Heroes, Rogues, & Lovers: Testosterone and Behavior (20 page)

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PART TWO
SOCIAL LIFE

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4
Ruthless Creatures

Hyenas

Spotted hyenas, who look like unkempt, malevolent dogs, live and hunt on the plains of Africa. They have short hind legs, powerful necks and shoulders, and jaws strong enough to crush the thighbones of zebras. Adults weigh between 147 and 165 pounds, and they are tough enough to compete with lions for food.
¹Male hyenas are dangerous, and females even more so. Female hyenas have higher levels of the adrenal hormone androstenedione than males. (Androstenedione is the hormone St. Louis Cardinal Mark McGwire made famous during the 1998 baseball season.) Adult female hyenas have high levels of testosterone, too, but unless they are pregnant, not so high as adult males. During pregnancy female hyenas have a shortage of the enzyme aromatase, which converts androstenedione into estrogen. Without aromatase, androstenedione is converted into testosterone, and the result is that pregnant females have more testosterone than males.
²

Female hyenas are exposed to high enough levels of testosterone
in utero
to masculinize them. Females, who are larger than males, have masculinized external genitalia, including penislike clitorides and empty scrotal pouches. The pseudopenis contains the urethra as well as the birth canal, and it becomes erect with excitement when the female hyena greets friends or threatens strangers. In ancient times people thought hyenas were hermaphrodites, having the sexual organs of both male and female, an idea that was later promoted by the writer Ernest Hemingway but is incorrect. Despite their high testosterone levels and

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masculinity, female hyenas are true females: they have ovaries and no testes, whereas male hyenas have testes and no ovaries.

Hyenas live in groups led by the alpha femalethe adult female with the most testosterone. She dominates the other females and shows little respect for males, who are allowed to eat only after she has finished eating. One of her daughters usually grows up to be the next alpha female. Hyena pups are born with open eyes, sharp teeth, and nasty tempers, and in the first few days of life it is common for the dominant pups to kill their same-sex littermates. Frequently one female and one male survive, with the female usually emerging as the dominant member of the pair. Researchers have found that pups were most murderous when competing for a limited supply of milk, usually from an undernourished, low-ranking mother.
³This high-testosterone version of sibling rivalry kills an estimated 25 percent of all baby hyenas before they are a month old,
⁴reducing the number of offspring, holding down the population, giving a surviving female a better chance to be the leader of the pack, and giving a surviving male a greater chance to mate. The first chore of a baby hyena is to do its part for the "survival of the fittest."

Violent Men and Women

Although the ratio of testosterone between the sexes is different in people and hyenas, both species have the same kind of testosterone, and it works the same way in both. Testosterone is related to unruly and violent behavior in people as it is in hyenas. Human violence that attracts our attention is often extreme, emerging in war, terrorism, fights with fists and weapons, spouse and child abuse, rape, and murder. These acts are defined as immoral, illegal, justified, or sometimes even heroic, according to where they take place. In one country, spanking a child is a crime, while in another country, terroristic killing is a patriotic act.

The big difference between people and hyenas is not the animal quality of testosterone, but the concepts of crime and morality, which are human inventions. Hyenas do not try to be civilized, but people do. Violent people and hyenas harm others, but violent people are often punished. They may be ostracized by their friends and families or locked up in prison. The result is that most people are fairly well-behaved, following the rules of their particular societies, as long as there

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is no extended period of social chaos. In times of war, famine, and economic collapse, however, people are not so well-behaved, and when things get bad enough, as they did in Bosnia and Kosovo in the late 1990s, it is hard to find a moral difference between the combatants and the hyenas. While there is no direct tie between testosterone and human criminality, there is an indirect tie: testosterone leads toward violence, and violence is often criminal. There are more than a million men and women in prison in the United States. They have committed crimes ranging from forgery to mass murder, and they vary in intelligence, personality, background, and testosterone level. To understand how testosterone is related to criminal behavior, my students and I have spent years studying differences among prison inmates.

In doing this, we first went to a maximum-security prison that held about fifteen hundred men, eighteen to twenty-two years old. With the blessing of the Department of Corrections and the prison warden, and some uneasiness on our part, we went in and met the inmates. We visited them in dormitories and day rooms. We visited them in individual cells, where we stood on the landing outside and talked through the bars. We told them we wanted to understand what they were like and how testosterone might affect their behavior. We explained that we could measure testosterone in a saliva sample. Most inmates we talked with agreed to participate. For them, the study was a break in a boring daily routine. For us, it was a chance to meet people we would not otherwise meet. Each inmate chewed a stick of gum and spit a teaspoonful of saliva into a plastic vial. In some cases, we had guards and other inmates rate the behavior of inmates. We took the samples back to the laboratory and froze them for later assay. Over a period of six years, we tested more than seven hundred male inmates.
⁵

After we had their testosterone scores, we searched prison computer records to see what crimes the inmates had committed and what prison rules they had broken. The inmates had spoken to us nicely enough when we visited, but their records were hair-raising. They had been convicted of crimes ranging from theft to assault, murder, and rape. My students were often surprised to find that a polite and friendly inmate had committed an especially cruel or bloody crime.

