Evolutionary psychology, which focuses on the evolution of human cognition, emerged in the 1980s out of sociobiology, a perspective that encompasses all behavior. Both sociobiology, which the evolutionary biologist Edward O. Wilson of Harvard University introduced in the 1970s, and evolutionary psychology adhere to the idea that every characteristic of every species is adaptive—that is, each characteristic has enhanced reproductive success. Applied to explain the evolution of human behavior, the idea proceeds with appealing but misleading simplicity: Animals are depicted as doing something people also do. Next comes an account of the evolutionary advantage of the behavior for the animals. The conclusion is that it is natural, and therefore inevitable, for people to behave that way, too.

Ever since sociobiology was introduced, critics such as the the late Stephen Jay Gould and evolutionary biologist Richard C. Lewontin of Harvard University have pointed out that the basic reasoning of sociobiology and evolutionary psychology relies on mistaken evolutionary thinking. Not all characteristics of organisms, the critics note, come about as a result of natural selection. Before natural selection can operate, there must be some original variation among individuals in a trait, such as good versus poor spatial ability. Furthermore, the trait must be genetically inherited, and one or another version of it must enable some individuals to reproduce more than others. But there are plenty of traits around today that don’t satisfy those criteria. Some traits have simply accompanied other traits that natural selection did favor, some are still hanging around as a result of a related trait in some distant ancestor, and some may persist purely by accident.

The most general objection to the idea that all traits are adaptive is that it results in stories about evolution that cannot be proved wrong. If someone develops a good reason that natural selection led to a certain trait, the explanation may be accepted merely because it is plausible or comforting or clever. If someone else gives a good counterargument to the explanation, a different adaptive reason can always be invented.

Critics of sociobiology have also pointed out another problem: the difficulty of establishing genetic inheritance of a trait. The action of genes depends both on the development and the environment of the organism. Behavior, furthermore, is social, developed in the context of our interactions with others. Children imitate the behavior of the adults they live with, and everyone modifies behavior according to circumstances. A man might be willing to ask for directions at some times but not at others.

Now, in Why Men Won’t Ask for Directions, Richard C. Francis takes on evolutionary psychology and sociobiology from a new perspective—as a neurobiologist. He describes accounts of how sexual behavior works—particularly the neural and hormonal processes involved in the behavior—to rebut simple adaptive explanations for its evolution. He contrasts questions about what goes on inside an animal’s body with questions about why natural selection favored a certain behavior. Francis shows that the answers to the “why” questions of evolutionary psychology ignore plausible, alternative “how” explanations.

Each chapter of the book describes one aspect of sexual behavior, outlines the adaptive explanation for it, and then offers a different account, on the basis of the physiology behind the behavior. Francis often argues that a particular behavior is a consequence of bodily processes rooted in evolutionary history, processes already in place when the behavior arose. Some sexual behavior, for instance, is a consequence of ancestral physiological pathways, rather than an innovation selected for its own sake.

Why, for example, do women have orgasms? According to the convoluted stories of evolutionary psychologists, because sperm enters the uterus more efficiently during orgasm, it is adaptive for women to be able to influence whose sperm can fertilize an egg, which they can do by choosing with whom they have an orgasm. Francis then describes an alternative explanation for female orgasm suggested by Elisabeth Lloyd, a philosopher of science at Indiana University in Bloomington, and others. Their idea is to look at the constraints imposed by development: the clitoris is derived from the same ancestral genitals as the penis. Natural selection for the ejaculation of sperm has favored the male orgasm, and having a clitoris leads, as does having a penis, to orgasms.

Most examples in the book are about animal, not human, behavior. (Francis’s own research has focused on the astonishingly varied and flexible sexual behavior of fish.) He explains why fish change sex, and how some cichlid males can change from being small males without territories to large, dominant males with territories, and then back again. Those changes are probably not determined by natural selection on territorial behavior, Francis explains. Instead, they can be traced to the gonadotrophin-releasing hormone (GnRH) and its effects on the brain and body.

