Image: Erwan Roussel
John Parkes has been hunting for life in unusual places for over 20 years and recently, his discovery of bacterial life deep beneath the oceans might mean that we'd have to rethink the definition of life and the possibility of finding it on another planet:
This means it is conceivable – but unproven – that some of the cells are as old as the sediment. At 1.6 km beneath the sea, that's 111 million years old. But in an underworld where cells divide excruciatingly slowly, if at all, age tends to lose its relevance, says Parkes.
Parkes' interest in prokaryotes goes far beyond those that are buried deep in the Earth. He thinks the cells found there could lead to life on other planets.
Previously, he has shown that the rocks beneath the oceans could be home to the largest population of prokaryotes on Earth, and account for one tenth of all living carbon. He estimates the combined undersea biomass could be equivalent to that of all the plants on Earth.
"We are all dominated by our surface existence where everything relates to photosynthesis and oxygen," he told New Scientist.
The possibility that there could be more forms of life beneath the surface than above it suggests that they have different and effective ways of surviving – ways that could be independent of light and oxygen. And if these "new" forms of life exist on Earth, they could exist on other planets too.