Unusual Clinical Sex Questions

Why must warm-blooded animals have external testicles? I understand that sperm production requires lower temperatures. Why sperm and not eggs? For that matter, how are sperm produced? The sex of of an early embryo is ambiguous. Does this apply to sperm/eggs? I've heard that a female is born with a set number of undeveloped eggs. One would guess about 360. Does this mean males start with the same number of parent sperm? Sperm live for several days. In that time do they get any sustenance? We evolved from both sexes in one entity, able to fertilize themselves to separate sexes. I once had an inspiration that this happened at the same time as the evolution of multi-cellular beings and pre-programmed death. I couldn't make any sense of it beyond that. Is this valid. Can anyone elaborate? I think the reasons for the above are supposed to be that we evolve faster by sharing genes with others, preferably genetically distant others. In domestic animals, we "improve the breed" by inter-breeding, but among humans, too close inter-breeding is considered destructive. I've never heard about any problems caused by incest among wild animals, or any behavior specifically intended to prevent it. Is it really clear that incest is produces defective humans more often? Logic says that inter-breeding in families with bad genes will multiply the defects, and among good genes it will multiple the superiority. This would seem good for some families, bad for others. Among animals, this is good because the bad genes are more easily culled out, naturally or artificially. Among humans, it would seem to be natural, because we produce more extremes of both good and bad. So why is it considered generally destructive? Is it really an attitude common among school children, that anything different from the norm is bad, including superiority?
Send me your thoughts.
Dan Robinson, danrob@efn.org, Eugene, Oregon
My home page: http://www.efn.org/~danrob/