Orgasm Linked to Genes, Sperm Quality to “Competition”
Nature is always the ideal stop for groundbreaking scientific research, but one suspects that it’ll get more than its normal share of readers today.
A woman’s genetic make-up accounts for at least a third of her ability to climax during sex, say researchers, and may even account for as much as 60%.
Further investigations into the genetic differences that influence orgasms in women could help produce drugs to treat female sexual dysfunction, they say.
To find out which factors most affect a woman’s ability to climax, [Tim] Spector and his colleagues sent a questionnaire to more than 4,000 female twins to complete anonymously. Recipients included nearly 700 pairs of identical twins, who share the same DNA.
The researchers asked how often the women climaxed during sex. Only 14% of the women reported always achieving an orgasm. At the other end of the spectrum, 16% of them said they never reach orgasm or are unsure about whether they do or not.
As in other studies of twins, the scientists assume that twins share similar family environments. The overall difference between trends in identical twins and fraternal twins is thus attributed to genetic influences. The analysis suggests that genes explain at least 34% of the probability that a woman orgasms during sex. When it came to masturbation, this number climbed to 45%, the researchers report in Biology Letters.
This number could go even higher, they add, if one could account for other variables, such as the different techniques of the women’s partners. Genetic influences have been seen to account for as much as 60% of variability in other complex traits, such as obesity.
It might sound unlikely, but men looking at explicit pictures of two naked men with a naked woman have been shown to produce higher-quality sperm than those watching pornographic images featuring women only.
Although this seems to go against common perceptions about male sexual preferences, it is consistent with the theory of sperm competition, says study leader Leigh Simmons of the University of Western Australia, Perth. This states that males (of many species, including humans) should produce better sperm when faced with a female who has other mates, because this stimulates them to boost their chance of procreation.
The findings may help fertility clinics to obtain the best possible sperm samples from their clients, by providing specialized images of intercourse for men to view. This might help prospective fathers maximize their fertility, Simmons suggests. Though he adds that some women may disapprove of their partner viewing such material.
This latter article is perhaps the perfect complement to Slate‘s “The Genius Factory,” in which David Plotz recounts his “short, scary career as a sperm donor.”