The Trouble with Testosterone

by Robert M. Sapolsky

  That bias must plague us scientists when we try to justify why we do the work we do. I don’t mean justifications we come up with in our grant proposals, the final paragraphs where we go on about the endless (and unlikely) benefits that will occur if the National Institutes of Health bless us with money for a few more years. I mean the justifications we come up with in the middle of the night, when we think about being in a profession that requires us to pour radiation down a sink or to kill animals, that calls on us to work so hard that the rest of our selves wither, so that we ignore our loved ones. All for that wisp of a hope of making a difference, to achieve that scientist’s state of grace where your work will help vast numbers of people somewhere down the line.

  It is that fantasy that fuels the way in which science must now be done: battling distributed villains, charging them with statistical guilt, laying the groundwork that might eventually lead to minute fractional victories. Sometimes in the middle of the night, you begin to wish that progress in your profession was of a different sort, something not so at odds with our fundamental cognitive bias. Sometimes, it would be nice to simply see the face of someone we helped.

  FURTHER READING

  Readers interested in Kahneman and Tversky’s work might check the following:

  D. Kahneman and A. Tversky, “Choices, Values and Frames,” American Psychologist 39 (1984): 341. Also see: A. Tversky and D. Kahneman, “The Framing of Decisions and the Psychology of Choice,” Science 211 (1981): 453.

  In addition, a nontechnical summary of their work can be found in K. McKean, “Decisions, Decisions: Two Eminent Psychologists Disclose the Mental Pitfalls in Which Rational People Find Themselves When They Try to Arrive at Logical Conclusions,” Discover, June 1985, 22.

  Descriptions of modern execution technology can be found in S. Trombley, The Execution Protocol (New York: Crown Publishers, 1992).

  The Young and the Reckless

  Mark Tansey, Myth of Depth, 1984; Private Collection, New York, courtesy Curt Marcus Gallery, New York

  I remember going off to college. I was so nervous and excited that I had the runs for a week beforehand. What if they had made a mistake by admitting me? Suppose I never made any friends. Would these really turn out to be the best years of my life? Queasy and vertiginous, I packed my bags onto a Greyhound bus, squirreling a bottle of Kaopectate into my knapsack.

  Actually, getting my bowels into such an uproar proved to be quite justified, given the momentous freshman-year events that awaited me: the epiphany when I knew I was never going to understand photosynthesis and should give up on being a biology major; the realization, as I contemplated four years of purple yogurt and Polynesian meatless meatballs in the cafeteria, that my mother was a fabulous cook; my first lesson in political correctness—I learned that I was now surrounded by women and not by girls; the pleasant discovery that some of those women were willing to talk to me now and then; the wonder of watching older guys suavely work references to Claude Lévi-Strauss and Buckminster Fuller into casual conversation; the giddy pleasure at finding that a joke that worked in high school worked equally well here too; the calming ritual of fighting with my roommate every evening over whether to open or to close the window.

  Growing up, and growing away. Off to college, off to war, off to work in the city, off to settle in a new world—home is never the same again, and sometimes home is never even seen again. What is striking about this maturational event is that it is central not only to us humans but to many of our primate relatives as well. The process of growing up and growing away has a remarkably familiar look of excitement and discovery and challenge.

  Some primates, such as orangutans, lead solitary lives, meeting only for the occasional mating. But the average group of primates is supremely social, whether it is a family of a dozen gorillas living in a mountain rain forest, a band of twenty langur monkeys on the outskirts of an Indian village, or a troop of one hundred baboons in the African grasslands. In such groups an infant is born into a world filled with relatives, friends, and adversaries, surrounded by intrigue, double-dealing, trysts, and heroics—the staples of great small-town gossip. Pretty heady stuff for the kid that’s learning whom it can trust and what the rules are, along with its species’ equivalent of table manners.

