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Thursday, July 11, 2013

Why are testicles kept in a vulnerable dangling sac?

Read the whole thing at Slate.  Excerpt:

Why, on the path from the primordial soup to us curious hairless apes, did evolution house the essential male reproductive organs in an exposed sac? It's like a bank deciding against a vault and keeping its money in a tent on the sidewalk.

Some of you may be thinking that there is a simple answer: temperature. This arrangement evolved to keep them cool. I thought so, too, and assumed that a quick glimpse at the scientific literature would reveal the biological reasons and I’d move on. But what I found was that the small band of scientists who have dedicated their professional time to pondering the scrotum’s existence are starkly divided over this so-called cooling hypothesis.

Reams of data show that scrotal sperm factories, including our own, work best a few degrees below core body temperature. The problem is, this doesn’t prove cooling was the reason that testicles originally descended. It’s a straight-up chicken-and-egg situation—did testicles leave the kitchen because they couldn't stand the heat, or do they work best in the cold because they had to leave the body?


  1. I often see people confuse the evolutionary mechanisms.

    it isn't that nature molds creatures to develop certain attributes. what it does is kills off the ones that have the poor or less durable attributes.

    while we may never have more then theories about many developments. (it is not only humans who dangle the cargo).

    we may be able to conclude that the dangles had more and healthier offspring favouring the danglers.

  2. The female can more readily judge the suitability of the male as the parent of her offspring by the size of his genitalia. IOW size matters. Always has; always will. Those males with the appropriate uh mass are more likely to be granted access to the treasure they seek.

  3. If you are a biblical creationist, this just isn't an issue at all.

    Just sayin'.