In another chapter Francis outlines research on sex differences in spatial ability, which investigators have studied in many animals, including kangaroo rats, voles, and people. The studies have discovered that males do better than females in various tests of spatial ability (though Francis argues that the data on people are dubious). In kangaroo rats and some vole species, investigators have found that male brains have a slightly larger hippocampus. Evolutionary psychologists maintain that natural selection has promoted a large hippocampus in male voles and kangaroo rats because spatial ability provides more reproductive advantages to males, who move long distances to mate, than to females, who stay home and let the males come to them. But, Francis reasons, in rodents the hippocampus is the site of GnRH production. To develop male gonads, a male must develop a larger hippocampus as well. Thus hippocampus size is related to sexual development, not to navigation, and there is no reason to imagine that selection on spatial ability has favored the large hippocampus of male rodents.

For some kinds of sexual behaviors, Francis combines physiological and adaptive explanations. He traces the weird sexual anatomy of female hyenas, whose clitoris looks like a penis, back to selection for female dominance. Female dominance, he notes, may be adaptive among hyenas, and selection for dominance would select for unusually high levels of androgen hormones in the developing female fetus. The female sexual anatomy thus need not be adaptive at all; instead, it probably originated as just a by-product of high female levels of androgen.

Francis gives a similar explanation for the exceptional mimicry of mockingbirds, suggesting that mimicry itself was not favored by natural selection. Mockingbirds belong to a lineage of birds that learn new songs throughout their lives. In some members of the lineage, males learn the song to which females are most receptive. Mockingbirds share with the rest of their lineage the neurological structures that make this learning possible. Francis suggests that in mockingbirds, this capacity leads to learning all the time, not just during mating behavior.

Francis is at his best when explaining physiological processes: his explanations are clear, straightforward, and step by step. In one section titled “Testosterone Rex,” he outlines the effects of testosterone on the brain. In a few pages he debunks the idea that testosterone makes men behave as they do. He notes that the action of testosterone actually depends on its access to the brain’s receptors for estrogen. And its action, in turn, depends on which genes have been turned on during early development. “Testosterone itself does not organize anything,” he concludes:

The credit for the organizing that gets done as a result of testosterone’s organizing effects should go primarily to the target tissues. . . . Next in importance, if we are ranking the developmental actors with respect to the magnitude of their causal role, are the androgen receptors. Testosterone comes in a distant third.

The descriptions Francis offers of animals and their behavior are vivid. Naked mole rats, he writes, are “shaped like late-season yams that have begun to sprout. . . . They seem to have been plucked from the womb much too early and then freeze-dried.” His sarcasm is usually light-hearted. In what Francis calls the “Fred and Barney” story—the names refer to characters in The Flintstones—he recasts the account of the behavior of our hunter-gatherer ancestors invoked by evolutionary psychologists: the men go out hunting while the women stay home cooking and cleaning. The story is supposed to explain why men don’t ask for directions: the idea is that women back then strongly preferred sexual partners who didn’t get lost on the hunt. If sons inherited the spatial abilities of their fathers, and women persisted in this preference, not getting lost would increase—until somehow, now, men prefer not to appear lost. Along with this far-fetched story, the imagined lives of Fred, Barney, and their friends have also been invoked to explain, Francis writes:

Why we are so prone to kill each other and why we die for each other, why we exhibit fidelity to our mates and why we are adulterous, why we court and why we rape, why we are doting parents and why we commit infanticide, why we are ethical creatures and why we are sociopaths, why we have rock stars, why we have art, why we have religion, why we have language, and why we wage war. All this may seem a heavy burden to put on Fred and Barney.

Francis’s emphasis on “how” rather than “why” questions points to the direction in which evolutionary biology will move. As more is learned about how organisms work, explanations based on physiological and ecological processes will replace hand-waving stories about how natural selection might have worked.

