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Genomic
diversity and admixture differs for stone-age Scandinavian foragers and farmers
Genomic
diversity and admixture differs for stone-age Scandinavian foragers and farmers
Date:
April 24,
2014
Source:
Uppsala Universitet
Summary:
Scientists report a breakthrough on understanding the
demographic history of Stone-Age humans. A genomic analysis of eleven Stone-Age
human remains from Scandinavia revealed that expanding Stone-age farmers
assimilated local hunter-gatherers, and that the hunter-gatherers were
historically in lower numbers than the farmers. The transition between a
hunting-gathering lifestyle and a farming lifestyle has been debated for a
century. As scientists learned to work with DNA from ancient human material, a
complete new way to learn about the people in that period opened up.
..................
An international team led by researchers at Uppsala
University and Stockholm University reports a breakthrough on understanding the
demographic history of Stone-Age humans. A genomic analysis of eleven Stone-Age
human remains from Scandinavia revealed that expanding Stone-age farmers assimilated
local hunter-gatherers and that the hunter-gatherers were historically in lower
numbers than the farmers. The study is published today, ahead of print, in the
journal Science.
The
transition between a hunting-gathering lifestyle and a farming lifestyle has
been debated for a century. As scientists learned to work with DNA from ancient
human material, a complete new way to learn about the people in that period
opened up. But even so, prehistoric population structure associated with the
transition to an agricultural lifestyle in Europe remains poorly understood.
"For
many of the most interesting questions, DNA-information from people today just
doesn't cut it, the best way to learn about ancient history is to analyze
direct data -- despite the challenges," says Dr. Pontus Skoglund of
Uppsala University, now at Harvard University, and one of the lead authors of
the study.
"We
have generated genomic data from the largest number of ancient
individuals" says Dr. Helena Malmström of Uppsala University and one of
the lead authors. "The eleven Stone-Age human remains were between 5,000
and 7,000 years old and associated with hunter-gatherer or farmer
life-styles" says Helena Malmström.
Anders
Götherström, who led the Stockholm University team, is satisfied with the
amount of DNA that they could retrieve.
"Not
only were we able to generate DNA from several individuals, but we did get a
lot of it. In some cases we got the equivalent of draft genomes. A population
genomic study on this level with a material of this age has never been done
before as far as I know."
The material
used in the study is from mainland Scandinavia as well as from the Baltic
island Gotland, and it comprises of hunter-gatherers from various time periods
as well as early farmers.
Professor
Mattias Jakobsson, who led the Uppsala University team, is intrigued by the
results.
"Stone-Age
hunter-gatherers had much lower genetic diversity than farmers. This suggests
that Stone-Age foraging groups were in low numbers compared to farmers,"
says Mattias Jakobsson.
Jan Storå at
Stockholm University shares Mattias' fascination.
"The
low variation in the hunter gatherers may be related to oscillating living
conditions likely affecting the population sizes of hunter-gatherers. One of
the additional exciting results is the association of the Mesolithic individual
to both the roughly contemporaneous individual from Spain but also the
association to the Neolithic hunter-gatherers."
The study
confirms that Stone-Age hunter-gatherers and farmers were genetically distinct
and that migration spread farming practices across Europe, but the team was
able to go even further by demonstrating that the Neolithic farmers had
substantial admixture from hunter-gatherers. Surprisingly, the hunter-gatherers
from the Baltic Sea displayed no evidence of introgression from farmers.
"We see
clear evidence that people from hunter-gatherer groups were incorporated into
farming groups as they expanded across Europe," says Pontus Skoglund.
"This might be clues towards something that happened also when agriculture
spread in other parts of the world."
"The
asymmetric gene-flow shows that the farming groups assimilated hunter-gatherer
groups, at least partly," says Mattias Jakobsson. "When we compare
Scandinavian to central European farming groups that lived at about the same
time, we see greater levels of hunter-gatherer gene-flow into the Scandinavian
farming groups."
This study
is part of the recently initiated "Atlas project" -- a large-scale
genomic investigation of ancient human remains in Scandinavia led by Stockholm
and Uppsala Universities and funded by the Swedish Foundation for Humanities
and Social Sciences and the Swedish Research Council. The present study brings
the first results from the project.
"We
have only begun to scratch the surface of the knowledge that this project may
bring us in the future" says Anders Götherström.
Story
Source:
The above
story is based on materials provided by Uppsala Universitet. Note: Materials may be
edited for content and length.
Journal
Reference:
- Skoglund et al. Genomic Diversity and Admixture differs for Stone-Age Scandinavian Foragers and Farmers. Science, 2014 DOI: 10.1126/science.1253448
Cite This
Page:
Uppsala Universitet. "Genomic
diversity and admixture differs for stone-age Scandinavian foragers and
farmers." ScienceDaily. ScienceDaily, 24 April 2014.
<www.sciencedaily.com/releases/2014/04/140424151807.htm>.
