There are no surviving members of an
ancient and mysterious group of people
who lived in North America for millennia.
Until now, scientists thought they had
vanished without a trace.
But new research shows that this paleo
group's genes live on today in several
indigenous cultures.
The finding is surprising, as other studies
had found that the people — one of the
first groups of humans to arrive in North
America — made little genetic contribution
to later North American people. [ 10
Things We Learned About the First
Americans in 2018 ]
Using cutting-edge techniques, however,
the new research shows that's not the
case. "They have never really gone
extinct in that way," study senior author
Stephan Schiffels, group leader of
population genetics at the Max Planck
Institute for the Science of Human History
in Germany, told Live Science. "They
have actually contributed to living
people."
The first wave of migrants arrived in North
America before 14,500 years ago, likely
by crossing the Bering Strait land bridge
during the last ice age. But as that ice
age ended and glaciers melted, sea
levels rose, flooding the land bridge. After
that, archaeological evidence suggests
that the next major wave of people
arrived about 5,000 years ago, likely by
boat, Schiffels said. This is the group of
people studied in the new research.
People continued arriving in the Americas
after that. About 800 years ago, the
ancestors of the modern-day Inuit and
Yup'ik showed up, and within 100 years,
the paleo group from 5,000 years ago
had vanished , according to
archaeological evidence.
So, what happened to this paleo group?
To learn more, Schiffels and his
colleagues, including study first author
Pavel Flegontov, a faculty member of
science in the Department of Biology and
Ecology at the University of Ostrava in
the Czech Republic, dug knee deep into
the genetics of this enigmatic people.
The excavation of three ancient
Athabaskan people. Researchers
studied the DNA of these ancient
people in the new study.
Credit: Tanana Chiefs Conference
The team received permission from
modern indigenous groups to take very
small bone samples from the remains of
48 ancient individuals found in the
American Arctic and in Siberia. The
scientists then ground these bone
samples into powder so they could
extract and study DNA.
Then, the researchers analyzed the
genomes of 93 modern individuals of
indigenous heritage from Siberia , Alaska,
the Aleutian Islands and Canada. For
good measure, the researchers looked at
previously published genomes from these
regions too.
With the novel method of looking for rare
genetic mutations that the paleo group
had passed down, as well as other
family-tree-modeling methods, the
researchers found that the paleo group
left a hefty genetic footprint; their genes
are found in modern people who speak
the Eskimo-Aleut and Na-Dene
languages, which includes Athabaskan
and Tlingit communities from Alaska,
northern Canada, and the U.S. West
Coast and Southwest.
The scientists generated so much data
that they could build a comprehensive
model explaining ancient gene exchange
between Siberia and the Americas. This
model shows that Na-Dene-speaking
peoples, people of the Aleutian Islands,
and Yup'ik and Inuit in the Arctic all share
ancestry from a single population in
Siberia related to the paleo group, the
researchers said.
"It is the first study to comprehensively
describe all of these populations in one
single, coherent model," Schiffels said in
a statement.
A facial reconstruction of a woman
from the Uelen burial site in
Chukotka, Siberia. The woman, who
lived about 1,500 years ago, is an
ancestor to present-day Inuit and
Yup'ik.
Credit: Elizaveta Veselovskaya
According to the model, after the paleo
group arrived in Alaska between 5,000
and 4,000 years ago, they mixed with
people who had a similar ancestry to
more-southern Native American peoples.
The descendants of these couplings
become the ancestors of the Aleutian
Islanders and Athabaskans. [ 25 Grisly
Archaeological Discoveries ]
Moreover, the ancestors of the Inuit and
Yup'ik people didn't just venture from
Siberia to North America once; they went
back and forth like pingpong balls,
crossing the Bering Strait at least three
times, the researchers found. First, these
ancient people crossed as that original
paleo group to Alaska; then, they
returned to Chukotka, Siberia; third, they
traveled to Alaska again, as bearers of
the Thule culture, the predecessor to the
modern Inuit and Yup'ik cultures of
Alaska, the Arctic, and High Arctic.
During their stay in Chukotka — a long
stint that lasted more than 1,000 years —
the ancestors of the Inuit and Yup'ik
mixed with local groups there. The genes
from these offspring remain in modern-
day people living in Chukchi and
Kamchatka, Siberia.
"There's a reason why this was hard [to
do] before," Schiffels told Live Science.
"These populations are very closely
related with each other, and it's very hard
to disentangle the different ancestry
components."
The study was published online yesterday
(June 5) in the journal Nature . In another
Nature study published online yesterday,
researchers found human teeth dating to
31,000 years ago, remains that are now
the oldest direct evidence of humans in
Siberia.
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