What we can learn about sex from evolution

By Professor Charles Kingsland, Consultant Gynaecologist & Specialist in Reproductive Medicine

There are lots of things we need to know about our fertility, but before we learn about our bodies, it’s essential we know where we came from and why we do what we do. If we don’t understand that, then it’s going to be difficult for us to grasp just what’s going on. So, I will start at the beginning.

Whilst our ancestors have been knocking around on the planet for a very long time, about six million years in fact, the modern form of humans only evolved about 200,000 years ago. Civilisation, as we know it, is only about 6,000 years old and industrialisation of our planet only commenced about 200 years ago. We’ve come a long way in a short time and if you think about it, so have our lifestyles in the way we do so many things.

The effect humans have had on the planet is immeasurable. We have inhabited every corner of the globe and survive in the most inhospitable of places. We have successfully utilised so many of the earth’s natural resources to grow and develop, but haven’t put much back. As a consequence, the planet is suffering under the weight of the seven billion people that live on it. Ice caps are melting, oil reserves are dwindling and greenhouse gases are filling the atmosphere, because the trees that put so many good gases back are being chopped down.


The first link to us humans began, as mentioned previously, about six million years ago. A primate group called Ardipthecus, living in Africa, stood up and started walking around. Once they learned to stand up, they could begin to use their hands to make tools and weapons to defend themselves. Then along came Paranthropus, about three million years ago. They had wider mouths and bigger teeth, so they could eat lots more things. Two million years ago, along came Homo sapiens... us.

We had big brains, could think better and travel around a bit more. We began to look like we do now about 200,000 years ago, survived the last great climate change, about 60,000 years ago, and came over to Britain then. Because of our big brains, our ability to survive, and most importantly our ability to breed and look after our babies – much better than other animals – here we are.


During all this development, we became more different from other animals and our closest relatives, mammals. We became more and more sophisticated and cleverer in the way we reproduce to ensure that we survived as a species.

As mammals, we still have similar characteristics to other mammals; we breathe, grow, reproduce, respond to our environment, eat and die. Whether you’re a baboon, whale or any other warm blooded animal, we do the same things.

But when it comes to reproduction, we do something that’s completely different to other mammals; we release an egg every month whereas other mammals come ‘on heat,’ that is, once or twice a year, they mature an egg from their egg store, but don’t release it. The egg just sits there on the outside of the ovary until there is a good chance it will be fertilised. They cannot afford to release the egg and run the risk of it not being fertilised, so it sits there. There are then things that the mammal does that maximises the chance of the egg being fertilised. The most well-known characteristic is that they release a hormone, known as a pheromone. This smell can cross many hundreds of metres and makes any male of the species aware of the fact that a female close by is ‘on heat’.

Next, the female makes herself as visible as possible to the male either by bushing out her feathers, fur, hair or better still making sexy movements. Mr lion, Mr Monkey or Mr Tiger, sitting there in the long grass, wondering where his next meal or sexual episode is coming from, smells the pheromones, sees the dance, feathers, fur or hair or in the case of a baboon, her bright big red bottom. He then bounds over to her. He jumps on her back, because he knows that her vagina goes backwards and downwards not upwards and forwards. He then grips onto the female and lets out a roar or shows his teeth in an act of male domination.

He does this to make sure that whilst he is vulnerable, i.e. during intercourse, he is relatively free from the risk of attack by another horny male who might have smelled the pheromone, but was a little slow on the uptake. He then may bite the female in an attempt to squeeze more ovulatory hormones out of her, and then during a frenzy of rattling, biting and banging, he ejaculates into her vagina. He then dismounts and retreats to a position of safety, maybe back in the long grass, where he sleeps.


Sometime later, maybe a hundred thousand years ago, we started to live and breed in communities. We discovered caves and learnt how to protect ourselves from predators. We realised it was quite nice to live together.

We learnt to help and support each other. We became hunter gatherers, collecting food, berries, nuts leaves; things, initially that grew above the ground, to eat for ourselves, but also for our communities and womenfolk. With our ability to design and build weapons, we were able to hunt, kill and eat other animals.

Our new found civilisation meant that reproduction became more predictable and less by chance and so women began to release their eggs as opposed to coming ‘on heat’. They released up to 13 eggs per year. Sexual intercourse became less random. Caves provided security and safety for both the male and female. As sex was now safer and more so with a single provider mate, it became slower and less risky. It was preferable to look each other in the eye and caress, maybe even cuddle and so grew the missionary position for sex – more acceptable and comfortable for most, but certainly not the best for reproduction.

