Prof Chandra Wickramasinghe, of Cardiff University, said new research “overwhelmingly” supported the view that human life started from outside our Earth.
The Astrobiologist said the first “seeds of life” were deposited on our plant from space 3,800m years ago.
He claimed microbes from outer space arrived on earth from comets, which then “multiplied and seeded” to form human life.
His said his evidence, published in Cambridge University’s International Journal of Astrobiology, showed humans, and all life on Earth, came from aliens brought to the earth by comets hitting the planet.
“Yes, we are all aliens – we share a cosmic ancestry,” Prof Wickramasinghe said.
“Each time a new planetary system forms a few surviving microbes find their way into comets.
“These then multiply and seed other planets.”
He added: “”We are thus part of a connected chain that extends over a large volume of the cosmos. Evidence is pointing inexorably in this direction.”
Prof Wickramasinghe believes life is transferred from planet to planet over billions of years.
He believes comets hit planets and pushed living matter out into space.
He said some survived and got transferred to new planets over a timescale of millions and millions of years.
But he accepts this model still does not explain how life actually began in the first place.
The professor and his late colleague Sir Fred Hoyle championed the so-cllaed “panspermia” theory from the 1960s.
“Evidence from astronomy overwhelmingly supports the view that life did not start on Earth but was seeded from outside,” Prof Wickramasinghe said.
“Although we have no definite knowledge how life started in the first place, once started its spread in the cosmos and survival is inevitable.
“As we enter a new decade – the year 2010 – a clear pronouncement of our likely alien ancestry and of the existence of extraterrestrial life on a cosmic scale.”
via All humans are ‘aliens from outer space’, scientist claims – Telegraph.