Deep below the surface of a small town in Ontario, Canada, scientists have discovered the oldest cache of water yet known on Earth. The water was first noticed by gold miners who saw it seeping out of boreholes, before researchers decided to find out just how old it was. Now, geochemist Greg Holland tells NPR that the water is at least 1.5 billion years old, and could be a billion more still. It was trapped in tiny cracks in rocks as they formed from magma; the water remained encased inside these rocks as they shifted around the globe. "It's managed to stay isolated for almost half the lifetime of the Earth," said Holland.

"If that happened on Earth, why shouldn't it have happened on Mars?"

The scientist believes that the body of water could contain clues to ancient life, or even life on other planets. The samples of water contain a lot of hydrogen, which has been found to provide sustenance for microorganisms in similarly remote environments. If organisms are present in the water, which a team of researchers hopes to ascertain within a year, they will likely have followed a different evolutionary path to that of the world above. This could reveal more about some of the earliest life forms on our planet — and possibly others. NASA research scientist Carol Stoker posits that Mars may contain similar pockets of water that could play host to life deep below the surface. "The logic is if that happened on Earth, why shouldn't it have happened on Mars?"