Chapter 8 was quite an uphill climb, but now you have got your breath, let’s take stock.
Sex differences in empathizing and systemizing are due to both social and biological factors. When one finds biological causes of sex differences in the mind, the obvious thing to consider is whether these differences may have evolved. That is, the genes that ultimately underlie these sex differences may have been selected because they improved the individual’s likelihood of surviving and reproducing. Even prior to specific genes being identified, studies of twins suggest that both empathizing and systemizing abilities are likely to have a heritable component.
Some theories suggest that our male and female ancestors occupied quite different niches and had very different roles. If true, the selective pressures are likely to have been very different for each, and could have led to the evolution of different types of cognitive specialization. Naturally, what may have been adaptive for one sex may not have been adaptive for the other.
In this chapter I speculate about why it might have been advantageous for females to have brain type E, and why it might have been advantageous for males to have type S.1 (Recall from Chapter 1 that brain type E is the description given to those who can empathize with greater skill than they can systemize, and brain type S is the mirror image of this.)
Because empathizing is such a fundamentally human ability that must be as old as the Homo sapiens brain itself, you might be prepared to accept that a relative talent in empathizing could characterize the female brain. But you might balk at the idea that a relative talent in systemizing could possibly characterize something as ancient as the male brain, since systemizing resembles the hypothesis-testing of a scientist, and scientific thinking is a recent human development. Let me put you right. Although academic science is relatively recent—a mere few hundred years old—“folk” science is as old as humans themselves. Tribal peoples have been developing their own understandings of natural systems, building their own technologies, formulating their own medical systems, and establishing systems to govern their social groups, for tens of thousands of years.2
So what might have been the evolutionary advantages of being a good systemizer or a good empathizer?
Good systemizers are skilled at understanding, using, and constructing tools, including mechanical systems and weapons. Tools allow you to do such things as hunt, fight, build, fix things, or work more efficiently. Being better at these things could have enabled not only a better chance of survival, but also an increase in wealth and/or social status. And higher social rank can lead to greater reproductive success.
For example, a good systemizer might notice that if an arrow is made too long or too short, its accuracy is affected; or if an axe blade is bound to its handle using a certain kind of knot, it is more durable; or a roof made of palm-tree leaves folded in a very precise pattern is more rainproof.
Being good at systemizing projectile weapons (such as throwing rocks, stones and spears, or shooting arrows) may explain the male superiority in throwing (in terms of accuracy, distance, and velocity), in blocking objects coming toward oneself, and in judging when an object will make contact with another. Using and defending oneself against projectile weapons could have been a major advantage in male–male competition.3
Good systemizers are also skilled at understanding and exploiting natural systems. Put yourself into the shoes of a hunter or tracker. He has to scan the forest for signs of where prey may be. Whereas you or I might look at a clearing in a forest and see only trees and shrubs, a good tracker might notice that the grass is crushed in a pattern indicating that a tiger slept here last night, or that there are certain marks on a particular kind of tree which indicate that an elephant passed by here and rubbed its body against the bark. He might listen to animal cries in order to work out if a predator is approaching: this monkey call indicates an eagle is above, or that monkey call indicates a tiger is nearby. All of these observations would enable a tracker to predict what kind of animal is where. When a good systemizer is tracking an animal, he might look closely at the feces on the ground because they would tell him not only how long ago the animal was here but also what kind of animal it was, and what other animals it was preying on. He might know the difference between the 900 species of birds in his forest, by sight as well as sound, to determine which produce edible eggs, where they nest, and when each migrates.
Being a hunter or a tracker also requires an excellent spatial memory for routes, so that even if he wanders for hours or days he still knows how to get back home. In the forest, there are no man-made signposts and no maps. Good systemizing allows you to build up a mental map of the area rapidly.4 In this way, instead of relying solely on landmarks (was this the tree where I turned to follow that deer?), a good systemizer could use geometric and directional cues, such as his or her movement relative to the sun. (If the setting sun is behind me, I know I’m heading east.)
