The Trouble with Testosterone

by Robert M. Sapolsky

  The oddity of senescent transfers becomes even more marked when considering what life will be like if the transition to the new troop is made safely. Moving into a world of strangers, of new social and ecological rules—which big, strapping males are unpredictably violent, who can be relaxed around? Which grove of trees is most likely to be fruiting when the dry season is at its worst? The new demands are made even harder given the nature of cognitive aging—“crystallized” knowledge, the recalling of facts and their application in usual, habitual ways, typically remains intact into old age, whereas declines are more common in “fluid” knowledge, the absorbing of new information and its novel and improvisatory application. It is an inauspicious time of life to try to learn new tricks.

  The physical vulnerability, the emphasis on continuity, the reliance on the familiar. All this suggests that it is madness for a baboon to pick up in his old age and try a new life. Why should he ever do it?

  A number of scientists, noting this odd event, have come up with some ideas. Perhaps the grass is greener in some other troop’s field, making for easier foraging. Maybe the male believes that a move is just the thing to rejuvenate his career, the chance for a brief last hurrah in some other troop. Some evidence for this idea has been found by Maria van Noordwijk and Carel van Schaik, of the University of Utrecht in the Netherlands, in their studies of macaque monkeys. One particular theory has the poignant appeal of a Hallmark card—perhaps aged males leave in order to return to their natal troop, their hometown, in order to spend their final frail years amid the care and support of their aged sisters and female relatives. As another theory, aged males may leave the troop in which they were in their prime when their daughters become of reproductive age. This would serve as a means to keep aged males from inadvertently breeding with their daughters. Susan Alberts and Jeanne Altmann of the University of Chicago have found some indirect support for this hypothesis in their baboon studies. A particularly odd twist on this idea comes from Alison Richards of Yale University in her studies of sifakas, a Madagascan primate. In a mixture of King Lear and bad Marlin Perkins, it appears to be the reproductive-age daughters who drive out the elderly fathers. No Hallmark cards there for Father’s Day.

  The data from my baboons suggest an additional reason for the occasional transfer of an aged male: in many ways, the last thing you ever want to do is spend your older years in the same troop in which you were in your prime. Because the current dominant cohort treats you horribly.

  When you examine the pattern of dominance interactions among the individuals in a troop, a distinctive pattern emerges. High-ranking males have their tense interactions with each other, one forcing another to give up a piece of food, a resting spot, disrupting grooming or sexual behavior. Number 3 in the hierarchy would typically have his most frequent interactions with number 2—breathing down his neck, hoping to slip in the knockout punch that ratchets him up a step in the pecking order—and with number 4, who is trying to do the same to him. Meanwhile, these high-ranking tusslers rarely bother with lowly number 20, a puny adolescent who has recently transferred into the troop (unless they are having a particularly bad day and need someone small to take it out on).

  This is the general pattern regarding the frequency of dominance interactions. Inspect the matrix of interactions, though, and an odd pattern will jump out—the high-ranking males are having a zillion dominance interactions with number 14. Who’s he, what’s the big deal, why is his nose being rubbed in his subordinance at such a high rate? And it turns out that elderly number 14 used to be number 1, back when he was in his prime and the current dominant generation were squirrelly adolescents. They remember. When I examined the rare males who had transferred into my troops in their old age, they all experienced the same new world—they were utterly subordinate, sitting in the cellar of the hierarchy, but at least they were anonymous and ignored. In contrast, the males who declined in the troop in which they were in their prime were subjected to more than twice the number of dominance interactions as were the old anonymous males who had transferred in.

  Why are the prime-aged males so awful and aggressive to the deposed ruling class? Are they still afraid of them, afraid that they may rise again? Do they get an ugly, visceral thrill out of being able to get away with it? It is impossible to infer what is going on in their heads. My data indicate, however, that the new generation doesn’t particularly care who the aged animal is, so long as he was once high-ranking. In theory, one might have expected a certain grim justice of what goes around comes around—males who were particularly brutal in their prime, treating young subordinates particularly aggressively, would be the ones most subject to the indignities of old age when time turned the tables. But I did not observe that pattern—the brutalizing of elderly males who remained in the troop was independent of how they went about being dominant back when. All that seemed to matter was that they once were scary and dominant. And that they no longer were.

