COULD LIFE HAVE ORIGINATED DEEP INSIDE EARTH?

The idea that life could thrive deep below earth’s surface was once regarded as heretical. Lacking any obvious source of energy, such as sunlight, and subjected to intense heat and pressure, subterranean organism would seem to have little chance of survival. Yet since the 1980s, bacteria, fungi and worm-like creatures have been found lurking kilometres down in mine boreholes and deep sea sediments. These organisms have extraordinary source of energy. For example, some bacteria rely on the reactions between water and rocks to get there energy.

Dating techniques suggest bacteria have existed at depths of several kilometres for at least 30 million years. What isn’t clear is where they fit into the history of life on earth: were they washed down, or are they progenitors of life on the surface? Either way, their existence has boosted hopes for life on Mars. While none has been found on the surface, NASA’s curiosity rover recently detected methane coming from within the planet – which may be the result of subterranean organisms.