[BITList] This is the first comprehensive population-level whole-genome study of human genetic diversity in Australia

[John Feltham]

G'day Folks,

 From a correspondent…


http://www.livescience.com/56191-unknown-branch-of-humanity-possibly-discovered.html?utm_source=ls-newsletter&utm_medium=email&utm_campaign=20160923-ls <http://www.livescience.com/56191-unknown-branch-of-humanity-possibly-discovered.html?utm_source=ls-newsletter&utm_medium=email&utm_campaign=20160923-ls>


Fascinating - just when we think we have it all sussed. I am pasting the whole article for those who are afraid of links.

NEWS TECH HEALTH PLANET EARTH SPACE STRANGE NEWS ANIMALS HISTORY HUMAN NATURE


Live ScienceHistory 

Mysterious Branch of Humanity Possibly Discovered

By Charles Q. Choi, Live Science Contributor | September 21, 2016 01:54pm ET421  147  11  3  38 MORE

Partner Series

Mysterious Branch of Humanity Possibly Discovered.

Researchers have found that Aboriginal Australians are some of the
oldest living populations on Earth. Here, Eske Willerslev talks to
Aboriginal elders n the Kalgoorlie area in southwestern Australia in
2012.

Credit: Preben Hjort, Mayday Film.

A group of humans migrating out of Africa some 40,000 to 70,000 years
ago mingled with an as-yet unknown branch of humanity, researchers
say.

Modern humans originated about 150,000 to 200,000 years ago in Africa.
However, scientists have long debated when and how the modern human
lineage spread out of Africa to nearly every corner of the globe.
Nearly everyone outside Africa descended from an exodus that occurred
between 40,000 and 70,000 years ago, but recent archaeological
findings and climate models suggest that migrations of modern humans
from Africa began at least 100,000 years ago.

One way to find out whether, in the past, modern humans dispersed from
Africa in one wave or many — and to see if they intermingled with any
other human lineages along the way — is to examine the genomes of
present-day modern humans. [See Photos of Our Closest Human Ancestor]

"We're interested in understanding how our species has come to be how
it is through the lens of ancient DNA," said Swapan Mallick,
bioinformatics director at Harvard Medical School in Boston and lead
author of one of the three studies appearing in the Sept. 22 issue of
the journal Nature.

Previous human genetic databases often sampled a relatively narrow
range of populations, which could skew results or miss key details
about the migrations of modern humans out of Africa. Now, three
studies have collected new, high-quality data from 787 human genomes
from more than 280 geographically diverse populations around the
world, including typically understudied and rapidly disappearing
groups.

Among the understudied groups researchers looked at are African
populations, which have considerable genetic, linguistic and cultural
diversity. They also examined genomes from Australia, where previous
research uncovered some of the earliest archaeological and fossil
evidence of modern humans outside Africa.

New branch of humanity?

The genetic analyses revealed the genomes of present-day aboriginal
Australians might harbor evidence of ancient interbreeding with an
unknown human lineage.

"Who these people are, we don't know," said Eske Willerslev at the
University of Copenhagen in Denmark, and senior author of one of the
three studies.

Previous research unearthed bones from a mysterious extinct branch of
the human family tree from Denisova cave in Siberia's Altai Mountains.
Analysis of DNA extracted from the fossils suggested these
"Denisovans" shared a common origin with Neanderthals, but were nearly
as genetically distinct from Neanderthals as Neanderthals were from
living people. [Denisovan Gallery: Tracing the Genetics of Human
Ancestors]

Recent work suggested that Denisovans have contributed about 5 percent
of their DNA to the genomes of present-day people of the Pacific
islands of Oceania. However, these new findings suggest that what
seemed to be evidence of Denisovans in the Pacific were actually signs
of an unknown human lineage.

"These guys were very distantly related to Denisovans, but by no means
Denisovan," Willerslev told Live Science. "They were even more
distantly related to Neanderthals, and they might have been even more
distantly related to modern humans. We believe that they interbred
with modern humans shortly before modern humans crossed into the
ancient continent of Sahul — what is now Australia, New Guinea and
Tasmania — some 50,000 to 60,000 years ago."

Leaving Africa

The new findings also shed light on the controversy over whether
modern humans dispersed from Africa in a single exodus or in multiple
distinct waves at different times. When it came to people from Papua
New Guinea, "we could discover, in the genomes of the Papuan
individuals analyzed here, small traces of an additional, early
expansion out of Africa that was previously hypothesized only from
archaeological remains," Mait Metspalu, an evolutionary geneticist at
the Estonian Biocenter in Tartu, Estonia, and senior author of one of
the three studies, told Live Science.

The researchers suggest that at least 2 percent of the Papuan genome
harbors traces of an early migration that happened about 120,000 years
ago. Previous research suggested that non-Africans largely descend
from an exodus that happened between 40,000 and 70,000 years ago.

"Our results, while for the most part confirming the already accepted
model of a single expansion out of Africa as the source event of all
non-African populations, show that additional expansions were not as
unlikely as we thought," Luca Pagani, a molecular anthropologist at
the Estonian Biocenter and lead author of one of the three studies,
told Live Science.

Oldest living population

The scientists also discovered that aboriginal Australians "are one of
the oldest living populations on Earth, and have been in the same area
for the past 50,000 to 60,000 years," Willerslev said.

There was a great deal of controversy "over whether or not aboriginal
Australians directly descend from the first humans entering
Australia," Willerslev said. "The answer to that question is yes — our
data is completely consistent with aboriginal Australians descending
from the first humans to enter Australia. It shows a very long
connection between those people and the land. [How Did Life Arise on
Earth]

"I can't think of any other place in the world where humans have been
so long in the same spot as Australia," Willerslev said. "Yes, there
are populations in Africa that are older, but we have no idea if they
stayed in the same area in Africa for as long a time."

This is the first comprehensive population-level whole-genome study of
human genetic diversity in Australia. "We found that because
aboriginal Australians have spent such a long time in Australia, they
are very genetically diverse," Willerslev said. "An aboriginal
Australian from eastern Australia and one from southwestern Australia
are almost as different genetically as an Asian is from a European."

The researchers noted that about 90 percent of aboriginal Australians
speak languages belonging to a single linguistic family, "but some
people in northwest Australia speak other language families,"
Willerslev said. "It'd be very interesting to see what the story is
there when it comes to how they migrated to Australia."



ooroo



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