The fossils found in a meteorite from Mars by United States scientists do not prove there is life there - and even if there is, they do not tell us how life began, according to a British meteorite expert who has been involved in Mars research.
David Rothery of the Open University said: "Most people who have thought about Mars have agreed that it has most of the ingredients needed for life, including water, so to find a microfossil there resembling terrestrial bacteria is not surprising. It does not prove that there is still life there, but once life got started there it could keep going." The Mars meteorites found on the Earth are all at least 200 million years old.
A paper on the microfossils in the meteorite, which is known as Allen Hills 84001, will be published next week in the US journal Science. Dr Rothery said that attention will focus on whether the fossil could have got into the meteorite during the 13,000 years it spent on Earth before being discovered.
Daniel Goldin, head of the National Aeronautics and Space Administration, whose scientists led the group which made the discovery, said that the evidence for Martian bacteria was "compelling but not conclusive". Even if life has been present on Mars, it could have come from the Earth, via meteorites blown out from the Earth's surface, or from space, as some mavericks such as astronomer Sir Fred Hoyle have proposed.