The Ancients may have wondered at the Fates snipping away at the threads of life; the churchmen may have debated predestination and providence; Hegel and his followers may have thought they glimpsed the tides of History; but in our science-besotted days, disputes over human destiny tend to be conducted in the language of biology. To what extent do our genes determine our future? Should divergent social outcomes between ethnic groups be chalked up to innate differences or cultural factors? Have men and women been “programmed” by evolution? Can our supposedly rational beliefs be explained in terms of neurobiology?

The answers to these sorts of questions shape how we understand ourselves and one another. They bear on our moral and political lives—often in surprising ways. And their public discussion is frequently attended by accusations of racism, sexism, censorship, and political correctness.

Richard J. Perry stakes out what appears to be an extreme position in these debates: that human “biological determinism”—the idea, as he puts it, that our biological makeup “strongly influences, molds, guides, impels, and limits how we feel, how we react, and what we’re likely to do”—is “noxious,” false, unscientific, and in need of constant rebuttal. Now retired after more than three decades as a professor at St. Lawrence University in northern New York, Perry is an anthropologist whose doctoral research and much of his subsequent fieldwork involved stints on an Apache reservation in Arizona. He has in the past forcefully defended his discipline against postmodernists and naïve multiculturalists, and to some extent the arguments in his irritating new book, Killer Apes, Naked Apes, and Just Plain Nasty People, arise from his longstanding belief that scholars in other fields really ought to bone up on anthropology.

Perry is chiefly motivated, however, by an admirable concern about the ways that biological determinism can lead to injustice—and the record of the past would seem to give him plenty of material with which to work. “[B]iologically themed arguments,” he writes, have long “asserted the necessity, inevitability, or ‘naturalness’ of slavery, of colonialism, of the inferiority of people designated a particular ‘race,’ of aggressive interpersonal behavior, of male dominance over females, of selfishness, and of war based on territorial ‘imperatives.’” After a quick and superficial sketch of only somewhat relevant ancient and early modern history, he plunges into the bad old days of eugenics.

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Although Perry does a poor job of connecting the dots, the dots themselves are likely to be so familiar to anyone reading the book that it is easy to make out the whole ugly picture. From Charles Darwin comes the idea of natural selection, which Herbert Spencer gave its familiar catchphrase “survival of the fittest.” From Gregor Mendel and Francis Galton comes a simple understanding of genetic inheritance. These legitimate scientific theories combined with pseudoscientific claptrap, racialist beliefs, and Progressive ideology to give rise to eugenics—first as an intellectual enterprise, then as a set of well-heeled social-reform campaigns, then as a popular movement.

To the eugenicists, the new understanding of human biology made it seemingly possible to ameliorate or even eliminate social problems that had been considered intractable, like poverty and crime and sickness. Improving mankind in this way would require letting the unhealthy die off—one reason some eugenicists condemned charitable institutions, which, by alleviating suffering, encouraged the survival of the unfit.

Improving mankind would also require preventing or slowing the natural increase of “inferior” individuals or groups, sometimes through coercion. “By the 1930s,” Perry writes, “more than thirty states had passed mandatory sterilization laws for numerous categories of people,” such as the “feebleminded,” the poor, Native Americans, and inmates in prisons and asylums. These policies, and the eugenic arguments supporting them, directly inspired Nazi efforts to eliminate those deemed unfit and to promote “racial hygiene,” culminating in the death camps, the gas chambers, the fires that turned living flesh and bone to ash.

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Other authors have told the grim story of eugenics much more intelligibly and interestingly than Perry—indeed, his short, disjointed account relies heavily on two excellent books, Edwin Black’s War against the Weak (2003) and Daniel Kevles’s In the Name of Eugenics (1985)—but Perry’s point is clear enough and undeniably correct: a crude form of biological determinism gave rise to great cruelty and bloodshed. Subsequent debates about different strains of biodeterminism take place in the shadow of this horrible fact.

