Little green men, little grey forms—the common archetype of aliens is that they're going to look quite different from ourselves. But an academic from Cambridge University in England, professor Simon Conway Morris, thinks they may well have evolved to look just like we do.
Morris is an evolutionary biologist and in a recently published book The Runes of Evolution he uses the familiar biological concept of convergent evolution to posit that aliens might have evolved with similar features, and intelligence, to us. Conway explains convergent evolution as "In essence it is a feature of evolution whereby organisms arrive at very similar biological solutions, but from very different starting points."
So different organisms can evolve similar characteristics and traits, and Conway thinks it's unlikely this concept just takes place on earth. He thinks it could take place across the universe, so it's possible that on earth-like planets aliens may have evolved to look, and act, very similar to us.
“The book is really trying to persuade the world that evolutionary convergence is completely ubiquitous. Wherever you look you see it." he told The Independent. "The theme is to try and drive the reader, gently of course, into the possibility that the things which we regard as most important, ie cognitive sophistication, large brains, intelligence, tool making, are also convergent. Therefore, in principle, other Earth-like planets should very much end up with the same sort of arrangement."
Which begs the question, maybe aliens have evolved to look like us and have also contacted earth, surreptitiously, and are living amongst us, waiting to take over.