Is it life, Jim?

WHEN the news broke about what seem to be traces of water on the surface of
Mars, I was at a conference in Valencia. It was a good opportunity to think
about water. Baking hot in summer, this part of Spain takes the stuff very
seriously. Its water court has been meeting outside the cathedral every week for
centuries to deal with irrigation disputes. And by chance, the city’s
beautifully cool botanical garden was the setting for the second of the American
Geophysical Union’s meetings on the Gaia hypothesis, which suggests that the
creatures of Earth have been regulating their…