This gives us realistic
time capsule that is around fifteen million years old that has also preserved a
large range of life forms that we can now compare to the extant suite. It is likely our only good chance to do this
and it is certainly welcome.
The time gap is also
good enough to generate viable conclusions regarding such things as DNA change
that we would both like to know comfortably and have a clean standard to work
against.
I am not surprised that
it is teeming with life either.
Antarctic Lake Vostok
buried under two miles of ice found to teem with life
A
giant lake buried more than two miles beneath the Antarctic ice has been found
to contain a "surprising" variety of life.
By Richard Gray, Science Correspondent
3:23PM
BST 06 Jul 2013
Analysis
of ice cores obtained from the basin of Lake Vostok, the subglacial lake that
Russian scientists drilled down to in 2012, have revealed DNA from an estimated
3,507 organisms.
While
the majority were found to be bacteria, many of which were new to science,
there were also other single celled organisms and multicellular organisms
found, including from fungi.
The
diversity of life from the lake has surprised scientists as many had thought
the lake would be sterile due to the extreme conditions.
Lake
Vostok was first covered by ice more than 15 million years ago and is now
buried 12,000 feet beneath the surface, creating huge pressures. Few nutrients
were expected to be found.
However,
samples of ice that had formed as water from the lake froze onto the bottom of
the glacial ice sheet above have revealed it is teeming with life.
This
will raise hopes that life may be found in other extreme environments on other
planets. One of Jupiter's moons, Europa, for example, is covered with an icy
shell that may hide a liqud ocean below where life could exist.
Dr
Scott Rogers, a biologist at Bowling Green State University, in Ohio, and led
the DNA analysis of biological material found in the ice cores, said: "We
found much more complexity than anyone thought.
"It
really shows the tenacity of life, and how organisms can survive in places
where a couple dozen years ago we thought nothing could survive.
"The
bounds on what is habitable and what is not are changing."
Lake
Vostok is around 160 miles long and 30 miles wide, covering an area of more
than 6,000 square miles beneath the Antarctic ice sheet.
Among
the bacteria found in the samples brought to the surface were those commonly
found in the digestive systems of fish, crustaceans and annelid worms, raising
the prospect there could be more complex life still living in the lake.
Isolated
from the rest of the world for 15 million years, some of the DNA sequences were
found to be unique to science and may belong to new species that have evolved
in the depths.
Writing
in the journal PLOS
One, Dr Rogers and his colleagues said: "The sequences suggest that a
complex environment might exist in Lake Vostok.
"Sequences
indicating organisms from aquatic, marine, sediment and icy environments were
present in the accretion ice.
"In
addition, another major proportion of the sequences were from organisms that
are symbionts of animals and/or plants.
"Over
35 million years ago, Lake Vostok was open to the atmosphere and was surrounded
by a forested ecosystem. At that time, the lake, which might have been a marine
bay, probably contained a complex network of organisms.
"As
recently as 15 million years ago, portions of the lake were ice free at least
part of the time. During these times, organisms were likely being deposited in
the lake.
"While
the current conditions are different than earlier in its history, the lake
seems to have maintained a surprisingly diverse community of organisms.
"These
organisms may have slowly adapted to the changing conditions in Lake Vostok
during the past 15–35 million years as the lake converted from a terrestrial
system to a subglacial system."
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