Are Men and Women Different?

Of course, you know the answer is yes. But many people have an ideology that makes them uncomfortable recognizing the differences, and particularly uncomfortable with biologically, evolutionarily-based differences. So this post is to help people who have been indoctrinated by that ideology, to help them return to reality. Btw, all I have to say on this subject is well-known to people familiar with evolutionary psychology. But I’m going to say it anyway, because I keep being surprised by how many people don’t know or don’t accept some of the basics of human existence. Given the importance of relations between the sexes in most people’s lives, it’s pretty important to understand at least the basics of these differences.

1. Common Observations

Nearly every adult has noticed large differences between men and women. Following are some of them. It should (but doesn’t) go without saying that these are on average differences, not differences between every man and every women. (People trying to avoid reality often pretend not to understand this.) Each trait is a spectrum along which individuals of each sex can vary. The “male-female difference” is a difference in the means (one sex has a higher mean amount of a given trait than the other). But the following are pretty big differences.

1. Men are physically larger and stronger, especially in the upper body.

2. Men are more violent. >90% of all murderers are men. They also physically fight with each other more than women do. ~80% of all murder victims are also men. In wars, men have traditionally been almost all of the soldiers fighting each other, across societies across history.

3. Men have much higher sex drive than women (like maybe 10x stronger). Related observations:

   1. Men find a much wider range of women to be sexually attractive, compared to the range of men that women find attractive.

   2. Men are ready to have sex much quicker (e.g., on the first date).

   3. Men want to have sex more often.

   4. They have more desire for a larger number of partners.

   5. They are much less likely to regret sex. (I would guess that most men have never regretted having sex and perhaps cannot even relate to that idea. It would be sort of like the idea of regretting accepting some free money.)

4. There is a trait of “interest in people versus things” that psychologists talk about. This influences, e.g., whether you would like to work with people, as in health care or education, or would like to work with inanimate objects or systems, as in engineering or computer programming. Males tend to be more interested in things and females more interested in people. This is a large difference, in the neighborhood of 1 standard deviation. (https://www.psychologytoday.com/us/blog/sexual-personalities/201904/sex-differences-in-brain-and-behavior-eight-counterpoints) The difference starts as early as 9 months of age, and is even larger in children than adults, which suggests that cultural influence may decrease the difference rather than increasing it. (https://bpspsychub.onlinelibrary.wiley.com/doi/10.1348/026151000165814; https://link.springer.com/article/10.1007/s10508-019-01624-7)

5. Women are more interested in babies and children than men are.

6. Men are more risk-seeking than women. The most dangerous jobs (e.g., lumberjack, roofer) are overwhelmingly male-dominated. Risky behaviors like motorcycle riding, skydiving, and mountain climbing are also male-dominated. Etc.

2. Is it Culture?

Some people, when hearing the above, will anxiously insist that some or all of the above differences are purely arbitrary cultural conventions. As far as I can tell, there is about zero basis for believing this. (Or rather, zero evidential basis; the basis is purely emotional and ideological.) I’ve heard people make the assertion many times, and I never hear them give any evidence. It is a pure article of faith.

The above differences are all cross-cultural, and most of them are even cross-species. E.g., even males of other species are more violent than females. If you don’t think human males have an instinct for aggression, then what you must be saying is that at some time in our evolutionary past, the instinct was selected out, and then replaced by cultural mechanisms that induce you to do the same thing. That is ridiculous.

3. Evolutionary Explanations

All of the above differences have evolutionary explanations; indeed, they all stem from the same basic fact about males and females.

a. Basic points about evolution

Humans evolved by natural selection like all the other animals. The other animals have instincts, so, unless you want to claim that those instincts were somehow selected out, we have instincts too.

Evolution selects for reproductive success. Evolutionary explanations seek to explain why a certain trait would, in the past, have increased the expected number of surviving offspring that an organism would have. It is thus often convenient to think about what an animal would do if it was trying to maximize reproduction. But this of course does not mean that people actually think to themselves “How can I maximize the number of offspring that I leave?” People just find themselves having emotions and desires that, in our evolutionary past, would have caused them to (roughly) maximize reproduction.

b. The essential difference

What is the defining difference between males and females? The answer, regardless of species, lies in their mode of reproduction. Female bodies make a larger investment in offspring than male bodies do. E.g., eggs are larger and require more resources to produce than sperm cells. Women gestate offspring within their bodies, while men only provide sperm. (Of course, men may provide food or other material resources for their spouses, but I’m just talking about what a person’s body inherently contributes to the offspring.)

c. Consequences

This basic difference has a series of consequences.

1. When a baby is born, the mother always knows that she is the mother, because the baby is coming out of her body. The father, however, cannot be as certain that he is the father. For this reason, it makes sense in evolutionary terms that females would be relatively more committed to their offspring than males are.