Good systemizers are also able to understand and predict other natural systems—I am thinking of things such as the weather (this cloud formation predicts a storm), the wind (my fishing boat is navigable if I use my sail in this way), and the stars (as a compass system for navigation). In terms of natural selection, a good systemizer could thus have survived physically in harsh conditions. Having a good grasp of the environment could mean the difference between life and death.
Good systemizing would allow you to spot fluctuations in any marketplace so that you know when to buy and when to sell; for example, if I buy when the price is low (input) and sell when the price is high (operation) then I will make a profit (output). The marketplace, after all, is a system like any other. The system in this case might be a currency, or it might be far less formal than that, such as an exchange of goods. Exchange is not a recent invention of the stock market in New York, but is as old as Homo sapiens.5
The skill is in detecting when some things are in demand and some things are surplus, and in spotting a good deal. Some things give you excellent returns, and some do not. The pay-off for such careful and accurate systemizing could again be wealth and social rank (and consequently reproductive success).
Naturally, a good trader needs both good systemizing skills and some degree of mindreading (being able to keep quiet about the other person’s potential losses if they have not spotted the inequality of the exchange, or even lying to persuade them that they are getting a good deal). The ability to deceive others has little to do with good empathizing, since the good trader cares little about the customer being the loser, or about the customer’s emotional state. They care only about their own profits, calculated by understanding the system.
Most primates are social. But what does this social interaction comprise? It turns out that a lot of socializing is about gaining, maintaining, and improving your social rank, and keeping track of everyone else’s social rank. And as a general rule of thumb, the higher your social rank, the higher your chances of survival. So if you are good at reading the group as a social hierarchy—a system—you could prosper.
It is not hard to see why your rank, and your skill at negotiating the ranks, determines your survival chances. For one reason, to be socially excluded is to lose the protection of the group. Equally, if you fail to recognize your place in the social system, you risk a conflict with someone higher up who also needs to protect his or her own social rank. Fine if you think you can win in a conflict with a “superior,” but if you can’t, the costs could be great. Among monkeys, for example, a shocking 50 percent of adolescent males are killed in conflicts over status. So the pressure is on to know your place, and monitor everyone else’s place.
Even though in this example we are talking about a social system, the same if-then (input–operation–output) conditionality rules are used. If I am number 5 in the pecking order (input), then I can threaten my “inferiors” (numbers 6, 7, and 8) (operation) relatively safely (output). If I threaten my “superiors” (numbers 4, 3, 2, or 1), I risk injury or death. If he is number 3 and challenges number 2 and wins, then he becomes number 2. Social systemizing.
Some actions will cost you rank, other actions will gain you rank, and the good systemizer will be tracking these outcomes. Call it politics. It might be at the level of individual relationships, such as competing in subtle ways so as to be recognized as better than your workmates, and thereby be offered the promotion (the opportunity to climb) when it arises. Or it might be at the level of systemizing whole groups of people, as in tribal or territorial expansion, or warfare over resources. Today’s equivalent of systemizing groups of people is seen in local or national politics. Here, a good systemizer can keep track of how big a swing of the votes their party managed, how many seats were won or lost, and so on. A good systemizer could also keep track of how many points a sports team won or lost, and how it affects their position in the rankings.
The other reason that people keep track of social rank is its connection with what Darwin called “sexual selection.” Females in many species, but especially among the primates, tend to be the choosy sex (in other words, they play a greater role in selection). This is understandable, because they typically invest more time and energy in producing the offspring. One sexual act may cost a man a few seconds or minutes, but it may cost a woman nine months of pregnancy, and the rest. So how does she make her choice? One way is to use social rank as a cue.
The consequence of this for males is that higher social rank means more access to females. Males of higher social status are attractive because their ascent up the social hierarchy is evidence of both healthy genes and their potential as a provider and defender. As explained earlier, a good systemizer is likely to end up with higher social status.6
Women may therefore find a man’s strong systemizing abilities attractive. Such a man is seen as independent, as someone who understands things, who knows how to evaluate the relevant information quickly and take decisive action, and who knows how to get ahead and climb socially.
