Zoobiquity (23 page)

Early one morning I walked in on this tableau: French fries wilted in their own grease on paper plates holding burger scraps and ketchup smears. A yellow bag of M&Ms gaped open beside a gutted sack of Doritos. Half-empty soda cans stood near a pizza box glistening with rainbow streaks of congealing oil.

This wasn’t a frat house on Sunday morning or a bulimic’s bedroom. No, this was the on-call room used by the overnight team of a cardiac care unit (CCU). The young doctors who had created this mess were on their cardiovascular medicine rotation; some were deep into their training to become cardiologists. These physicians, handpicked from the best med schools, had spent the past twenty-four straight hours treating some of the deadliest conditions known to modern humans: heart attacks, artery ruptures, strokes, and aneurysms. Their night had been a whirlwind of chest pain, abnormal EKGs, angiograms, defibrillations. And most of this trauma had been caused by their patients’ underlying coronary artery disease, the leading killer in the United States, which is strongly linked to diets high in sugar, refined carbohydrates, salt, and certain fats.

Throughout my training, in teaching hospitals around the country, catering departments would lay out what used to be called “midnight meals”—sumptuous spreads of pasta, sandwiches, thick cookies, granola bars, hamburgers, greasy fries, and candy. These spreads were reward and encouragement for our extreme working hours. They were good opportunities to bond with our colleagues. But for many of us, the unfettered access to all that tasty temptation in the middle of the night, with the overlay of constant stress, was precisely the “obesogenic” environment we now routinely tell our patients to avoid.

You don’t have to be a cardiologist to know what you
should
eat, or at least that a diet of candy and pizza is problematic. But this is precisely why that CCU on-call room is so illuminating. Cardiologists see with their own eyes and hold in their very hands the diseased body parts that come from eating poorly. Putting aside the CCU interns’ and residents’ youthful sense of invulnerability, a junk-food–eating cardiologist seems like a medical oxymoron. Along with other subspecialty death wishers, including chain-smoking oncologists and alcoholic hepatologists, they are the living (for now) embodiment of the cognitive disconnect between intention and consumption. We consume the dietary weapons of mass destruction even when all our training and experience tell us not to.
A survey of almost 300,000 U.S. physicians conducted in 2012 revealed that 34 percent of cardiologists report being overweight, with 4 percent actually obese. Forces beyond knowledge and free will are clearly at play when we eat.

The evolutionary biologist Peter Gluckman calls contemporary obesity an example of “mismatch,” the widening gulf between our genetic inheritance and our environment. (From animal ancestors we’ve inherited eating behaviors that evolved to keep us alive through feast and famine. But thanks to human culture, we’ve created a mismatched, fat-promoting environment of Frosted Mini-Wheats and electric skateboards.)

Mismatch explains why that scene in the CCU on-call room, instead of being the embodiment of what’s
worst
about the way we eat, may represent the legacy of millions of years of inherited eating strategies that have
worked
. And the young on-call doctors are not alone in preferring cookies and other treats when given the opportunity.

In the dry western United States, red harvester ants have adapted over millions of years to eat seeds. For them, it’s an ideal food source. Seeds
store well. They provide nutrients—protein, fat, carbohydrates—in good ratios.

Seed eating essentially makes these animals vegetarians. But put a slice of tuna in front of the ants, or a sugar cookie, and watch what happens. Forget the carefully calibrated generations of evolution. Forget millions of years of natural selection favoring prudent food-storage behaviors. Those ants devour the meat and the cookie.

Something similar happens with marmots.
These sandy-blond rodents live in alpine areas around the world, including California’s Sierra Nevada and Colorado’s Rocky Mountains. They’re mostly herbivorous, feeding on grasses, although they will eat the occasional spider or insect. Yet biologists who’ve spent careers studying them say that these preferential vegetarians will wolf down raw meat given the slightest opportunity. So will chipmunks and squirrels, who are vegetarian except when they are lactating; then they become not only carnivores but cannibals, eagerly scarfing down road-killed kin.

The reason, says the UCLA evolutionary biologist Peter Nonacs, is pretty simple. Ounce for ounce, meat and processed sugar offer the most nutrients for the least amount of effort. They provide more calories, and they’re more digestible. As he puts it, “
You don’t have to eat a lot of meat to survive.” Harvesting a pile of seeds requires a lot of work. Munching on bales of grass requires energy. If an ant or a marmot can skip all that and get straight to the nutrients, that’s what it will do.

