Zoobiquity

  Movies like these have been terrifying teens for decades. Seen from an animal behaviorist’s perspective, though, they may simply be a cinematic tool adults have created to compel human adolescents to inspect their biggest killer: motor vehicles.

  Although the threat posed by cars is new, the techniques employed by Red Asphalt are age-old. From frightening campfire stories of what lies in the woods to 3-D surround-sound gorefests, human culture routinely uses tales of murder and peril to scare and then instruct. Not only are they age-old, but they’re also incredibly popular. And who’s drawn to them? Adolescents. Hollywood is populated by wealthy producers who figured out that, like young animals, teenagers will flock to horror movies and gaming worlds their parents have outgrown. A quick glance at the line for a monstrous roller coaster will similarly tell you all you need to know about which age group is drawn to the simulated danger but chemically identical adrenaline rush of a perilous fall. We may not think of these mass entertainments as evolutionarily linked to the antipredation strategies of other animals. But just like mature animals mobbing predators to teach youngsters, human grown-ups write the stories, produce the movies, and build the roller coasters—making money off teens’ inherited physiological craving for calculated risk.

  Learning to deal with threats doesn’t involve only confronting them head-on. It also involves learning when and how to hide from them. For every parent who’s been frustrated by a teen who won’t meet their gaze, consider what direct eye contact can mean in the wild. It often means you’ve been targeted. While baby animals often stare at everything around them, adolescents must learn that catching the gaze of the wrong set of eyes can be deadly. Looking-away responses have evolved in many animals, from mouse lemurs to jewel fish. Staring at chickens and lizards causes them to become rigid. House sparrows take flight more readily when eyes are directed at them. Gaze aversion in animals begins during the transition from infancy to adulthood. Studies of humans note a surge of eye gaze aversion in the preteen and teen years.

  While young animals are learning how to be vigilant, they can at times be overattentive, identifying threats where none exists. Some overreact to every rustling leaf, looming shadow, or strange smell. I once watched a group of about thirty sea otters startle at a loud noise that turned out to be a false alarm. As the frightened animals raced away to the other side of the lagoon, the adolescents led the way, cutting through the water with full-out swimming strokes. Leisurely pulling up the rear, carefully keeping their heads dry, were the mature otters, who’d had more experience with true danger.

  As they test their danger-detection skills, inexperienced yet eager-to-learn vervet monkeys, beavers, and prairie dogs often cry or scream out unnecessary alarm calls. The older members of the group can be surprisingly forgiving toward youths who cry wolf (or jaguar, snake, or owl)—responding with a reassuring return call or simply ignoring the errant signals.

  But learning to recognize and avoid predators is really just preparation for a vastly more important and riskier moment in most young animals’ lives: leaving the nest.

  The young of many species leave their families in adolescence, sometimes for a temporary journey of discovery, sometimes for good. Leaving home, a process behaviorists call “dispersal,” varies from animal to animal, by species, and by sex. But whether undertaken by a caterpillar or a zebra, it’s an exceedingly dangerous time of life.

  Vervet monkeys make an interesting example because their social progression parallels many classic human tales of young men going off to prove themselves. These clever, cat-sized primates, found in sub-Saharan Africa and on the Caribbean islands of St. Kitts and Barbados, have gray-green fur on their backs, whitish bellies, black faces, and wide, soulful brown eyes. Vervet childhood will sound familiar to many human parents. During an extended infancy that lasts for about a year, a baby vervet sticks close to its mother. At a year, the young monkey’s circle widens to include adult members of the group. Yearlings of both sexes play boisterous chase-and-wrestle games.

  As they move into their second year—which corresponds roughly to eight to ten years of age in people—the boys’ play becomes more frenetic and intense. But the girls drop out of the rough-and-tumble games, their attention suddenly caught by different diversions: playing with infants and figuring out the social hierarchy in which they will spend their lives. Vervet females do not leave their birth group.

