a bonobo humanity?

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Archive for the ‘ovulation’ Category

back to bonobos – and sex

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Canto: We’re reading Rebecca Wragg Sykes’ brilliant book, Kindred, an almost up-to-date account (published in 2020) of all the new discoveries about our close relatives the Neanderthals, and the speculations resulting from them. And of course we’re always alert to the slightest mention of bonobos in any works of anthropology…

Jacinta: Yes, we’ve been a bit timid about talking too much about bonobos and sex, but a few mentions in Kindred have emboldened us.

Canto: W’ve seen the odd photo or video of chimps or bonobos with erect penises, and it was a scary but also puzzling sight, but we’ve not really explored the difference between theirs and ours, so now is the time to do so. So here’s some interesting comments linking humans, Neanderthals and our chimp/bonobo rellies:

Anatomically, pelvic dimensions point to vaginas very similar to ours, and as penises are tailored to fit, those too were probably more like living men’s equipment than that of chimpanzees.

Luckily for all concerned, unlike chimps Neanderthal males lacked the genes for ‘penis spines’. While in apes they’re more like tiny hardened pebbles than spikes, their presence does affect copulation: marmosets have sex and orgasms that last twice as long when the spines are removed.

We should probably therefore picture Neanderthal sex as more leisurely and satisfying than chimp-style rapid thrusting bouts. Not forgetting clitorises – organs solely existing for pleasure – unluckily for Neanderthals, like us they probably lacked bonobo-like versions that make face-to-face orgasms easier. But masturbation in some form is pretty much guaranteed, whether during sexual encounters as is found among humans, or more generally for social bonding and diffusing tensions, as in bonobos where it takes place between pretty much anyone.

Kindred, Rebecca Wragg Sykes, p 271

Jacinta: So this makes me want to know more about the bonobo penis, and ‘penis spines’. It sounds like it isn’t ‘made for pleasure’, which helps to explain why female-female sex is the most practised type among bonobos.

Canto: Then again chimps have the same penises as bonobos but they’ve evolved differently. So here we go with ‘penile spines’. First, Wikipedia:

Many mammalian species have developed keratinized penile spines along the glans and/or shaft, which may be involved in sexual selection. These spines have been described as being simple, single-pointed structures (macaques) or complex with two or three points per spine (strepsirrhines). Penile spine morphology may be related to mating system.

This is news to me, but fascinating.

Jacinta: Just up our alley, so to speak. So to elaborate on this last quote, again using Wikipedia (largely), strepsirrhines are a suborder of primates including lemurs, galagos or bushbabies, pottos and lorises. Sexual selection is, I presume, a form of mating system, which Darwin reflected upon in The Descent of Man, inter alia. Macaques are a type of Old World monkey, with 23 known species. Interestingly, they’re matriarchal and frugivorous, like bonobos.

Canto: Apparently they’re a feature of felines – penile spines, that is. In cats, it’s speculated that they may contribute to pregnancy, as they ‘rake the walls of the female’s vagina [during withdrawal], which may serve as a trigger for ovulation’. I’m wondering, though, how that might relate to sexual selection. ‘A spiny dick, nothing turns me on more.’


It all works below the conscious level, mate. I mean, female bowerbirds hang out with the males with the best display, but I don’t think they’re thinking about sex, especially considering how much of a nothing bird sex generally is. But getting back to bonobos, Wragg refers in the above quote to ‘bonobo-like’ clitorises that make face-to-face orgasms  easier than it was for Neanderthals and, more to the point, we H sapiens. How could we have missed this in all our explorations of the bonobo world?

Canto: Hmmm. I blame the prudery of researchers. Including ourselves. Anyway, it probably all gets back to genes and their expression. So we need to explore – but should we look at penises first or clitorises – is that the plural?

Jacinta: Not sure, I can only cope with one at a time. So here’s something we should never have missed:

Bonobo clitorises are larger and more externalized than in most mammals; while the weight of a young adolescent female bonobo “is maybe half” that of a human teenager, she has a clitoris that is “three times bigger than the human equivalent, and visible enough to waggle unmistakably as she walks”. In scientific literature, the female–female behavior of bonobos pressing genitals together is often referred to as genito-genital (GG) rubbing. This sexual activity happens within the immediate female bonobo community and sometimes outside of it. Ethologist Jonathan Balcombe stated that female bonobos rub their clitorises together rapidly for ten to twenty seconds, and this behavior, “which may be repeated in rapid succession, is usually accompanied by grinding, shrieking, and clitoral engorgement”; he added that it is estimated that they engage in this practice “about once every two hours” on average. As bonobos occasionally copulate face-to-face, evolutionary biologist Marlene Zuk has suggested that the position of the clitoris in bonobos and some other primates has evolved to maximize stimulation during sexual intercourse. The position of the clitoris may alternatively permit GG-rubbings, which has been hypothesized to function as a means for female bonobos to evaluate their intrasocial relationships.

