Skull
of Cheddar Man (Wikicommons)
The first modern Britons, who lived about 10,000 years ago, had "dark to black" skin, a groundbreaking DNA analysis of Britain's oldest complete skeleton has revealed.
The fossil, known as Cheddar Man, was unearthed more than a century ago in Gough's Cave in Somerset. [...] It was initially assumed that Cheddar Man had pale skin and fair hair, but his DNA paints a different picture, strongly suggesting he had blue eyes, a very dark brown to black complexion and dark curly hair.
The discovery shows that the genes for lighter skin became widespread in European populations far later than originally thought. (Devlin 2018)
An ancient DNA study has made a big splash in the news. Its authors took the unusual step of releasing their findings to the media before presenting them at a scientific conference or in an academic journal. Not until more than a week later did they provide a paper describing their methods and their results. This paper was made available on BioRxiv, a preprint online repository, and it has yet to be accepted by a peer-reviewed journal.
Not
surprisingly, these findings have been discussed in an atmosphere of Gotcha!
journalism and trite moralizing. One of the authors, Yoan Diekmann, opined in an
interview that the connection between Britishness and whiteness is "not an
immutable truth. It has always changed and will change" (Devlin 2018).
Well,
obviously. If I could travel back in time, I would encounter people who look less
and less like me the farther back I go, and this would be true for any people anywhere
in the world. We think of the Amerindians as being native to the Americas, yet
their ancestors had earlier replaced a people with very dark skin and frizzy
hair, similar in appearance to the natives of Papua New Guinea (Frost 2018). In
Europe, the first modern humans to arrive some 45,000 years ago would have
looked very African—not only in their skin color but also in their hair form,
face shape, and body proportions.
This
is what evolution is about, perhaps more so with our species. Human evolution
is like a logarithmic curve. More genetic change has happened over the past
10,000 years than over the previous 100,000. And more has happened during those
100,000 years than over the previous one million. Our species is unique in
having to adapt not only to a slowly changing natural environment but also to a
faster-changing and increasingly diverse range of cultural and social
environments (Hawks et al. 2007).
Another
point: the Cheddar Man finding wasn't unexpected. We've already examined the
DNA of two other Mesolithic humans, one from Loschbour in Luxembourg, dated to
8,000 years ago, and the other from La Braña in Spain, dated to 7,000 years
ago. Both show the same combination of dark skin and blue/green eyes (Lazaridis
et al. 2013; Olalde et al. 2014). How dark is 'dark'? They would have been much
darker than a normal native European. The alleles in question are now so rare
in native Europeans that anyone with them today most likely has a recent
African ancestor.
Yes,
this study has been criticized for inferring skin color from alleles at 16
genes. Although this number is adequate for European and Asian individuals, it
isn't for Africans—among whom skin color is determined by alleles at many more
genes (Barras 2018). This is the case with most genetically influenced traits:
Europeans and Asians have much less genomic variability than do Africans
because their ancestors left Africa as small 'founder' groups that took with
them only a fraction of the original variability. But Cheddar Man, despite his skin
color, was European; he was descended from humans who went through the
Out-of-Africa bottleneck. Therefore, the study's methodology should work.
So
Western Europe was once home to hunter-gatherers who, other than their blue
eyes, were still largely African in appearance. Again, this is to be expected.
If we go far enough back in time, we come to ancestors who didn't look like us.
Perhaps less expectedly, we don't have to go very far back. The dark-skinned
Mesolithic individual from Spain lived some 7,000 years ago, and there is no
reason to believe he was the last of his kind. Indeed, dark skin seems to have
persisted into the early Neolithic in some parts of Western Europe, like a
Neolithic individual from England nicknamed 'Sven' and dated to 4,000-5,000 BP:
"Sven most likely had intermediate to dark skin pigmentation, brown eyes
and black possibly dark brown hair" (Brace et al. 2018). That last date
puts us within the realm of recorded history—almost the time of Hammurabi.
All
of this is consistent with earlier findings. Palaeontologists Marcellin Boule
and Henri V. Vallois noted the African-like appearance of many Neolithic
remains from Western Europe:
'In Brittany, as well as in Switzerland and in the north of Italy, there lived in the Polished Stone period, in the Bronze Age and during the early Iron Age, a certain number of individuals who differed in certain characters from their contemporaries', in particular in the dolichocephalic character of their skull, in possessing a prognathism that was sometimes extreme, and a large grooved nose. This is a matter of partial atavism which in certain cases, as in the Neolithic Breton skull from Conguel, may attain to complete atavism. Two Neolithic individuals from Chamblandes in Switzerland are Negroid not only as regards their skulls but also in the proportions of their limbs. Several Ligurian and Lombard tombs of the Metal Ages have also yielded evidences of a Negroid element.