  Most young primates are socialized in this way quite effectively, and home must seem homier all the time. Then, inevitably, a lot of the young must leave the group and set out on their own. It is a simple fact driven by genetics and evolution: if everyone stayed on, matured, and reproduced there, and if their kids stayed on, and their kids’ kids too, then ultimately everyone would be pretty closely related. You would have the classic problems of inbreeding—lots of funny-looking kids with six fingers and two tails (as well as more serious genetic problems). Thus essentially all social primates have evolved mechanisms for adolescent emigration from one group to another. Not all adolescents have to leave. The problem of inbreeding is typically solved so long as all the adolescents of one sex go and make their fortune elsewhere; the members of the other sex can remain at home and mate with the newcomers immigrating to the group. In chimpanzees and gorillas, it is typically the females who leave for new groups, while the males stay home with their mothers. But among most Old World monkeys—baboons, macaques, langurs—it is the males who make the transfer. Why one sex transfers in one species but not in another is a complete mystery, the sort that keeps primatologists happily arguing with each other ad nauseam.

  This pattern of adolescent transfer solves the specter of inbreeding. To look at it just as a solution to an evolutionary problem is mechanistic, however. You can’t lose sight of the fact that those are real animals going through the harrowing process. It is a remarkable thing to observe: every day, in the world of primates, someone young and frightened picks up, leaves Mommy and everyone it knows, and heads off into the unknown.

  The baboons that I study each summer in East Africa provide one of the best examples of this pattern of adolescent transfer. Two troops encounter each other at midday at some sort of natural boundary—a river, for example. As is the baboon propensity in such settings, the males of the two troops carry on with a variety of aggressive displays, hooting and hollering with what they no doubt hope is a great air of menace. Eventually everyone gets bored and goes back to eating and lounging, ignoring the interlopers on the other side of the river. Suddenly you spot the kid—some adolescent in your troop. He stands there at the river’s edge, absolutely riveted. New baboons, a whole bunch of ‘em! He runs five steps toward them, runs four back, searches among the other members of his troop to see why no one else seems mesmerized by the strangers. After endless contemplation, he gingerly crosses the river and sits on the very edge of the other bank, scampering back down in a panic should any new baboon so much as glance at him.

  A week later. When the troops run into each other again, the kid repeats the pattern. Except this time he spends the afternoon sitting at the edge of the new troop. At the next encounter he follows them for a short distance before the anxiety becomes too much and he turns back. Finally, one brave night, he stays with them. He may vacillate awhile longer, perhaps even ultimately settling on a third troop, but he has begun his transfer into adulthood.

  And what an awful experience it is—a painfully lonely, peripheralized stage of life. There are no freshman orientation weeks, no cohorts of newcomers banding together and covering their nervousness with bravado. There is just a baboon kid, all alone on the edge of a new group, and no one there could care less about him. Actually, that is not true—there are often members of the new troop who pay quite a lot of attention, displaying some of the least-charming behavior seen among social primates, and most reminiscent of that of their human cousins. Suppose you are a low-ranking member of that troop, a puny kid a year or so after your own transfer. You spend most of your time losing fights, being pushed around, having food ripped off from you by someone of higher rank. You have a list of grievances a mile long and there’s lit
tle you can do about it. Sure, there are youngsters in the troop that you could harass pretty successfully, but if they are pretransfer age, their mothers—and maybe their fathers and their whole extended family—will descend on you like a ton of bricks. Then suddenly, like a gift from heaven, a new, even punier kid shows up: someone to take it out on. (Among chimps, where females do the transferring, the same thing occurs; resident females are brutally aggressive toward the new female living on the group’s edge.)

  Yet that’s only the beginning of a transfer animal’s problems. When, as part of my studies of disease patterns among baboons, I anesthetize and examine transfer males, I find that these young animals are teeming with parasites. There is no longer anyone to groom them, to sit with them and methodically clean their fur, half for hygiene, half for friendship. And if no one is interested in grooming a recent transfer animal, certainly no one is interested in anything more intimate than that—it’s a time of life where sex is mostly just practicing. The young males suffer all the indignities of being certified primate nerds.

