In the aftermath of severe emotional trauma, it is not uncommon to experience a loss of memory and concentration. At ﬁrst glance, that is a little puzzling. It makes a certain intuitive sense that people who have been through a traumatic experience would have nightmares, depression, emotional numbness, angry outbursts, and a feeling of alienation and isolation. But why persistent and often severe deﬁcits in the ability to concentrate or remember things, even things not at all associated with the traumatic events themselves?
Post-traumatic stress disorder (PTSD) has never been a sharply deﬁned syndrome, its vagueness well captured in the various names and guises it has assumed during the past century, from “shell shock” in World War I to “combat fatigue” in World War II. Yet loss of memory and concentration has been noted as a persistent and distinctive feature in patients who have endured repeated, chronic stress, such as combat veterans and victims of childhood sexual abuse.
Recently, several separate teams of neuroscientists wondered whether brain imaging studies might reveal a physiological basis for this phenomenon. For some time, scientists have known that the brain’s hippocampus is crucial in forming and retrieving memories. Laboratory rats that have their hippocampus artiﬁcially destroyed have dramatic and permanent memory loss. Alzheimer’s patients display extensive damage to the hippocampus. But these cases result from clear physical trauma inﬂicted by the surgeon’s knife or by degenerative disease. What was astonishing when neuroscientists did imaging studies of patients with PTSD was the discovery that, as a result of nothing more than an intense emotional experience, the size of the hippocampus had shrunk by greater than 25 percent.
“That’s like reporting that an emotional trauma eliminates one of the four chambers of the heart,” writes Robert M. Sapolsky, Ph.D., in “Stress and Your Shrinking Brain,” one of the most fascinating essays in Monkeyluv: And Other Essays on Our Lives as Animals.
ON HOME TURF
Monkeyluv is an uneven collection of pieces, all previously published in popular magazines such as Discover, Natural History, and The Sciences. Arranged into sections on “Genes and Who We Are,” “Our Bodies and Who We Are,” and “Society and Who We Are,” Sapolsky’s topics range widely: the genetic “arms race” between the sexes, child abuse, the role of “junk” DNA in evolution, the evolution of male attractiveness, the neuroanatomy of dreams, the potency of intermittent rewards, the human proclivity for revenge, and why people older than 30 do not usually try sushi for the ﬁrst time or come up with breakthrough mathematical discoveries.
Not coincidentally, the chapter on PTSD is not only among the most interesting of these short essays but is also the one most closely related to Sapolsky’s own research. Sapolsky is a professor of biology and neurology at Stanford University and the author of Why Zebras Don’t Get Ulcers (1994) and The Trouble with Testosterone (1997). In writing about stress and hormone levels he is on his home turf. Sapolsky’s big discovery in this ﬁeld (which earned him a MacArthur “genius” award, among other scientiﬁc accolades) was that socially induced stress in baboons and rats can lead to chronic elevation of hormones known as glucocorticoids. When released by the adrenal glands in response to a sudden stressful situation, glucocorticoids perform a vital and necessary function of mobilizing a rush of energy to muscles, shutting down other nonessential functions such as reproduction, and actually stimulating the hippocampus to reinforce memory. “For 99 percent of the beasts on this planet,” Sapolsky explains, “stress is about three minutes of screaming terror...after which it’s either over with or you’re over with. Problems begin because we cognitively sophisticated humans are capable of secreting glucocorticoids chronically for reasons of sustained psychological and social stress. In contrast to the helpful actions of glucocorticoids in the face of an acute, physical stressor, too much of the hormones in response to chronic stress, and all sorts of stress-related problems such as high blood pressure, reproductive impairments, and immune suppression, become more likely.”
Strikingly, as Sapolsky’s own research showed, a few days of elevated stress hormone levels can also leave the neurons in the hippocampus vulnerable to damage; after a few weeks, the neurons actually begin to shrivel up; after months or years of chronic assault, the neurons die.
One of the best things about “Stress and Your Shrinking Brain” is the way Sapolsky leads the reader through the evidence, the multiple possible explanations, the pitfalls of leaping to a conclusion, the subtle and counterintuitive ways that the seemingly obvious explanation could be exactly 180 degrees backward from the reality. You almost have the feeling you are doing the science yourself.
