Tuesday, May 19, 2009

Why Humans Are Built for Sperm Wars

A woman in Houston has given birth to twins who were conceived by different fathers.

Most of the sperm that men produce are not designed to fertilize an egg, but to fight a war against sperm from other men. Nearly ever time that sperm from two men are in a woman's vaginal canal at the same time, only one can win. Not this time.


Anonymous said...

New low gruntled.

D- said...

Are the twins identical? I kid.
I always wondered if that was really possible in a practical sense, now I guess I know.

(Turn away if squeamish warning)Anyway, to start an interesting (and a little bit gross) conversation, recent studies have shown little to no evidence for the 'Kamikaze Sperm Hypothesis' and others ideas like it (that there is a separate class of sperm produced specifically for fighting or blocking another male's sperm) in humans or mammals. While a good amount sperm produced by male humans is useless the favored opinion now seems to be that these are just old, or mistakes.

Quick point though that 'sperm competition' is a different, more general concept pertaining to all the factors that get a male's sperm to fertilize an egg and absolutely occurs in humans (and most other sexually reproducing species). It is simply an evolutionary outcome of Sexual Selection, the all-powerful female choice, and cheating/extra-pair copulations. Sperm Competition can have to do with things like spermatazoa speed and fitness, etc. as well as extra-pair copulators (the cheaters) ejaculating more.

A study:
A fascinating (if your into this sort of thing) overview:

TallCoolOne said...

Several origin myths about Herakles have him and his twin brother being the products of Zeus (in disguise, natch) and their mother's husband.

I've always wondered why Arthur Pendragon was not a twin? What does that say about the difference between early antique and early medieval accounts of property?