interbreeding and DNA
How much Neanderthal DNA
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is in modern humans?
As Homo sapiens migrated out of Africa, tens of thousands of years ago, many members of the species interbred with Neanderthals and Denisovans along the way. But what sort of effect has this interbreeding had on the DNA of modern humans? Two different groups of US researchers decided to find out.
S
exist at much higher frequencies, reaching up to about 65%. The researchers’ study, published in the journal Current Biology, finds that the genes humans tudies have already shown that
inherited from Neanderthals or Denisovans
non-African individuals inherit about 2% of
are important for our interactions with the
their genomes from Neanderthals, while people
environment. For example, Neanderthal and
of Melanesian ancestry inherit another 2–4% of
Denisovan sequences were found in seven
their genomes from Denisovan ancestors. But
parts of the genome known to play a role in the
until now, it hasn’t been clear what influence those
characteristics of our skin.
DNA sequences have had on our biology, traits and evolutionary history.
“The ability to increase to such high population frequencies was most likely facilitated because
Scientists from the University of Washington
these sequences were advantageous,” said study
(UW) conducted a study using genome-scale maps
co-author Joshua Akey. “In addition, many of the
of Neanderthal and Denisovan sequences identified
high-frequency sequences span genes involved in
in more than 1500 geographically diverse people.
the immune system, which is a frequent target of
While the vast majority of surviving Neanderthal
adaptive evolution.
and Denisovan sequences were found at relatively
“Our work shows that hybridisation was not
low frequencies (less than 5%), the analyses turned
just some curious side note to human history, but
up 126 places in our genomes where these sequences
had important consequences and contributed
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