  They are also highly vulnerable. If a predator attacks, the transfer animal—who is typically peripheral and exposed to begin with—is not likely to recognize the group’s signals and has no one to count on for his defense. I witnessed an incident like this once. The unfortunate animal was so new to my group that he rated only a number, 273, instead of a name. The troop was meandering in the midday heat and descended down the bank of a dry streambed into some bad luck: a half-asleep lioness. Panic ensued, with animals scattering every which way as the lioness stirred—while Male 273 stood bewildered and terribly visible. He was badly mauled and, in a poignant act, crawled for miles to return to his former home troop to die near his mother.

  In short, the transfer period is one of the most dangerous and miserable times in a primate’s life. Yet, almost inconceivably, life gets better. One day an adolescent female will sit beside our nervous transfer male and briefly groom him. Some afternoon everyone hungrily descends on a tree in fruit and the older adolescent males forget to chase the newcomer away. One morning the adolescent and an adult male exchange greetings (which, among male baboons, consists of yanking on each other’s penis, a social gesture predicated on trust if ever I saw one). And someday, inevitably, a terrified new transfer male appears on the scene, and our hero, to his perpetual shame perhaps, indulges in the aggressive pleasures of finding someone lower on the ladder to bully.

  In a gradual process of assimilation, the transfer animal makes a friend, finds an ally, mates, and rises in the hierarchy of the troop. It can take years. Which is why Hobbes was such an extraordinary beast.

  Three years ago my wife and I spent the summer working with a baboon troop at Amboseli National Park in Kenya, a research site run by the behavioral biologists Jeanne and Stuart Altmann from the University of Chicago. When I’m in the field, I study the relationships between a baboon’s rank and personality, how its body responds to stress, and what sorts of stress-related diseases it acquires. In order to obtain the physiological data—blood samples to gauge an animal’s stress hormone levels, immune system function, and so on—you have to anesthetize the baboon for a few hours with the aid of a small aluminum blowgun and drug-filled darts. Fill the dart with the right amount of anesthetic, walk up to a baboon, aim, and blow, and he is snoozing five minutes later. Naturally it’s not quite that simple—you can only dart someone in the mornings (to control for the effect of circadian rhythms on the animal’s hormones). You must ensure there are no predators around to shred the guy, and you must make certain he doesn’t climb a tree before passing out. And most of all, you have to dart and remove him from the troop when none of the other baboons are looking so that you don’t alarm them and disrupt their habituation to the scientists. So essentially, what I do with my college education is creep around in the bushes after a bunch of baboons, waiting for the instant when they are all looking the other way so that I can zip a dart into someone’s tush.

  It was about halfway through the season. We were just beginning to know the baboons in our troop (named Hook’s troop, for a long-deceased matriarch) and were becoming familiar with their daily routine. Each night they slept in their favorite grove of trees; each morning they rolled out of bed to forage for food in an open savannah strewn with volcanic rocks tossed up aeons ago by nearby Mount Kilimanjaro. It was the dry season, which meant the baboons had to do a bit more walking than usual to find food and water, but there was still plenty of both, and the troop had time to lounge around in the shade during the afternoon heat. Dominating the social hierarchy among the males was an imposing character named Ruto, who had joined the troop a few years before and had risen relatively quickly in the ranks. Number two was a male named Fatso, who had had the misfortune of being a rotund adolescent when he’d transferred into the troop years before and was named by a callous researcher. Fat he was no longer. Now a muscular prime-age male, he was Ruto’s most obvious competitor, though still clearly subordinate. It was a fairly peaceful period for the troop; mail was delivered regularly and the trains ran on time.