Just imagine if Homo sapiens had to be relaxed to reproduce, in those ancient Neanderthal days when at any minute, one could be attacked by a hairy mammoth or worse. It always makes me smirk when I read articles, usually in women’s magazines that support the idea of being relaxed during sex to maximise your chance of conceiving. Relax, pamper yourself and sit with a pillow under your bottom for twenty minutes or even more after intercourse, the health guru’s bleat. Where on earth does that idea come from? Reproduction and conceiving has nothing to do with relaxation! More about that later, for now let’s get back to avoid being accosted by a large hairy beast during coitus.

And so, it came to pass that the idea of love making came about – hearts, owers, romance, Champagne and Michael Buble playing gently in the background. Women came ‘on heat’, and began to release an egg at the same time every month, safe in the knowledge that there was a good chance that her upright hunter gatherer mate would return from the bushes, ready and willing to fertilise her egg whilst lying upon her and ejaculating in the wrong direction.

But here’s the thing, she would probably have more than one opportunity to fertilise her egg, because she may have sex again. Similarly, and often to the advantage of the male, he would have fairly exclusive rights to his partners egg, free (most of the time anyway) from competition. Hence, his sperm maybe fairly poor in quality, but he would have multiple attempts to fertilise it and continue his genes, which is of course the reason why we are here.

The same situation does not exist in lower mammals where competition is rife. During her oestrus (being ‘on heat’), a lady baboon, with her big red attractive bottom, may have sex with five or six mates. The one with the best sperm count will probably fertilise her egg and so the ones with lesser sperm will fail and probably die out. That’s why poor sperm counts are rare amongst other mammals, male factor infertility being confined to the male humans.


When you read information about fertility, infertility, how to get pregnant and how not to get pregnant, most articles will tell you about your weight, what to eat, what not to eat, not to smoke, relax, pamper yourself, don’t get stressed etc.

Most avoid the absolute barn door reason we are all here, in fact why we are put on the planet. We are on the planet to continue our species. Whether we like it or not, we are here to pass on our genes to the next generation and we can only do that by one tried and tested method. Yes, you’ve got it, sexual intercourse.

Let’s get biblical for a moment. I want you to imagine its 200,000 years ago and you and your partner are the only two Homo sapiens on the planet and it’s your job to populate the planet with other humans. It’s your total responsibility. Of course, you have to compete with lots of other animals, creepy crawlies and various other creatures of varying degrees of unpleasantness. Don’t forget, it’s your job to procreate.

So, given this hostile environment, which of course actually existed at that time, let me ask you the following questions: Firstly, do you have sex quickly or slowly? What would happen if you had sex slowly? Correct, you would probably get attacked, eaten or worse! Which animals have you ever seen having sex lying down? Assuming you have, on occasion watched animals having sex, by chance, of course. Answer: None. What would happen if pigeons, for example had sex slowly in the town square? There wouldn’t be many pigeons left, I can tell you. Similarly, and on a much lower development level, what happens if you find two amorous fies having sex on a wall? Yep, you squash them. Try squashing them if they have sex quickly whilst buzzing around.

Next question, and remember, you’re the only two humans on the planet: Do you have sex standing up or lying down? What would happen if all those generations ago, we could only achieve offspring by having intercourse in the horizontal position? Well we might not have survived, because when you are lying down, again, you are vulnerable to attack whereas if you stand up, you can run away at a moment’s notice, when you hear that bellow of the hairy mammoth breathing down your neck.

There is another thing you should consider; an ejaculate has two ingredients; firstly the spermatozoa, or sperm as they are more commonly known. These are the tiny, microscopic creatures that carry all the information about you and have one thing in mind, to try and reach the egg first.

You can’t see them in an ejaculate, so there is no point in looking, unlike one of my patients a few years ago. This lady came with her husband to my clinic in a state of extreme distress. The couple had been trying for a baby for a number of years without success. In an attempt to alleviate the problem, the lady had decided to examine her partner’s sperm and became distraught because she couldn’t see any sperm.

It was actually Anton Van LeeLeeuwenhoek, a Dutch draper and scientist in the 17th Century, who first saw sperm down his invention, the microscope. One wonders what he was doing immediately before he made his discovery on that otherwise fairly boring afternoon.

