Why Men Don't Have Sensory Whiskers and Spiny Genitals 226
sciencehabit writes "Most male mammals wield a penis covered with spines made of keratin, the same material that forms fingernails, to sweep out competitors' sperm and irritate a female into ovulating. Even chimpanzees, our closest relatives, have penile spines. So why don't men? A new study suggests that this feature disappeared due to a chunk of DNA that went missing after our evolutionary divergence from chimps. The researchers have identified another DNA deletion that may have contributed to humans' bigger brains."
Re:I don't have spines on my penis (Score:5, Interesting)
...because I refrain from sex with porcupines and hedgehogs. And I didn't even have to RTFA.
You mean like these 2 Russians [mosnews.com]
Occam's Razor (Score:5, Interesting)
...because women, generally, don't want them? They by & large run the reproductive sweepstakes, even back in the "me big strong caveman, me conk woman on head" days when "consent" was a little more broadly interpreted.
And which came first, male lack of spines, or female concealed ovulation?
When analyzing the genetic record, how can one 'sort out' the distinction between DNA changes that have happened due to mutation, compared to the changes induced by broad and consistent female choice?
Re:Occam's Razor (Score:2, Interesting)
That's all fine and dandy, but considering that presumably, females of other species don't want them, either, why do they still exist there?
Pearly Penile Papules (Score:5, Interesting)
Still in the genepool only very diluted: https://secure.wikimedia.org/wikipedia/en/wiki/Hirsuties_coronae_glandis [wikimedia.org]
There's a lot more going on here (Score:5, Interesting)
First off, human males *do* have a mechanism to sweep out sperm from other males, consisting of the most visually obvious part of the male penis and protracted mechanical movement. We lost spikes, we evolved something else to do the same function. Secondly, there are many other mammals that have different methods for accomplishing the same thing: male squirrels have something like superglue that forms a plug after coitus, to prevent other males gaining access afterwards. (And female squirrels have claws and quite a bit of expertise in removing those same plugs, as you'd expect in any good arms race.) Likewise, many male lizards and insects avoid the problem by just staying connected until the female is ready to lay her eggs, which puts a whole lot of stress on the female during that period: they both get eaten pretty often.
But if you really want to get weird, go look at insects like bedbugs, where males practice traumatic insemination: they don't go looking for an orifice, they make one, and let the female's body figure out what to do with the results. Or bees, where the barbs aren't there to stimulate ovulation but to make sure the penis breaks off and acts as a plug that can't be removed.
And the next step weirder is hermaphrodites, where mating is a contest in which both wish to inseminate the other without getting inseminated, so mating strategies get seriously complicated. (The phrase 'penis fencing' has been used.)
Anyone who is curious about this should read the brilliant book Promiscuity: the evolutionary history of sperm competition [amazon.com] by Tim Birkhead. It will make you relieved to be human.
Re:Huh? (Score:5, Interesting)
What, you mean these spines on my penis aren't normal?.
Let's hope it stays that way. from the article:
"The interesting question - which for some reason the scientists didn't want to answer - is whether we could use a gene therapy to replace that deleted regulatory DNA. Basically, we'd add an activation switch to the whisker/spine sequence, flip it to "full blast," and start growing new body parts."
I for one, do not think man should have his hands in his genes fiddling with himself. But then again, this is slashdot afterall, so...............