Evolutionary biologists think the desire for protein—which includes the taste for fat and salt—is an ancient, long-preserved mechanism. A drive for sugar is probably slightly younger, most likely arising about a hundred million years ago, when plants began flowering and concentrating sugars in their seeds and fruits. As humans, we share ancestors—and we also may share urges—with protein- and sugar-seeking animals.

This suggests that the scene in the on-call room, with its fatty pizza, sugary candy, and salty fries isn’t necessarily an example of depraved human eating. It may be more a demonstration of preserved food-class preferences. If, for hundreds of millions of years, animals have shared the urge to snatch protein, fat, salt, and sugar, it’s almost naively optimistic to think that hearty advice to “just resist junk food” and “eat a healthy diet” could compete with it.

Modern-day food manufacturers, perhaps cynically, have hitched a ride on these evolutionary urges by amping up those elements in their
products. There’s a reason you can’t eat “just one.” In an analogous situation, a marmot can’t either.

And sometimes that’s okay. Animal weight goes up and down—in some cases dramatically and several times throughout the year. Throughout the animal kingdom, this is a sign of health. Indeed, zoo nutritionists do not set single weight goals for the animals in their care. They establish weight
ranges
, and they worry if animals from giraffes to snakes don’t move from one end of their range to the other, depending on the season and life stage. In the wild, males of many species fatten in the weeks prior to mating season. Female animals store body fat to nourish eggs and support milk production or other food provisioning for their young. Seals, snakes, and other animals whose bodies require a calorie-draining molt are obliged to store energy as fat in the days and weeks leading up to it. Hibernation, iconically, requires a tremendous shift in body mass to support a months-long fast. Migration, too, triggers key fattening and thinning cycles. And among the most metabolically taxing moments in any animal’s life are its first few hours or weeks after being born. Infancy is a time of peak fatness for many creatures, from nestling birds to newborn humans.

Even insects’ body fat goes up and down during critical phases of their lives. Some fatten before metamorphosis or laying eggs. With adequate nutrition, bees produce fat in bulk: honeycomb wax is a form of apian fat. And fat exists in plants, too—as waxy, waterproof coatings on leaves and fuel packs in seeds.

But nature imposes its own “weight-maintenance plan” on wild animals. Cyclical periods of food scarcity are typical. Threats from predators limit access to food. Weight goes up, but it also comes down. If you want to lose weight the wild animal way, decrease the abundance of food around yourself and interrupt your access to it. And expend lots of energy in the daily hunt for food. In other words: change your environment.

This is something many zoos are already doing.

If you happen to find yourself at the Copenhagen Zoo at just the right time, you’ll witness something one won’t see at many other zoos around the world.

A dead impala lies in the middle of an enclosure. Crawling over it, like flies on a discarded slice of salami, are a dozen or so lions. The full-grown male with his distinctive mane sits high on the beast, tearing
at its throat and face. A couple of favored females crouch near him, methodically munching. Two or three others work on the carcass’s abdomen, loosening the entrails inside. Young cubs—as supple-limbed and clumsy as puppies—dart in and out between their elders, snagging jawfuls of flesh, their muzzles dripping with blood. There’s an eerie hum of contented growly purrs, punctuated by the unique snap of teeth going through bone. The big cats stuff themselves until they can barely move, their eyelids drooping in a satisfied daze.

This human-staged simulation of a feast on the African veldt is known as carcass feeding. Nutritionists at the Copenhagen Zoo and others who carcass-feed their lions, tigers, cheetahs, wolves, jackals, and hyenas choose the prey carefully. They make sure the carrion is free of disease and that it’s appropriately nutritious. Often the animal to be eaten is from another part of the zoo, euthanized and “recycled” as a meal for the carnivores. Proponents say this whole-food approach (hooves, fur, eyeballs, and all) gives the meat eaters a figurative and literal taste of how they would consume meals in the wild, the way nature intended.

