Semang
from the Malayan Peninsula, Wikicommons
Before
the Europeans came, the Americas were settled by three waves of people from
northeast Asia: the oldest wave beginning some 12,000 to 15,000 years ago,
which gave rise to most Amerindians, and two later waves, which gave rise
respectively to the Athapaskan and Inuit peoples of northern Canada and Alaska.
That's the conventional view.
Kennewick Man. An
earlier form of Northeast Asian?
There
is growing evidence, however, for earlier waves of settlement. There's
Kennewick Man, who lived nine thousand years ago in the American northwest and
who looked more European than Amerindian, the closest match being the Ainu of
northern Japan. He also looked a lot like Patrick Stewart.
Nonetheless,
a DNA study has found him to be closer to Amerindians than to any other
existing population in the world (Rasmussen et al., 2015). He was apparently
descended from the same Northeast Asians who would later become today's Native
Americans. Those earlier Northeast Asians looked more European because they lived
closer to the time when these two groups were one and the same people. It may
be that the Ainu best preserve the appearance of this ancestral population that
would later develop into present-day Europeans, East Asians, and Amerindians.
But
why would Kennewick Man be closer anatomically to an Ainu while being closer
genetically to an Amerindian? The answer is that the genes that shape our anatomy
are a tiny subset of the entire genome. Most genes are of low selective value,
often being junk DNA, so they change at a steady rate through random processes.
Taken as a whole, the genome thus provides a "clock" that can measure
how long two populations have been moving apart since their common ancestors.
Genealogically speaking, Kennewick Man is closer to present-day Native
Americans than he is to the Ainu. Anatomically speaking, the reverse is true
... probably because his ancestors had escaped the extreme Ice Age conditions
that affected northeast Asia 20,000 - 15,000 years ago by retreating to an
ice age refugium on the Northwest Pacific Coast. The Ainu may have similarly sat out the Ice Age in another refugium on the other side of the Pacific.
[...] ancient plant and animal remains found on
several offshore islands provide evidence that some areas of land on the outer
coast remained unglaciated and habitable during the Ice Age. These ice-free
areas are called refugia, and evidence for their existence has been found off
the Pacific coast from Alaska to southern British Columbia.
Although
there is no direct evidence for human occupation of these refugia during the
mid-glacial period, it is clear that a chain of habitable environments existed
along the Pacific Northwest Coast, and that these environments could have
supported people as they made their way down the coast.
If
people moved down the West Coast, and then into the interior from there, where
and when did this inward movement occur? Is there any archaeology suggesting
that populations on the coast began moving inland?
A
few sites from the interior areas of Washington State, Oregon and Idaho may
demonstrate this. Stemmed projectile points are found in a site along the Snake
River in Washington State, with dates ranging from 8,800 to 10,800 years ago.
Another site in south-central Oregon, Fort Rock Cave, contained a layer of
gravel that had two obsidian points within it. Dates from this layer are as old
as 13,000 years BP. Wilson Butte Cave from Idaho also contains human made
artifacts dating to between 14,500 and 13,000 years ago. Perhaps these sites
are examples of early people moving in-land; however the small number of sites
uncovered so far makes it hard to determine definitively whether the early
settlers came from the coast, or from the east. (VMC, 2005)
Kennewick
Man may thus have been part of an earlier wave of people moving into the
Americas, which was long confined to the coastal Northwest. With the end of the
ice age, circa 12,000 years ago, another wave of settlement opened up via an
ice-free corridor running from Alaska to Montana along the eastern side of the
Rockies. This second wave, associated with the Clovis culture, brought more
people than the first one and ultimately contributed the most to present-day
Amerindians.
There were humans
even earlier
But
the story doesn't end here. There seems to have been another people before the
Amerindians and even before the older and more European-like Kennewick humans.
A recent study has looked at the gene pool of Native Americans from the Amazon.
Not surprisingly, most of it closely matches that of Northeast Asians. But a
tiny portion is like what we see in the natives of Australia, Papua New Guinea,
and Melanesia (Skoglund et al., 2015)
It
would be easy to dismiss this finding as a fluke, were it not for other
evidence of a very different people who once lived in the Amazon basin 16,000
to 9,000 years ago (Roosevelt et al., 1996). While overlapping in time with the
Clovis culture, they show none of its emphasis on big game hunting, as seen in
the well-known Clovis projectile point and other hunting tools. In fact, they were much
like tropical foragers of central Africa or Papua-New Guinea. And their
earliest remains precede the Clovis culture by at least three thousand years,
even though the Amazon rain forest should have been one of the last areas to be
penetrated by former denizens of the Arctic.