Canto: What can I say?

Jacinta: So this quote, from Wikipedia, compares the bonobo clit to the human one, but says nothing about chimps. I mean, it occurs to me that this enlarged clit, and the pleasure derived from it, would help to explain female-female sexual bonding, leading to social bonding, leading perhaps to matriarchy, if we can call it that. But if chimps have the same-size female pleasure-place, that thesis collapses.

Canto: Good point. So, googling ‘chimp clitoris’ takes me first to an essay from nearly 40 years ago on ‘The external genitalia of female pygmy chimpanzees’, an early term for bonobos. The abstract actually compares Pan paniscus (bonobos) and Pan troglodytes (chimps) as if just to resolve your dilemma:

The external genitalia of four adult female pygmy chimpanzees (Pan paniscus) were examined during a 2-year period. It was found that the labia majora are retained in adults of this species and that, when tumescent, the labia minora effectively relocate the frenulum and clitoris so that they point anteriorly between the thighs. When detumescent, the configuration of the labia minora and clitoris resembles that of immature common chimpanzees (P. troglodytes). It is suggested that the simple, structural relocation of the clitoris from the normal [sic] condition noted in adult P. troglodytes makes possible the homosexual, intergenital rubbing observed in P. paniscus, when ventroventral juxtaposition of the individuals permits eye-to-eye contact. In addition, this change probably increases sexual stimulation of the female during heterosexual, ventroventral copulations.

Jacinta: Wow. So bonobos separated from chimps between 1 and 2 million years ago. And in that time a kind of structural change took place in the positioning of the clitoris. Is that plausible? And what about the swelling?

Canto: Hard to get clear info, but the general genital swellings of chimps versus bonobos differ in one respect – in chimps, they’re indicative of fertility, or ovulation, but bonobos, like humans have ‘concealed’ ovulation. A wonder that this can occur in the relatively short time since the split. Or maybe not, I’m no primatologist.

Jacinta: Apparently bonobos and humans aren’t the only primates with concealed ovulation – it also occurs in  Vervet monkeys, but the very concept of ‘concealed ovulation’ is a bit controversial – as if it’s being done deliberately, which would surely be absurd. But it certainly does mean that, in those primates that don’t exhibit clear signs of ovulation, copulation occurs through all stages of the menstrual cycle. It could be a way of preventing males from being aware of their own offspring, thus reducing the infanticidal tendencies found in male, and sometimes female, chimps. As for the position of the clitoris, its shift to a more ‘accessible’ spot for genito-genital rubbing in bonobos is often mentioned as a great development for female bonding, but I can find nothing much on how this anatomical change could’ve happened.

Canto: Well, think of Darwin’s finches in the Galapagos. Certain beak shapes were more adaptive to the particular vegetation on particular islands, and birds with those beak shapes outbred other birds and became dominant, and ultimately the outright winners. With bonobos, okay this different clitoral positioning might not have led directly to those females outbreeding other females, since it might not have made it easier for males to have sex with females (though where there’s a willie there’s a way), but it might have led indirectly to females becoming dominant through sexually stimulated female bonding, allowing the females with the most changed and, to females, most alluring clitorises to choose the most male partners and so produce the most offspring.

Jacinta: Female rather than male choice. Or even females ‘sexually assaulting’ males? Definitely sounds interesting. But as always, more research is required…


Rebecca Wragg Sykes, Kindred: Neanderthal life, love, death and art. 2020








Written by stewart henderson

July 29, 2023 at 10:54 am

erogenous zones, domination, submission, bonobos and other sexy stuff

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Jacinta: So Simone de Beauvoir has a section in The second sex called ‘Sexual initiation’, which seems to me much influenced by all that Freudian stuff we’ve been exploring in Freud’s women, particularly all that clitoral versus vaginal malarky. However, she does try to get to the bottom of the physiological aspects rather than the psychological, which the Freudians (and many of their opponents) seemed to be stuck on. Still, she seems overly influenced by the passive-active distinction that Freud, especially in the early years, assumed as ‘natural’ vis-a-vis the female-male attitude to coitus.