  Vervet boys follow a different path. Males must strike out into the world on their own, leaving everything behind. Relatives and friends. Familiar foraging territory. Group and adult protection from predators.

  But danger comes not just from isolation and the predators they may meet along the way. It’s also in the social minefield they’re heading into. They must join a new group of monkeys. Approaching and integrating into a vervet group makes our tortured process of applying to college or getting a first job seem almost easy. All alone and newly independent, the adolescent has to first locate a group of strangers. He has to approach them. Then he has to threaten, challenge, try to intimidate, and, finally, fight the dominant, mature males. But diplomacy is critical. If he comes on too strong, he will lose the respect and tolerance of the females in the group—which can be a deal breaker, since vervet groups are matrilineal and females wield the power. Vervet females will not tolerate being threatened. Scaring babies is also strictly taboo. So while he’s trying to intimidate the males, the adolescent newcomer has to simultaneously charm the females.

  Lynn Fairbanks, a professor of psychiatry and biobehavioral sciences at UCLA, has spent more than thirty years studying wild and captive populations of vervets. She told me that these weeks of male transition are extremely stressful, yet exceedingly critical. How the adolescent performs may affect his status and his access to mates, food, and shelter for the rest of his life. And intriguingly, Fairbanks has discovered that the males who transition most successfully are the ones that show a special willingness to “go for it.”

  As she told me, in vervets, a degree of impulsivity may be “necessary.” It motivates males to leave home and take on the challenges and risks of getting into a new group.

  While most vervet immigrants have to settle for second-tier status, the ones who become alphas in their groups share another common trait. Their brashness emerges strongly during adolescence but doesn’t stay at peak intensity forever. After they achieve dominance, their impulsivity sinks down to more moderate levels. Fairbanks writes that her findings support “the idea that an age-limited increase in impulsivity in adolescence is not a pathological trait, but instead is related to later social success.” In other words, acting a little cocky when you’re a teen may not necessarily mean you’re going to turn out to be a wild adult. It might even push you up the social ladder.

  A similarly lowered risk threshold—indeed, a new pleasure in risk taking—likely propels nearly grown birds out of nests, hyenas out of communal dens, dolphins, elephants, horses, and otters into peer groups, and human teens into malls and college dorms. As we’ve seen, having a brain that makes you feel less afraid enables, perhaps encourages, encounters with threats and competitors that are crucial to your future safety and success. The biology of decreased fear, greater interest in novelty, and impulsivity serve a purpose across species. In fact, it could be that the only thing more dangerous than taking risks in adolescence is not taking them.

  Linda Spear, a professor of psychology at the State University of New York at Binghamton and the author of The Behavioral Neuroscience of Adolescence, agrees. During years of studying the neurology of humans and other species, she has observed “age-specific behavioral characteristics.” She explains that, although we notice behaviors in the context of what we call human “culture,” adolescent transformations have biological underpinnings and “are deeply embedded in our evolutionary past.”

  In other words, what we observe as uniquely human adolescent behavior may in fact be shared physiology at work. Admittedly, humans do have a unique ingenuity f
or amping up the danger. When an adolescent rat or vervet monkey impulsively bursts out to explore something new, he’s not also piloting a two-ton SUV full of his friends. A gazelle in thrilling pursuit of a cheetah isn’t also tripping on the latest designer drug.

  For human parents, knowing that brain and body shifts are causing predictable and universal behaviors is not going to relieve the worry of late nights or the anguish of seeing a tattoo around the ankle of a formerly straight-arrow daughter or son. It certainly won’t ease the grief of a parent who’s lost a child to what seemed like extreme or unnecessary risk. But putting adolescent impulsivity in a context that sees it as not just normal but physiologically and evolutionarily necessary may make bewildering behavior slightly more bearable.

