Originally Posted by nemesis

No they would not. They wouldn't look anything like us. It is difficult for me to explain why, but it has to do with evolution and the environment. Scientists are able to come to this conclusion based in part because how life develops on Earth. If a certain function does not evolve independently between various lifeforms on our own planet chances are it would not evolve on another.

An example would be flight. Birds, insects and bats all developed the ability to fly independently so finding an alien (sentient or not) that is capable of flight isn't that far fetched. On the other hand a more specific evolutionary trait like our humanoid body frames has only evolved among primates who all evolved from a common ancestor in Africa. No species without a connection to primates has ever developed a humanoid body (out of the billions of species of animals on our planet) therefore the chances that such form would develop on another planet would be rare. Not impossible but exceedingly rare.

To find a species that looks just like us is flat out impossible. What are the chances that an alien would develop the same skeletal structure, body mass, sensory organs (eyes, noses, ears and such) located in the exact same places when the planet they hail from has completely different species of animals evolving on them? It's not going to happen.