Why are males injured more than females?

Everybody who works in the field of injuries knows that after infancy, and before old age, males engage in more behavior that exposes them to the risk of injury, experience more injuries, and die more frequently from injuries. For example, in the US, among 15 to 19 year olds, males are 2.5 times as likely as females to die of any unintentional injury, and about five times as likely to die of homicide or suicide. The sex diVerence is most pronounced in drowning, where males are more that 10 times as likely to die as females of the same age. No category of injury, and hardly any risk behavior fails to show the higher male rate. The same is true for all countries that keep such statistics. Why is this so? (Bear with me. I’m sure you already know the answer.) The usual answer of both specialist and layman is that the socialization process leads males, from the time they are little boys, to engage in more risky behavior than females, and to be supervised less by someone who might protect them from risk. This explanation is the only one available under our present gender theory. Derived from the social sciences, prevailing gender theory attributes all sex diVerences in behavior to diVerential socialization and diVerential normative constraints. This theory provokes certain puzzling comparisons. Observations made on other primates, and even other mammals, show the same sex diVerences in injury and death-byinjury patterns. In fact primates show overall patterns of sex diVerences in behavior that are surprisingly parallel to those of humans. For example, juvenile rhesus monkeys show the same diVerences in toy preferences by sex that human children show at age 3, when tested with human toys such as balls, dolls, and trucks. Harlow showed four decades ago that juvenile rhesus monkeys show the same sex diVerences in rough-and-tumble play and aggressive behavior that human children do. At this point we can look for reconciliation in one of two directions. We can use a diVerent theory for humans than for other primates. The two theory route works best if we abandon evolutionary models for humans and opt for special creation. For humans the cause is gender socialization. For other animals the cause is fundamental biological sex diVerences. Or we can try to fit our human gender theory to non-humans. Actually it doesn’t sound like such an outlandish idea for chimpanzees. Female chimp children stay close to their mothers, while male toddlers wander, get into fights, and do other dangerous things. This occurs because their mothers are saying to the little girl chimps, “it’s OK for your brother to do that, but nice little girl chimps don’t, etc.” Even for lions we might imagine that boy lions use their fathers as role models, while girl lions, etc.... For chickens this argument begins to be a stretch. A few readers may feel that perhaps the socialization model of sex diVerences doesn’t fit other animals very well. Yet psychological researchers have shown us for years that theories of socialization and parental modelling of sex diVerences don’t fit humans very well either. Maccoby and Jacklin concluded that “socialization pressures, whether by parents or others, do not by any means tell the whole story of the origins of sex diVerences”. For example, children do not resemble their same sex parents to any greater degree than they resemble adults of the same sex generally. But the currently prevailing theory of sex diVerences in the social sciences was never based on scientific observation. Maybe what we need to do is to keep the human socialization models for us alone, and go with a biological theory to explain sex diVerences in other animals. This strategy leads us deep into commitment to creationism. There is already a fine theory for sex diVerences in behavior among mammals, including primates. This theory has been shaping up for a thousand years. In its primitive form it says that there is something about the testicles of a bull that makes him behave diVerently from a cow. In its modern form, the details of the primate theory are well specified. For primates, the theory goes something like this. (For other animals the timing and the details are diVerent variations on the same general model.) In mid-gestation, the testes of the male fetus produce huge quantities of testosterone. The testosterone not only masculinizes the genital anatomy, but also permanently masculinizes the brain. Female fetuses do not experience this, and in the absence of testosterone they develop as females, with female brains. As juveniles, the sex hormones of maturity further distinguish the biology of the sexes. Thirty years of experimental data confirm that it is the prenatal sex diVerences in hormone experience and the subsequent actions of adult hormones on this prenatal foundation that are responsible for almost all sex diVerences in the behavior of primates. Detailed experiments show it is possible to change Injury Prevention 1998;4:94–95 94