One of the best things about “Stress and Your Shrinking Brain” is the way Sapolsky leads the reader through the evidence, the multiple possible explanations, the pitfalls of leaping to a conclusion, the subtle and counterintuitive ways that the seemingly obvious explanation could be exactly 180 degrees backward from the reality. You almost have the feeling you are doing the science yourself. Consider another amazing study that Sapolsky discusses. Roger Pitman’s group at Harvard recently compared a set of Vietnam veterans with PTSD with their identical twins who stayed home during the war. Astonishingly, it turned out that the twins had equally small hippocampi. Does this mean that the seeming cause-and-effect relationship is reversed? Could it be that people who get PTSD are those who start out with genetically smaller than normal hippocampi to begin with, which makes them susceptible to ﬂashbacks and other memory problems? On the other hand, Sapolsky also points out that among victims of some types of chronic trauma, such as multiple rape, greater than 90 percent develop PTSD symptoms. Surely they cannot all have had smaller-than-average hippocampi to begin with.
The real lesson from this fascinating look at the process of neuroscience research in action is the often extraordinarily complex interactions of genes and environment that are involved in producing human and animal behavior. That theme at least implicitly runs through much of Monkeyluv, and it is a bit curious that Sapolsky leaves it unexplored in “Stress and Your Shrinking Brain.”
SCIENTISTS, SCIENCE WRITING, AND THE PUBLIC
That is a small complaint in its speciﬁcs; but thereby hangs a tale, or really three tales, all involving issues about science and its public understanding that this book unwittingly raises. These issues are the problems of communicating science to the public in general, especially when scientists themselves do the communicating; the unsatisfying limitations of the collection-of-essays form that has, for all the wrong reasons, become a standard vehicle for scientists-turned-writers; and the inescapable political shadow that the hoary nature/nurture debate still casts over discussions of intelligence and behavior, especially human intelligence and behavior.
A scientist who can write ought, in principle, to be ideally suited for translating what scientists do into terms the average lay reader can understand. Yet this is rarely the case. (As a professional journalist and writer who no longer writes much about science, I can make this assertion now without worrying too much about being accused of simply protecting my own turf.) Sapolsky’s ﬁrst two books were mostly about his own research, and in them he demonstrated a terriﬁc gift for explaining complex subjects. His personal account of how he became a primatologist who did ﬁeld research on baboons in Africa (A Primate’s Memoir, 2001) was also a superb look at the scientiﬁc endeavor from the inside, as well as often being funny. The humor was not forced, and it proved an engaging vehicle for telling a fascinating story that combined great science with great personal adventure. From an early age, Sapolsky knew he wanted to be a primatologist. He spent endless hours at the Museum of Natural History in New York, imagining he was living in one of the African dioramas; he wrote fan letters to famous primatologists; he taught himself Swahili while still in high school.
One of the best things in A Primate’s Memoir was the way he pulled back the curtain on the sorts of things one takes for granted in reading formal, sober scientiﬁc accounts of research in the formal, sober scientiﬁc literature. I must have read a hundred times about research that involved ﬁring tranquilizing darts into animals, but I am ashamed to say it never really occurred to me to ask what was involved in actually doing this in the ﬁeld. Sapolsky has a hilarious description of his fanatical, obsessive practicing with a blowgun in his dorm room—fast spinning shots, shots into the wind (using a small fan), shots pointing up or down. He talks a grad school friend, an ex-high school football lineman, into letting him practice tackling him as though he were taking down a darted baboon. Sapolsky then has fantasies of darting a famous octogenarian Nobel Prize-winning biochemist who shufﬂes past his dorm window every day.
Sapolsky said in an interview a few years ago that fellow Stanford biologist Paul Ehrlich warned him about the risk of becoming “Saganized”: that his fellow scientists would not take him seriously if he wrote about science in a popular and engaging manner for a general audience (as had the enormously popular astronomer-science writer Carl Sagan). This, of course, was grand irony, because Ehrlich, who made a fortune writing books setting forth sensationalistic, unscientiﬁc, and repeatedly wrong predictions of impending global doom, has not done any serious science himself for decades. What is rather more hazardous to the scientist who gains some initial success in writing for the general public, however, is the danger Sapolsky has unfortunately succumbed to in this volume. As he writes about topics outside his own area of research, he becomes less a scientist explaining his own profession and work from the inside, and becomes, well, just another science writer.