2. Women’s reproductive capacity is maxed out at 1 offspring per 9 months. Men’s reproductive capacity, however, is limited only by the number of sexual partners they can get. If a man gets a second wife, he doubles his reproductive capacity. If a woman gets a second husband, she does not double her reproductive capacity; she can still only reproduce once per 9 months. That is why men have more desire for multiple partners than women do.

3. Males can more easily abandon their offspring to be raised by the other parent – they can impregnate a woman and then skip town (perhaps hoping to move on to another woman, and so on). A woman can’t do this because the offspring is in her body.

4. Sex has a much larger cost for women. If a woman mates with the wrong partner, this could result in the partner abandoning her while she is pregnant, as described above; it can also physically prevent her from mating with a better partner. For men, the cost of sex, in purely biological terms, is virtually zero. Mating with a woman does not incur any risk of the woman abandoning the man with the child, nor does it physically prevent him from mating with another woman.

   Points #2-#4 are why men have much higher sex drive, why they are ready for sex much more quickly, and why they are less selective about partners.

5. Because of point (2), male reproductive success is potentially much more variable than female success. Because it is physiologically possible for a man to vastly increase his reproductive success by getting more partners, there are going to be some men who do that. This of course means that there must be other men who don’t get to reproduce at all. A large majority of human societies have practiced polygamy. Of these, the vast majority practiced polygyny (men having multiple wives), and only a few polyandry (women having multiple husbands).

6. Because of (5), men in our evolutionary past had to compete with each other for women. Most women reproduced, but most men did not, because the women were taken by the high-status men. This means that in evolutionary terms, the median man had nothing to lose; his reproductive success was going to be zero in the ordinary course of events. It can’t go down from there, even if he dies. But if he takes a big risk and succeeds, his reproductive success might go up. By contrast, it doesn’t make evolutionary sense for women to take great physical risks, since they’re probably going to get to reproduce in the ordinary course of events, and they would be jeopardizing that for little potential gain. That is why men are more risk-seeking than women.

7. That is also why men are more violent than women.

8. That’s also why men are larger and stronger than women, especially in the upper body. Upper body strength is for fighting other men. (https://fakenous.substack.com/p/why-humans-fight)

   1. Aside: It could also be helpful for hunting, but fighting other men is a lot more demanding than hunting; that’s why I say that the main driver for male strength is the need to fight other men. Btw, this is similar to antlers and horns on the males of other species — they are also for fighting male conspecifics.

4. So What?

I think you can see, if you look at it impartially and not ideologically, that the above explanations are very plausible and much more satisfying than the explanation, “Culture taught men and women to be like that.” All of the big, well-known differences between men and women that almost everyone has noticed are naturally derived from this one underlying explanatory factor, the difference in parental investment between men and women. All of these are very natural explanations, not dependent on ad hoc auxiliary assumptions. Unlike some evolutionary explanations, I don’t see any way in which you could, with comparable plausibility, explain the opposite observations if we had made opposite observations. It seems, in other words, that the evolutionary theory pretty unavoidably predicts all the listed differences between men and women. I think there is essentially no doubt that these explanations are generally correct.

(By contrast, the cultural “explanation” predicts essentially nothing, because no matter what we observed about women’s and men’s behavior, you could always say, “Culture made them do that.”)

Why is this important? For one thing, understanding male and female psychology is probably helpful in your personal life, since you probably have to interact with the opposite sex often. Things probably won’t go very well if you keep thinking they’re just like you when they aren’t.

For another thing, it can also help us better understand society and choose better public policies. For instance, if you think that the differences in jobs occupied by men and women are due to “systemic sexism” in our society, you might think that we need affirmative action and other sorts of policies to reduce these differences. But if the differences are due to biologically-based differences in preferences, then there is no obvious reason why we need to do anything about them.

The latter hypothesis is supported by the evidence of the “gender equality paradox.” This is the empirical fact that as societies become more prosperous and egalitarian (e.g., see the Scandinavian countries), sex differences in occupational choice increase. (https://pubmed.ncbi.nlm.nih.gov/29442575/) This suggests that these differences are due to free choice, not prejudice or cultural pressures.

Some people say that society pressures men and women to conform to stereotypes. But often, it’s just the opposite: society tamps down the stereotypical behavior patterns, shrinking the observed differences between men and women that are due to biology.

Aside: Some of the above facts are unpleasant. It is unpleasant to think, for example, that a predisposition towards aggression is in men’s genes. The reasons for many of the differences are intrinsically upsetting, as they have to do with possibilities like war, polygamy, and men abandoning their offspring. I assume this is a large part of why many people don’t accept these facts, and why they are not taught in school. But in life, it is better to recognize unpleasant realities so you can figure out what to do about them, rather than covering your eyes and insisting that reality has to conform to your vision of how it should be.

In later posts, I’ll reflect more on the practical implications of the male-female differences.