London - If they are out there somewhere, aliens will not look like little green men with elongated limbs and saucer-like eyes.
Instead, according to a leading evolutionary biologist, intelligent extraterrestrial life will, far from resembling ET, look like Star Trek's Mr Spock - very similar to us.
In his book, Professor Simon Conway Morris, of Cambridge University, argues aliens that resemble human beings should have evolved on at least some of the many Earth-like planets recently discovered by astronomers.
The Runes of Evolution builds on the principal of convergent evolution - that different species will independently evolve similar features. For example, an octopus and human have both, independently, evolved a similar type of eye. Professor Conway Morris believes this phenomena will not just take place on Earth.
“The book is really trying to persuade the world that evolutionary convergence is ubiquitous,” he told The Independent. “Wherever you look you see it.
“The theme is to try and drive the reader into the possibility that the things which we regard as most important, such as cognitive sophistication, large brains, intelligence, tool-making, are also convergent. Therefore, in principal, other Earth-like planets should very much end up with the same sort of arrangement.”
Professor Conway Morris, a Fellow at St John's College, said it follows that plant and animal life on other planets able to support life would also look similar to Earth's.
He said: “Certainly it's not the case that every Earth-like planet will have life let alone humanoids. But if you want a sophisticated plant it will look awfully like a flower. If you want a fly there's only a few ways you can do that. If you want to swim, like a shark, there's only a few ways you can do that. If you want to invent warm-bloodedness, like birds and mammals, there's only a few ways to do that.”
His theory begs the question of Enrico Fermi's famous paradox - why, if aliens do exist, have they not made contact? He admits his book goes “off-piste for a bit of fun” in the last chapter when dealing with this problem.
“The problem is exceedingly acute: we shouldn't be alone but… all the evidence suggests we are,” Professor Conway Morris said. “Maybe [aliens] are hiding. I don't honestly know. My suspicion is we have only begun to scratch at the surface of reality, for want of a better word.”
Professor Conway Morris said one of the main themes of his book was his desire to “re-energise people and get their sense of curiosity running again”. Convergence is demonstrable at every point of evolutionary history, he argues.
“Convergence is ubiquitous and if you think complex things are difficult to make, well, with great respect, think again,” he said.
The Independent