by Sara Pascoe
An exciting/terrifying aspect of the mesolimbic pathway is that it works cyclically and can get us in a real tizzy. It can be greedy. Dopamine production can stimulate a need for even more dopamine, which results in a build-up of craving. In this way the pathway creates infatuation: the more we see the object of our desire, the more we want to see them. With this chemical reward our brain teaches us that THAT PERSON is VITAL for our survival, like sustenance; we become hungry for them. You’ll have felt this, wanting to be around someone constantly, not being able to concentrate when they’re nearby. First thought in the morning, last thought at night, hoping to bump into them and not leaving the very boring party in case they arrive later, dreaming about them, writing a poem about missing them although they’ve only popped to the toilet.
Falling in love is an obsessive behaviour, a compulsive need for another person. And while this sounds unhealthy expressed in those terms, evolution gave us this emotional machinery because we needed to be aggressively into each other for the survival of our species, for all those inept-baby reasons elucidated earlier.
We could argue that love is a socially acceptable form of addiction, because it’s all the same procedures at work. Addictive behaviour is caused when the mesolimbic pathway sets up an obsessive desire for something that does not benefit survival, something that may in fact be hindering it. An easy example is food, an undoubted necessity for us all, but for some people the motivation to eat is never sated; everything eaten creates a desire to consume even more. Food addicts become very overweight, dangerously unhealthy and terribly misunderstood by society. The mesolimbic pathway can create the very definition of a vicious cycle. This brain circuitry that evolved to keep us alive and striving thousands of years before doughnuts were invented can become confused by the excesses possible in the modern world.
Oh, before we move on – an intriguing detail. An antidote to the withdrawal symptoms experienced by addicts is oxytocin, the bonding hormone we explored a few pages ago. Oxytocin can work as an antidote to craving. This is so interesting: if dopamine is creating our urges, needs, wants – our desire – then oxytocin is sating it. This is why being with the person you love is so satisfying, while unrequited love is pure agitation. Our dopamine pathway is a powerful motivator to getting what we want, but when we can’t get it, if we are fixated on something or someone impossible, then it can leave us anguished.
Which leads us nicely to another cause of male anguish, penis size.
Big Penises and What the Testicles Know
Humans have big brains and we have big penises too. Much bigger than they need to be and, proportionally, much larger than those belonging to the other apes. But unlike the brain, the benefits of a large penis are unclear. How has it assisted our species? We can only theorise.
A fun exercise for the male ego is to compare the human phallus with those of his ape bros. Gorillas are physically massive, twice the size of us, yet their penis is only about two and a half inches long when erect. While chimpanzees are our closest relatives, their penis is not at all close in length. The average human’s is around six inches; for chimps it’s only half that.
As clarified a few pages ago, for a trait to exist in modern humans it must have benefited us via natural selection (improving our chances of survival) or sexual selection (improving our chances of breeding). But there is a rogue third option, a kind of cop-out, shrugged-shoulders, we-don’t-know area of biology. By-products. Some parts of our anatomy are believed to be surplus to requirements, neither aiding nor impeding our lives but remaining to baffle us thanks to the way we physically develop. The perfect example of a by-product is the male nipple. The female body requires nipples for feeding children, but as all bodies begin development along the same framework in utero (as we saw earlier) male bodies grow them too. Having nipples does men no harm, so they continue to sit on their chests stupidly, often hairily.
You’re saying the big male penis is a by-product? Because vaginas are roomy?
I am absolutely not. That would actually mean it was sexually selected because larger penises would perform better in larger vaginas. They’d be able to insert semen deeper, thus increasing the chances of fertilisation. In reality, the human vagina expands to accommodate whatever size penis is inserted, and there is no evidence that a larger penis improves the ability to conceive in humans. THERE IS NO EVIDENCE IT BENEFITS CONCEPTION. This is why it’s a mystery … why have a big penis? If it doesn’t aid conception, what the hell IS it doing?
We are going to explore all theories, but first let us descend a couple of inches to the testicles – a far less cryptic sexual organ. Our dicks are large, but our balls, not so much. Human testicles are a perfectly respectable medium size. Fascinatingly, this directly corresponds to how our species mates and bonds. All of the questions you might have about human sexuality – are we naturally monogamous? Is infidelity inevitable? To what extent did males dominate females in our evolution? Balls can tell us the answers …
Scientists can ascertain the promiscuity level of every species by the size of the male gonad. Isn’t that exciting? For instance, gibbons are completely monogamous; they pair up, stay that way and consequently have very small testicles. Gorillas also have tiny testicles, but for the opposite reason – because one male has dominance over a group of females, his harem. What the gibbon and the gorilla have in common is that their sperm doesn’t need to compete with that of any other male, because their females are not multi-partnering.
Small balls = small competition between males for females. Big balls = big competition. Chimpanzees have massive testicles because their females copulate with multiple males. A male’s chances of impregnating a female are improved if he ejaculates more sperm. It’s entirely logical: the more widely a female mates, the more sperm a male’ll need to be in with a chance of fertilising her. Testicle size has evolved in response to female sexuality.
