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Our Neanderthal Ancestry

Published: Wed 3 Mar 2021 10:20 AM
I'm a neanderthal man
You're not a neanderthal girl
Let's make hybrid love
In this neanderthal world
[with apologies to Hotlegs, 1970]Homo Stupidus?
After my partner read Dan Salmon's novel Neands – written during lockdown in 2020 – I decided to renew my interest in our distant ancestry, in part with a concern that homo neanderthalensis has been unable to shake off, so far, its unflattering reputation in popular culture. In the last few years it has become known that all humans alive today – with the exception of those of pure African ethnicity – have up to six percent Neanderthal DNA.
I have been reading Tim Flannery's Europe; a Natural History (written in 2017), having read Svante Pääbo's Neanderthal Man; In Search of Lost Genomes (2013) – by Svante Pääbo, whose team did the first genetic sequencing of Neanderthal and Denisovan DNA – and Neanderthals Rediscovered (2014, by Dimitra Papagianni and Michael Morse).
Pääbo is a specialist paleogeneticist; principally a dot maker, though also a capable dotjoiner. (We think of scientific scholars as discovers of facts, aka 'dots'; and we think of intellectuals as joiners of those dots to tell sensible stories.) Indeed Pääbo is a disciple of world renown New Zealand evolutionist, the late Allan Wilson. (The Allan Wilson Centre for Molecular Ecology and Evolution was established in Palmerston North in 2002, but sadly in 2015 became a victim of New Zealand government austerity.) Flannery – a former Australian of the Year – is a natural historian of wide scope; in abovementioned terms a dotjoiner more than a dotmaker, an interpreter and a gifted storyteller, a public intellectual.
Wilson was an important early proponent of the Recent African origin of modern humans hypothesis, which states that all humans alive today are descended from a population (homo sapiens) that lived in Africa and spread from Africa 70,000 to 80,000 years ago. The strong Wilsonian version of the hypothesis was that all humans today are wholly descended from that African population. Pääbo calls this population departing from Africa 'The Replacement Crowd'.
While Pääbo explicitly accepts that the Replacement Crowd need not have evolved in Africa, he evokes Occam's Razor (the idea that the simplest story is the most probable) to suggest that he favours the 'homo sapiens evolved in Africa' story. Flannery bluntly assumes that homo sapiens evolved in Africa.
(We might consider the possibility of a 22nd century global catastrophe from which the only survivors were New Zealanders; and that the subsequent population of the world originated in 'lifeboat Aotearoa'. Scientists in the 102nd century may well have an 'Out of Aotearoa' hypothesis, which would be accurate; but that would hardly be proof that humans had evolved in Aotearoa.)
The main story I want to relate here, however, is Flannery's account of the mixing of Africans and Europeans. Archetypal Europeans – homo neanderthalensis – lived in Europe (and West Asia) from 400,000 to 40,000 years ago, give or take a year or a thousand. They evolved pale skin, and were hunters welladapted to a planet that was for the most part much colder than it is now. The accepted story is that Neanderthals – or at least pure Neanderthals – became extinct between 40,000 and 30,000 years ago. (While the authors of Neanderthals Rediscovered reject the idea that a volcanic explosion caused this 'extinction' of the Neanderthals, revised dating suggests that indeed a supervolcanic event in Europe 39,000 years ago – indeed of the Vesuvius field – could have had a substantial demographic impact on the Europeans of that time.)
In the Linnaean (Latin) system of species nomenclature, the discoverer of a new species gets to name it. The first Neanderthal bones were discovered in 1856 in a cave in Germany's Neander Valley, just before Charles Darwin published The Origin of the Species. Scientific analysis took place in the mid1860s. Two of the first scientists to get access to these bones – which included skulls – were William King and Ernst Haeckel. Both named this new hominid species. King chose the name – homo neanderthalensis – based on the place the bones were found; fortunately he published the name first. Haeckel – presumably seeking a match for homo sapiens ('wise man') – published the name homo stupidus. This was the time when one pseudoscience (phrenology) was giving way to another (eugenics). Phrenology "involves the measurement of bumps on the skull to predict mental traits".
The Neanderthal skulls were seen as apelike, and hence were assumed to be the remains of an inferior hominid species. Modern humans had already (and prematurely) been dubbed 'wise' (sapiens). At the time scientists did not know about the African origins of 'wise men'. The eugenicists came up with an Aryan theory of racial superiority; a theory that helped to associate in the European mind the idea of 'white supremacy'. (The irony is, of course, that the stillpopular unscientific view of Neanderthals is in reality one of 'white inferiority', and the label homo sapiens could be taken to mean 'black superiority'.)