But I think Francis concedes too much when he accepts an adaptive explanation, if plausible, as probably correct. Empirical testing of evolutionary hypotheses is difficult, but not impossible. At least sometimes, it is already possible to do more than decide which explanation is more appealing. Research in evolutionary ecology can demonstrate how natural selection is acting now. The hope is that the more data available on the ways natural selection is currently working, the more realistic will be the stories of how it happened in the past.

Unfortunately, only the choir—people such as Gould, Lewontin, or Lloyd—seems to hear the preaching by critics of sociobiology and evolutionary psychology. It is hard to explain why—in spite of so much intellectual energy devoted to demonstrating the mistakes of sociobiology and evolutionary psychology—the scientific rebuttals have had so little effect. Simplistic evolutionary explanations seem to crop up like a pernicious fungus around every new discovery in behavioral science. Does the persistence of adaptive accounts of human behavior merely reflect a collective fondness for explanations that are easy to understand, and comfortable because they justify the status quo?

Francis offers a different reason for the current addiction to adaptive explanations. He suggests that the need for “why” answers is analogous to paranoia, to a delusional belief in the operation of an external force. Just as the paranoid thinks someone is always out there, trying to hurt him, so evolutionary psychologists think something is out there, making everything happen for a reason. That belief comes close to religious faith, and in biology Francis traces this belief back to William Paley, the nineteenth-century theologian who argued, against Darwin, that God, rather than evolution, creates species. Perhaps, Francis suggests, evolutionary psychology is best understood as religious faith dressed up as science.

Deborah M. Gordon is a professor of biological sciences at Stanford University and the author of Ants at Work: How an Insect Society Is Organized (Norton & Company, October 2000).

By Laurence A. Marschall

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Locust: The Devastating Rise and Mysterious Disappearance of the Insect that Shaped the American Frontier by Jeffrey A. Lockwood, Basic Books, 2004; $25.00

AMONG THE MORE THAN 30 MILLION ITEMS in the National Collections of Insects and Mites of the Smithsonian Institution is a pair of nondescript specimens: two dark grasshoppers of the species Melanoplus spretus, commonly known as the Rocky Mountain locust. In the 1800s vast armies of these creatures rose up every few years, rolling across the Great Plains and leaving nothing but ruin in their wake. Their approach was heralded only by an eerie grayness. Then the horizon disappeared beneath an advancing cloud of blackness, while a deafening buzz swelled out of the gloom. Frontier farmers ran for cover, choking and flailing at the air. The locusts shredded fields of ripening wheat, stripped the wood from the handles of farm tools, ate the very clothes off of farmers who ventured outdoors to drive them away. There were reports of trains unable to move, because the rails were greased for miles by the bodies of crushed locusts.

The devastation was biblical. A trained observer measured one swarm in Nebraska to be at least 110 miles wide. The swarm included an estimated 3.5 trillion insects. No wonder, then, that the homesteaders viewed the locusts as the wrath of an angry God.

More pragmatic souls devised ways to fight back, patenting devices like the King Suction-Machine, a horse-drawn contraption that vacuumed locusts into a chamber where they were hurled to their deaths against a wire screen and blown into bags for disposal. But nothing proved effective. It is no exaggeration to say that locusts were a critical factor in limiting growth on the American frontier, as well as in allocating public resources—as important to consider as climate, railways, and the struggle with Native Americans.

Yet the two insects in the Smithsonian collection are notable for another reason: they were the last living specimens of the Rocky Mountain locust. Because major infestations were sporadic and unpredictable, no one in the 1890s had noticed that the locust populations were in decline. Norman Criddle, a Canadian naturalist who collected the two museum specimens in 1902, had no way of knowing that the little dark grasshoppers would never be seen again. Yet, as if the prayers of the pious had been answered, the Rocky Mountain locust disappeared from the face of the Earth.

