"A newly-discovered life form that froze on Earth 30,000 years ago was apparently alive all that time and started swimming as soon as it thawed, a NASA scientist reports.
Dr Richard Hoover, of NASA's Marshall Space Flight Centre in Alabama, says the find has implications for possible contemporary life on Mars.
The organism - a bacterium dubbed Carnobacterium pleistocenium - probably flourished in the Pleistocene Age, along with woolly mammoths and sabre-tooth tigers.
Speculation: The thawed bacterium adds weight to theories of life on Mars. [File photo] (Reuters)
Dr Hoover discovered the bacterium near the town of Fox, Alaska, in a tunnel drilled through permafrost - a mix of permanently frozen ice, soil and rock.
'When they cut into the Fox tunnel, they actually cut through Pleistocene ice wedges, which are similar to structures that we see on Mars,' Dr Hoover said.
Dr Hoover says these ice wedges contain a golden-brown layer about half-a-metre thick, and this layer contained a group of microscopic brownish bacteria.
'These bacteria that had just thawed out of the ice ... were swimming around,' he said.
'The instant the ice melted, they started swimming. They were alive... but they had been frozen for over 30,000 years.'
Dr Hoover says this discovery, coupled with research released this week by the European Space Agency, makes it more likely that life could be found on Mars.
Life on Mars
Scientists have focused on Mars as the most likely spot in our solar system for Earth-like life, but none has so far been confirmed.
What has been found is ample evidence that water once flowed on the currently cold and frost-locked planet.
This is significant because liquid water - not ice - has been seen as a prerequisite for life as it is known on Earth.
Images made by the European Mars Express space probe indicate a giant frozen sea near the Martian equator, the first time scientists have detected evidence of ice beyond Mars' polar caps.
Dr Hoover says this this vast sea is covered by a layer of dust, which might be heated by the sun and could conduct heat down to create sub-surface layers of water from time to time.
"Those layers would be ideal regions for microbiological activity and so that means that the presence of this frozen sea, if that turns out to be precisely what's going on, it greatly enhances the possibility that there may be life existing on Mars today," he said.
The discovery of the living bacteria in Alaska's permafrost raises another possibility, Dr Hoover says.
"The other thing that's exciting: Just like we found in the Fox tunnel of Alaska, frozen biology in the form of unicellular bacteria might even have remained alive, frozen in the Martian sea," he said.
Dr Hoover found the bacterium in 2000, but it took five years to confirm that it was in fact a new form of life.
The finding was published in January in the International Journal of Systematic and Evolutionary Microbiology, the official journal of record for such matters.