New evidence there may have been life on Mars

Here is why we should hope they find no life on mars. <a href="http://www.nickbostrom.com/extraterrestrial.pdf" rel="nofollow">http://www.nickbostrom.com/extraterrestrial.pdf</a> (PDF) This is also an interesting discussion by Nick Bostrom on the Fermi paradox and why we may be alone in the galaxy.

One thing I don't understand in all of these discussions about there having been life on Mars in the past: wouldn't it still be there today?<p>Even given that the planet's climate has changed entirely over time, as long as life had begun at some point and had a non-negligible amount of time to evolve it would have expanded into every available niche. There's life here on Earth in environments far less hospitable than those on Mars, isn't there?