To the admittedly small company of grasshopper lovers (doubtless more numerous now, however, than in the 1800s), the disappearance of the Rocky Mountain locust remained one of the great biological puzzles of all time. Had some inadvertent environmental insult made it impossible for the locusts to survive? Had the settlers’ infernal contraptions and pesticides accomplished their intended task after all? Had the locusts transformed (as some insects have been known to do) into an alternate form—a different-looking, more benign grasshopper?

The mystery was finally solved by Jeffrey A. Lockwood, an entomologist at the University of Wyoming in Laramie, who, after considerable searching, found frozen remains of locust swarms in remote glaciers in the Rockies. With modern techniques, Lockwood and his collaborators could rule out many of the old theories. Finally, over the decade of the 1990s, a satisfying picture of the fate of the insect emerged. Lockwood deserves credit, not only for his scientific acumen but for being a first-rate writer of natural history, and I will not spoil a great story by giving away his best lines. Suffice it to say that he has brought the Rocky Mountain locust to life, thankfully only on the pages of this lucid and eminently entertaining book.

Our Affair with El Niño by S. George Philander Princeton University Press, 2004; $26.95

FOR CENTURIES, RESIDENTS OF PERU’S ARID COAST have welcomed a warming of the normally frigid offshore waters, which comes every few years at Christmastime. They called it El Niño, Spanish for the baby Jesus. Fishermen still look to El Niño’s arrival as a temporary respite from their work; most of their edible catch thrives best in colder waters. But when the waters of El Niño are particularly warm and linger longer than usual, the effects on local climate can be memorable. “The desert becomes a garden,” recalled a visitor in 1891. “The soil is soaked by the heavy downpour, and within a few weeks the whole country is covered by abundant pasture.” Residents have reported armies of yellow-and-black water snakes floating in balmy swells, along with bobbing armadas of bananas and coconuts.

These mysterious effects hinted that El Niño was somehow connected with events far from the shores of Peru, and that, indeed, turned out to be the case. During the International Geophysical Year (actually an eighteen-month period from July 1957 until December 1958), a worldwide collaboration to collect data on the state of the planet, oceanographers first recognized the phenomenon for what it was: Peru’s El Niño was just the easternmost edge of a strip of unusually warm water that periodically overspread the equatorial Pacific. What’s more, they discovered, El Niño has a sister phenomenon, La Niña, a period of unusually cold waters that seemed to alternate with El Niño.

At the same time, meteorologists recognized characteristic shifts in the patterns of prevailing winds accompanying the seasonal temperature changes. Within a few decades El Niño’s influence had been linked to a wide variety of weather and climate changes thousands of miles from its origin: the arrival of monsoons in India, the severity of winters in the United States, the intensity of droughts in southern Africa. Today scores of buoys continuously monitor wind and water conditions across the Pacific, updating El Niño’s vital signs (check out www.pmel.noaa.gov/toga-tao).

There’s a danger, though, warns S. George Philander, a geoscientist at Princeton University: all the supposed linkages can get pushed too far. In the popular mind El Niño has become the whipping boy for any change in climate that seems out of the ordinary.

The real phenomena, Philander explains, are far more complex. As elaborate as computer models of climate are today, they can only begin to approximate how water temperatures affect winds, how winds affect ocean currents, how increasing carbon dioxide alters baseline ocean temperatures, and how a host of other factors combine. Climatologists are only beginning to turn today’s weather data into a reliable guide to the climate of the future.

El Niño is not just an oceanographic and meteorological curiosity. It has also come to prominence at the right time for focusing attention on the complexities of global climate. Environmental science and policy will turn to El Niño both as a starting point for research and as an object lesson on the connectedness of nature.