To put the sizing into perspective, if all apes were human-sized then gorillas’ testes would resemble olives. So we know human females are more promiscuous than gorillas. Using the same system, a giant mouse lemur’s testicles would be the size of grapefruits, so we know human women are positively frigid in comparison. Human testicles are medium-sized. We are not as promiscuous as chimpanzees and lemurs, but we aren’t as faithful as gibbons; our mating strategy is somewhere in between. Our species pair-bonds deeply, but we also practise multi-partnering. Men’s balls say something about the sexual behaviour of women—
They say, ‘Stop sleeping with other men please.’
Well here’s the thing, jealousy exists in our species because of our parental contribution. If a male is investing effort, energy and resources into his family it’s imperative for him that the children are his. During our species’ evolution, males who were not jealous and did not mate-guard, did not suspect anything was going on with the guy next door … those males were cuckolded. They were less genetically successful than dominating, controlling males and sneaky, philandering males. Our morality and modern-day ideas make it problematic to admit this, but being a possessive arsehole was of evolutionary benefit to men.
Consider this now: each pair of medium-sized human testes produces enough sperm to impregnate every fertile woman on the planet within a fortnight. If there was some disaster – perhaps a Zumba class got out of hand, took to the streets, committed a menocide and there’s only one guy left, Kelvin, who was in the toilet and escaped the rampaging wiggling women – Kelvin would easily be able to continue humanity, he wouldn’t want to, but he could! Wouldn’t it make a great movie? Kelvin hates those bitches, yet he must get them pregnant. Even while they’re trying to kill him, with Zumba.
I’m trying to demonstrate that there’s a vast disparity in the male and female reproductive potential. A male could potentially have thousands of children in his lifetime, whereas a woman, she’d be very lucky to reach ten. An increase in partners doesn’t increase the number of children the female body can produce, so why does she do i
t? To increase their quality. And for variety.
While the female of our species cannot spray her eggs about and have many reasons I lost my friends children, multi-partnering offers her the advantage of a range of genetic combinations for her offspring. If a woman breeds with one man, even if it’s someone great like Prince Harry, then the offspring will be more limited in physical attributes, have similar responses to environmental challenges—
They’ll all be pale and freckly.
They might all have the same congenital disease, the same weakness—
For Nazi regalia.
A woman who remains pair-bonded but has sexual encounters on the side is genetically spread-betting. If we take all morality and social conditioning out of the equation, it is the best mating strategy for females. She has the support and resources to raise her young, yet the opportunity to diversify and upgrade.
You’re saying Meghan should put it about.
I sincerely believe she should kiss us all, it’s her princessly duty.
Similarly for human males, the most effective mating strategy is to be pair-bonded but enjoy some extrapair copulations with other partners. This is something men have evolved to do, and the proof is in their competitive sperm.
Sperm Competition
As we’ve already established, any species that shares its females around has males pitted in direct competition to fertilise them. Over millions of years evolution has created a multitude of creative approaches to this problem. Let’s start with a gross one: mating plugs. Guinea pigs can do this, and house mice. After ejaculation, the semen hardens inside the vagina, blocking the path for any subsequent suitors. It’s disgusting but effective. There are subtler methods too. There’s a desert ant whose sperm links up in groups so that it can swim faster towards the queen’s egg, and an ingenious fruit fly whose semen contains mood-altering chemicals, so the female doesn’t fancy any other guys!
It turns out that humans have a subtle method too. Human males can adjust the quality of their ejaculate. Not on purpose, not by thinking about it and squeezing really hard, but as an automatic response to certain situations. Studies have found that men released ‘better’ sperm when their partner returned from time away. After a separation of several days males were treating their partner to sperm at the top end of the motility range, especially if she’d been around other men. THIS IS HUGE. This means that the male body is subconsciously aware that its sperm might have to outswim some other dude’s. He adds a little extra and makes sure the product is tiptop in order to improve his game. Further experiments on men in new relationships found that those who rated their partners as more attractive were ejaculating fitter, healthier sperm. How flattering. The male body is making assessments of mate value and potential competition, and the quality of semen can be adjusted accordingly. I love the idea of testicles talking to each other. ‘Let’s do our best today, she’s been with Sexy Steve from work.’
The mechanics of the testes are amazing. Sperm production is most efficient at thirty-four degrees Celsius, a couple of degrees lower than body temperature. This is why male gonads dangle down between the legs, to keep cool. Storing spermatozoa like this ensures that they are dormant, preserved in chilly hibernation. When ejaculated inside the body of another person, the heat wakes them up. Now they can swim about and do their business with full energy, because they haven’t wasted any doing laps in the balls. There is a special adjustment system in place to allow for changes in local temperature. The cremaster muscle can move the testicles up and down – nearer to the body if it’s cold, further away if it’s heating up – and it does this automatically, reflexively. The testes are dancing a little ‘get the heat just right’ boogie. Their sperm cannot compete if they’ve been frozen to death or burned alive.
In another example of incredible evolutionary design, the penis itself is a tool in the fight against rival sperm. We’ve already acknowledged how large it is for an ape our size, but it’s also a unique and distinctive shape. A shape that is very important.