  This all seems rather sad to me, this feature of life among our close relatives—how, in one’s old age, it can be preferable to take your chances with the lions than with the members of your own species, how one might choose to rely on the kindness, or at least the indifference, of strangers.

  Looking at this grim pattern, the puzzlement before—why should an elderly male ever leave the troop?—gives rise to the inverse—why should he ever stay? Yet roughly half of them do, living out their final years in the troop in which they were in their prime. Are these the ones who have held on to a protective high rank longer, who for some reason are less subject to the harassments of the next generations? My data indicated that this is not the case. Instead, the males who stayed had something unique to sustain them during the hard times—friendship.

  Aging, it has been said, is often the time of life spent among strangers. Given the demographics of aging among humans, old age for a woman is often spent among strangers because she has outlived her husband. And given the typical patterns of socialization that have been documented, old age for a man in our society is often spent among strangers because he has outlived his perceived role—job-holder, breadwinner, careerist—and has discovered that he never made any true intimates along the way. Studies of gender-specific patterns of socialization have shown how much more readily women make friends than do men—they are better able to communicate in general and about emotions in particular, more apt to view cooperation and interdependence as a goal rather than as a sign of weakness, more interested in emotionally affirming each other’s problems than simply problem solving. And by old age, women and men differ dramatically in the number of friends and intimates they still have. In an interesting extension of this, Teresa Seeman and colleagues at Yale University have shown that close friendships for an older man are physiologically protective, while for a woman, it is the quality of the friendship that is important. Interpretation—intimate friendships are so rare for an older man that that in and of itself is a unique and salutary marker. In contrast, for an aged woman, intimate friends are the norm, not such a big deal in and of itself. Far too often, intimacy at that age means the woman has the enormously stressful task of taking care of someone infirm, hardly a recipe for her own successful aging. Seeman’s studies show physiological protection for the women whose intimate relationships are symmetric and reciprocal, rather than a burden.

  I think there are some parallels here to the world of baboons. Females, by dint of spending their whole lives in the same troop, are surrounded by relatives and by nonrelatives with whom they’ve had decades to develop relationships. Moreover, social rank in females is hereditary and, for the most part, static over the lifetime, so the jostling and maneuvering for higher rank is not a feature in the life of a female. In contrast, a male spends his adult years in a place without relatives, typically apart from the individuals he grew up with, where the primary focus of his social interactions is often male-male competition. In such a world, it is a rare male who has friends.

  To use this term is
not an anthropomorphism. Male baboons do not have other males as friends—for example, over the years, I can count on one hand the number of times I’ve seen adult males grooming each other. The most a male can typically hope for out of another adult male is a temporary business partner in a coalition, and often an uneasy partner at that. For the rare male who has “friendships,” it is with females.

  This has nothing to do with sex—shame on you for such tawdry, lascivious thoughts. It’s purely platonic, independent of where the female is in her reproductive cycle. They’re just friends. This is an individual that the male grooms a lot, and who grooms him in return. It is someone he will sit in contact with when either is troubled by some tumult in the baboon world. It is someone whose infant he will play with or carry protectively when a predator lurks.10

  Barbara Smuts, of the University of Michigan, published a superb monograph a decade ago analyzing the rewards and heartbreaks of such friendships, trying to make sense of which of the rare males are capable of such stability. And she documented something that I know many baboonologists have observed in their animals: males who develop these friendships are ones who have placed a high priority on them throughout their prime adult years. These are males who would put more effort into forming affiliative friendships with females than making strategic fighting coalitions with other males. These are the baboons who maximize reproductive success through covert matings with females who prefer them, rather than through the overt matings that are the rewards of successful male-male conflict. These are males who, in the prime of life, might even have walked away from high rank, voluntarily relinquishing dominant positions, rather than having to be decisively defeated (and possibly crippled) in their Waterloo.

