This week we discovered that a 45-minute test given to three-year-olds has an extraordinary ability to predict their chances of leading a productive and law-abiding life. The test, given to a thousand children in New Zealand born in the early 1970s, measured their IQ, motor skills, language, restlessness, impulsivity and persistence. They were also rated for deprivation and maltreatment. Forty years later, those in the bottom fifth on this overall measure of brain health were responsible for 97 per cent of the violent crime in this cohort, two thirds of its benefit claims, three quarters of its one-parent families and two fifths of its obesity.
The predictive power of this test doesn’t mean its results are inevitable. It tells us that if these problems are evident so young, then some combination of biology, genetics and early experience is far more important than we knew. It implies huge social rewards if we find why this small group is so troubled, and how we might change the paths of those most at risk.
Until a couple of decades ago it was unacceptable for academics to suggest that anything other than social contexts could influence behaviour. There was great nervousness about exploring biological and genetic factors in case that was seen as determinism, or justifying eugenics. But the new understanding of the human genome and of epigenetics has changed the climate. Now there is increasing evidence that how we behave is not just a matter of will. Some people’s brains are wired, whether through genetics, injury or stress, so that they are much less able than the rest of us to control their instincts, understand others or see the consequences of actions.
In Mauritius in 1973, 1,800 three-year-olds were tested for their ability to learn from experience. Electrodes were placed on their fingers while a low-pitched tone was played; ten seconds later it was followed by an unpleasant noise. It took only three trials for the majority of the children to start to sweat in anticipation and anxiety, but a minority of children did not respond at all. Twenty years later, all the children were tracked. The 137 who had criminal records had all been non-responders in the original experiment. Their brains could not warn them of what was to come.
One of the foremost investigators of the links between biology and behaviour is the neuroscientist Adrian Raine. In his book The Anatomy of Violence, he cites hundreds of studies showing how inheriting or developing less-functioning brains predisposes people to rule-breaking or violence. In one stunning study, the adopted children of criminals were much more likely than others to commit crime and the more criminal convictions the birth parent had the more offences the children committed.
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“Psychopaths don’t necessarily become criminals: charm, ruthlessness and indifference to others’ feelings can make them highly successful
In another study, murderers’ brain scans show that they have a less developed prefrontal cortex, the part of the brain that deals with self-control, risk and problem solving. Sometimes that’s developmental, sometimes it’s the result of accidents or assaults. In other studies, psychopaths have been shown to have abnormal amygdalae, the area of the brain that governs emotion. That development happens in the womb, meaning that psychopaths just cannot empathise as the rest of us do.
Researchers like Raine are adamant that biology is not destiny. It is the interaction with the environment that counts. Psychopaths don’t necessarily become criminals: charm, ruthlessness and indifference to others’ feelings can make them highly successful. A recent Australian study concluded that while only 1 per cent of the population are psychopaths, one in five CEOs were — much the same proportion as prisoners.
Similarly, a low resting heart rate is associated with antisocial behaviour. People with this low rate desperately seek arousal to feel alive. In the right context their fearlessness makes them indispensable risk-takers; they are hugely over-represented among bomb-disposal experts. If they aren’t offered a socially productive outlet for their cravings they may join drug gangs, run guns, start fights, smash cars. The message from these studies is not that social factors don’t matter, it’s that they are critical. Raine estimates that 50 per cent of behaviour is inherited. The other 50 per cent is decided by how we are nurtured; our pre-natal and childhood levels of stress, nutrition, abuse and how our nervous system and neural connections are developed in the womb. The connection between mothers’ smoking and children’s violence, for example, is stronger than the connection between smoking and lung cancer, even after every confounding variable — education, poverty and more — is taken into account.
All this means that structure, purpose and strong parenting matter more for children whose brains are distorted than for anybody else. Currently we write many of them off by assuming that they can learn and behave as easily as others do, and then punishing them for their failure.
If we are to minimise the acute social problems they cause we should be identifying the troubled ones early and taking extra care; either by taking the children out of damaging homes or by giving their parents more support; supplying the nutrition their developing brains need, finding ways to teach them about consequences, offering them productive, exciting activities. Shrugging our shoulders about cuts and leaving children to misbehave and roam the streets as we do now is agonisingly short-sighted. In the future, doing nothing about this issue will come to seem as bafflingly blind as the 19th century’s failure to recognise mental illness seems to us now.