This turned out to be Frans de Waal's last book; he died in March 2024. In it, he compares the sexual differences in behavior of humans and primates, where the focus is on the bonobos and the chimpanzees, the two species that are genetically most close to humans. He navigates the controversial subject very well. The average differences in behavior and physiology between males of females of these species are discussed in the light of evolution, ecology and culture.
He does not agree with the view that there are no significant differences between the sexes in humans. He rejects the blank slate view of human nature. But neither does he agree with the idea that such differences automatically can tell us what is socially, ethically or politically right or wrong. He is very clear about the fundamental impact that culture has on sex and gender, and describes instances of this from chimpanzees and bonobos.
In general, I find his account convincing and well argued. There are of course the occasional instancse where he gets things wrong, or holds a view with, what I consider, insufficient arguments. But I am still impressed with how he manages to walk through this minefield of controversy without serious missteps.