When De Waal asserts that male apes and men are both judged by the width of their shoulders, he doesn’t even offer a footnote. After observing that male chimpanzees exaggerate their size by making their hairs stand up, he turns to men’s fashions. “We too pay special attention to male shoulder width, which is why suits have shoulder pads,” de Waal declares.
Professor de Waal, I have Joan Crawford on line one waiting to talk to you. Joan Collins is online two.
Sometimes de Waal’s evidence for a link between humans and other primates feels more like free association. When discussing violence inflicted by men on women, he claims that unrelated women can protect each other just as female bonobos do. “The #MeToo movement comes to mind. So does the Green Sari movement,” he writes.
“Different” would have benefited from less free association and more sustained argumentation. I was not sure what to make of the fact that humans are like chimpanzees in some regards and bonobos in others. After all, they’re both equally related to us, belonging to a lineage that split off from our own around six million years ago.
When de Waal ventures further away on the primate tree, things get more confusing. In a chapter on parental care, he describes how cotton-top tamarin fathers put in a lot of effort raising young. (They can burn off 10 percent of their body weight lugging around their kids.) As we’re waiting to learn what cotton-top tamarin fathers can tell us about human fathers, de Waal loses interest. “These monkeys are quite distant from us, however, which makes them less relevant to human evolution,” he declares, turning to gibbons. Will cotton-top tamarins be on the midterm?
There’s a deeper problem with writing about cotton-top tamarins this way: They are different from their own close relatives. The ancestors of cotton-top tamarins started out as a species in which fathers offered little care at all. And then a mysterious combination of evolutionary factors pushed the ancestors of cotton-top tamarins onto a peculiar path.
We humans are peculiar too. We may not be quite as special as we’d like to think, but we have undergone some big changes since our lineage split from chimpanzees and bonobos. Our ancestors started walking upright, lost much of their hair, evolved big brains, and began speaking full-blown language. It is shaped hard to tell from “Different” to what degree our genders have been by history before and after our split from our fellow primates.