Humans are the product of Earths biology and no other. Conscious, intelligent life forms from other planets would be of their relative planetary biology. Science knows through detection that light particle energy is everywhere in space. And it just so happens that a particle of light contains the DNA to start life and much more. We also know from our planet that nature repeats itself on every level. So it looks like a planet that can support life will probably have life. It just makes reasonable sense that earth is not the only planet to possess conscious intelligent life form when there are trillions of other planets in an endless universe. Your response is appreciated.