Richard Wrangham's "The Goodness Paradox"

Homo sapiens are unique among mammal species for our low levels of "reactive aggression," meaning chance encounters with other members of our species seldom lead to violence. For most other mammals, including close human relatives such as chimpanzees, such meetings are characterized by extreme wariness and suspicion, if not outright bloodshed. Yet humans, while relatively chummy in interpersonal encounters, have a capacity for organized and calculated violence on a massive scale unlike anything found in the animal kingdom. This is the paradox that Richard Wrangham explores in "The Goodness Paradox."

Early in the book, Wrangham describes a collection of characteristics that are found in domesticated animals known as "domestication syndrome." These include such traits as floppy ears, light coloration on foreheads and feet, and curly tails. While humans obviously lack these traits, we do exhibit other important signals of domestication including small teeth, flatter faces, similar male/female anatomy, and paedomorphic features (juvenile characteristics, both physical and behavioral, that persist into adulthood). Early scholars of evolution, such as Charles Darwin, noticed these similarities between humans and domesticated animals. We think of humans as actively domesticating animals over time. But then who domesticated humans? And is our lack of reactive aggression a consequence of our domestication?

According to the science (Wrangham delves deeply into anthropology, archeology, and gene expression throughout), the surprising answer is that we probably domesticated ourselves. There is evidence that animal populations who select against reactive aggression develop domestication syndrome. In other words, domestication syndrome traits like paedomorphic features and smaller teeth follow from a reduction in reactive aggression (not the other way around). So how did human evolution select against reactive aggression? The most promising theory is that as humans developed the unique ability to communicate and collaborate using language (around 200,000 years ago), they also gained the capacity to collectively murder alpha males and bullies who became too aggressive. To simplify the theory, capital punishment—which apparently is consistently evident in ancient human remains as well as more contemporary hunter/gatherer societies—has effectively selected against reactive aggression over the past 300,000 to 200,00 years.

The same lingual prowess that allowed humans to conspire against bullies also unlocked cooperative problem-solving, the preservation and furthering of newly discovered skills across generations, and the ability to gossip (this last development probably led to shared values and moral senses). An unfortunate offshoot of this penchant for cooperation is that homo sapiens, despite its status as a domesticated species, can wage war and orchestrate mass violence.

Wrangham delves deeply into the science and I found some sections were a bit dense with historical scientific findings. I enjoyed his explanations of primate behavior, drawn from his deep experience as a primatologist, and I especially appreciated his descriptions of bonobo and chimpanzee behavior. These two very different human relatives have much to teach us about our own origins as a species. Overall, this was an interesting account of how the march of evolution, combined with the potent ingredient of complex language, has shaped some of the most vexing contradictions of human behavior.