  Work by Smuts, Craig Packer of the University of Minnesota, and Fred Bercovitch of the Caribbean Primate Center has shown that male baboons are more likely to form such affiliative relationships with females as they mellow into old age. But, to infest the world of baboons with some psychobabble, the males with the highest rates of these affiliative behaviors are the ones who made their distinctive lifestyle choices early on. And it is this prioritizing that differentiates them in their old age. When I compared males who, in their later years, remained in the same troop with those who left, the former were the ones with the long-standing female friendships—still mating, grooming, being groomed, sitting in contact with females, interacting with infants. These are the males who have worked early on to become part of a community.

  A current emphasis in gerontology is on “successful aging,” the study of the surprisingly large subset of individuals who spend their later years healthy, satisfied, and productive. This is a pleasing antidote to the view of aging as nothing but the dying of the light. Of course, how successfully an individual ages can depend on the luck of the draw when it comes to genes, or the good fortune of the right socioeconomic status. Yet gerontologists now appreciate how much such successful aging also reflects how you live your daily life, long before reaching the threshold of old age. It’s not a realm where there’s much help from quick medical fixes or spates of resolutions about eating right/relaxing more/getting some exercise, starting first thing tomorrow. It is the despair of many health care professionals how difficult humans find the sorts of small, incremental daily acts that constitute good preventative medicine. It looks like when it comes to taking the small steps toward building lifelong affiliations, your average male baboon isn’t very good at this either. But the consequences for those who can appear to be considerable; there’s a world of difference between doing things today and planning to do things tomorrow.

  No doubt, somewhere, there is a warehouse crammed with unsold, musty merchandise, left over when various fads of the sixties faded, cartons of cranberry-striped bell-bottoms and love beads. There may still be a market for some of that stuff: perhaps baboons might pay attention to one of those posters that we all habituated to, the horribly clichéd one about today being the first day of the rest of your life.

  FURTHER READING

  For a more technical treatment of this subject, see R. Sapolsky, “Why Should an Aged Male Baboon Ever Transfer Troops?” American Journal of Primatology 39 (1996): 149. Also see C. Packer, “Male Dominance and Reproductive Activity in Papio anubis,” Animal Behaviour 27 (1979): 37. Also see F. Bercovitch, “Coalition, Cooperation and Reproductive Tactics among Adult Male Baboons,” Animal Behaviour 36 (1988): 1198.

  A review of crystalline and fluid knowledge with respect to aging can be found in J. Birren and K. Schaie, Handbook of the Psychology of Aging, 3rd ed. (San Diego, Calif.: Academic Press, 1990).

  The work of Maria van Noordwijk and Carel van Schaik can be found in “Male Careers in Sumatran Long-Tailed Macaques (Macaca fascicularis),” Behavior 107 (1988): 25. The studies of Susan Alberts and Jeanne Altmann are published in “Balancing Costs and Opportunities: Dispersal in Male Baboons,” American Naturalist 145 (1995): 279. That paper also demonstrates the two- to tenfold increase in mortality when young baboons transfer. The work on sifakas is reported in A. Richards, P. Rakotomanga, and M. Schwartz, “Dispersal by Propithecus verreauxi at Beza Mahafaly, Madagascar: 1984-1991,” American Journal of Primatology 30 (1993): 1.

  Gender differences in patterns of successful aging is the subject of T. Seeman, L. Berkman, D. Blazer, and J. Rowe, “Social Ties and Support and Neuroendocrine Function: The MacArthur Studies of Successful Aging,” Annals of Behavioral Medicine 16 (1994): 95. For a wonderful overview of gender differences in emotional expressivity, see Deborah Tannen’s 1990 book, You Just Don’t Understand (New York: Morrow). I firmly believe this should be required reading for all newlyweds.