  A number of miles south of the Triangle of Death, near the Moss Landing power plant and slough, there’s a sheltered lagoon. Beginning kayakers come here to practice paddling. Ecotourists can board an open-air safari boat to view harbor seals and pelicans. But the sightseers’ biggest draw is a group of fifty or so sea otters calmly rafting, grooming, foraging, sleeping, spinning, and occasionally wrestling in the tranquil water.

  I spent an overcast August morning observing the Moss Landing otters with Gena Bentall, a research biologist for the Sea Otter Research and Conservation Program at the Monterey Bay Aquarium who has spent thousands of hours documenting the behavior of these marine mammals. As her beagle, Harry, watched from his special bed in the back of her pickup truck, Bentall and I discussed the single distinguishing feature of this otter group: they’re all male. Ranging in age from sleek, dark adolescents to grizzled mature adults, these he-otters use the Moss Landing site as a stopover rest area. After swimming long distances along the California coast to breed, explore other territories, or challenge other males, an otter will pull into the Moss Landing lagoon. Some are full-time residents. Some show up only at night. For some, the Moss Landing group is a part-time sanctuary. Food is plentiful; predators are minimal; responsibilities are few. It’s a place where territorial males can pass time in a nonterritorial mode and young males can learn the ropes. The relaxed camaraderie of the group reminded me of a men’s locker room—a place for growing and grown men to gather, groom, eat, nap, socialize, and play … without having to compete for females.

  Adolescent male dolphins, elephants, lions, and horses, as well as the teen males of many primates, join so-called bachelor groups like this in the period between leaving their birthplace and starting their own families.

  Adolescent African elephants, for example, use them to prepare for the “ritualism of male-male competition,” by sparring with other males their own age. According to biologists Kate E. Evans and Stephen Harris, of the University of Bristol, adolescence is an “important learning period” for these young pachyderms, a time of transitioning from “the highly structured breeding herd” to the “much more fluid social system of adult males.” Bulls fake-fight with each other as adolescents to determine who is dominant at that moment, and to learn the rules of “bull society.”

  These groups of young male elephants are especially friendly compared to groups of older animals; they greet one another with gestures like trunk entwining, ear flapping, trumpeting, and joyful defecation. Gena Bentall has cataloged similar familiar greeting behaviors among groups of sea otters, who shove, stroke, nose, and sniff one another. Male wild horses and zebras, which also migrate into all-stallion groups when they leave their birth herd, at about two or three years old, bond through roughhousing and frisky urination.§

  Evans and Harris spotted a notable interloper in the adolescent elephant groups: older male bulls. But instead of treating these older males as unwelcome chaperones, the younger elephants seemed to prefer having them around. Evans and Harris write that the elders serve as mentors, socializing the younger elephants and helping them learn to “become dominant males without posing a competitive threat.” They also reported that the presence of the mature bulls seemed, in some cases, to suppress testosterone-driven pugnacity in the younger animals.‖

  Sea otter bachelor groups also include males of mixed ages. Although Bentall did not speculate on whether the presence of the older males affected the younger males hormonally, she said that one of the ways the Moss Landing adolescents find their way to the sheltered lagoon in the first place is by following a mentor male.

  For California condors, mentors have played a key role in reeling this endangered species back from the brink of extinction. In 1982, with just twenty-two of these enormous birds left in the world, biologists took emergency action with an accelerated breeding program. By carefully removing eggs from nests as soon as they were laid, the scientists were able to begin building a captive breeding population. By 1992, wildlife conservation teams were ready to reintroduce the condors to their natural habitats in California’s redwood and mountain regions.

  But they ran into an unexpected problem. They had modeled the release plan on the successful North American reintroduction of the peregrine falcon several years earlier. In that program, biologists had flooded the landscape with fledglings—young birds that were strong enough to fly but still sexually immature and in transition between needing parental care and being able to fend for themselves. The transitioning adolescent falcons had no trouble moving out into the surrounding territory and before long began breeding with one another, reviving the population of the species.

  But the condors were different.

