Homo
sapiens' sex with extinct species was no one-night stand
Send a link to a friend
[March 19, 2016]
By Will Dunham
WASHINGTON (Reuters) - Our species, Homo
sapiens, has a more adventurous sexual history than previously realized,
and all that bed-hopping long ago has left an indelible mark on the
human genome.
|
Scientists said on Friday an analysis of genetic information on
about 1,500 people from locations around the world indicated at
least four interbreeding episodes tens of thousands of years ago,
three with our close cousins the Neanderthals and one with the
mysterious extinct human species known as Denisovans.
People living on the remote equatorial islands of Melanesia
represented the only population found to possess an appreciable
level of Denisovan genetic ancestry. These Melanesians, like most
human populations, also had Neanderthal genetic ancestry.
The researchers found some of the genes inherited from these extinct
species were beneficial for our species.
Many are involved in the immune system and likely helped protect
against pathogens, and some play important roles in skin and hair
biology, said University of Washington evolutionary geneticist
Joshua Akey, who helped lead the study published in the journal
Science.
The researchers analyzed DNA sequences from 35 people living on
Northern Island Melanesia off the coast of New Guinea. These
Melanesians were found to have about 2 percent Neanderthal ancestry
plus an additional genetic contribution of roughly 2 to 4 percent
from Denisovans.
The non-African populations studied had roughly 1.5 to 4 percent
Neanderthal genetic ancestry, Akey said. African populations do not
have either Neanderthal or Denisovan ancestry because those two
species were never on that continent.
Denisovans, discovered in the past decade, are known only from a
pinky finger bone and two teeth from a northern Siberian cave.
[to top of second column] |
The robust, large-browed Neanderthals prospered across Europe and
Asia from about 350,000 years ago until disappearing shortly after
40,000 years ago. Less is known about the Denisovans.
The fact that the only known Denisovan remains come from northern
Siberia but that their genetic contribution is seen in people living
far away in Melanesia suggests Denisovans had a broad geographic
range extending across Asia, Akey said.
Binghamton University molecular anthropologist D. Andrew Merriwether
said the researchers also detected a contribution to people's genome
from a fourth, unknown source.
"So this paints a picture of probably at least four species of
hominins (our species and extinct human species) alive at the same
time and interbreeding at times over the last 100,000 years.
Definitely not something most people supposed before 10 years ago,"
Merriwether said.
(Reporting by Will Dunham; Editing by Sandra Maler)
[© 2016 Thomson Reuters. All rights
reserved.]
Copyright 2016 Reuters. All rights reserved. This material may not be published,
broadcast, rewritten or redistributed.
|