Perry soon sets his sights on the intelligence test, the subject of some of the most prominent biodeterminism controversies of recent decades. He offers, again, a hurried historical account. Alfred Binet, a French psychologist, devised some of the earliest intelligence tests to “identify children who needed remedial help in school to catch up to their peers.” Although Perry does not mention it, Binet was a model of scientific caution who explicitly worried about potentially harmful applications of the empirical study of intelligence.

Binet was right to worry. Intelligence quotient (I.Q.) testing would become “a tool for weeding out the less fit, determining winners and losers at an early age,” Perry notes. Some early I.Q. tests were flawed in a way that is obvious today, and it is too bad that Perry’s modus operandi throughout his book is to make sweeping generalizations instead of offering illustrations, for here he could have supplied many risible examples—such as these multiple-choice questions that appeared on the intelligence exams administered by the U.S. Army to draftees in the early 1920s:

12. Chard is a: fish, lizard, vegetable, snake
13. Cornell University is at: Ithaca, Cambridge, Annapolis, New Haven
14. Bueno Ayres is a city of: Spain, Brazil, Portugal, Argentina
15. Ivory is obtained from: elephants, mines, oysters, reefs
16. Alfred Noyes is famous as a: painter, poet, musician, sculptor

Those are neither the most difficult nor the most strange questions to appear on the Army’s intelligence exams—so it is no wonder the resulting scores were low. The testers found that the drafted white soldiers given the exam supposedly had an average “mental age” of about 13 years, while the drafted black soldiers fared even worse.

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Perry doesn’t mention my favorite absurd practice from the history of I.Q.: estimating I.Q.s for dead historical personages. According to the granddaddy of such studies, published in 1926, Oliver Cromwell had an I.Q. of 115, Darwin clocked in at 140, and Mozart at 155. Although the illegitimacy of such estimates should be self-evident, the silly practice somehow lingers on. In 2006, for example, a psychologist at the University of California, Davis, offered a retrospective assessment of the I.Q.s of all the U.S. presidents to date. John Quincy Adams ranked highest, with an estimated I.Q. of 175; Ulysses S. Grant was on the bottom with just 130.

Many of the problems with early I.Q. tests were rectified by researchers in subsequent decades, and experimental techniques for studying human intelligence became more sophisticated. In their book, The Bell Curve (1994), Richard Herrnstein and Charles Murray were able to supplement their own analysis of intelligence and class structure in America with the findings of a substantial body of other researchers’ work. The Bell Curve, however, met with an explosive reception. Anyone willing to wade through the debris, carefully sidestepping the shards of calumny, can find among the reviews bits and pieces of very intelligent criticism of its biodeterministic arguments. Perry, however, gives no indication of having actually read The Bell Curve or the literature responding to it. His treatment of Herrnstein and Murray’s book is short (just a couple of paragraphs), weak (with a bad paraphrase and a lame insult), and careless (he wrongly puts Murray at the Heritage Foundation, when he has long been at the American Enterprise Institute).

There is today wide agreement on many of the fundamental facts in this area: the results of I.Q. tests are imperfect indicators of human intelligence, but I.Q. is nonetheless highly predictive of performance in several spheres of life; intelligence is in some degree inherited, and it correlates with certain physical characteristics of brains (even though we know very little about specific genetic markers or specific brain structures that might be linked to I.Q.); different ethnic groups have average I.Q.s that are quantifiably different; and many countries are witnessing a rise in average I.Q. (the “Flynn effect”), for which there are several competing explanatory hypotheses. There are still many contested conceptual and philosophical questions related to I.Q.—including questions about just what intelligence is—and there are many unanswered questions about the social causes and effects of intelligence. But to suggest, as Perry does, that the whole field is merely a jumble of racism and fraud is to do a disservice to the respectable hard work of many scholars across many years.

