Ancient DNA reveals surprises about how early Africans lived, traveled
and interacted
New research provides evidence of demographic shifts in sub-Saharan
Africa

Date:
February 23, 2022
Source:
Rice University
Summary:
A new analysis of human remains that were buried in African
archaeological sites has produced the earliest DNA from the
continent, telling a fascinating tale of how early humans lived,
traveled and even found their significant others.



FULL STORY ==========================================================================
A new analysis of human remains that were buried in African archaeological sites has produced the earliest DNA from the continent, telling a
fascinating tale of how early humans lived, traveled and even found
their significant others.


==========================================================================
An interdisciplinary team of 44 researchers outlined its findings in
"Ancient DNA reveals deep population structure in sub-Saharan African foragers." The paper was published today in Nature and reports findings
from ancient DNA from six individuals buried in Malawi, Tanzania and
Zambia who lived between 18,000 and 5,000 years ago.

"This more than doubles the antiquity of reported ancient DNA data
from sub- Saharan Africa," said David Reich, a professor at Harvard
University and investigator at the Howard Hughes Medical Institute whose
lab generated the data in the paper. "The study is particularly exciting
as a truly equal collaboration of archaeologists and geneticists."
The study also reanalyzed published data from 28 individuals buried at
sites across the continent, generating new and improved data for 15 of
them. The result was an unprecedented dataset of DNA from ancient African foragers - - people who hunted, gathered or fished. Their genetic legacy
is difficult to reconstruct from present-day people because of the many population movements and mixtures that have occurred in the last few
thousand years.

Thanks to this data, the researchers were able to outline major
demographic shifts that took place between about 80,000 and 20,000 years
ago. As far back as about 50,000 years ago, people from different regions
of the continent moved and settled in other areas and developed alliances
and networks over longer distances to trade, share information and even
find reproductive partners. This social network helped them survive and
thrive, the researchers wrote.

Elizabeth Sawchuk, an author of the study who is a Banting Postdoctoral
Fellow at the University of Alberta and research assistant professor
at Stony Brook University, said a dramatic cultural change took place
during this timeframe, as beads, pigments and other symbolic art became
common across Africa.

Researchers long assumed that major changes in the archaeological record
about 50,000 years ago reflected a shift in social networks and maybe
even changes in population size. However, such hypotheses have remained difficult to test.



========================================================================== "We've never been able to directly explore these proposed demographic
shifts, until now," she said. "It has been difficult to reconstruct events
in our deeper past using the DNA of people living today, and artifacts
like stone tools and beads can't tell us the whole story. Ancient
DNA provides direct insight into the people themselves, which was the
missing part of the puzzle." Mary Prendergast, an author of the paper
and associate professor of anthropology at Rice University, said there
are arguments that the development and expansion of long-distance trade networks around this time helped humans weather the last Ice Age.

"Humans began relying on each other in new ways," she said. "And this creativity and innovation might be what allowed people to thrive."
The researchers were also able to demonstrate that by about 20,000 years
ago, people had stopped moving around so much.

"Maybe it was because by that point, previously established social
networks allowed for the flow of information and technologies without
people having to move," Sawchuk said.



========================================================================== Prendergast said the study provides a better understanding of how people
moved and mingled in this part of Africa. Previously, the earliest African
DNA came from what is now Morocco -- but the individuals in this study
lived as far from there as Bangladesh is from Norway, she noted.

"Our genetic study confirms an archaeological pattern of more local
behavior in eastern Africa over time," said Jessica Thompson, an assistant professor of anthropology at Yale University, an author of the study and
one of the researchers who uncovered the remains. "At first people found reproductive partners from wide geographic and cultural pools. Later,
they prioritized partners who lived closer, and who were potentially more culturally similar." The research team included scholars from Canada,
Kenya, Malawi, Tanzania, the United States, Zambia and many other
countries. Critical contributions to the study came from curators and co-authors at African museums who are responsible for protecting and
preserving the remains.

Potiphar Kaliba, director of research at the Malawi Department of
Museums and Monuments and an author of the study, noted that some of
the skeletons sampled for the study were excavated a half-century ago,
yet their DNA is preserved despite hot and humid climates in the tropics.

"This work shows why it's so important to invest in the stewardship
of human remains and archaeological artifacts in African museums,"
Kaliba said.

The work also helps address global imbalances in research, Prendergast
said.

"There are around 30 times more published ancient DNA sequences from
Europe than from Africa," she said. "Given that Africa harbors the
greatest human genetic diversity on the planet, we have much more
to learn." "By associating archaeological artifacts with ancient DNA,
the researchers have created a remarkable framework for exploring the prehistory of humans in Africa," said Archaeology and Archaeometry
program director John Yellen of the U.S. National Science Foundation,
one of the funders behind this project. "This insight is charting a new
way forward to understanding humanity and our complex shared history." ========================================================================== Story Source: Materials provided by Rice_University. Original written
by Amy McCaig. Note: Content may be edited for style and length.


========================================================================== Related Multimedia:
* Malawi_and_ostrich_eggshell_beads ========================================================================== Journal Reference:
1. Lipson, M., Sawchuk, E.A., Thompson, J.C. et al. Ancient DNA
and deep
population structure in sub-Saharan African foragers. Nature,
2022 DOI: 10.1038/s41586-022-04430-9 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220223111223.htm

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