However, detractors (mostly in North America and some parts of the United Kingdom) say the practice is cruel, not to mention off-putting for visiting families unaccustomed to such natural carnage. So although many of them are privately in favor of carcass-feeding, British and American zoo nutritionists bow to public opinion. They serve meat that’s already dismembered or entirely ground up. On the occasions when they do feed an animal, say, a big bloody beef leg or haunch, they do it behind the scenes (“off-exhibit”) or after hours.

When I asked Mads Bertelsen, a veterinarian at the Copenhagen Zoo, about carcass-feeding, he was unapologetic.

“
It’s what the animal is meant to do,” he told me. Zoos that avoid it for fear of a public outcry are, he said, “bending to a minority of loud voices.” He pointed out that if you feed a tiger a patty of minced horse meat, it’s still eating a horse but receiving none of the nutritional benefits of crunching though bone, gnawing on gristle, and digesting fur and hair. Indeed, zoos that allow their carnivores to feed on the whole prey animals they would naturally hunt (Tasmanian devils on kangaroos, lions on elands, cheetahs on gazelles) notice cleaner, stronger teeth, healthier gums, and even positive behavioral changes, like a more relaxed demeanor. Like most vets, who abhor anthropomorphizing the animals
in their care, Bertelsen stopped short of saying the lions in Copenhagen experience pleasure while they’re eating in this more natural way. But he did grin and say that the felines “seem to be having a good time.”
^*

Reconciling how an animal eats in captivity with how that same animal might eat in the wild is a challenge for the veterinarians who treat them and the nutritionists who formulate the menus. In the wild, an animal ideally has free access to choose and eat the healthiest and best-balanced meal it can get its fangs and claws on. But more important, its food is intricately connected with the many activities—both physical and cognitive—it must undertake to get it. Stomach and spirit are rarely separated in wild meals, whether in the thrilling adrenaline rush before a chase, the reward of a morsel of clam meat after wrestling the shell open, or the relaxing sensation of a full belly after a period of hunger.

For a zoo animal, however, feeding decisions for the most part are made
for
him. What he eats. When he eats. How much and even where he’ll eat. Yet while a zoo environment limits the whole fleet of inherited, wild instincts to hunt, forage, and be alert to danger, it doesn’t entirely erase them. Carcass-feeding is one way to put feeding decisions back in the paws and snouts of zoo animals. Creatively spreading forage items like string beans around an enclosure is another. It gives an animal more control and more challenge than does simply slurping chow out of a bowl. Modifying an animal’s surroundings in order to improve its health or well-being is called “
environmental enrichment.”

Environmental enrichment as an animal husbandry standard came into its own in the 1980s, largely as a way for zoos to reduce undesirable behaviors, like pacing, in the animals in their care.
Settings that allowed for more “natural” or “wild” expressions of behaviors could in some cases make the animals healthier.

At the Smithsonian National Zoo, in Washington, D.C., for example, environmental enrichment for octopuses includes adding shelves, archways,
tunnels, and doorways to their tanks for them to explore. As they do in the jungle, orangutans can swing hand over hand along the Orangutan Transport System, a 490-foot-long aerial cable network strung along eight fifty-foot-high towers. Naked mole rats sometimes find their tunnels blocked by pieces of beet or carrot, left there by keepers who want to encourage the animals to gnaw or burrow their way around the obstruction, as they would a root in the wild.

Besides the animal’s physical environment, feeding is the main area where veterinarians, nutritionists, and keepers concentrate enrichment.
Nutritionists provide smaller and more frequent meals. They scatter and hide food. They offer live prey. Changing these aspects of the animals’ environment makes eating a
process
.

No animals evolved to have food placed on a plate in front of them. They ran. They dug. They schemed. They starved. Eating was the reward for all that “work.” Even when human agriculture began to improve the predictability of food supplies, those humans still had to catch or raise the meat they ate. Farming crops is essentially just organized foraging.

Nowadays, like many pets and zoo animals, most of us no longer worry about where our next meal is coming from (although sadly one in seven still does). Yet as we increasingly outsource where and what we eat to agribusinesses, supermarkets, and restaurant chains, we hand over not just the inconvenience of food gathering and preparation but also the challenge, the puzzle, and even the excitement of eating. Like that of captive animals, modern human eating has become more and more detached from the complex physiological and behavior-based impulses and decisions around food that natural selection forced us to develop.