How did it all start?

A group of eminent scientists are spending two days discussing the origins of life on Earth. The Guardian's science correspondent, James Randerson, joined them.

The first morning of a two-day meeting at the Royal Society on the origins of life on Earth was dominated by the search for it on Mars. Studying the red planet is useful because it shares some characteristics with the early Earth and so might give scientists clues about what happened here.

So what does Martian life have going for it? Water for starters, the scientists say. The dry channels and flood plains seen by Nasa's unmanned Viking missions in the 70s confirmed that the apparently parched surface of Mars must once have been abundant in water.