
Professor Davies said: 'It could be right under our noses, or even in our noses. It could even be that "weird life" and real life are intermingled.' Calling on scientists to launch a 'mission to Earth', he said it was possible that life had evolved more than once, meaning we are not alone on our planet.
He said: 'Life as we know it appears to have had a single common ancestor, yet could life on Earth have started many times? Might it exist today in extreme environments and remain undetected because our techniques are customised to the biochemistry of known life? If someone discovers shadow life or weird life, it will be the biggest sensation in biology since Darwin. We are simply saying "Why not let's just look for it?"
'It doesn't cost much compared with looking for weird life on Mars.'
Professor Davies, of Arizona State University, said any aliens that do exist on Earth will be too small for the naked eye to see. Their unusual biochemistry could allow them to thrive in arsenic-rich lakes or in blistering hot vents underneath the ocean.
There is even a theory that alien particles, a tenth the size of bacteria, live inside our bodies and trigger the formation of kidney stones, the American Association for the Advancement of Science's annual conference in Chicago heard. (Source: Daily Mail)