Sex, Primates, Hormones & Social Behaviour

Professor Robert Sapolsky teaches a fascinating class at Stanford University on neurology and biological sciences.  Thanks for Boing Boing, I just watched two of his lectures on primate sexuality.

I honestly haven’t watched something so educational and stimulating in a long time.  Sapolsky’s lecture style and humor makes me miss college and inspires me to pursue a graduate degree in sociology or anthropology.  At the very least, I want to literature he provides for the class. (Gotta find that “zebra” book.)

I posted the videos below.  They’re over 3 hours total, so here are some highlights:

• The dominate female primate leads the ovulation of the rest of the females in the group (“OMG! We’re on the same cycle!”) because if there’s an available male, she wants to be the only one to get impregnated.  That way, she guarantees that her genes are passed on.  If all the females were on different ovulation periods, then there’s a higher chance of more offspring being born.  Females in competition can also shorten their ovulation cycles to get a better chance of getting pregnant.
• In specific species where the animals are very isolated, they can force ovulation, usually through tactic stimulation.  The male will touch the female through coitus, after which she would start ovulating.  This saves energy on the part of the female.
• If a male guinea pig fornicates with a female until he’s utterly exhausted, his energy will be renewed if you take the female from the cage and replace her with a new one.  His interest is piqued, and he regains his fever in copulating.
• The study proving that homosexual male brains are actually more like those of females has actually never been proven and replicated.  The human male brains harvested for the study were from males who had AIDS, a condition which could have affected the area of the brain used for comparison.  However, a separate study proved that transgendered people actually have similar hormone levels (I believe) compared with those of their desired gender.  That is, if the person is born male but feels like he/she should be a female, there are stimuli in the brain that actually mimic those of the female gender.  Again, I don’t think this study has been successfully replicated.  But both transgendered and transsexuals (those who have gone through a sex change operation) have shown these results.  Non-transgendered patients who have had hormone and gene therapy do not, showing that these results are expressed solely in those who are transgenders or transsexuals.
• Primates that mate for life or are monogamous couples actually produce hormones in both the male and female brains that strengthen the bond between the two individuals after a period of repeated mating.  They enjoy the monogamy.  This has not been proven in humans.  [In the social context, females in fact may not be emotionally linked for males after sex, despite pop culture.]
• Testosterone in males don’t cause a hyperactive sex drive.  In fact, more sex creates more testosterone.
• Cologne has cat urine, and perfume has contains male pheromones.  Women closer to ovulation have a more acute sense of how much testosterone is in a sample of body odor.  Because women are the primary buyers of scents, perfume actually contains male pheromones (musk, a.k.a. male animal pheromones) to attract those buyers.
• Non-human primates, such as orangutans, chimpanzees, etc., have similar pheromones to those of humans.  Therefore, a male chimp may try to initiate sex with a female trainer, when she’s ovulating and releasing high levels of pheromones.

If you have 3 extra hours, I seriously suggest you watch these videos.  What I’ve noted above are just a few highlights.  There’s so much more.

Prof. Robert Sapolsky on the Neurobiology of Primate Sexuality: Part 1

Prof. Robert Sapolsky on the Neurobiology of Primate Sexuality: Part 2