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There is much less empirical evidence supporting sociobiology, which Perry targets next. Darwin taught that, like the other animals, we human beings evolved in response to many natural pressures and threats. Sociobiology—first proposed in the 1970s by Harvard biologist E.O. Wilson and later amplified and extended by the work of other scientists and theorists—goes further by claiming that evolutionary theory doesn’t explain just our bodies, it also explains our social behavior. Sociobiology holds that, in Perry’s words, “many individual traits—shyness or aggressive behavior, for example—are due to the presence or absence of particular genes.”

Such a deterministic account leaves “little room for the operation of many phenomena that appear to be unique to the human species—language, culture, and the ability to process and create information with high levels of complexity.” Sociobiologists tend to write about “generic human beings” without acknowledging the cultural differences that Perry and his fellow anthropologists are primed to notice. And sociobiologists often resort to an illogical and unscientific kind of analysis—what Perry calls the “since…, then…” argument: “The reasoning is that ‘since’ a given form of behavior has a genetic basis, then it must have originated earlier in human evolution.”

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Similarly faulty logic is sometimes employed in evolutionary psychology, the field Perry calls “the foster child of sociobiology.” Evolutionary psychologists have often been accused of fabricating “just-so stories” to explain the evolutionary origins of human behavior and culture; they “begin with the result and then devise an explanation for how it ‘must have’ originated,” writes Perry. Their unwarranted assumptions are sufficiently sizeable that evolutionary psychology remains controversial even among scientists whose work focuses on evolution.

In making his case against biological determinism, Perry takes aim at Richard Dawkins’s “selfish gene” theory, at Raymond Dart’s “killer ape” theory (the idea that violence and aggression made us human), and at Desmond Morris’s description of humans as “naked apes.” Perry also squeezes off a drive-by shot at the vogueish research purporting to show that our political beliefs are largely rooted in our biology—a notion with troubling implications for democratic politics. And he spends much of a chapter criticizing Steven Pinker, the Harvard cognitive psychologist who, especially in his impressive book The Blank Slate (2002), argues against behaviorism, social constructionism, and other flavors of “denial of human nature.” But Perry oversimplifies and mischaracterizes some of Pinker’s arguments, reading him about as uncharitably as Pinker himself reads those he disagrees with—which is saying something indeed.

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Misreading Pinker is hardly Perry’s worst feature, however. He has a stunningly weak grasp of intellectual and political history, and the book suffers especially from his ignorance of, and bitterness toward, conservatism. For conservatism, you see, is the reason biodeterminist arguments won’t stay dead no matter how often they are defeated. “The idea that [human beings and society] are the way they are because of inherent biological factors, and therefore are not susceptible to rapid change, has an inherently conservative appeal,” he maintains. Perry imagines connections between biodeterminism and the Iraq war, the gender pay gap, Mitt Romney’s immigration proposals, Paul Ryan’s budget, and on and on. In his eyes, conservatives are just social Darwinists who want the unwashed to die off; conservatives believe in nature so as to avoid having to pay for nurture.

The crankishness is exacerbated by painfully bad writing and, apparently, no editing. What a pity. A popular critique of the excesses of biological determinism would be welcome. Perry is right to say that these ideas are influential, even if he grossly mischaracterizes how their influence works. But for such a critique to be worth anyone’s time, it would have to come from someone less eager to caricature his opponents and more savvy about the role of ideas in political life.

It is unlikely that any amount of future research will definitively settle the heredity-versus-environment debates. But that very uncertainty—the knowledge that we are stuck in between nature and nurture—may prove to be a crucial bulwark of our freedom. On the one hand, knowing that human beings can in important respects rise above our biological limitations means that we are and must be free and responsible moral and political actors. On the other hand, the fact that we are subject to limitations imposed by our embodiedness means that utopian social engineering schemes and tyrannies grounded in a denial of human nature are always in the long run doomed to fail. It seems we are destined to be free.