Canto: Well, to be fair, in much mammalian coitus, the male ‘mounts’ and the female assumes the ‘lordosis position’, according to zoologists. It all appears a bit dominant-submissive to me.

Jacinta: Yeees, sort of, and this seems to have much to do with the evolved features of the sexual apparatus. Think of birds – the male jumps on top, wiggles around and that’s it, it lasts a couple of seconds. Consider that birds generally bond in lifelong pairs, with the odd bit on the side, and the males aren’t generally dominant, though it varies a lot species-wise, and birds, at least some species, are quite intelligent…

Canto: Yeah we don’t tend to think of the lifelong psychological effects of the physical act, or positioning, of sex in birds, or cats and dogs. We’re very speciesist that way.

Jacinta: Which reminds me of another story – actually a memory, of a dog we had, a female who regularly masturbated on top of her favourite fluffy toy, when she wasn’t ‘fighting’ with it all over the house. I can’t remember whether she’d been desexed or not, but clearly her erogenous zones were still intact. Was this clitoral or vaginal stimulation? Does it really matter? But of course for we humans it’s all so much more complex, apparently. Especially for us women. Here’s what Beauvoir has to say – and I sympathise to some extent:

The act of love [sic] finds its unity in its natural culmination: orgasm. Coitus has a specific physiological aim; in ejaculation the male releases burdensome secretions; after orgasm, the male feels complete relief regularly accompanied by pleasure. And, of course, pleasure is not the only aim; it is often followed by disappointment: the need has disappeared rather than having been satisfied. In any case, a definitive act is consummated and the man’s body remains intact: the service he has rendered to the species becomes one with his own pleasure. Woman’s eroticism is far more complex and reflects the complexity of her situation…. instead of integrating forces of the species into her individual life, the female is prey to the species, whose interests diverge from her own ends; this antinomy reaches its height in woman; one of its manifestations is the opposition of two organs: the clitoris and the vagina.

The second sex, pp 394-5

Canto: Yes… well, if dogs don’t much care if it’s clitoral or vaginal pleasure, why should women? It’s all an erogenous zone, some parts more than others maybe, but when the ‘act is consummated’, who cares? And the remark that ‘the female is prey to the species’ presumably refers to pregnancy and all its attendant issues. Beauvoir was writing before the contraceptive pill, which changed so much, at least in the WEIRD world.

Jacinta: Well, yes but there’s the whole issue of teen pregnancy, due to rape, ignorance and the like, and abortion and its enemies. Look at the USA today, still messed up about this issue. But, yes, this clitoris-vagina stuff is largely a red herring to me.

Canto: Yes it all smells a bit fishy.. oh sorry that was a bit below the belt…

Jacinta: Haha I recall an American sex video actor saying all her male co-performers’ dicks stank of marihuana – which may or may not be worse depending on your taste. But speaking of sex, there is an obvious imbalance in the sex game. How often do women rape men? Or even ‘coerce’ men into having sex. And think of gang rape. And the horrific consequences for women. And of course most men don’t rape, or even give it a moment’s thought – at least I hope they don’t – but I know the danger is often on the minds of women when they’re having a night out.

Canto: Safety in numbers, and that seems to be the bonobo way too, and getting back to other mammals again, it’s generally the case – think dogs, horses, any four-legged beastie – that the male mounts the female. Often from behind, like sneakily, creepily. Males on top, and females more or less taken unawares, more or less unwillingly. It seems like the urge to copulate invariably comes from the male.

Jacinta: Yes, evolution appears to have worked it that way, though social evolution can turn this around, at least somewhat. Not just safety, but power in numbers, that seems to be the bonobo way.

Canto: So how exactly do bonobos deal with the sex issue? I’d like some details. I know they engage in regular stimulation of each others’ erogenous zones, aka masturbation, but what about actual copulation, for the purpose of reproduction, though presumably they don’t make the connection. And when did we humans make the connection, when it comes to that?