Since the publication of Verneau's memoir, discoveries of other Negroid skeletons in Neolithic levels in Illyria and the Balkans have been announced. The prehistoric statues, dating from the Copper Age, from Sultan Selo in Bulgaria are also thought to portray Negroids. In 1928 René Bailly found in one of the caverns of Moniat, near Dinant in Belgium, a human skeleton of whose age it is difficult to be certain, but which seems definitely prehistoric. It is remarkable for its Negroid characters, which give it a resemblance to the skeletons from both Grimaldi and Asselar.
It is not only in prehistoric times that the Grimaldi race seems to have made its influence felt. Verneau has been able to see, now in modern skulls and now in living subjects, in the Italian areas of Piedmont, Lombardy, Emilia, Tuscany, and the Rhone Valley, numerous characters of the old fossil race (Boule & Vallois 1957: 291-292).
So
the Western European hunter-gatherers didn't die out completely. They represent
about 25% of the ancestry of Neolithic British individuals and about 10% of the
ancestry of present-day white British (Brace et al. 2018). Nonetheless, they
were largely replaced by people from elsewhere, perhaps beginning in the late
Mesolithic—as suggested by the more intermediate skin color of the Loschbour
individual (Brace et al. 2018).
How, then, did Western Europeans become white? When ancient DNA was first being
retrieved, the answer seemed simple: the last hunter-gatherers in Western
Europe were dark-skinned and the first farmers in Central Europe were
light-skinned. Therefore, the modern European phenotype must have been brought
to Europe by those farmers, who had apparently come from Anatolia (present-day
Turkey).
This
picture changed with retrieval of ancient DNA from hunter-gatherer sites in
northeastern Europe, specifically Motala in Sweden (8,000 BP), Karelia in
Russia (7500-7000 BP), and Samara in Russia (7,500-7000 BP). Those individuals
had a fully modern European phenotype: pale skin with diverse hair colors (red,
blond, black) and diverse eye colors (blue, brown) (Anthrogenica 2015; Eupedia
2015; Frost 2014; Frost et al. 2017; Mathieson et al. 2018). The modern
European phenotype must have emerged even earlier, most likely during the last
ice age of the Upper Paleolithic within an area stretching from the Baltic to
mid-Siberia. To date, the earliest known individual with the derived allele for
blond hair is from Afontova Gora (c. 18,000 BP) (Mathieson et al. 2018).
But
what about the Neolithic farmers? How did they get to be white-skinned? Most
likely through introgression. As they advanced into Europe, they intermixed
with the native population.
Agriculture in a region may have been introduced by immigrants, but that does not mean that the immigrants carried mainly Near Eastern genes (Richards 2003; Rowley-Conwy 2004b; Zvelebil 2005). The LBK, for example, originated in the Carpathian Basin; the population that moved westward emerged there carrying a complex mix of European and Near Eastern mtDNA and no doubt picking up more as it moved. (Rowley-Conwy 2011: S434)
In some cases, farming communities took in hunter-gatherer individuals, especially women. In other cases, replacement was followed by reverse replacement, as with Neolithic culture in northwestern France: "After a couple of centuries it disappeared, replaced by a more widespread local Neolithic. Agriculturalized foragers appear to have absorbed the immigrants" (Rowley-Conwy 2011: S439).
In
Western Europe, hunter-gatherers made a smaller contribution to the Neolithic
gene pool (~25%) because of their low population density. The situation was
like that of European settlers and native Amerindians in North America.
Introgression was greater during the long time (7500-6000 BP) when the advance
of Neolithic farmers stalled along a line stretching from the Low Countries in
the West to the Black Sea in the East. To the north, along the shores of the
Baltic and the North Sea, were hunter-fisher-gatherers with a relatively high
population density (Frost 2017; Price 1991).
So
to what degree are Europeans today descended from native Mesolithic
hunter-gatherers and to what degree are they descended from Neolithic farmers
of Anatolian origin? This question still has no reliable answer. On the basis
of mtDNA, Skoglund et al. (2012) estimated Anatolian admixture at 95% in
Sardinians, 52% in northwest Europeans, 31-41% in Swedes, and 11% in Russians.
This methodology has a major flaw, however: if a group is a mixture of two
other groups, its allele frequencies are assumed to be determined solely by the
degree of intermixture. No allowance is made for differences in natural
selection.