Whereas most ape penises are smooth, like a skinned banana, the human penis has a capped glans, like a banana with a hat on. For illustration please see overleaf, or any school graffiti.
The human penis has this unusual headgear, and it’s theorised that it works as a sperm displacement device. IT REMOVES RIVAL SPERM! Gordon G. Gallup sounds like something you might shout at a penis as encouragement, so it’s fitting that the man dedicated himself to the study of this organ. Gallup claims the coronal ridge around the glans exists to remove the sperm of other men. Sperm can live for several days inside a woman’s reproductive tract, so the ability to scrape out a gentleman caller’s gentleman callers may have given our male ancestors a competitive advantage. Gallup oversaw some incredible experiments with prosthetic female genitals, latex phalluses and a pseudo-semen made from flour and water. I’m sure you can guess what he was up to, although the man in the sex shop may’ve been confused. The fake willies were all six inches. One was smooth, one had a ridge of 0.12 inches and another a ridge of 0.2 inches. Experimenters popped some fake semen in the fake female, thrust away with the fake male and measured which dildo displaced the most. The smooth one removed the least, around 35 per cent, but both ridged fellows got out over 90 per cent.
Even more interesting perhaps is that the experiments found that deeper thrusting resulted in more effective displacement. When the phalluses were entered only halfway, no fluid was removed. Shallow thrusting removed less semen and thus was ineffective sperm competition. Gallup et al. then did a follow-up: they surveyed two groups of students and found they reported deeper thrusting after a period of separation or when there was suspicion of female infidelity. Just as with the unconscious adjustment of ejaculate content, it seems men also feel an instinct to use their penis as a displacement device. My mind jumps straight to all the deep, aggressive thrusting in porn – a situation where the instinct for sperm competition would definitely be on high alert as you’re watching a woman fucking someone else. I’m thinking about all the dirty talk that comes along with sex – it’s all ‘you’re so deep’, ‘go at me hard’. Maybe I’ll chuck in a ‘your coronal ridge is right up there, mate’ to complete the Your Sperm Is Competing Really Well triptych.
Then I got worried – surely the penis removes all of its own sperm too? But Gallup’s theory explains that this is why the penis becomes sensitive immediately after ejaculation. It quickly loses rigidity and cannot keep thrusting, and shrivels its way out, leaving the semen behind. It has been argued that this is the reason for the male body’s refractory period. Evolution has built in some resting time via temporary impotence so that Mr Penis doesn’t go straight back in and dig up his newly sown seeds.
The idea that sperm competition may be deeply instinctual helped me understand some baffling products I saw online. There’s a range of pills that claim to help men create more semen. Why? WHY? I stared at my computer; why would anyone want more of the sticky annoying bit? I clicked on a product called Yummy Cum which promises you’ll produce super tasty spunk. While I understand the generous intention to improve one’s flavour, what is attractive about more? I wondered if they were preying on insecurity caused by porn. Are some teens fretting about not spraying enough on their beloved’s face? Unfortunately, because I clicked on one ad, all my pop-ups are semen-enhancing drugs now. There’s one called Semenax, ‘clinically proven’ to provide ‘massive loads of your own semen’. Volume Pills promise ‘up to 500 per cent more cum’, which is surely, surely 499 per cent too much. I’m no semen prude, but be reasonable, you’re not decorating a room with it. When I first encountered these products, they didn’t make sense to me. But if sperm competition has made men feel that a larger load relates to being an effective competitor, then perhaps there’s a subconscious pleasure in making more of a mess.
Alongside deep thrusting, the amount of time spent thrusting is significant. According to Jared Diamond, author of Why Is Sex Fun?, the average human copulation is
around four minutes long. So the answer is ‘cos you can get it finished in an ad break’. It’s also fun to find out that four minutes is far longer than sex needs to be. It has been proved in experiments that lengthy sex is not necessary for conception and does not increase the likelihood of conception. Chimp intercourse lasts about fifteen seconds and they’re not facing extinction. Could our species’ thrusty sessions be about sperm removal? Getting that ridge deep inside and having a good clear-out? Of course, as we’ve already discussed, some of the chemicals released during sex promote bonding between couples, so that four-minute session could be about feeling nice and close to each other. It’s probably a combination of both.
Remarkably, sexual stamina is also connected to status. The reason I say this is because newly sexual men, young men, inexperienced men ejaculate quicker. Heightened excitement can be quite difficult to control. Evolutionary psychologists theorise that this is because sex was quite a dangerous thing for our ancestors to do. Focused upon your partner, naked and aroused, sex makes people vulnerable. That’s why we hide away to do it and do it in the dark (mostly) and in secret (most of us). Fear inhibits the sexual response in most people. If there’s danger around, a person needs to be alert and defensive, not balls deep and oblivious. Stress hormones can even affect a man’s ability to get an erection. In nature this is a sensible mechanism, preventing him from forgetting himself in sexual abandon when he needs to be alert to protect himself. In the modern world, where people get stressed about the HR department and the price of ham, this mechanism seems unhelpful, but it’s actually very clever.