The combination of low empathizing and high systemizing abilities might mean a rapid ascent of a man to the top of the social pile. This is because men in every culture compete against each other for success in social rank. As we mentioned above, a male’s position in the social dominance hierarchy in most species directly affects his fertility. For example, in some species it is only the alpha male that gets to reproduce. And even today, among modern humans, men with higher social status tend to have more children and more wives, compared with men of lower social status. To achieve social dominance, males use physical force, or the threat of force, or other kinds of threat (for example, withdrawing support). That is why, in most species, males are bigger, stronger, and more aggressive than females.7
Men compete not just through threat but also through shows of strength and status, and are selected by women for these qualities. These qualities may include not only physical strength but also the ability and drive to climb to the top of the social group. Lower empathizing makes it easier for you to hit or hurt someone, or in less extreme ways, simply to push them aside in a competition, or abandon them when they are no longer useful to you.
As we saw in Chapter 4, in most studies of emotion recognition, men score lower than women. But when it comes to detecting threat from direct eye contact—crucial in anticipating a potential loss of rank in the social system—and sensitivity to dominance hierarchies (key in male–male competition), men actually score better than women. These examples are not signs of high empathizing but high systemizing.8
In existing pre-industrial societies, men travel farther than women. They do not do this just in order to hunt, or to find a mate, but also to conduct raids on other groups. Just as in war, conducting raids on other groups brings power. It is presumably easier to use aggression toward others if you are poor at empathizing. Planning how to attack (which tactical maneuver or physical method would be most efficient), and planning your route to and from the attack, would be far easier for someone with good systemizing and low empathizing skills. Even leaving aside direct attacks, low empathizing would result in a person engaging in greater social control with less empathy or guilt.9
The other trick for gaining a high position in a social hierarchy is cultural success—being the best at something your culture values, and/or controlling valued resources. The drive to systemize is essentially the drive to control or understand a system to the highest level—by definition, since otherwise the system would be suboptimal. Systemizing requires us to understand a system as completely as possible. So competition in systemizing could lead a person to be the best at making a plough or a spear, a musical instrument or a home, thus achieving higher social rank.
Some tasks that require good systemizing, such as tracking animals or inventing a new tool, take a long time. They might take days, months, or years. Many such tasks benefit from a lack of distraction and lots of hard concentration, preferably in solitude.
So it might be that even if you were good at systemizing you might never accomplish anything great if you were also good at empathizing, since you might then have an equally strong drive to socialize. But supposing you were low on empathizing. You might then be content to lock yourself away for days without much conversation, to focus long and deep on the system that was your current project. In pre-industrial societies this could involve fixing old axe-heads, or perhaps a four-day trek into the forest in search of food for your family (this might be the ancestral equivalent of the modernday pilot). The pay-off from not needing people as much as others do could be great.
In humans and other primates, males typically attempt to control the sexual activities of their partners through the use of threat. Being willing to threaten your female mate with aggression presumes a low level of empathizing. Hurting another person, or putting fear into them, is not a caring act. If it works, a man increases the likelihood that the child he is providing for is indeed genetically his.
Even among human cultures today, monogamy is not the norm. The most common marriage system is polygyny (one man, many wives). Polyandry (one woman, many husbands) is very rare. Polygyny presumably became the most common marriage system as a result of some men becoming dominant in social status, through the accumulation and control of valued material resources. Control of such resources is typically accomplished through the formation of kin-based coalitions between men. Even in monogamous societies in the West, polygynous mating by powerful, highstatus men has been the norm.10
Aggression is not only a sign of limited empathy. It is also a very efficient strategy for establishing social dominance or resolving social conflict, especially when other social displays or rituals fail. In evolutionary terms, the bravest and most skilled fighters in male–male competition would have earned the highest social status, and thus secured the most wives and offspring.
