By Will Dunham
WASHINGTON, April 7 (Reuters) – The largest-ever genetic
assessment of the woolly mammoth has yielded new insight into
this elephant cousin – an icon of the Ice Age – including about
its fluffy hair, small ears, cold tolerance, fat storage and
even dry ear wax.
Researchers on Friday said they had analyzed the genomes of
23 woolly mammoths – including 16 newly sequenced ones – based
on remains preserved in Siberian permafrost. They then compared
them to the genomes of 28 modern-day Asian and African
elephants.
“The objective was to find those mutations that are present
in all mammoths but not in any of the elephants – that is, the
genetic adaptations exclusive to the woolly mammoth,” said
evolutionary geneticist David Díez-del-Molino of the Centre for
Palaeogenetics in Stockholm, lead author of the study published
in the journal Current Biology.
“We find that woolly mammoths had molecular adaptations in
genes related to coping with cold Arctic environments, such as
thick fur, fat storage and metabolism, and thermal sensation,
among others,” Díez-del-Molino added.
The genomes included a mammoth from 700,000 years ago – near
the origination time of this species on the Siberian steppes –
and others that lived later in their history, thus showing how
genetic adaptations evolved.
The species, which arose at a time when Earth’s climate was
cooling, inhabited parts of northern Eurasia and North America.
Most mammoths went extinct roughly 10,000 years ago amid a
warming climate at the last Ice Age’s end, with scientists
debating whether human hunting played a role. The last ones died
out on Wrangel Island off Siberia’s coast 4,000 years ago.
The first complete mammoth genome was sequenced in 2015,
after a partial genome in 2008.
The new study showed that 92% of unique mutations already
existed at the outset of the species, with continued evolution
on certain traits. For example, mammoths evolved ever-fluffier
fur and ever-smaller ears over time.
“Our 700,000-year-old woolly mammoth may have had larger
ears than the mammoths of the last Ice Age,” Centre for
Palaeogenetics evolutionary geneticist and study senior author
Love Dalén said.
One highly evolved gene was one that when “turned off” in
laboratory mice results in unusually small ears. Woolly mammoths
were about the size of modern African elephants, around 13 feet
(4 meters) tall, but had much smaller ears to guard against
losing body heat from a larger ear surface.
Several genes involving fur type and growth differed from
modern elephants. One of them in humans is associated with
Uncombable Hair Syndrome, a condition characterized by dry and
frizzy hair that cannot be combed flat. In mammoths, fluffier
hair, as well as fat deposits, would have helped provide
insulation in the cold.
The mammoths had a mutation in a gene that in people is
associated with having dry ear wax, though it is unclear how
this gave them any advantage. The same mutation is associated
with reduced body odor in the armpits in humans, though this may
not mean mammoths had a dainty aroma.
“I very much doubt mammoths would have been sweating into
their arm pits. This is a very unique human thing, I think.
Other mammals regulate their body temperature in other ways. So
it is very unclear if mammoths would have smelled differently
because of this gene variant,” Dalén said.
The study helped clarify variable shades of mammoth hair
color – brownish with a touch of red. Mutations in an immune
system-related gene indicated the species adapted to a serious
pathogen outbreak at some point.
While the researchers are not involved in trying to
resurrect the mammoth through cloning, their work could assist
any such effort.
“The dataset we present could be seen as the first element
of a road map towards resurrection,” Dalén said. “But it should
be pointed out that the road ahead is long, likely to be full of
pot holes, and in the worst-case scenario leads nowhere.”
Teeth from Siberian mammoth yields 1.2 million-year-old DNA
Giant meatball of extinct mammoth unveiled in The Netherlands
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(Reporting by Will Dunham, Editing by Rosalba O’Brien)
((Will.Dunham@thomsonreuters.com; 1 202 898 8300;))
Keywords: SCIENCE MAMMOTHS/ (PIX)
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