London: Life on Earth may have been kick-
started by meteorites which bombarded our planet four billion
years ago, a new study has suggested.
Previously planetary scientists thought that nothing
could have survived the "heavy bombardment".
But, now a team at Aberdeen University has claimed
that microbes -- the primitive forms of life -- survived the
massive barrage of impacts by taking refuge deep underground
-- and actually thrived on the temperatures generated.
For their study, the researchers analysed a mineral
called pyrite, in a crater on Devon Island, a wilderness in
the Canadian High Arctic, which were deposited by a type of
microbe which likes heat and is also capable of withstanding
temperatures close to boiling point.
According to them, hyperthermophiles had colonised all
of the Haughton Crater - over 12 miles across and at least 200
metres below the Earth`s surface, indicating they would have
been able to live deep underground in the darkness known as
the "deep biosphere", `The Daily Telegraph` reported.
"When the Earth was young, over four billion years
ago it was repeatedly hit by large meteorites which would have
shocked and melted the planet`s surface. Until now scientists
have imagined that primitive life would not have been able to
withstand this pummelling.
"But our analysis of the mineral told us that
this ancient microbe could have been able to survive meteorite
bombardment through a combination of living underground and
reinvading the surface rock while it was still very hot.
"So the asteroid bombardment may well have led to the
primitive lifeforms flourishing rather than wiping them out.
"Our findings add to a growing body of evidence that
there is much life on our planet that lives deep below out of
sight and that this is where early life on Earth may have
"Similar meteorite craters with similar minerals occur
on Mars, and this work highlights an approach that could help
us look for evidence of life there," Prof Parnell, who led the
team, wrote in the `Geology` journal.