I really hate it when those who don't believe in aliens try to stick rules that apply to humans on to possible aliens. Who knows, maybe aliens don't breathe air! Maybe they breathe some other gas, or don't even breathe at all. I'm sure had humans evolved on say, the Moon, we would have adapted to live in that environment. Look at ants, for instance. They live in a hive-type society, with one dominant Queen ruling over all other ants within the colony. They can survive for up to a week underwater. Just because they came into existence on Earth doesn't mean they have to be just like us.