There's
more. A site in central Brazil has yielded several skulls dated to between
8,200 and 9,500 years ago. They don't look at all Amerindian:
[...]
they exhibit strong morphological affinities with present day Australians and
Africans, showing no resemblance to recent Northern Asians and Native
Americans. These findings confirm our long held opinion that the settlement of
the Americas was more complicated in terms of biological input than has been
widely assumed. The working hypothesis is that two very distinct populations
entered the New World by the end of the Pleistocene, and that the transition
between the cranial morphology of the Paleoindians and the morphology of later
Native Americans, which occurred around 8-9 ka, was abrupt. [...] The
similarities of the first South Americans with sub-Saharan Africans may result
from the fact that the non-Mongoloid Southeast Asian ancestral population came,
ultimately, from Africa, with no major modification in the original cranial bau plan of the first modern humans.
(Neves et al., 2003).
Similar
findings have emerged from analysis of skulls from Mexico dated to between
9,000 and 11,000 years ago and skulls from Colombia dated to between 7,500 and
8,300:
[...]
only 6 out of 25 comparisons displayed in Table 3 tend to tie an early Mexican
specimen to an Amerindian sample. Conversely, 19 of the 25 comparisons reflect
the greatest similarity to Africans (6/25), Paleoindians (5/25), Australians
(3/25), Polynesians (3/25), South Asians (1/25), or the Ainu (1/25). When
first-place positions are explored, all five are circum-Pacific, either recent
or early. Among second-place positions, 4 out of 5 are circum-Pacific, and the
remaining one is African.
[...] To summarize, analyses of
individual skulls against reference samples suggest that the early Mexican
fossils studied do not share a common craniofacial morphology with Amerindians
or East Asians, as reported elsewhere for South Paleoindians, some North
Paleoindian specimens […] and some modern groups like Fuegian-Patagonians and
the Pericúes from Baja California.
[...]
This study does not support continuity between Early and Late Holocene groups
in the Americas: Archaic remains from Colombia are not an intermediate point
between Paleoamericans and modern groups. Moreover, the data presented here
support the idea that the first settlers of the New World preceded the origin
of the more specialized morphology observed in modern populations from Northeast
Asia. (Gonzalez-Jose et al., 2005)
This
shouldn't be too surprising. Here and there in Southeast Asia we find relic
groups of small, dark-skinned, and woolly-haired hunter-gatherers: the
Andamanese of India, the Semang of Malaysia, and the Aeta of the Philippines.
They used to predominate throughout that region as late as four thousand years
ago. Farther back in time, in prehistory, they may have also lived farther
north, perhaps at one point the entire East Asian littoral ... and from there
into the Americas. This would be before the last ice age, and probably before
another wave of modern humans moved into northern Eurasia.
The
past is another country, just as the future is another country. We unthinkingly
assume that a place has always been home to a people who look a certain way,
behave a certain way, and organize their lives a certain way. This is as untrue
for the Americas as it is for anywhere else. Going back in time, we see people
who look more and more ancestral not only to Amerindians but also to Europeans
and East Asians. Eventually, those ancestral Eurasians disappear and we meet a
very different sort of human.
What
happened to those first inhabitants of the Americas? Did they go peacefully
into the night when the newcomers arrived, retreating farther and farther into more
remote areas? Or did the two groups fight it out? There was probably a range of
scenarios—perhaps small numbers of newcomers initially worked out a modus
vivendi with the natives, which later broke down as they became more and more
numerous. In any case, the process matters less than the result. Those first
Americans went into the night, peacefully or not.
References
Gonzalez-Jose,
R., W. Neves, M. Mirazon Lahr, S. Gonzalez, H. Pucciarelli, M. Hernandez
Martinez, and G. Correal. (2005). Late Pleistocene/Holocene Craniofacial
Morphology in
Mesoamerican Paleoindians: Implications for the Peopling
of the New World, American Journal of
Physical Anthropology, 128,
772-780
http://www.hectorpucciarelli.com.ar/pdf/112.AJPA-Gonzalez-Jose%20et%20al.%202005(b).pdf
Neves,
W.A., A. Prous, R. Gonzalez-Jose, R. Kipnis, and J. Powell. (2003). Early
Holocene human skeletal remains from Santana do Riacho, Brazil: implications
for the settlement of the New World, Journal
of Human Evolution, 45, 19-42.
http://www.museunacional.ufrj.br/arqueologia/docs/papers/Prous/nevesprous2003skeletalremains.pdf
Rasmussen,
M., M. Sikora, A. Albrechtsen, T. Sand Korneliussen, J.Victor Moreno-Mayar, G.