SORROWS OF THE SCIENTIST AS BEST-SELLING AUTHOR
One problem is that writing well about subjects to which one is an outsider is a craft and skill like any other, requiring extensive practice to master. The instinct for asking the right question, for ﬁnding the right anecdote, for balancing details of personality with narrative and explanation, for developing a story line that serves both the reader and the truth is a métier that few writers master without years, more usually decades, of painful practice. It is not a coincidence that the best science writing (just as the best history and biographical writing) is often written by those who are not experts in the ﬁeld at all, but who are writers ﬁrst and foremost. For example, even just in terms of explaining the science in a clear, rigorous, and accessible manner, by far the best book about the Manhattan Project was written by an English major, novelist, and professional writer, Richard Rhodes (The Making of the Atomic Bomb, 1986). By far the most understandable and engaging book about the human genome—Genome: The Autobiography of a Species in 23 Chapters, 2000—was written by a professional science writer and former Washington, DC, correspondent for the Economist magazine, Matt Ridley, rather than by any of the scientists directly involved in the work.
One tell-tale sign that Sapolsky the writer has far less to say than Sapolsky the scientist is the way the humor that was natural and genuine in Sapolsky’s earlier books becomes formulaic and repetitive in too many of the essays in Monkeyluv: cute allusions to pop culture personalities, forced jokes and joviality (the brain is “the Big Enchilada of Consciousness”), and a kind of trademark geeky non sequitur that is funny the ﬁrst time but grows stale with repetition (“Couples typically ﬁnd themselves struggling over money, in-laws, ex-lovers, and how much the woman’s placenta should grow when she is eventually pregnant”).
Another problem, arguably even more serious, is that popular fame has a way of going to a scientist’s head. He starts to think that whatever random ruminations he has about any subject are automatically of interest. This is a well-known, often irreversible afﬂiction of Nobel Prize winners; but in a milder form it is known to addle the brains of other academics who have become media stars, excessively popular campus lecturers, or best-selling authors. The delusion of being automatically fascinating is part of what feeds the phenomenon of scientist-writers publishing collections of essays, and it is part of why such collections are so unsatisfying. The essays are too often too brief to make a complete point and thus tend to retreat into glibness, clever little observations, and bits of unconnected insight, however interesting these bits sometimes are.
Besides the PTSD essay, my favorite in Monkeyluv is the last. Originally published in the New Yorker, “Open Season” is good precisely because Sapolsky is once again reporting his own original research. In this case, the research is a bit tongue in cheek, but it is also exactly the kind of thing that makes the best case for the scientist-writer. Only someone with the scientiﬁc sensibility, training, and resources of Sapolsky could have conceived and carried out the reporting he brings to this piece.
Sapolsky begins with the commonplace enough observation that he cannot stand the music his young administrative assistant plays in the ofﬁce. Despite his own rather hippie-dippy sensibilities, he is ﬁnding himself growing more and more narrow in his preferences as he gets older. So “I wanted to test whether there are some clear-cut maturational time-windows during which we form our cultural tastes, are open to new experience, even gravitate to it for its own sake,” he explains. He phones radio stations, sushi restaurants, and body-piercing parlors in various parts of the country to ask the average age of their listeners and clientele. The sushi results are typical: the average age of the customers of sushi restaurants in Midwestern towns closely correlated with the year that sushi ﬁrst appeared there; basically, if you were older than 28 when sushi ﬁrst came to town, you were unlikely ever to try it, and if you were older than 39 you were almost certain never to try it. Sapolsky does not in the end come up with any terribly convincing neurophysiologic explanation for the aversion to novelty that seems to accompany advancing age, but the research itself is fascinating (and amusing) enough as it is.