  Then one morning we arrived to find the baboons in complete turmoil. It is not an anthropomorphism to say that everyone was mightily frazzled. There was a new transfer male, and not someone meekly scurrying about the periphery. He was in the middle of the troop, raising hell—threatening and chasing everyone in sight. This nasty, brutish animal was soon named Hobbes (in deference to the seventeenth-century English philosopher who described the life of man as solitary, poor, nasty, brutish, and short).

  This is an extremely rare, though not unheard of, event among baboons. The transfer male in such cases is usually a big, muscular, intimidating kid. Maybe he is older than the average seven-year-old transfer male, or perhaps this is his second transfer and he picked up confidence from his first emigration. Maybe he is the cocky son of a high-ranking female in his old troop. In any case, the rare animal with these traits comes on like a locomotive, and he often gets away with it for a time. As long as he keeps pushing, it will be a while before any of the resident males works up the nerve to confront him. Nobody knows him yet; thus no one knows if he is asking for a fatal injury by being the first fool to challenge this aggressive maniac.

  This was Hobbes’s style. The intimidated males stood around helplessly. Fatso discovered all sorts of errands he had to run elsewhere. Ruto hid behind females. No one else was going to take a stand. Hobbes rose to the number one rank in the troop within a week.

  Despite his sudden ascendancy, Hobbes’s success wasn’t going to last forever. He was still a relatively inexperienced kid, and eventually one of the bigger males was bound to cut him down to size. Hobbes had about a month’s free ride. At this point he did something brutally violent but which had a certain grim evolutionary logic. He began to selectively attack pregnant females. He beat and mauled them, causing three out of four to abort within a few days.

  One of the great clichés of animal behavior in the context of evolution is that animals act for the good of the species. This idea was discredited in the 1960s but continues to permeate Wild Kingdom—like versions of animal behavior. The more accurate view is that animals usually behave in ways that maximize their own reproduction and the reproduction of their close relatives. This helps explain extraordinary acts of altruism and self-sacrifice in some circumstances, and sickening aggression in others. It’s in this context that Hobbes’s attacks make sense. Were those females to carry through their pregnancies and raise their offspring, they would not be likely to mate again for two years—and who knows where Hobbes would be at that point. Instead he harassed the females into aborting, and they were ovulating again a few weeks later. Although female baboons have a say in whom they mate with, in the case of someone as forceful as Hobbes they have little choice: within weeks Hobbes, still the dominant male in the troop, was mating with two of those three females. (This is not to imply that Hobbes had read his textbooks on evolution, animal behavior, and primate obstetrics and h
ad thought through this strategy, any more than animals think through the logic of when they should reach puberty. The wording here is a convenient shorthand for the more correct way of stating that his pattern of behavior was almost certainly an unconscious, evolved one.)

  As it happened, Hobbes’s arrival on the scene—just as we had darted and tested about half the animals for our studies—afforded us a rare opportunity. We could compare the physiology of the troop before and after his tumultuous transfer. And in a study published with Jeanne Altmann and Susan Alberts, I documented the not very surprising fact that Hobbes was stressing the bejesus out of these animals. Their blood levels of Cortisol (also known as hydrocortisone), one of the hormones most reliably secreted during stress, rose significantly. At the same time, their numbers of white blood cells, or lymphocytes, the sentinel cells of the immune system that defend the body against infections, declined markedly, another highly reliable index of stress. These stress-response markers were most pronounced in the animals receiving the most grief from Hobbes. Unmolested females had three times as many circulating lymphocytes as one poor female who was attacked five times during those first two weeks.

  An obvious question: Why doesn’t every new transfer male try something as audaciously successful as Hobbes’s method? For one thing, most transfer males are too small at the typical transfer age of seven years to intimidate a gazelle, let alone an eighty-pound adult male baboon. (Hobbes, unusually, weighed a good seventy pounds.) Most don’t have the personality needed for this sort of unpleasantry. Moreover, it’s a risky strategy, as someone like Hobbes stands a good chance of sustaining a crippling injury early in life.