In studies of pre-industrial societies, aggression has typically been found to take the form of blood revenge (in other words, revenge for the murder of a member of one’s kin), economic gain (such as looting and taking people as slaves), capturing women as additional wives, or the maintenance of personal prestige and reputation. All of these routes can lead a man to acquire high social status within the community, which makes him more desirable as a marriage partner.
David Geary gives the following example of the reproductive pay-off for men who take the risk of competing with other men. In a study of the Yanomamo tribe, a present-day pre-industrial people who live in the Amazon rainforests of Brazil and Venezuela, some men were found to have no children at all, while one man (Shinbone) had forty-three children. Shinbone’s father had fourteen children (a small family), but these gave him 143 grandchildren, who in turn gave him 335 great-grandchildren and 401 great-great-grandchildren. Shinbone’s father had 401 more great-great-grandchildren than his neighbor, who had no great-great-grandchildren at all. If his aim was to spread his genes, Shinbone’s father was doing very well. Obviously, such men can sire a large number of children in societies where polygyny is allowed.11
Now here is the really scary bit. According to Laura Betzig, in the first civilizations (ancient Mesopotamia, Egypt, the Aztec, the Inca, imperial India, and China), “powerful men mate with hundreds of women, pass their power on to a son by one legitimate wife, and take the lives of men who get in their way.”12 As I explained earlier, these men may have been powerful because they were good systemizers. The fact that they eliminated those who stood up to them implies that they were also low empathizers. And they certainly seemed to have an efficient means of disseminating their genes (polygyny). So we can envision how the genotype for brain type S might have spread widely throughout a male population.
Is aggressive male competition just something of the past? Are we so very different nowadays? Let’s look again at the Yanomamo, who can be viewed as a model of pre-industrial society. Here we find that two out of every five men in this tribe have participated in at least one murder. This is astonishing to us. I don’t know any men who have committed murder, and I’m guessing that you don’t either. So clearly, industrialized societies may make it harder to discern evolutionary pressures.
Worse still, among the Yanomamo, men who kill other men end up with higher social status than those who do not. We know that in an industrialized society murderers lose their social rank, by being imprisoned. Not so in traditional societies. Consistent with evolutionary theory, those who have committed murder end up with more than double the number of wives, and more than three times the number of children, compared to those who have not. This gloomy picture is not restricted to this present-day tribe but has been found in other pre-industrial societies.13
Team projects need leaders. The success of the project often depends on the firm hand of the leader. Consider the team leader who keeps a singleminded focus on the overarching goal, whether it be making something, or capturing a new territory. The leader will consider how to achieve this goal in the minimum number of tactical steps and with the most efficient timetable, something that is known in business or technology today as the “critical path.”
A leader who is a good systemizer has the advantage of being able to see a group of people as a system. Like cogs in a mechanical system, each person (or group) may have a specific function in the system. Any system, be it a group of people or a tool, needs careful control. A leader with lower empathy will spend less time worrying about how each member of the team feels about having to play their individual part in the project. Instead, such a leader will focus on how the function of that individual contributes to the overall goal of the system.
The functions may be indispensable, but the individual workers who carry out these functions may be very dispensable. If a particular person is underproductive, a leader with lower empathy and good systemizing skills would find it easier to identify this individual as a problem and replace them. Sacking this team member involves the ability to cast them to one side, and not worry about the consequences for that individual.
Lower empathizing and high systemizing abilities would thus have been a more adaptive profile for a successful leader. Such a leader would gain access to greater resources, and consequently social rank and reproductive opportunities.
We can see how high systemizing and lower empathizing abilities (the male brain) might have been adaptive, but what about the opposite profile (the female brain)? How might this have conferred an evolutionary advantage?
Being a good empathizer requires skill in understanding relationships, and not just in terms of power politics. Good empathizers are good communicators who are concerned if a friend takes offense at something they have said, or is being treated unfairly, and they find it easy to anticipate another person’s needs, responding rapidly and appropriately to someone else’s feelings. Good empathizers are more democratic; they consult others and are more diplomatic in conversation. They do not force their own view on another person or on a group, at the expense of the other person’s wishes. Operating in this way is likely to win friends, not make enemies.