ILLUMINATING THE NATURE-NURTURE DEBATE—UP TO A POINT
The one thing about this volume that most made me wish Sapolsky had written a more thorough and coherent book, rather than a collection of somewhat random essays, is the ghost that haunts a half dozen or so of the chapters: namely, the old nature/nurture debate. I should say at once that I think Sapolsky’s basic position is right. As he explains in the chapter titled “Genetic Hyping,” “Genes inﬂuence behavior, environment inﬂuences behavior, and genes and environment interact...What that means is that the effects of a gene on an organism will usually vary with changes in the environment, and the effects of the environment will vary with changes in the genetic makeup of the organism.”
Yet there remains so much confusion, political name-calling, and misrepresentation that surrounds this issue that I wish Sapolsky had done a much more thorough job of explaining and showing how the relative effects of nature and nurture are almost never an either-or proposition. Sapolsky himself inadvertently adds to the confusion, I think, by invariably demonizing only one side in the panoply of wrong-thing-sayers on this subject: The genetic determinists are always the promoters of “myths,” “urban legends,” “hype,” “medieval” beliefs, and “total crocks,” with their claims that gene X “causes” behavior Y.
Undeniably, there has been a disturbing rash of newspaper stories about “the” IQ gene, or the gay gene, or the depression gene. But there is also a raft of misleading information from the other side, which, to this day, frequently suggests that the only alternative to the incorrect assertion “genes determine behavior” is the (equally incorrect) assertion “genes have no effect on behavior whatsoever”—and, parenthetically, that anyone who suggests otherwise is aligning himself with fascism, eugenics, and social fatalism. Matt Ridley in his book Nature via Nurture (2003) offers many amusing and not-so-amusing examples of extremism on the nurturist side every bit as egregious as the extremism Sapolsky cites from the genetic determinist camp. Indeed, the widespread spin given to the announcement in 2001 that the human genome had been sequenced was the assertion by Craig Ventner that because it turned out we had “only” 30,000 genes, this proved that “the wonderful diversity of the human species is not hard-wired in our genes,” period.
Ridley makes the point that all such dogmatic assertions magniﬁcently miss the entire way genes and environment interact at the most fundamental level. Take the physical trait of body weight. The evidence is overwhelming that the dominant factor operating here is genes. Identical twins reared in the same family show an 80 percent correlation in body weight; identical twins reared apart show a 72 percent correlation. By contrast, unrelated siblings reared in the same family show just a 1 percent correlation. Well, many purely behavioral traits, including personality and intelligence, also show a similarly striking degree of genetic inﬂuence when such comparisons among twins are made.
But even in the case of body weight, it is nonsense to go from the correct conclusion that your weight is almost entirely a result of your genes to the patently absurd conclusion that therefore your weight is unaffected by how much you eat. Most people in America these days have access to a (more than) adequate diet; if they did not, the results of the study of inﬂuences on body weight would have been much different, with the environmental inﬂuence coming to the fore instead of genes. It is probably safe to say, for example, that during the Great Depression differences in body weight (and adult height) were comparatively much more affected by differences in the availability of nutrition than differences in genes. Indeed, what many of these studies show is that in environments that are roughly similar, the underlying genetic variations that do exist are what end up being the most exposed to view.
Sapolsky at one point tries to suggest that only in extreme environments do genetic differences really matter. He points to the gene 5-HTT (5-hydroxytryptamine transporter), which in one form is associated with increased risk of depression in humans. Sapolsky rather triumphantly points out that this increased risk (double the risk of depression and four times the risk of suicide) only occurs, however, among people with a history of major stressful events such as death of a loved one or loss of a job. “What knowledge about those genes keeps teaching us is that we have that much more of a responsibility to create environments that interact benignly with those genes,” he concludes.
Fair enough. Yet, ironically, the more common situation may be the one that Ridley calls to our attention. The more we seek to implement the “nurturist” program of leveling the environmental playing ﬁeld— by ensuring, for example, that all children receive adequate nutrition, parental care, education, and opportunity—the greater inﬂuence genes will have in the differences that inevitably will remain, in everything from weight to intelligence. Again, this is not an argument for abandoning social policy or for fatalism; far from it. Things would certainly be much worse were people with “bad” genes to experience inadequate education or emotional trauma or parental neglect. But it does mean that the interaction between genes and the environment can lead to some surprisingly paradoxical results. It is not so simple as the usual political sloganeering on both sides implies.
