Stedric every biologist on the planet would disagree , I'll take their word first thanks , as would every zoologist. It's not random at all (which would be inferred by your statement). Some species can even become Transexual and all of it is a direct result of overpopulation. Or lack of "females" or "males" in the case of transexuals. If I read your statement wrong please clarify me . (also in every biology course I took in university thats what we were taught if you have a more learned perspective then the biologists I would be willing to listen).