  Antidotes to worries about anthropomorphisms about primates: For the definitive discussion of platonic intimacy, see B. Smuts, Sex and Friendship in Baboons (New York: Aldine Publishing Company, 1985). For temperament and personality among primates, see A. Clarke and S. Boinski, “Temperament in Nonhuman Primates,” American Journal of Primatology 376 (1995): 103. Also see J. Ray and R. Sapolsky, “Styles of Male Social Behavior and Their Endocrine Correlates among High-ranking Baboons,” American Journal of Primatology 28 (1992): 231. And for an overview of cultural differences among primates, see R. Wrangham, Chimpanzee Cultures (Cambridge, Mass.: Harvard University Press, 1994).

  The general and encouraging subject of aging not always being dreadful is reviewed in P. and M. Baltes, Successful Aging (Cambridge, Eng.: Cambridge University Press, 1990).

  Curious George’s Pharmacy

  Mark Tansey, Nature’s Ape, 1984; private collection, Honolulu, courtesy Curt Marcus Gallery, New York

  It was the first lecture of a neurobiology course in graduate school, and the instructor did a fabulous job of tripping us up on a romantic bias. The lecture was about synapses, the tiny gaps in between cells in the brain. The lights came down and, unexpectedly, the first slide was of a beautiful Egyptian tablet, filled with hieroglyphics. We hushed as he started off in a stagy Rod Serling voice. “During the reign of Amenhotep the First, more than 3,500 years ago, at the height of their power, the ancient Egyptians . . . knew nothing whatsoever about the synapse.” We all fell for it, expecting instead to have been told about how detailed descriptions of the synapse could already be found in that fragile papyrus. It’s the Wisdom of the Ancients syndrome, the public TV phenomenon where no fact in some field like astronomy, for example, can be cited without first noting how the Egyptians, Greeks, or Incans knew that centuries ago. Brain surgery, flying machines, how to get the VCR to record automatically—they knew it all back then. Then there’s the Wisdom of the Non-Westernized syndrome, a relative newcomer, but an irresistible one for the folks who’d love to go dancing with wolves. And for a crowd-pleaser, there’s always the Wisdom of the Children.

  But if you want a real tried-and-true performer, go with the Wisdom of the Animals. For us humans, our well-advertised intelligence so rarely seems to be user-friendly; it is such a taxing, muscular process. We rack our brains, sort out our optio
ns, put on our thinking caps. It’s all so, well, unnatural. “Brainstorming” even sounds neurologically dangerous, as if our neurons might short-circuit. But animals, on the other hand, just know. No energetic striving for them; theirs is the realm of instinct and reflex. They fly vast distances without getting lost, unerringly find food they’ve buried, recognize relatives on first encounter. They sense impending earthquakes, intuit human emotions, predict downward trends in the stock market. It is a seamless kind of wisdom that reflects a profound equilibrium with the environment.

  Much of this is nonsense. Animals sometimes do indeed perform amazing feats of intelligence. But the idea of animaux savants is soggy with romanticism. Animals are not merely machines of effortless cognitive instinct. Their intelligence is more of an active, exploratory process, nowhere more prominent than in primate behavior. In the name of social competition, primates scheme and plot in remarkably sophisticated and all too familiar ways: they think through their next gambit; they try out new strategies; they screw up and learn from their mistakes.

  All of this is a preamble to evaluating a new version of the Wisdom of the Animals. It’s one that has generated tremendous excitement and, I feel, not enough skepticism. So the goal here is to help the reader to ask, What exactly do these beasts know and how do they know it?

  In the late 1970s the primatologists Richard Wrangham of Harvard University and Toshisada Nishida of Kyoto University, conducting fieldwork in the Gombe National Park in Tanzania, noticed something odd about the feeding patterns of the local chimpanzees. On waking, presumably with an empty stomach, some of the animals would dine on the leaves of a shrub called Aspilia. What was strange was the way they ate the leaves: instead of chewing them, the chimpanzees wadded them under their tongues, held them there for a while, and then swallowed them whole. Off and on throughout the meal the chimpanzees would make faces: Aspilia apparently was no tasty treat. Stranger still, the leaves passed through the animals’ guts undigested, emerging essentially intact in their feces. Unpleasant to the palate, with little nutritive value, Aspilia posed a question: Why did the apes even bother?