceded them in the same ecological area: they essentially replaced them instead.

      1. it is statistics from research about cannibalism in the amazone, that also sidesteps on this. hm yes vikings were ironage, but they were also less agricultural, in that sense closer to hunter gatherer and tainted with the bias of ‘wildness’, wich to the current day get’s people to look at their roots and tribal tradition (eh eg. in afghanistan). slavery as an institute in agricultural society comes with foodstress, i only know from several incidences that enslavement may be a component of canibalism, headhunting, and violence as phenomenons of foodshortage. also in north america cannibalism and enslavement appear to go hand in hand when they occur.

        1. My point is that agriculturalists are normally very different from hunter-gatherers: their societies are, their cultures are and their values are too. “Wild” farmers from Papua or Scandinavia are surely much closer to modern or historical societies than to hunter-gatherers. Of course civilization (and other elements) add further distinctions but in my opinion foraging and farming are just two totally different socio-economical realities and the most fundamental such barrier that humankind has ever crossed.

          I do not accept farmers as example of hunter-gatherers in any case. Farmer societies are generally much complex, with growing notions of property and hierarchy that can’t exist among hunter-gatherers. While from the city is maybe the easy thing to see them all as “savage” or “primitive”, there is a cultural and socio-economic abyss among them.

        2. thats ok. however research into absolute huntergatherer situation is much more limited to archeology. for example in educational values and the position of woman there is a scale , huntergatherer- herding- sedentary agriculture, where their rights are progressively disrespected. so i think sometimes deductions from comparably remote technologies society’s are valid. glad you don’t acknowledge research indeed warrants to see this relation between protein-shortage and slavery. btw i didn’t know inuit had the romantic wife kidnapping thing, there is the assumption of replacement by the ‘tunuit’ (the big inuit) i know, but i have not seen wether that has been proven to exclude the (kidnapped) tunuit females from reproduction. possibly because that mostly concerns research from before the human genome.

  6. I watched the video- out of Africa. It showed that the Navajos and the Nomads of ancient Siberia shared Genes. Which means during the ice age Russia and Alaska were connected. Both Native Americans and Russians, share some Genes, like High cheek bones. Germans and the Neanderthals have high cheek bones.Humans migrated just like any other animal with a vertabre. With migration comes change, and that creates differences. Different climates create differnces with many spieces. Maybe one day will find if the 2 spieces interbreeded.

  7. Nathan: high cheek bones seem quite widespread among archaic humans. They prove nothing on their own (it’s like saying “prognathism” or “browridges”).

  8. What an amazing amount of unsupported speculation from what should be a scientifically based website blog.
    Slavery? rape? seriously? This is what you think of AMH?
    Let the genome do the talking about whether or not there was interspecies breeding, and leave all the drama to Fox News.

  9. I am sure the two species interbred, whether it was consensual, by rape or both.

    “Modern man” continues to have sex with animals, so please, what would stop them from having sex with Neanderthals and vise versa?

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