We are increasingly coming to understand that Neanderthals and Africans were neither superior nor inferior; just a bit different.Neanderthal Genetics
Flannery states that the Neanderthal nuclear genome is 0.3 percent different from that of modern humans. (Compare chimpanzees, at 1.2 percent different from humans.) While it is not yet clear what the different genes do, it is known that green eyes, red hair and pale skin are Neanderthal features; attributes which possessors should feel free to celebrate, in the same sense that Afro hair might be celebrated. Twenty percent of the Neanderthal genome (ie 20% of the 0.3%) is present in modern humans, though individual people today derive no more than six percent of their human genes from Neanderthals. (Indeed it is now possible for individuals to take a DNA test to estimate what percent of our human genes are of Neanderthal origin.)
Flannery mentions that none of the Neanderthal Ychromosome (the male chromosome) is present in modern humans. Superficially, this suggests that, when Africans and Europeans first met (most likely in the Levant), it was African (modern) men who mated with European (Neanderthal) women; meaning that the Africans were dominant (much as Europeans were dominant over Africans in eighteenth century America). Flannery infers that African invaders captured European women, maybe killing the men.
However, from reading Pääbo, the initial genetic research showed that Neanderthal mitochondrial DNA (passed through the female line) is also not present in modern humans. This would mean that the initial sexual contact must have been Neanderthal men mating with African women, and that subsequent 'hybrid' males were unable to reproduce (in line with 'Haldane's rule').
An important developing feature of evolutionary biology is the discovery of hybrid 'species', with Europe providing an environment in which many wild 'purebred' species were able to interbreed with related subspecies, creating what we might call 'mongrel' species; and that mongrel species could have – in certain environments – superior fitness attributes over the constituent species. (Flannery uses bears as an example of historical hybridisation in Europe.)Our Neanderthal Story
So, the story that I glean is as follows. This is my interpretation.
Between 40,000 and 50,000 years ago, African refugees met up with Europeans, probably in the Levant. Further, something similar probably happened around 70,000 years ago, with Africans mixing with West Asian Neanderthals. (East Asians then were probably substantially 'Denisovan'; Denisovans – first discovered in Siberia – and Neanderthals share common African ancestors about a million years ago; contrast the common ancestry between Neanderthals and Africans at about 500,000 years ago. Denisovan DNA is present today in native Australians and Papuans. Pääbo's last chapters are about his team's work on the Denisovan genome.)
Some Neanderthal men mated with African women, probably members of a refugee community, with the hybrid offspring being raised as Africans. (While neither Africans nor Europeans should be regarded as superior, refugee populations are vulnerable to their 'hosts'.) Hybrid male offspring were unable to reproduce, at least for a few generations until a kind of 'mestizo' hybrid 'race' was established. This mixed but mainly African population – with substantial amounts of Neanderthal DNA – gained a degree of fitness that allowed them to successfully spread into southern Europe. (Northern Europe was heavily glaciated then, though not as heavily as in the peak of the Ice Ages.)
As such, the hybrid population prevailed in an evolutionary sense over the pure Neanderthal population. The hybridised African immigrants were probably less carnivorous – more omnivorous – than the Neanderthal Europeans, and (as Papagianni and Morse note) were more coastal dwellers (fisher folk) than big game hunters.
Then – 39,000 years ago – the Vesuvius supervolcano erupted, severely affecting both populations, but leaving the hybrid population best placed to recover. Subsequently, increased glaciation ensured that the human population of Europe would remain very low
From 14,000 years ago – as the most recent ice age started to ebb – Europe was then subject to immigration from Asia; this includes the arrival of the first farmers. These central and west Asian immigrants were from a longer established hybrid population; their arrivals into Europe had the effect of diluting the Neanderthal component of the European genome. These Asians had paler skin than Africans. Melanin in the skin was probably selected against, as people moved into northern Europe and northern Asia (and America) in the years of glacial contraction following the last great ice age.
Possibly the most genetically Neanderthal people in the world today are the AngloCeltic natives of the British Isles, that outer archipelago of Europe where red hair remains a common population feature.
Neanderthals were probably not well adapted to Aotearoa – where ultraviolet sunlight is at its most intense. Nevertheless, as a quirk of human fate, Aotearoa – the 'Britain of the south' as it was once called – has become a bastion of Neanderthal genes. Indeed, my redhead Scottish ancestors bequeathed me with freckly skin, and my partner has gorgeous green eyes.
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Keith Rankin, trained as an economic historian, is a retired lecturer in Economics and Statistics. He lives in Auckland.
Keith Rankin
Political Economist, Scoop Columnist
Keith Rankin taught economics at Unitec in Mt Albert since 1999. An economic historian by training, his research has included an analysis of labour supply in the Great Depression of the 1930s, and has included estimates of New Zealand's GNP going back to the 1850s.
Keith believes that many of the economic issues that beguile us cannot be understood by relying on the orthodox interpretations of our social science disciplines. Keith favours a critical approach that emphasises new perspectives rather than simply opposing those practices and policies that we don't like.
Keith retired in 2020 and lives with his family in Glen Eden, Auckland.
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