  As Michael Clark, the head of the Los Angeles Zoo’s California Condor Propagation Program, explained to me, unlike peregrine falcons, which are more solitary and don’t need mentors, California condors are extremely social. They go through a long preadult phase, during which, by imitation and example, they learn complicated condor conventions for everything from foraging and feeding to resting and nesting. Key to their learning process is living in multiage groups where younger birds can observe older mentors. Hatched in incubators and raised by humans in condor orphanages, the early groups of chicks did not have this experience. Releasing the socially inept preadults created what Clark called a “Lord of the Flies situation.” The inexperienced birds didn’t know what to do when they were out on their own. Some ate garbage and got sick from malnutrition and poisoning. Not knowing better, some landed on telephone poles and electrocuted themselves. Many hung around the release sites before eventually, slowly, moving out into new territory. But perhaps most poignant of all, in the absence of competent adult leaders, some birds followed anything that soared—from eagles to hang gliders. One young bird flew from the Grand Canyon to Wyoming in a single day, dutifully following a false mentor and winding up miles away from home at the end of the day.a

  Group life provides animals with many long-term benefits. But sometimes what pulls individual adolescents into groups are short-term brain-based rewards. As Alan Kazdin, a professor of psychology and child psychiatry at Yale and the director of its Parenting Center and Child Conduct Clinic told me, research has shown that simply being physically next to same-aged peers and engaging in activities with them activates pathways for dopamine and other reward neurochemicals.

  “Having peers around is a reward and not having them around is felt as the opposite, which begins to explain your 14-year-old’s sullen, moody, heedless demeanor around the house,” he noted wryly in Slate magazine.

  Although bachelor groups are seen in many species, adolescent animal groups are not always single sex. Transitioning albatrosses form coed groups called “gams” for several months between fledging and starting their own families. Although they mingle with the opposite sex, they don’t mate. Zebra finches, too, congregate in mixed-sex peer groups. Males fine-tune their courtship songs for females and practice outsinging other males. Boy and girl finches preen together; every once in a while the young birds’ groups break apart so the kids can fly back to their parents’ nests and beg for food—a tendency that may sound familiar to many human moms and dads.

  Ancient adolescents also formed group
s. One fossil band of dinosaurs was found in a ninety-million-year-old lakebed in Mongolia. They were all between the ages of one and seven—still a few years away from their species’ sexual maturity, typically seen at ten years of age. Paleontologists suggested that these two-legged plant eaters may have roamed together in social herds without adult supervision.

  Pink salmon, too, grow up entirely without the watchful eyes of parents. A few days after hatching, they emerge from their gravel nests and, under cover of darkness, begin to migrate downstream to the open ocean. Before diving into the wide water of the northern Pacific, however, the young fish stop for a week or two in the shallow, calm waters of coastal estuaries. It’s here, in this safe environment, that the preadults start figuring out how to swim in a school. First, they group in twos and threes. A few days later, larger groups of five and six eventually combine into a much larger formation. Their daily schedule is much like a human adolescent’s. Mornings and afternoons are spent in the school. At nightfall, the groups break up, and the young fish drift individually around the surface of the water before coming together again in the morning. As the salmon learn the choreography and conventions of their fish life, they are also figuring out where they fit into the salmon social hierarchy. With no adult fish to model ideal behavior, the adolescents rely on innate instincts and trial and error to figure out how to get the best feeding spots and secure dominance as adults. It had never occurred to me that fish need to learn the iconic synchronized swim patterns we call schooling. Or that some would be better at it than others.

  Schooling, herding, or flocking—moving within and belonging to a group—gives protection to an individual exiting infancy. A group means more lookouts, more eyeballs, more voices to raise danger alarms. But it comes with a price. Individuals coming together to form a group must learn to be inconspicuous. One fin sticking out in an odd direction, a zig when the rest of the group zags, flashing white fur or feathers when all its peers are wearing gray—anything odd or conspicuous makes an animal more obvious to a predator. Adolescent lessons in blending in may serve an animal well for the rest of its life.