I was horrified. Young primates starting a life of because they observed it? The brain strives to avoid pain. What could motivate it to initiate pain? “Stress” is not an adequate answer because a survival-driven organism has incentive to avoid pain when stressed.

I searched for an answer, and ran across the story of a bonobo mother who actually pulled her child’s hair out. She did it for so long that the hair stopped growing back. This was not , but “grooming gone wild” in the words of Barbara Natterson-Horowitz. She explains in Zoobiquity that grooming is nature’s self-soothing strategy. Animals groom others as well as themselves, and that builds soothing social bonds. When the going gets tough, mammals groom. Many repetitive behaviors are variants on grooming. The behavior may get repeated endlessly if a mammal has a persistent sense of threat.

You might blame zoos for that sense of threat, but life in the wild is too. In the state of nature, hunger threatens as soon as you stop foraging, and when you forage unsuccessfully. Predators lurk, and if you relax your vigilance you may end up watching your child being eaten alive. Social relations are precarious in the wild and a mammal often defers to avoid a conflict that can escalate into painful biting and clawing. Romantic illusions about life in the state of nature are wishful thinking.

The mammal brain evolved to manage this stress. It builds skills for avoiding pain. Foraging skill avoids the pain of hunger. Predator- avoidance and conflict-avoidance skills avoid pain. In the state of nature, a mammal doesn't waste energy on counter-productive behavior. Harsh reality teaches it to reduce stress by taking care of business.

But when a mammal’s needs are met by others, as in captivity, it can invest energy in futile efforts without loss of food or safety. The brain might even connect futile efforts to the successful meeting of its needs. Food and protection keep coming when the mammal self-harms, so the brain has reason to expect more of the same. The mammal brain constantly wants to “do something” to promote its well-being. It does whatever worked in the past. Once a self-destructive behavior appears to “work,” the mammal brain repeats it as if its life depended on it.

This is relevant to self-harm in humans. People repeat a wide range of behaviors that hurt themselves. Many self-destructive behaviors are homologous to the grooming habits of other primates. Stress is often blamed for self-destructive behavior. But reducing stressors often fails to stop such habits. For example, let’s say my child invests a lot of her energy in self-destructive behavior. I decide to reduce her stress so I do everything nice I can think of to "help" her. From her mammal brain's perspective, harmful behavior gets rewards. This is what her brain "knows" about how the world works. In my eagerness to "support" her, I deprive her of valuable opportunities to learn the connection between her actions and real-world outcomes. I may cause her as much suffering as those bonobo mothers.

What is the alternative? We cannot withholding food and protection from children, but we can stop rewarding self-destructive behavior in other ways. We can pay closer to what we reward and restrain ourselves from well-intentioned responses that inadvertently reward self-harm. We can reward self-enhancing behavior while we carefully avoid rewarding bad habits.

In the state of nature, well-being depends on a creature's skill at meeting its needs. Experience builds skill in foraging, avoiding predators, and grooming allies. And skill brings a sense of security that one will be able to meet one's needs despite a world of challenges. This is nature's stress relief. It builds in the state of nature because rewards depend on effective behavior. It doesn't build in an artificial environment because rewards come regardless of actions. The self-harming animal still gets its needs met so it does not learn from nature's feedback. Thus it never develops the sense of security that comes from personal effectiveness.

People who work with animals know this. Humans know it instinctively, but our desire to “help” can over-ride it. There's lots more on personal agency and the mammal brain in my book, Beyond Cynical.