|This graphic shows how Mars might have looked billions of years ago, when scientists believe the planet had a large northern ocean.|
For years, scientists have been saying that although present-day Mars is an inhospitable place, it was much more habitable billions of years ago. The findings from NASA's Curiosity rover on Mars have added fresh support to such claims.
Is Benner's story too kooky to believe? One thing's for sure: Benner is not a kook. He was one of the first chemists to voice skepticism about the claims for arsenic-based life, which stirred up such a fuss in 2010. "I'm the guy they bring in to throw a wet blanket over all the enthusiasm," he told NBC News at the time.