The survival advantages of having good friends is that you have social alliances and help when the going gets tough. A high-empathizing female, engaged in childcare, is better equipped to create a community of friends who could watch over her children when she is unable to keep an eye on them all the time. Remember, predators are just waiting to pick off the youngest and most vulnerable members of the group: infants.
There is another advantage to being able to make close friends. Communities of friends make for a more stable community, reducing the risk of aggression between adults. Community instability adversely affects child development, both emotionally and in terms of child mortality. So anything that contributes to community stability can only increase the survival chances for both children and women. Since women are the sex that invests far more time and resources in parenting, one can argue that such benefits of reciprocal relationships will be more relevant to them.14
Let’s face it: infants can be hard to read. They cry, but they can’t tell you what they are feeling or wanting. In older children or adults, language serves as a partial printout of their mental states. But when an infant cries, how can you tell what is in his or her mind? You could try to systemize an infant by checking the most likely six options: are they wet, hungry, sleepy, sick, cold, or uncomfortable? Supposing they are none of these, and they still keep on crying. What do you do next?
Good empathizers find it easier to tune in to their child’s needs and feelings. It gives them access to a far more subtle set of possibilities; they can imagine their child’s mind. Maybe the child feels angry because they thought that you handled them too roughly. Maybe they are feeling resentful because you went away for too long. Maybe they feel ignored because although you were physically present, your mind was preoccupied, rather than connected with theirs. Maybe they just need more love because they are in an unfamiliar place.
If you can imagine all these possibilities, together with hundreds of other feelings your infant might be having, your good empathizing skills would lead your infant to believe that you were in tune with their needs; they would feel cared for and supported, and thus they would develop a more secure attachment. And securely attached infants not only learn faster but they are more easily accepted by their peer group, they are rated as more popular, and they develop more stable relationships throughout their lives.
The infant of a parent who is a good empathizer is likely to grow up with the ability to make stable relationships in adulthood. This itself promotes their own children’s physical survival and mental health—a transgenerational cycle that obviously has long-term reproductive pay-offs. And in the short-term, being sensitively attuned to one’s infant means that they are less likely to be neglected, and thus less at risk of infant mortality through fatal accident. In this way, a mother with good empathizing skills could end up with greater reproductive success.15
This idea has grown into a major theory: some have argued that empathizing co-evolved with primate parental investment.16 This makes a lot of sense, and it immediately suggests why one finds a female advantage in empathizing. Females—among non-human primates, and therefore presumably among our hominid ancestors—were the principal caregivers.
If an infant monkey is holding tight to its mother’s fur on her belly while she walks through the deeper waters, the mother will not check if her baby’s face is out of the water. The result is that her offspring is at major risk of drowning. This strongly suggests that female monkeys as mothers cannot take into account the perspective and needs of another animal (in this case, her baby). Among the great apes, such as the chimpanzee, this never occurs. Primatologist Frans De Waal suggests that this is because the great apes have rudimentary empathy. Examples of empathy in apes include “targeted help” (where one animal will provide just the right sort of help that the other needs) and “consolation” (for example, caressing an animal who has suffered a loss).17
Good empathizing abilities give you access not just to reciprocal communication and the benefits of friendship through talking but also to gossip. The best way to get information about your social group is to be in the loop.
Someone with lower empathizing may make fewer close friends or be less comfortable simply chatting than those with high empathizing abilities, and therefore may hear less gossip. A person with good empathizing skills is likely to have more close friends, or be able to sustain social chit-chat, and will pick up important information about people, such as their trustworthiness.
Most importantly, anthropologist Robin Dunbar at Liverpool University argues that participating in such social gossip is the human equivalent of primate grooming, providing the social lubricant for getting to know one another and developing dependable alliances. In this way, one could imagine that a good empathizer might have better chances of survival.
