19:19 25 January 2017
Columbia University scientist Caleb Scharf said that we may all be aliens. The radical theory, called Panspermia, claims that life may have begun on Mars before coming to Earth on an asteroid. The theory was first proposed in 1871 and has since been gaining traction among the scientific community.
Scharf said: 'We can find pieces of Mars here on Earth and we suspect that there are pieces of Earth on Mars.
'If that material can carry living organisms on it, it's possible that we are Martian.'
Peter Ward, a biologist at the University of Washington in Seattle said: 'I think the case for Mars as the origin of Earth life is pretty good.'
'It's a big blow. For some religious fundamentalists, it is an axiom that there is but one life and it is here on Earth.'
Professor Chandra Wickramasinghe, an astrobiologist at the University of Buckingham and long time supporter of panspermia, said: 'This was conjecture in the past, purely theoretical, but now we have evidence for it. It's changing slowly, but surely.'
In a paper published in 2015 in the Journal of Astrobiology, the scientists wrote: 'Recent studies have led to detections of some 900 exoplanets in a nearby small sample volume of our galaxy.
'Extrapolations from this study give an estimate of 140 billion habitable planetary systems in our galaxy alone, most of these being associated with faint red dwarf stars.
'On such a basis the mean distance between life-friendly planetary systems is only a few light years.
'This relatively short interplanetary distance is easily bridged by escaping dust, debris, meteorites and comets.
'Material expelled at speeds greater than the escape speed from a planetary system like our own solar system will, in general, have hyperbolic orbits with respect to a nearby star, so the probability of direct capture will in general be very low.
'However, sub-micron dust including bacteria and viruses released by transiting cometary bolides, even if they are in hyperbolic orbits, will be easily be stopped by friction (gas drag) in the interplanetary disc of the recipient planetary system, and thus serve to infect habitable planets.'