Walden Pond: A History by W. Barksdale Maynard Oxford University Press, 2004; $35.00

ASKED TO NAME THE MOST IMPORTANT BODIES OF WATER IN THE U.S., an Australian schoolboy in the 1940s listed the Great Lakes, the Mississippi River—and Walden Pond. That’s mighty impressive company for Walden, a freshwater lake outside Concord, Massachusetts, that is popular with residents of the western Boston suburbs as a picnic area, fishing hole, and bathing site. Measured by its area (barely sixty acres, depending on seasonal rainfall) or commercial value, Walden Pond surely isn’t worth much more than any similar plot of real estate in New England. Yet the schoolboy was right: it is hard to think of a place of greater importance to the intellectual and spiritual development of the U.S.

A century and a half has passed since Henry David Thoreau wrote Walden; or, Life in the Woods, a chronicle of the author’s two years of “deliberate living” in a small cabin on the lake’s northeast shore. But that brief historical connection has made Walden Pond a holy shrine of the environmental movement. W. Barksdale Maynard, an architectural historian, begins his exhaustively researched narrative with Thoreau’s first visit to the shores of the pond, at age four, in 1821. Maynard’s real story, though, is the sometimes rocky history of the pond’s “beatification,” which he brings up to the present day.

Even before Thoreau’s essay, Walden Pond exerted a magnetic appeal on writers such as Ralph Waldo Emerson, who saw the pond and its surrounding territory as an American counterpart to England’s Lake District. There, William Wordsworth and other English Romantic poets advocated rusticity, in the form of rough-hewn cottages and quiet country lanes, as an antidote to the corruption of industrial civilization. Concord, even wilder and more rough-hewn than the English countryside, was a natural pulpit from which Emerson could preach the “Transcendentalist” gospel of nature, urging his contemporaries to leave the bustle of city life and seek peace and spiritual renewal among the pines.

Maynard puts Thoreau’s great work squarely in the context of the Concord Transcendentalists, and shows how the modern conservation movement took root along the shores of Walden Pond. Walden Pond was not written as an environmental tract. But it is easy to see the pond as a microcosm of the struggle between conservation and development anywhere on the planet.

Even in the 1840s the pond was visited frequently by fishermen and woodcutters, and Thoreau could hear the rumble of the Boston-to-Fitchburg railroad as it passed along the western shore. After Thoreau left, his humble house was moved, and later torn down. Local memory of the site began to fade. In the late 1800s developers established a commercial picnic grove and amusement park along the railway at one end of the lake, and Walden Pond and its surrounding woods faced continuing threats from local developers right through the twentieth century.

Yet in those same years Thoreau’s essays were becoming part of the canon of American arts and letters. As the country grew and development advanced, a largely successful effort to preserve and protect Walden Pond was carried on by the heirs of the Transcendentalists. Early on the preservationists included such Concord landowners as the Emersons, but, eventually, a host of people, inspired by Thoreau’s writings were moved to help: from the ant expert, Edward O. Wilson of Harvard University, to Don Henley, a singer and drummer with the Eagles.

Books about the history of famous places seem destined for souvenir shops, where they may be purchased to sit on living-room bookshelves, unread. It would be a shame if Maynard’s book were to share this fate, for it is important, illuminating, and of great narrative appeal. So read this Walden, perhaps after you’ve reread Thoreau’s, at the shores of the pond or ocean of your choice.

Laurence A. Marschall, author of The Supernova Story, is the W.K.T. Sahm professor of physics at Gettysburg College in Pennsylvania, and director of Project CLEA, which produces widely used simulation software for education in astronomy.

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Olympian Sites By Robert Anderson

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The Olympic Games are rooted in something far more ancient than the first footraces held at Olympia in the eighth century B.C. Many people, it seems, are naturally drawn to physical superlatives—strongest, fastest, fittest. Independently, ancient cultures evolved formal competitions to show off these attributes. A thousand years earlier, Egyptian athletes swam in the Nile and played tug of war and gymnastics (see www.touregypt.net/historicalessays/ancsportsindex.htm). In the New World, Mesoamericans competed in ballgames—often to the death—as early as 1500 B.C. (see www.ballgame.org).