Among humans (and other great apes), males tend to stay in their birth group, while females tend to move to their mate’s community. Males therefore are surrounded by their kin more often than females are, and of course they know their kin well, and vice versa. So there may have been less pressure on males to develop good empathy if males typically have had to put far less effort into building and maintaining relationships. Making relationships with individuals you are not genetically related to requires much greater sensitivity to reciprocity and equality, since these are relationships that you cannot take for granted.18 A woman with low empathy might have had a much harder time being accepted by her in-laws, and earning their support.
Women who had a talent for decoding their male partner’s next move would have had greater success in avoiding spousal aggression. Women who were good at detecting deception would have also been more skilled at finding sincere males to mate with, and at judging whether a man would treat them well or just impregnate them. One can see how high empathizing would have been adaptive to females. Being able to empathize with one’s partner also makes one more compassionate and tolerant, which can prolong the life of the relationship. In this way, a woman with high empathizing skills might have had a better chance of keeping her relationship stable during her offspring’s vulnerable years, thus promoting their survival and the spread of her genes.
In this chapter on evolutionary speculations, we have so far considered how high systemizing, high empathizing and even low empathizing abilities might each have been adaptive. But what about low systemizing?
A low systemizer would find it difficult to use tools or fix things, would be less obsessed with social systems such as status, and would find it tricky to learn spatial routes. It is hard to imagine any scenario in which low systemizing could be adaptive, but a trait could have a genetic basis and remain in the gene pool if it was not truly maladaptive. Low systemizing could be maladaptive if the person was also low at empathizing, and we might think of such an individual as having a general learning disability. They would be impaired at both socializing and understanding their physical environment. They might end up with low social rank on both counts, and carry the lowest chances of reproductive success.
On the other hand, low systemizing in the presence of high empathizing need not have been maladaptive at all. It would not have prevented such an individual from receiving all the benefits of social inclusion, as discussed earlier. And that individual’s superior empathizing could even have meant that when a system needed fixing (a tool was broken, a well had dried up), they had all the social skills to persuade a good systemizer to come and help them sort it out. So the profile of lower systemizing in combination with good empathizing (the female brain) was unlikely to have been maladaptive.
We can see the clear survival and reproductive advantages of being either a good systemizer (the male brain) or a good empathizer (the female brain), but surely it would have been doubly advantageous to be good at both (in other words, to have the balanced brain)? Although one form of the balanced brain (low systemizing with low empathizing) clearly has no adaptive advantage, what about if you were average to high on both?
Although such a balanced brain would give rise to the best of both worlds (to have a systematic mind and to be an empathic friend), one could imagine that, for a male, this would be slightly less successful than the male brain. For example, in any competition between two leaders, the good systemizer with slightly reduced empathy might be prepared to do what was necessary to win, even if this required the sacrifice of someone’s feelings to make it possible. Think of the army general who decides that for the greater good of the regiment, they leave the wounded behind to face certain death but save the healthy members of the unit. Someone with the balanced brain might be a nicer person to have as a boss, but he or she might lack the ruthless edge needed to survive and prosper when the going gets tough. And for a female, such a balanced brain could mean less time spent in relationships, with the risk of less social support.
According to this theory, the male and female brains are perfectly adapted for certain niches. These are specialist niches—one adapted to survival and integration in the social world, and the other adapted to predicting and controlling events.
A different explanation for why we might find the balanced brain to be less common—and this needs proper testing—may be that the development of empathizing and systemizing is a “zero-sum game,” in other words, there is a trade-off, so that the better one becomes at empathizing, for example, the worse one becomes at systemizing. While this is clearly not an inevitable trade-off (we all know of people who are good at both), it may be partly true, and needs further exploration.
To summarize, neither brain type E nor S is better or worse than the other. They appear to have been selected as specializations for entirely different goals and niches. So far we have only considered those brain types that are the commonest in the general population. But what about the extremes, those at the margins of this continuum? In the next chapter we make a further specific prediction, that the extreme male brain will also be less common, because it is in some ways maladaptive. Let’s have a closer look.