De Waal is the world’s most famous expert on bonobos, who along with chimpanzees are humanity’s closest relatives. Here, he shows how observing primate behavior can shed light on human behavior. This book takes an informal, almost chatty tone, with de Waal often writing in the first person about his personal experiences with both apes and with humans. Even though our species branched apart a good 6 or 7 million years ago, we still have very much in common with chimps and especially bonobos. Our resemblance is more than physical. It is also cultural. Moreover, the two are often intertwined.
Chimps form complex alliances in the same way humans do, forming 2-against-1 relationships where possible, and scheming to divide enemies where so they don’t put up a united front. In a 2-against-1, don’t be the 1. As de Waal points out, human diplomacy follows similar strategies, just on a global scale. Nation-states play the same roles as individual chimps.
De Waal also offers some insight on biology and anatomy, especially sexual dimorphism. Species with drastically different male-to-female size ratios tend to have male-dominant cultures. Similarly, testicle size is related to promiscuity. Gorillas and human cultures tend towards monogamy, and this manifests itself in smaller testicles. Promiscuous chimps and bonobos have more competition, so they have larger testicles to produce more sperm. These dynamics show up in their behavior. Male chimps will often commit infanticide when they know the child is not theirs. Females intentionally confuse matters by having several possible fathers. This strategy changes male behavior, saving young lives.
De Waal goes off the rails toward the end, when he makes it uncomfortably clear that his expertise does not extend to economics or public policy. Here, the discussion is on par with a Facebook or Twitter political rant, lacking of command of either emotions or facts. That awkwardness can be safely skipped. The rest of the book is excellent.