We classified each crime as violent or nonviolent. Violent crimes are what the FBI calls personal crimes, where someone is threatened,

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hurt, or killed. Nonviolent crimes are what the FBI calls property crimes, where something is taken but there are no threats or personal violence. The main violent crimes among our inmates were rape, child molestation, homicide, assault, and robbery. The main nonviolent crimes were burglary, theft, and drug offenses.

We found that testosterone was related to an inmate's crime and to his behavior in prison. Figure 4.1 shows mean testosterone levels among inmates who behaved in different ways. The mark at the top of each column is an error bar, showing the statistical limits within which the results should fall if we repeated the study. We found that inmates who committed violent crimes were higher in testosterone than those who committed nonviolent crimes, and inmates who violated prison rules were higher in testosterone than those who did not violate rules. We also found that the kind of rules violated by high-testosterone inmates involved disruptive and combative behavior, and that these inmates were noticed by others around them. Guards and other inmates called high-testosterone inmates "bo-hogs," a country term meaning tough, and they called low-testosterone inmates "scrubs." It is common for men's prisons to have a pecking order, in which a few inmates at the top control the others,

Figure 4.1
Relation of testosterone to crime and to behavior in prison.

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and those at the top of the pecking order were higher in testosterone.
⁶

Kant said that with men, the normal state of nature is not peace but war,
⁷which leaves us wondering what the normal state is with women. Not all men are violent, and not all women are peaceful. One out of twenty prison inmates is a woman, and many women commit violent crimes. Sometimes women who commit violent crimes are provoked and act in self-defense, and sometimes their violence is unprovoked. Testosterone is an equal-opportunity hormone, affecting women the same way it affects men. As mentioned earlier, women have less testosterone, but they are more sensitive to small amounts. My students and I studied 171 women in two prisons.
⁸As with the men, we visited the prisons and asked inmates to spit, measured their testosterone, and related it to their crimes and prison behavior.

Working with women was different from working with men. There are no ''bo-hogs" in a women's prison. Unlike men, women do not have a pecking order in which a few of the tough ones dominate the rest. They organize into pairs and small groups, where they support each other. Fighting often breaks out because somebody has wronged a friend. Women bring to prison some of the more polite behavior that goes with being female in our society, and that includes not spitting in public. Getting women inmates to spit into a vial took some encouragement on our part.

As with men, testosterone in women was related to misbehavior. Women who committed violent crimes were higher in testosterone than women who committed nonviolent crimes. Women who were more aggressive and dominant in prison, as rated by staff members, were also high in testosterone. The inmates we studied ranged in age from seventeen to sixty years, a wider range than in our male sample. Older women were lower in testosterone than younger women, had committed fewer violent crimes, and were less aggressive and dominant in prison. As women get older, their behavior changes partly because of the lowered testosterone that comes with age and partly because of other psychological and physical effects of aging. Figure 4.2 shows a statistical model of these findings. The striking relation in the figure is that age lowers testosterone, thereby decreasing the biological support for both violence and dominance.

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Figure 4.2
Age, testosterone, and behavior in women prison inmates. Age
lowers testosterone levels, and in so doing it decreases criminal
violence and aggressive dominance associated with
testosterone. The direct effects of age that are not mediated by
testosterone are negligible. The numbers indicate how much of
the standard deviation of the variable following an arrow can be
accounted for by the variable preceding the arrow. Minus signs
mean that an increase in the first variable leads to a decrease in
the second variable. Asterisks indicate statistically significant
relationships.

Women sometimes kill men who have abused them, and it is a popular view that women kill mostly in self-defense. If women themselves are victims who kill in self-defense, we might expect their circumstances to be more important than their testosterone levels. However, as we studied women in prison, we found that women murderers were higher in testosterone than other inmates, just as we had found with men. Testosterone alone did not make the women kill, but it apparently helped to mobilize them into action. We have not studied as many women as men, and much remains to be learned about how their testosterone is related to violence.

Classifying a crime as "violent" or "nonviolent" leaves a lot unsaid. The same crime can be committed in more or less violent ways. It may be that how much testosterone people have affects the way they commit the same crime. Marian Hargrove, a student of mine who was once an assistant to the Alabama attorney general, knows quite a bit about murder and mayhem. When she read detailed descriptions of crimes committed by our inmates, she said, "I think when a high-testosterone man kills you, you are
very
dead." High-testosterone killers seemed to

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