Jacinta: Well bonobos reproduce at the same rate as chimps, despite all their sexual shenanigans. Humans differ from our primate cousins in that we don’t ‘come into season’ with ‘attractive’ pink swellings, which have an effect on the males, that’s both visual and probably chemical – pheromones and all.

Canto: And if we did – I mean if you females did – it might well be covered up, not only with clothing but deodorants and the like. I wonder if there’s any vestigial elements of being ‘in heat’. as they say, in humans.

Jacinta: Well this is where we move onto hormones. Here’s a quote from a sexual health website, which is pretty reliable:

Medical experts associate changes in sex drive with changes in the ratio of estrogen and progesterone, hormones that are produced by the ovaries. These shifts occur at different phases of your monthly cycle. During your period and for a few days after, the concentration of both hormones is low, resulting in less sexual desire. By the time ovulation rolls around, estrogen peaks, naturally increasing libido. Once the process of ovulation wraps up, there’s a boost in progesterone production, and you might notice a dip in your sex drive.

Canto: Ah yes, menstruation – I don’t recall Freud saying much about that. Do bonobos menstruate?

Jacinta: Do bears shit in the woods? We should do a whole interaction on the menstrual cycle, for your benefit. Anyway, here’s a useful brief guide to bonobos and chimps:

  • Bonobos are sexually receptive for a large portion of their reproductive cycle, even when not near the time for ovulation.
    • This trait has sometimes been called concealed ovulation because the male has no clear signal for the optimum time for mating.
    • Bonobos also engage in sex in non-swelling phases of their cycle in about 1 out of 3 copulations.
    • Chimpanzee females tend to be sexually active only during their maximum swelling phase.

Canto: Right. Uhhh, no mention there of menstruation. Forgive my ignorance but what’s the difference/connection between ovulation and menstruation?

Jacinta: Okay here’s the story with us humans. Ovulation starts at puberty. It’s when an egg is released from one of the ovaries (we have a left and right ovary). You can say this is when we’re fertile, when we’re liable to get pregnant. Ovulation occurs at around day 14 of the 28-day menstrual cycle, on average. The cycle starts, and ends, with that thing called ‘the period’, when material from the endometrium, the lining of the uterus, is shed, along with blood and other yucky stuff. You can imagine the psychological impact that might have on girls when they’re not prepared for it. It can be a real trauma. So menstruation strictly refers to the whole cyclical process, but it’s often used to refer to that flushing out ‘period’. All of this is mediated by hormones. Estrogen is the main builder of new endometrium – the biochemistry of it would require a whole other conversation.

Canto: Yes that’s enough for now, but it seems that oestrogen also boosts libido…

Jacinta: Yes, that’s important, the urge to copulate doesn’t just come from the males. And this physiological stuff seems like solid ground after all the flights of psychoanalysis we’ve been trying to get our heads around recently.

Canto: And we haven’t yet gotten onto what has been made of Freudian and post-Freudian theory by the likes of Lacan, Kristeva, Irigary, Cixous, Derrida, Deleuze, and of course Guattari, among many others…

Jacinta: Yeah, mostly French – funny that. It seems Freud’s influence has waned, though, in the 30 years since Freud’s women was published. The broad Freudian notion of the unconscious – rather than the unconscious processes that go on through our nervous and endocrine systems – has been buried, it seems, by neurological advances, which, as Robert Sapolsky points out in his book Behave, have been fast and furious in the 21st century. But that period, and that physical and metaphysical region centred around Vienna when Freud was active in the first decades of the 20th century, was very fruitful, and in many ways revolutionary. Anil Seth, one of today’s leading researchers into human consciousness, paid tribute to it in his book Being you:

In the fluid atmosphere of Vienna at that time, the two culture of art and science mingled to an unusual degree. Science wasn’t placed above art, in the all too familiar sense in which  art, and the human responses it evokes, are considered to be things in need of scientific explanation. Nor did art place itself beyond the reach of science. Artists and scientists – and their critics – were allies in their attempts to understand human experience in all its richness and variety. No wonder the neuroscientist Eric Kandel called this period ‘the age of insight’, in his book of the same name.

Canto: Well, that’s a nice conciliatory note to end this conversation on.


Simone de Beauvoir, The second sex, 1949

Lisa Appignanesi & John Forrester, Freud’s women, 1992





Robert Sapolsky, Behave, 2017

Anil Seth, Being you: a new science of consciousness, 2021

Written by stewart henderson

December 12, 2022 at 11:41 am