British professor Chandra Wickramasinghe believes that humans are aliens and share a cosmic ancestry.
The scientist claimed that the human race began as microbes brought to Earth by comets millions of years ago, reports The Sun.
Wickramasinghe said: "We are all aliens. We share a cosmic ancestry.
"Each time a new planetary system forms, a few surviving microbes find their way into comets.
"These then multiply and seed other planets. We are thus part of a connected chain that extends over a large volume of the cosmos. Evidence is pointing inexorably in this direction."
According to Wickramasinghe, an astrobiologist at Cardiff University, the first "seeds of life" were deposited on Earth 3,800 million years ago.
He added: "Although we have no definite knowledge how life started in the first place, once started, its spread in the cosmos and survival is inevitable." (ANI)