Yet it is the Greek tradition of competition we celebrate. To search the Internet for information about the first Olympic Games, start at Rodney Polasky’s site (www.archaeolink.com). Click on “Ancient Civilizations” and search the list of specialized topics for “Ancient Olympic Games.” Polasky, an archaeologist and Web publisher, presents an impressive register of Olympic-related links.

First on the list is a link to a page from a special exhibit posted at “The Perseus Digital Library,” at Tufts University. Among other things, the page describes all the ancient sports in detail, including chariot racing and the pancration (a combination of boxing and wrestling, spelled pankration on the Web site). [See “With Hands or Swift Feet,” by David C. Young.]

When you’re tired of tuning in to the remote past, you can fast-forward to the 2004 games (www.athens2004.com) and preview this summer’s events and venues in and around Athens.

Since the revival of the games in 1896, science has played an ever-larger role in helping athletes gain a critical competitive edge. In 1996, when the summer games were held in Atlanta, a site known as “The Why Files,” maintained by the University of Wisconsin–Madison, addressed the subject with what is still the best general introduction to the topic. On the site is a special fourteen-page section called “Sport science meets the Olympics” (whyfiles.org/019olympic).

Today’s professional athletes can combine the latest innovations in science and technology to scrutinize their own performances and find out what it takes to win. To see one example of how it’s done, go to the site of the pioneering sports biomechanist Gideon B. Ariel (www.sportsci.com). A former discus thrower and member of the Israeli Olympics team, Ariel owns a company specializing in computerized performance-enhancement products. Take a look at the site’s collection of video segments (www.sportsci.com/media). They include “The Perfect Jump,” a glimpse of Bob Beamon’s world-record-shattering long jump in 1968, and Carl Lewis’s quest to beat it in the 1984 Olympics. (Lewis never did, but Mike Powell outjumped Beamon by two inches in 1991.)

How do athletes—even the ones with access to the latest techniques and technology—stack up against the rest of the animal kingdom? You can find world and Olympic records for people on a page of the official Olympics site (www.olympic.org); just enter “Olympic records” or “world records” on the site’s search engine. And Petra H. Lenz, a neurobiologist at the University of Hawai’i in Honolulu, has tracked animal Olympians (www.pbrc.hawaii.edu/~petra/animal_olympians.html). On her site I learned that human beings don’t even hold the record for being the fastest primates; that title belongs to the patas monkeys, which can sustain running speeds as fast as thirty-four miles an hour. (Compare that with the speeds of the fastest human runners: sprinters have reached a speed—albeit for only an instant—of just over 26.5 miles an hour; the fastest average speed clocks in at a little more than twenty-three miles an hour.)

“OceanLink” (oceanlink.island.net/records.html), maintained by the Bamfield Marine Sciences Centre in Bamfield, British Columbia, has data for many marine-animal record breakers, in a number of categories: the fastest fish, the Indo-Pacific sailfish, has been clocked at 68.18 miles an hour, whereas the sea horse ambles along at about one foot per minute (0.01 miles an hour).

At “The University of Florida Book of Insect Records 2003” (ufbir.ifas.ufl.edu), investigators have tracked the medal winners in the six-legged category—from the fastest flyers and runners to the insect with the shortest reproductive life. A species of Australian tiger beetle wins the gold for running speed, at 5.6 miles an hour.

If any of these sites pique your interest for the latest experiments in animal locomotion, check out a site maintained by Robert J. Full, a biologist at the University of California, Berkeley (polypedal.berkeley.edu). To hear Full’s lecture on his experiments with giant cockroaches and centipedes, and to watch the insects running on a treadmill, click on “Intro to Bob Full’s Projects” and then on the “locomotion” icon.

Robert Anderson is a freelance science writer living in Los Angeles.

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Copyright © Natural History Magazine, Inc., 2004