The debate over whether Mars harbored life at some point or, indeed, whether it may be harboring life right now, is still going. Hopefully, Curiosity will be successful in its goal and will provide valuable and conclusive data, one way or another.
Still, no matter how barren the planet is right now, scientists agree that it very likely had surface, liquid water at one stage of its development.
The water, an atmosphere and the distance to the sun are strong indicators that life was possible and maybe even present on Mars some time ago.
So, what would a "living" Mars look like? Well, images created by software engineer Kevin Gill could provide an indication, though, by his own account, not a completely scientific one.
He used terrain data from Mars to generate images of what the planet would look like if it had an ocean, atmosphere and even vegetation. While the terrain data is accurate, most of everything else is educated guesswork. Still, the images should at least give us an idea of what Mars would look like if it were more like Earth.