Biologist Simon Conway Morris, an expert in evolution at the University of Cambridge, said the chances of alien life evolving elsewhere in the universe are "pretty high".
Morris, in a new book called The Runes Of Evolution, discusses a theory called convergence, which suggests evolution may proceed along certain lines rather than being a chaotic process.
If true, this would mean extraterrestrials are "almost guaranteed" to possess limbs and a head, and think intelligently - just like us earthlings, 'mirror.Co.Uk' reported.
"I would argue that in any habitable zone that doesn't boil or freeze, intelligent life is going to emerge," Morris said.
"And given the number of potential planets that we now have good reason to think exist, even if the dice only come up the right way every one in 100 throws, that still leads to a very large number of intelligences scattered around, that are likely to be similar to us," he said.