by Nathan Falde
Innovative DNA analysis
has unlocked genetic secrets
to human history in the Americas.
Source: svetlaborovko / Adobe Stock
It was a little over a decade ago that the evolutionary biologist
Eske Willerslev successfully applied innovative DNA analysis and
decoding technology to unlock genetic secrets from the past.
In that case it was a
sample of 4,000-year-old hair recovered from the arctic permafrost
This was a landmark
achievement, since it was the first time a scientist had been able
to sequence an entire genome belonging to someone who had lived and
died in ancient times.
Just over 10 years ago,
Willerslev used DNA analysis on a hair frozen in Greenland
Image shows reconstruction of a member of the extinct Saqqaq culture
created using the results of this DNA analysis.
Decade of Ancient DNA Analysis
In celebration of the burgeoning field of ancient DNA analysis,
Professor Willerslev, who is now the director of the Lundbeck
Foundation GeoGenetics Centre at the University of Copenhagen, has
just published a comprehensive review of what has been discovered
about the ancient genomics of the Americas over the past 10 years.
In the June 2021 edition of Nature, Willerslev and the Southern
Methodist University (Texas) archaeologist David Meltzer
explain how ancient DNA sequencing technology has revolutionized
archaeology, anthropology, and evolutionary biology.
In this article, entitled
Peopling of the Americas as inferred from
ancient genomics, the
authors demonstrate that ancient genome recovery and DNA analysis
has opened the doors to a new era of discovery, filled with fresh
and exciting insights into the genetic history of humanity,
including its relatives and predecessors, including the
"The last ten years
has been full of surprises in the understanding of the peopling
of the Americas," Professor Willerslev said in a statement
issued by St John's College at the University of Cambridge
(where Willerslev is a Fellow).
"What has really
blown my mind is how resilient and capable the early humans we
have sequenced DNA from were - they occupied extremely different
environments and often populated them in a short space of time."
"We were taught in
school that people would stay put until the population grew to a
level where the resources were exhausted," continued Willerslev.
"But we found people
were spreading around the world just to explore, to discover, to
The world-famous scientist and adventurer, Eske Willerslev,
at the forefront of DNA analysis
unlocking the secrets of human history.
Analysis to Understand Migration Patterns
Traditional archaeology has helped scientists uncover many details
about how humans lived in the past.
But genetic relationships
between peoples located in different regions were hard to identify.
Without access to the information encoded inside DNA, mistaken
assumptions about ancient migration patterns were inevitable.
it was previously believed that non-Native American
people probably resided in the Americas before the ancestors of the
Native Americans arrived between 12,000 and 15,000 years ago.
DNA analysis taken from fossilized human skeletons recovered in the
Americas has not detected any non-Native American DNA.
One thing that researchers did discover, however, was genetic
evidence linking people who lived in what is now Siberia 24,000
years ago with both Native Americans and modern Siberians.
scientists sequenced a genetic sample of a four-year-old boy whose
skeletal remains had been discovered by Russian archaeologists in
south-central Siberia in the 1920s.
Between Siberia and the Americas
The boy was shown to have belonged to a group of people that had
never before been detected, yet had contributed to the genetic
inheritance of the forerunners of the Native Americans.
evidence has shown connections that we didn't know existed between
different cultures and populations and the absence of connections
that we thought did exist," Professor Meltzer explained.
population history is far more complex than previously thought."
Given the northerly location where the boy's remains were found,
this discovery helped confirm the theory that Native American
ancestors resided in Siberia in the distant past, before making
their way to the Americas via the Bering Strait land bridge.
land feature connected Siberia and Alaska during the last Ice Age,
when sea levels were lower, between 12,000 and 15,000 years ago.
Some Native Americans crossed the bridge on foot before heading
southward along ice-free corridors.
Others sailed down the Pacific
coast from launching points located along the bridge, landing at
various spots on the North and South American coastlines and
migrating eastward from there.
Facing no resistance from indigenous populations, the first Native
Americans spread out across North, Central, and
South America quite
Over the next few
thousand years, they built a complex array of distinct and unique
Native American societies.
"We have seen how
rapidly people were moving around the world when they have a
continent to themselves, there was nothing to hold them back,"
"There was a
selective advantage to seeing what was over the next hill."
DNA analysis has been able to solve multiple mysteries
to our ancient history, such as in the case
of the Kennewick Man, whose facial reconstruction
can be seen above.
(Brittney Tatchell / Smithsonian Institution )
Migrations and the Peopling of Two Continents
In 2015, Professor Willerslev led a team of scientists who sequenced
the first complete ancient Native American genome.
The DNA sample
was extracted from the skeleton of a male infant who'd been
ceremoniously buried near what is now Anzick, Montana more than
12,000 years ago.
Willerslev and his colleagues received quite a bit of attention for
another successful sequencing project they also completed in 2015.
In this analysis, they proved that an ancient intact skeleton known
Kennewick Man had belonged to an individual related to the
modern Colville Tribe in Washington state.
To understand the significance of this work, multiple Native
American nations had sued the U.S. Army Corp of Engineers, claiming
control over the territory where the Kennewick Man was found near
the Columbia River.
results were announced, the skeleton of what was referred to as the
"Ancient One" was turned over to the Colville Nation for burial.
Image shows a press conference in 2015
which the late Jim Boyd of the
Confederated Tribes of the Colville
announced the results of groundbreaking DNA analysis
M°rk / Magus Film)
Migratory Movements Using DNA Analysis
But Willerslev's most important and revealing work in the field was
completed in 2018.
The biologist and his
colleagues performed a comprehensive DNA analysis on human remains
15 sites in North, Central, and South America,
spanning from Alaska to Patagonia...
This included famous
finds such as the
Lovelock skeletons from Nevada, the Lago Santa
skeletons of Brazil, an Incan mummy , extremely ancient remains
found in southern Chile, and the world's oldest natural mummy,
Spirit Cave in Nevada.
Putting together the pieces of a complex puzzle, the scientists used
the genetic information recovered from these DNA samples to trace
the migratory movements of many ancient Native Americans peoples
They were also able to track the interactions that
occurred between different groups.
From this data, they were able to conclude two things.
the original native settlers had spread across the Americas at
Second, that no outside DNA had ever
entered the collective gene pool, meaning there was no reason to
believe any humans were already living in the region when the first
Native Americans arrived.
"Over the past decade human history has been fundamentally changed
thanks to ancient genomic analysis ," Professor Willerslev stated,
summing up the results of his groundbreaking research.
incredible findings have only just begun."
Willerslev's statement applies to more than just the Americas.
Sequencing has been performed on DNA samples obtained from human
skeletal remains recovered from across the globe, and from a broad
variety of other hominin and animal species as well.
Every day new
and fascinating information is emerging from these studies, and in
the future our understanding of the history of our planet may be
dramatically altered thanks to the discoveries of ancient DNA