When I was little, our family had a white and caramel-spotted cat named Bumble. In her golden years she developed a “hot spot” on her hip. Bumble licked this one particular wound so repeatedly, and so fiercely, that she abraded her hair in a section the size of a half dollar. The exposed skin eventually became inflamed and began to ooze. Still, Bumble licked. And nibbled. And bit. Her eyes took on a trance-like look as she worked on her hot spot; sometimes she would dig in with her canines so hard, and with such deep focus, that she would comically topple herself over.
It never occurred to me, until reading Zoobiquity: The Astonishing Connections Between Human and Animal Health, that the parallel human malady to Bumble’s affliction might be self-injuring behaviors such as cutting, burning, or bruising oneself on purpose. Grooming behaviors in many animals—such as licking in cats, feather preening in birds, and louse picking in primates—has a calming effect because, the authors write, “It releases opiates into our bloodstreams… decreases our blood pressure… and slows our breathing.” (It can also foster social structures in some animal groups, such as primates and even fish.) But in some individuals, the biochemical processes that create this calming effect go a little haywire, and the animals get a dose of feel-good even when their behaviors cross over from benign grooming to painful activities. Hence, the connection between Bumble chewing on her spot and a teenager dragging a razor shallowly across her inner thigh; what should yield pain instead produces pleasure.
As much as we attempt to divide ourselves from the rest of the animal kingdom, the truth is that members of Homo sapiens are, well, animals. So it shouldn’t raise eyebrows to learn that humans and animals share many common—and not so common—ailments, such as heart anomalies and cancers. In Zoobiquity, authors Barbara Natterson-Horowitz and Kathryn Bowers dig deeply into these commonalities. But they don’t simply search for similar diseases and afflictions shared by man and beast, they also explore and explain the possible evolutionary underpinnings of these links.
Natterson-Horowitz is a practicing cardiologist at the University of California-Los Angeles Medical Center who began consulting at a regional zoo. Her forays into treating animal patients led her to understand that medical doctors and veterinarians often have different names for similar diseases and behaviors shared by their patients. In the book’s opening scene, Horowitz recalls how she realized that the risk of her Emperor tamarin patient developing capture myopathy was eerily similar to the human condition of takotsubo cardiomyopathy, which is also known as broken heart syndrome.
After that experience, Horowitz began asking if animals get specific kinds of cancers. She discovered parallels between the tumors growing around branding sites in livestock to those growing around the traumatized skin of people’s tattoos and scarifications. And just as mutations in the BRCA1 gene are known to be connected to breast cancer in people, in some animals (such as jaguars and English springer spaniels), carriers of this mutated gene also develop breast cancers.
Zoobiquity takes readers on a journey connecting the dots between seemingly unconnected behaviors: for example, how the roots of substance addiction and other self-destructive habits may actually be byproducts of survival strategies, and how fainting in people may be related to behaviors that evolved in prey animals to escape being eaten.
Chapter Seven was one of my favorites: “Fat Planet: Why Animals Get Fat and How They Get Thin.” Here, the authors ask whether animals ever get fat, and their question inevitably leads them to a zoo. I have always held yin-yang emotions about visiting zoos because although I adore watching the animals, I abhor seeing them out of shape, pudgy and bored… as zoo animals often are. It’s true, captive animals who lead sedentary lives and have an abundance of food they don’t have to work for tend to get fat. Kind of like us. Natterson-Horowitz and Bowers discuss compelling examples of animal diets and feeding schedules gone awry in zoos, and how careful nutritional regulation, enrichment stimulation, and even seasonal variance in the types and amounts of foods given helped to slim down a pair of lumbering grizzly bears.
But their discussion isn’t limited to a food-in/food-out scope. Rather, they discuss at length the connections between food, behavior, and an animal’s environment. For example, exposure to a disjointed or unnatural light-dark cycle can influence both human and animal weight gain (or maintenance); a phenomenon I saw affect a once-slim friend who worked a night nursing shift for several years. And zoo animals that seek out and discover variable food items in their enclosures, rather than having the same old feed slopped into a bowl day-after-day, spend more time moving around their habitat foraging… just as they would in the wild.
Two of the more fascinating tidbits they discussed about animal weight gain and loss dealt with the shape and structure of an animal’s intestines, as well as what lives within them. It turns out that some animals, such as migrating birds, harbor intestines that literally change shape to accommodate the slow, nutrient-snagging passage of food or the rapid digestion and expulsion of food with fewer nutrients absorbed. Animals, including us, tend to harbor certain types of bacterial bugs that can be broken down into two main groups: Bacteroidetes and Firmicutes. Individuals whose intestines contain an abundance of the first group tend to be lean, while individuals whose intestines contain an abundance of the second group tend to be porkers because these bacteria are able to strip more calories from food items than are the Bacteroidetes.
A true strength of this book is that Natterson-Horowitz addresses head-on the general lack of respect by practitioners of human medicine toward veterinarians. She recognizes that physicians have much to learn from their counterparts who treat animals, and that by joining forces they can each be better doctors to their respective patients. Throughout the book she calls for a “zoobiquitous” approach to medicine, one that examines human and animal maladies in light of their common evolutionary origins.
Zoobiquity is a delightful book. Natterson-Horowitz and Bowers make an amiable and graceful team in their quest to trace connections between human and animal health and behaviors. Their writing is engaging, sometimes humorous, often light-hearted, but always highly readable. Complex ideas or terms are clearly explained, and discussions never went so deep into the weeds that I felt I’d lost sight of the sky. This was the sort of book that after putting down I couldn’t wait to pick up again.
Paperback, April 2013
Random House/ Vintage Books
398 pages with Acknowledgements, Notes, & Index