[Anders]

Originally Posted by Bruno

Note that an impotent man in modern culture can often still have children, but he'll need medical assistance.

My favorite story is about the guy who got help from a hamster. His testes lacked one of the proteins needed for sperm development, but he had the stem cells, and these proteins are highly conserved. So they took a path of his testes which had stem cells and transplanted into a the testicles of a hamster (immune reaction are generally not a problem in the testicles). And since sperm from humans and sperm from hamsters look very different, separating out the human sperm was very easy.

Medical Miracle!