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Book Summary: The Book of Humans: A Brief History of Culture, Sex, War and the Evolution of Us

Author: Adam Rutherford

Substory: Oral Sex in Bears

Autofellatio may be rare in humans, and autocunnilingus surely is close to physically impossible (as far as my research goes, there is no academic literature on this). Nevertheless, oral sex is a common and popular version of non-reproductive sex between human partners. We do it because it’s pleasurable, but we are far from unique in performing this act. Oral sex is widespread among animals, and the reasons are more difficult to scrutinise. Heterosexual oral sex is common, strikingly in the fruit bat Cynopterus sphinx, where females lick the shaft of their partner’s penis during penetrative intercourse (done dorsoventrally, that is, from behind, but they do it hanging upside down). This has the possibly counterintuitive effect of prolonging sex. There are plenty of scientific theories why they do this, none of which can be summarised as ‘because they can’, disappointingly. Prolonged intercourse may increase the likelihood of fertilisation, or it might be an act of mate-guarding – that is, preventing another male from having a go. It might even be another way to prevent sexually transmitted diseases: fruit bat saliva may have antibacterial and antifungal properties, so to add it to the vaginal lubrication during penetration might be a safe-sex method of guarding against chlamydia and other infections.

While not quite oral sex (for anatomical reasons), the male dunnock Prunella modularis often pecks at the cloaca of females to remove the sperm of a rival male. These rather dull hedge sparrows have sex up to a hundred times a day, an impressive fact that is only slightly undermined by the knowledge that each act takes about a tenth of a second.

If both of these acts of oral sex seem quite functional and untender, the first report of oral sex in bears may offer a different perspective. Published in 2014, it details how two unrelated male brown bears engaged in repeated daily bouts of fellatio for six years in Zagreb Zoo, Croatia. The giver and receiver was always the same way round, and the act itself fairly ritualised into a predictable pattern. One would approach the other who would be lying down on his side. The giver would physically part the receiver’s rear legs, and begin fellatio, often while humming. It typically lasted between one and four minutes, and clearly appeared to result in ejaculation by the receiver, as qualified by muscular spasms. These bears were raised in captivity, and again, this behaviour might be abnormal, at least compared to bears living in the wild, where ursine fellatio has never been observed. The researchers speculate that it might have started in an absence of maternal suckling behaviour, the bears having been orphaned when cubs. However it originated, it seems perfectly plausible that the behaviour continues because it is pleasurable.

Pleasure is the reason we perform oral sex. Again, as with examples of masturbation in other animals, the idea that motivation for non-reproductive sexual acts might be the same as in us is not something that scientists are drawn to. Whether this reluctance is valid or not is difficult to ascertain, but certainly, examples where parsimonious explanations can plausibly include pleasure – such as in the Croatian bears – are rare. We need to be more open to the possibility that some animal behaviours, sexual or otherwise, might be driven by pleasure, but we also need to be better at assessing it. Until then, the joy of sex is limited to us, mostly.