Sapolsky expends much energy fulminating against genetic determinism and pointing to mechanisms by which gene expression and regulation are directly inﬂuenced by everything from temperature to emotional stress. That is all well and good, but I fear it may (despite the occasional caveat that he is not really “bashing” genes) obscure the more basic point, a la Ridley, that there is simply no need to set genes and environment in opposition in the ﬁrst place. That genes inﬂuence human behaviors, from sexual orientation to love of novelty to criminality to religious fundamentalism to neuroticism (all well-established by twin studies), does not in any way suggest that environment does not also inﬂuence those things.
Ultimately, Monkeyluv is a frustrating book largely because, given its author’s talent for explaining complex ideas, his insider’s knowledge of the scientiﬁc process, and his expertise in an arena of vital public importance, the book far too often favors the quirky and facile over the truly interesting and insightful, the cheap laugh over the deep irony.
The old dictum “write what you know” is by no means a universal wisdom; most great books have been written by people who started out knowing next to nothing about the subjects they chose to tackle. But perhaps a modiﬁed version of the dictum is apropos: write what you know—unless you are willing to approach reporting and writing with the same obsessive zeal that it takes, say, to learn how to dart a ﬂeeing baboon with a blowgun.
From Monkeyluv and Other Essays on Our Lives as Animals by Robert M. Sapolsky. © 2005 by Robert M. Sapolsky. Reprinted with permission of Scribner Press.
Despite my best efforts to ignore him, my administrative assistance was getting on my nerves. Fresh out of college, Paul was working for a few years before starting English-lit grad school. It wasn’t any problem with his work, which was superb. It was his taste in music. He’d be hunched over his computer, his CD recorder blasting away something horrendous by whatever group twenty-year-olds are listening to. That was fine; while it could be scientifically proven that his music was inferior to what my generation listened to, it was his prerogative to listen to nothing but that junk. What was irritating was that he didn’t just listen to that. Sonic Youth for hours and then suddenly, late Beethoven. And then Grand Ole Opry. He kept switching what he listened to. Gregorian chants, Shostakovich, John Coltrane. Big-band hits, Yma Sumac. Puccini arias, Pygmy hunting songs. Philip Glass, klezmer classics. He was spending the first paychecks of his life in methodical exploration of new types of music, giving them a careful listening, forming opinions, hating some of the stuff, loving the process.
He was like that in all regards. He had a beard and longish hair, and then, one day without fanfare, everything was shaved to a bald pate–“I thought it would be interesting to try out this appearance for a while, see if it changes the way people interact with me.” In his time off, he would spend a weekend at a film festival of Indian music, just for the experience. He’d pore over Melville, followed by Chaucer, followed by contemporary Hungarian realists. It was irritating how open-minded he was, how amenable to novelty.
It was more than irritating. It was depressing, because it made me reflect on my own narrowing. I listen to music constantly, but I can’t remember the last time I listened to a new composer. It’s even worse. I love all of Mahler, for example, yet I seem to only listen to the same two favorite symphonies all the time. The same for reggae, yet it’s always the same trusted tape of Bob Marley’s greatest hits. And if I’m going out to dinner, I’ve become more and more likely to be ordering the usual favorite.
How did this happen? When did it become so important to me to have solid, familiar ground underfoot? How did I become one of those people who buy “best of” anthologies advertised on late-night television?
For many people, this would be the point where one might do some soul-searching introspection, some painful confronting of truths as a means of personal growth. Being a scientist, I decided to avoid this by Studying the Subject. Donning my lab coat and positioning a microscope nearby, I started making phone calls.
I wanted to test whether there are some clear-cut maturational time-windows during which we form our cultural tastes, are open to new experience, even gravitate to it for its own sake. In particular, I wanted to determine whether there was a consistent age at which such windows of openness slammed shut.
As a CD of Wagner highlights played on ukelele boomed just outside my office, I wondered, When do we form our musical tastes, and when do we stop being open to most new music? My research assistants and I started calling radio stations that specialize in period music–contemporary rock, the “Stairway to Heaven” seventies stations, the fifties doo-wop stations, and so on. In each case, we would pose the same questions to the station manager. “When was most of the music that you played first introduced? And what is the average age of your listeners?”