Richard Wrangham and Dale Peterson, Demonic Males: Apes and The Origins of Human Violence (1996)

I purchased Demonic Males at the same time that I purchased The Ape and The Sushi Master (June 17, 2010 post), and as both books focus on and compare primate behavior with human behavior, they deserve to be read together. Richard Wrangham focuses on the darker side of human behavior: why do humans kill others in their own species and are humans unique in that respect? Why is this violence essentially a characteristic of the male of the species? The answer to the first question is no, humans are not entirely unique in seeking out others within their species to kill them, but there are very few species who share this type of behavior. And among the few species who commit violence against others within their species, the notables are evolutionarily close to humans: orangutangs, chimpanzees and gorillas. Male orangutangs are notable for rape; gorillas are notable for killing infant gorillas; and chimps are notable for battering other chimps as well as searching out other chimps and killing them. In exploring the world of organgutangs, chimps, gorillas, and another evolutionary offshoot of the chimp --- bonobos --- we can learn much about the origins of human violence and why violence is primarily associated with the male of the species.

Decades of research on chimpanzees in their African habitat reveals that they raid nearby chimp communities for the purpose of killing. Two conditions, explains Wrangham, account for the chimp's tendency to look for killing opportunities: party gangs and male bondedness. Party gangs evolve because of competition for a scarce food supply, and they need to defend the food supply of their existing territory or expand their existing territory. Males are selected for this aggression, says Wrangham, because males walk faster than females and do not carry infants with them; this results in bonding among chimps. And Wrangham finds similarities between chimpanzees and humans that are either not as strong or non-existent between chimps or humans on the one hand, and other primates on the other. In all cases, territorial control and domination is a common feature in explaining primate aggression, but only in the case of humans and their genetically closest primate, the chimp, is the common element a deliberate search for victims.

Social hierarchy is a characteristic of chimp communities, just as it is in human communities, and competition for dominance is particularly a characteristic of male chimps. Wrangham says that "we exaggerate only barely in saying that a male chimpanzee in his prime organizes his whole life around issues of rank" ---- attempting to attain alpha status. Female chimpanzees do not seem to care as much about rank. Wrangham asserts that the driver here is pride (and arrogance), not violence for its own sake. I don't know how he knows this, but it sounds like an example of what Frans DeWaal called in The Ape and The Sushi Master (June 17, 20101 post) "naive anthropomorphisim" --- asking, how would I feel in this situation? Wrangham notes, "Pride obviously serves as a stimulus for much interpersonal aggression in humans, and we can hypothesize confidently that this emotion evolved during countless generations in which males who achieved high status were able to turn their social success into extra reproduction."

I don't want to dwell on this book. If this was the only book one read on the subject of the origins of human behavior, you would conclude that male humans are born to kill, and empirical observation tells us that is not the only truism one can declare about male humans. Demonic Males is very interesting for what it documents: the apparent origins of human violence can be found in other primate species closest to humans, which indicates a genetic and evolutionary foundation for violent behavior among human males. But there is more to the story that primatologists are telling us about the commonalities among primate behaviors, including the origins of social cohesion, cooperation, and even morality and altrusim. Michael Gazzaniga's Human (September 27, 2009 post) contributes much to this broader understanding of human evolution. Wrangham barely mentions these other common attributes of primate social systems. Violence is only one behavioral aspect of our social nature. Importantly, however, Wrangham validates DeWaal's thesis in The Ape and The Sushi Master about the importance of recognizing continuity between humans and other animal species.