I digress. The second constituent of an ejaculate is semen, the thick white fluid in which the sperm swim. Semen has two major properties; it is gluey. It has to be so the sperm can jump into the vagina. Semen is also full of fructose, a type of sugar. The sperm need this to feed on because they have a long journey ahead of them to get to the egg. It is approximately the same as
a man swimming from Liverpool (UK) to New York (US), but they would be swimming at approximately 600 miles an hour. Nevertheless, it is a long way so they need lots of energy and they need to be doing front crawl as well.

Once the ejaculate is safely in the vagina, it is essential that the little sperm escape from the gloopy semen. So, they need to escape. That’s why after intercourse, semen dribbles out. Think of ejaculation as sending a rocket to the moon. The nose cone contains the spermonauts. The semen is the fuel tank. The difference here between a rocket and an ejaculate is that unlike a rocket, which takes off slowly, an ejaculate, in most circumstances gets a good old acceleratory spurt, which helps propel the sperm high up into the vagina. After that, it is important that the rocket tanks fall to earth, they’ve done their bit, just like the semen.

So, why do women’s magazines ask you to sit with a pillow under your bottom to stop semen falling out in order to maximise your chance of conceiving? Could you imagine what would have happened if that was the only way of getting pregnant in the primeval soup? Absolutely not. We had to be ready to run away again. Hence, semen dribbles out. It’s supposed to.

Who thought of the notion that in order to stand the best chance of conception one has to be as stress free as possible during sex I ask you? No one has ever linked stress with infertility. Of course, when stress becomes so bad, it interrupts your daily life, so called distress, then naturally your chances decrease, but let’s face it, most times when people conceive it’s at the least opportune moments – when they are highly aroused, drunk or both, in circumstances when they perhaps shouldn’t be getting pregnant.

There is a lot of evidence, that when men in particular are highly aroused or stressed, their sperm count increases as does their performance. It may answer the question as to why teenagers having sex for the first time have such a high pregnancy rate. Is it because they are looking longingly into each other’s doughy eyes thinking “How is this for you darling?” Of course it’s not; they are probably standing up behind a door, thinking at any minute they are going to get caught. Similarly, it may answer why victims of rape have a high pregnancy rate, where often and for obvious perverse reasons, the male is very highly aroused.


I remember, many years ago neighbours of ours were trying to get pregnant. At the time we lived in a little cul-de-sac of no more than eight houses and occasionally I would get a lift home with the husband. I remember, on one such occasion we were turning into the driveway to be greeted at the doorway of his house, some fifty meters away by his wife, in her best fluffy mules and bright red lipstick, leaning against the door. “Oh my God he pronounced, with a combination of consternation and impending fear. She’s ovulating.” At that moment I believed I actually heard my dear friends testicles begin to squeak and shrink as they retracted into his scrotum.

This is an example of what not to do. Men perform best when they least expect it. It’s that jungle mentality that dates back all of those thousands of years. Lovemaking, with all its attendant romance is all very well, but it has nothing to do with getting pregnant. Surely that must make some sense.

Just receding back into those dim and distant days, immersed in the primal swamp, up to the neck in pheromones, bright red bottoms, feathers, writhing and yelps, did you ever wonder what happened to our pheromones, or sexual displays? True, we no longer possess those inherent and highly potent inbred characteristics. So, what do we do instead? You only have to venture into your local store in the high street or duty free at the local airport and what do you see? Yes, pheromone substitute made by all those purveyors of those romantic, but somewhat ridiculous adverts that appear on your television every Christmas. Perfume! What about the bright red bottom? Well nowadays we call it makeup, and lipstick and dancing and short skirts and high heeled shoes to make us look extra tall to stand out from the crowd.

From an evolutionary point of view, with the help of our enormous brains, we have moved on from basic procreation to enjoy immense quality in most of our lives. Today, we wear perfume and makeup and wonderful clothes for the benefit of ourselves first and our friends. But the basis of all these additional beautifying elements can be traced back to Noah’s Ark, to the primeval swamp, to make us different, to make us stand out and attract a mate, who is probably lying down the long grass, maybe dozing or maybe just watching television. What we are here to do, however, whether we like it or not, is to make sure that our genes survive and have the best chance of living in somebody else for generations to come. Ladies and Gentlemen, I’m afraid it’s all about sex.

Juliana Kassianos