Nature via Nurture: Genes, experience and what makes us human. Matt Ridley
FOLK PSYCHOLOGY
Boys like David Reimer want to be boys. They like toys, weapons, competition and action better than dolls, romance, relationships and families. They do not come into the world with all these preferences fully formed, of course, but they do come with some ineffable preference to identify with boyish things. This is what the child psychologist Sandra Scarr has called ‘niche picking’: the tendency to pick the nurture that suits your nature. The frustrations of David Reimer’s youth were caused by his not being allowed to pick his niche.
In this sense, cause and effect are probably circular. People both like doing what they find they are good at and are good at what they like doing. But that implies that this sex difference is at least jump-started by instinct, by innate behavioural differences that pre-date experience. Like many parents who have had children of both sexes, I found the differences surprisingly strong and early. I also had no difficulty in believing that I and my wife were reacting to, rather than causing, such gender dissimilarities. We bought trucks for the boy and dolls for the girl not because we wanted them to be different, but because it was painfully obvious that one wanted trucks and the other dolls.
Exactly how early do these differences emerge? Svetlana Lutchmaya, a student of Simon Baron-Cohen’s at Cambridge, filmed 29 girls and 41 boys at 12 months old and analysed how often the baby looked at its mother’s face. As expected, the girls made far more eye contact than the boys. She then went back and measured the testosterone levels present in the womb during the first trimester of each baby’s gestation. This was possible because in every case the mother had had amniocentesis and a sample of amniotic fluid had been stored. She found that the foetal testosterone level was generally higher for the boys than the girls, and that, among the boys, there was a significant correlation: the higher the testosterone level, the less eye contact made by the baby as a one-year-old.34
Baron-Cohen then asked another student, Jennifer Connellan, to go back even further, to the first day of life. She gave 102 24-hour-old babies two things to look at: her own face, or a physical-mechanical mobile of approximately the same size and shape as a face. The baby boys slightly preferred to look at the mobile; the baby girls slightly preferred the face.35
So the relative female preference for faces, which gradually turns into a preference for social relationships, seems to be there in some form from the start. This distinction between the social and physical world may be a crucial clue to how human brains work. The nineteenth-century psychologist Franz Brentano divided the universe rather starkly into two kinds of entities: those that have intentionality and those that do not. The former can move themselves spontaneously and can have goals and wants; the latter obey only physical laws. It is a distinction that fails at the edges – what about plants? – but as a rule of thumb it works rather well. Evolutionary psychologists have begun to suspect that human beings instinctively apply two different mental processes to understanding such objects: what Daniel Dennett has called folk psychology and folk physics. We assume that a footballer moved because he ‘wanted to’, but that a football moved only because it was kicked. Even babies express surprise when objects appear to disobey the laws of physics – if they move through each other, if large objects seem to go into smaller ones, or if they move without being touched.
You can see where I am heading, I suspect: on average, men are more interested in folk physics than women, who are more interested in folk psychology than men. Simon Baron-Cohen’s research focus is autism, a difficulty with the social world that affects mainly boys. Together with Alan Leslie, Baron-Cohen pioneered the theory that autistic boys have trouble theorising about the minds of others, though he now prefers to use the term ‘empathising’. There are many other features of severe autism, including difficulty with language, but in what is probably its ‘purer’ and less severe form, Asperger’s syndrome, autism seems mainly to consist of a difficulty in empathising with other people’s thoughts. Since boys are less good at empathising than girls anyway, then perhaps autism is just an extreme version of the male brain. Hence Baron-Cohen’s interest in the inverse correlation between prenatal testosterone and eye contact: the masculinisation of the brain by testosterone may go ‘too far’ in autistics.36
Intriguingly, Asperger’s children are often better than normal at folk physics. Not only are they frequently fascinated by mechanical things, from light switches to aeroplanes, but they generally take an engineering approach to the world, trying to understand the rules by which things – and people – operate. They frequently become precociously expert in factual knowledge and mathematics. They are also more than twice as likely to have fathers and grandfathers who worked in engineering. On a standard test of autistic tendencies, scientists generally score higher than non-scientists and physicists and engineers score higher than biologists. Baron-Cohen says of one brilliant mathematician, a winner of the Fields medal, who has Asperger’s: ‘Empathy passes him by.’37
To demonstrate how a difficulty with folk psychology can coexist happily with expertise at folk physics, psychologists designed two remarkably similar tests called the false-belief test and the false-photo test. In the false-belief test, the child sees the experimenter move a concealed object from one receptacle to another while a third person is not watching. The child then has to say where the third person will look for the object. To get the right answer, he has to understand that the third person holds a false belief. All children pass this test for the first time around the age of four (boys later than girls), but autistics are especially late developers.
In the false-photo test, by contrast, the child takes a Polaroid photograph of a scene, then, while the picture is developing, sees the experimenter move one of the objects in the scene. The child is asked which position the object will occupy in the photograph. Autistics have no difficulty with this test, because their understanding of folk physics outstrips their understanding of folk psychology.
Folk physics is just part of a skill that Baron-Cohen calls ‘systemising’. It is the ability to analyse input-output relationships in the natural, technical, abstract and even human world: to understand cause and effect, regularity and rules. He believes that human beings have two separate mental abilities, systemising and empathising, and that, though some people are good at both, others are good at one and bad at the other. Those who are good systemisers and bad empathisers will try to use their systemising skills to solve social problems. For instance, one person with Asperger’s said to Baron-Cohen that ‘Where do you live?’ was not a good question, since it could be answered on many levels: country, city, district, street or house number. True, but most people solve the problem by empathising with the questioner. If speaking to a neighbour, he might name the house; if to a foreigner, the country.
If Asperger’s people are good systemisers and bad empathisers, with extreme-male brains, the thought arises that there are probably people who are good empathisers and poor systemisers, with extreme female brains. A moment’s thought will confirm that we all know such people, but their particular skill combination is rarely classified as pathological. It is probably easier to live a normal life in the modern world with poor systemising skills than with poor empathising skills. In the Stone Age, it might have been less easy.38
A MIND IN PARTS
The empathy story illustrates a very William James theme of separate instincts. To be good at empathising you need a domain, or module, in your mind that learns to intuitively treat animate creatures as having mental states as well as physical properties. To be good at systemising, you need a domain that learns how to intuit cause and effect, regularities and rules. These are separate mental modules, separate skills and separate learning tasks.
The empathy domain seems to rely on circuits around the paracingulate sulcus, a valley of the brain close to the mid-line and near the front of the head. In the studies of Chris and Uta Frith in London, this area lights up (in a suitable scanner) when a person reads a story that requires ‘mentalising’ – imagining the