Meteorites could have kick-started life on earth 4 billion years ago

London, March 11 : A new study has shown that Meteorites that bombarded Earth four billion years ago could have kick-started life rather than wiping it out.

Microbes are believed to have survived the massive barrage of impacts by taking refuge deep underground - and actually thrived on the temperatures generated.

Previously scientists thought that nothing could have survived the 'heavy bombardment', but now researchers believe it could have even been beneficial to certain organisms.

The earliest physical evidence of life on Earth in the shape of fossils only dates back to 3.8 billion years.

But, according to a report in the Telegraph, the new research suggests that it began hundreds of thousands of years before this - and could yield new clues about primitive life on Mars.

Professor John Parnell's team found minerals in a crater on Devon Island, a wilderness in the Canadian High Arctic, had been deposited by a type of microbe which likes heat - and is capable of withstanding temperatures close to boiling point.

"The mineral containing the microbe is pyrite - otherwise known as fool's gold - and pyrite likes sulphur of which there is plenty on the surface of Mars," he said.

"So these microbes known as hyperthermophiles may have existed on Mars when the planet was much warmer than it is now," he added.

Scientists had believed that life on Earth could not have survived the bombardment.

But, hyperthermophiles had colonised all of the Haughton Crater - over 12 miles across and at least 200 metres below the Earth's surface, indicating that they would have been able to live deep underground in the darkness known as the 'deep biosphere'.

According to Prof Parnell, of Aberdeen University, "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."

"Up until now, scientists have imagined that primitive life would not have been able to withstand this pummeling," he said.

"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," he added.

"So, the asteroid bombardment may well have led to these primitive lifeforms flourishing rather than wiping them out," he said.