As mentioned previously in this blog, I have been lapping up the writings of evolutionary biologist, Jesse Bering, in his book “Why is the penis shaped like that?”, in particular his essay on human semen.
This serendipitous work came to light from research into the puzzle about menstrual synchrony. The puzzle is this: heterosexually active women living together tend to exhibit a high degree of menstrual synchrony, whilst sexually active lesbians living in close proximity exhibit no sign of menstrual synchrony. What causes the difference? Researchers quickly realised a difference between the two groups was the presence or absence of semen; ‘Lesbians have semen free sex.’
Semen is largely a bulk fluid to carry and protect sperm, the sperm making up 1 to 5% of total volume in ejaculate. The seminal plasma – the large part left after accounting for sperm has an interesting composition, including of over fifty compounds ‘including hormones, neurotransmitters, endorphins, and immunosuppressants’.
‘Perhaps the most striking of these compounds is the bundle of mood-enhancing chemicals in semen. . . . Such anxiolytic chemicals include . . . cortisol (known to increase affection), estrange (which elevates mood), prolactin (a natural antidepressant), oxytocin (also elevates mood), thyrotropin-releasing hormone (another antidepressant), melatonin (a sleep-inducing agent), and even serotonin (perhaps the best known antidepressant neurotransmitter).’
Researchers hypothesised that ‘women having unprotected sex should be less depressed than suitable control participants’.
Their resultant study was of 293 college females, the results being published in the Achives of Sexual Behavior”. Even after adjusting for frequency of sexual intercourse, women who engaged in sex and “never” used condoms showed significantly fewer depressive symptoms than did those who “usually” or “always” used condoms. Importantly, these chronically condom-less, sexually active women also evidenced fewer depressive symptoms than did those who abstained from sex altogether. By contrast, sexually active heterosexual women, even really promiscuous women, who used condoms were just as depressed as those practicing total abstinence. In other words, it’s not just that women who are having sex are simply happier, but happiness appears to be a function of the ambient seminal fluid pulsing through one’s veins. (The vagina has long been recognised as a fast track for drug delivery into the blood stream. This is because of the ‘impressive vascular network’ surrounding the vagina.)
The researchers, Gordon Gallup and Rebecca Burch, urge caution in interpretation of ‘these data (that) are preliminary and correlational in nature’. This, of course, does not stop them wondering of ‘the possible antidepressant effects of oral ingestion of semen, or semen applied through anal intercourse (or both) among both heterosexual couples as well as among homosexual males.’
Jesse Bering asks if this mood enhancement may be a factor in ongoing ‘barebacking’ (unprotected anal sex among gay males), given the HIV risks involved. Bering goes on to quote from a postmodernist view of why gay men still bareback:
“The body becomes the locus of never-ending fights, a carnal battlefield. The escape route (lines of flight) is intrinsic to the deterritorialisation of the Body-without-Organs through which one becomes some-one else. …….”
There are another couple of hundred words of this which Bering says “reads as if the authors were cobbling together a Braille sentence using the random distribution of acne on someone’s back.” Bering prefers an evolutionary approach, supporting the semen triggered mood enhancement model.
Which seems to me to be as good a place as any to leave this most tasteful subject, at least for the moment. Of course we could have explored the semen ingestion rituals involving young boys in the Sambia Tribe of New Guinea, but that will have to wait another day.
(Quotes from ‘An Ode to the Many Evolved Virtues of Human Semen’ in “Why is the Penis Shaped Like That?” Jesse Bering, Corgi Books, London, 2013)