David Poznik, C.P.E. Zollikofer, M.S. Ponce de Leon, M.E. Allentoft, I. Moltke,
H. Jonsson, C. Valdiosera, R.S. Malhi, L. Orlando, C.D. Bustamante, T.W.
Stafford Jr. D.J. Meltzer, R. Nielsen, and E. Willerslev. (2015). The ancestry
and affiliations of Kennewick Man. Nature,
early view
http://www.nature.com/nature/journal/vnfv/ncurrent/full/nature14625.html
Roosevelt,
A.C., M. Lima da Costa, C. Lopes Machado, M. Michab, N. Mercier, H. Valladas,
J. Feathers, W. Barnett, M. Imazio da Silveira, A. Henderson, J. Silva, B.
Chernoff, D.S. Reese, J.A. Holman, N. Toth, and K. Schick. (1996). Paleoindian
cave dwellers in the Amazon: The peopling of the Americas, Science, 272, 373-384.
http://www.researchgate.net/profile/William_Barnett3/publication/235237012_Paleoindian_Cave_Dwellers_in_the_Amazon_The_Peopling_of_the_Americas/links/00b7d524c6599de57c000000.pdf
Skoglund,
P., S. Mallick, M.C. Bortolini, N. Chennagiri, T. Hunemeier, M.L. Petzl-Erler,
F. Mauro Salzano, N. Patterson, and D. Reich. (2015). Genetic evidence for two
founding populations of the Americas, Nature,
early view.
http://www.nature.com/nature/journal/vnfv/ncurrent/full/nature14895.html
VMC
(2005). A journey to a new land.
Coastal Refugia
http://www.sfu.museum/journey/an-en/postsecondaire-postsecondary/refuges_cotiers-coastal_refugia
6 comments:
I was under the impression that the Kennewick DNA findings discredited the theory that he was part of a prior migration to the Americas. If indeed he his genome fits comfortably within the range of modern Amerindians, why posit population replacement at all?
There is a parallel study by Raghavan et. al. - titled "Genomic Evidence for the Pleistocene and Recent Population History of Native Americans" - in the latest issue of "Science," which calls into question the alleged Australasian affinities of groups like the Fuegians and the Pericues of Baja California, on both genetic and morphological grounds.
That said, the physical similarities between modern Northeast Asians and Native Americans are too close to be persuasively explained by parallel in-situ evolution. Since the classically "Mongoloid" facial structure does indeed appear to be heavily influenced by a small number of genes - EDAR370-A, I think, is one of them - it's entirely possible that one of the smaller late migrations to the New World - say, that of the Eskimo-Aleuts - enabled these traits to introgress into the older and more numerous Amerind groups without altering their overall genomic makeup.
This hypothesis would account for why Amerindians show considerable differences from, as well as similarities to, Northeast Asian peoples in their outward appearance. It might even explain some of the regional variation one still encounters in New World populations.
I am reminded of the two racial types depicted by the Olmecs, the oldest civilisation in Mexico. The first is represented by the huge stone heads, which are distinctly Negroid in appearance ie flat noses, thick lips, and curly hair. Meanwhile, the reliefs on the stone walls depict "Uncle Sams" ie long faces, long noses, long hair, and goatee beards.
I still wonder who was camping out at Lake Lewisville 30,000 years ago...
Anon,
I don't think the Kennewick humans were replaced. It's just that they were submerged by a later and larger wave of migrants. I feel it's important to posit a separate and earlier wave because we are still faced with the difference in facial structure. Genetically, they were close to present-day Amerindians, but they seem to correspond to an earlier stage of evolution in northeast Asia.
I don't follow your suggestion that the Eskimo-Aleuts made the Amerindians to the south look more Mongoloid through gene diffusion. It sounds too much like the tail wagging the dog.
Malcolm,
I had the same thought while writing this post. Were the Olmecs descended from these "First Americans"?
Anon,
"During construction, members of the Corps of Engineers stumbled upon an archaeological site.[3] In 1956, Wilson W. Crook, Jr. and R.K. Harris announced that Carbon-14(14C) testing on artifacts from the site, including a Paleo-Indian Clovis projectile point, indicated that humans had lived there c. 36,000 BP.[4][5] This led to much controversy in the archaeological community.[6][7] It was not until 1978 that the water levels of the lake would go down far enough to access the site once again. Between 1978 and 1980, Dennis Stanford of the Smithsonian Institution performed a more thorough analysis of the site. He concluded that the original dating was probably due to a rare form of cross-contamination and that a date of c. 12,000 B.P. was probably more correct."
https://en.wikipedia.org/wiki/Lewisville_Lake
@Malcolm and Peter: A quick browse of le Wik says that they resemble people who live in and around Veracruz today.
I see this has just come out:
https://www.smithsonianmag.com/science-nature/dna-search-first-americans-links-amazon-indigenous-australians-180955976/
Cheers,
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