If
we compare late hunter-gatherers with present-day Europeans, we see that the
main change to mtDNA has been the loss of haplogroup U. Today, this haplogroup
reaches high levels only among the Saami of Finland and the Mansi of
northwestern Siberia, both of whom were hunter-gatherers until recently
(Derbeneva et al 2002). Does the hunting-gathering lifestyle somehow favor this
haplogroup? Balloux et al. (2009) argued that trade-offs between thermogenesis
and ATP synthesis favor some haplogroups over others. In particular, haplogroup
U is associated with reduced sperm motility—an indication that the energy
balance is shifted from producing ATP to producing heat. Being nomadic,
hunter-gatherers spend more time in the cold, especially when sleeping in
temporary shelters. In contrast, farming makes possible a more sedentary
lifestyle, including a warmer sleeping environment, and would therefore select
against genetic variants, like haplogroup U, that increase body temperature at
the expense of ATP production.
This
hypothesis is testable. If haplogroup U disappeared because Anatolian farmers
partially replaced native hunter-gatherers, this genetic change should coincide
with the time boundary between late hunter-gatherers and early farmers. If this
haplogroup disappeared through natural selection, the change should have
occurred gradually over a longer period. The second scenario seems closer to
the truth. In a study of 92 Danish human remains from the Mesolithic to the
Middle Ages, Melchior et al. (2010) found that high incidences of haplogroup U
persisted long after the advent of farming and apparently as late as the Early
Iron Age.
Haplogroup
U was likewise found to persist across the Mesolithic/Neolithic boundary when
Jones et al. (2011) compared ancient DNA from Latvia and Ukraine. They also
used nuclear DNA to compare the Mesolithic and Neolithic samples, as opposed to
the mtDNA methodology of Skoglund et al. (2012). This time there was no
evidence of Anatolian admixture in any of the Neolithic samples.
This
is not to say that Anatolian farmers didn’t contribute to the European gene
pool. They did, but researchers have overestimated this contribution by
attributing all of the genetic differences between farmers and hunter-gatherers
to population replacement. This is particularly the case with haplogroup U—the
mtDNA marker that most sharply distinguishes farmers from hunter-gatherers. If
mtDNA shows that Russians are 11% Anatolian, while nuclear DNA shows that
Ukrainians are 0% Anatolian, the discrepancy is probably due to differences in
methodology rather than a real difference between Russians and Ukrainians.
Conclusion
With
the end of the last ice age, Europe had three major populations:
Western
Hunter-Gatherers - attested from sites in Spain, Luxembourg, and England
-
African appearance except for blue eyes (dark skin, dark curly hair)
Anatolian
Farmers - attested from sites in central and southern Europe
-
Spread into Europe from the southeast and intermixed with native
hunter-gatherers as they advanced northward
-
White skin, dark hair, dark eyes
Eastern
Hunter-Gatherers - attested from sites in Sweden and Russia
-
Fully modern European phenotype: white skin with a diverse palette of hair and
eye colors
-
By the late Mesolithic, high population densities along the Baltic and the
North Sea
The
Western Hunter-Gatherers went extinct after 7,000 BP, being replaced by
Anatolian Farmers who by then had become heavily intermixed with native
hunter-gatherers. After a relatively rapid expansion into southern, central,
and western Europe, their wave of advance came to a halt around 7500 BP along a
line stretching from the Low Countries to the Black Sea.
Meanwhile,
Eastern Hunter-Gatherers along the Baltic and the North Sea had increased their
numbers by exploiting marine resources (fish, shellfish, seals). As
fisher-hunters they were able to create semi-sedentary societies with
relatively large populations and high social complexity, thus forming a
demographic barrier to the advance of farming until around 6,000 BP. They then
adopted farming through cultural diffusion rather than population replacement.
As farmer-fishers, they now expanded westward and southward, an expansion that
continued into the historical period.
In
this prehistoric drama, we like to see Mesolithic hunter-gatherers as beautiful
losers who were steamrolled out of existence by savvier and more numerous
farming peoples. This was true for the Western Hunter-Gatherers. There was
another Mesolithic population, however: the hunter-fisher-gatherers along the
shores of the Baltic and the North Sea. They achieved levels of population
density and social complexity not only on a par with Neolithic societies but
also rich in possibilities for future advancement. Of the three major populations
in prehistoric Europe, they were the ones who would ultimately have the greatest
demographic impact and lead the way to behavioral modernity, i.e.,
individualism, reduced emphasis on kinship, and the market as the main
organizing principle of social and economic life. They not only survived but
also went on to create what we call the Western World. Not bad for a bunch of
losers.
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