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. Continue reading