The primate tales that de Waal uses to discuss gender are both fascinating and enlightening ... But as an argument about humans, I found Different less satisfying ... De Waal sometimes stretches evidence to fit his claims ... 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 ... Sometimes de Waal’s evidence for a link between humans and other primates feels more like free association ... Different would have benefited from less free association and more sustained argumentation ... It is hard to tell from Different to what degree our genders have been shaped by history before and after our split from our fellow primates. None of this is to take away the value of the stories of Donna and the rest of the primates that have filled de Waal’s life. If you don’t know your bonobo from your gibbon, Different has many surprises in store for you, surprises that will leave you humble about complex primate evolution has been, and how much we have yet to learn about how it shapes our lives.

De Waal turns again to the ape world, this time to explore the connection between gender and biology. As I said, brave. Whether he’s convincing is another matter ... He points to differences in the behavior of male and female primates as evidence that biology explains more of human gender differences than many would like to believe. That is not necessarily a baseless argument, but de Waal never provides a concrete definition of 'biology' for us to consider ... An explicit definition of biology, by way of hypothetical genetic mechanisms, would have gone a long way in supporting the central premise ... Still, de Waal’s book is a valuable addition to the public discussion of sex and gender. Analyzing the behavior of close evolutionary relatives is a scientifically sound way to understand the origins of our own behavior ... Even if Different doesn’t provide satisfying answers to our questions about gender and sex, it is still a valuable collection of amusing, heartwarming and sometimes heartbreaking anecdotes about our animal cousins.

There are readers who will walk away from this text more sympathetic to homosexuality and gender fluidity in humans and more open to the idea that women can be powerful and men can be nurturing. Amid the hypermisogynistic conclusions of most pop-evolution pundits, this is not nothing; I could imagine Different as a useful if mild prophylactic against, say, Jordan Peterson. But to be seduced by essentialism, and especially zoological essentialism, would be a mistake for feminists ... Surely, the right to live free from gender prescriptions does not depend on the existence of Donna the butch chimpanzee but instead on a basic human right to seek happiness where it does not imperil the pursuit of happiness in others. We do not need to search for a nonhuman precedent to permit ourselves gender fluidity any more than we did before forming democracies or writing lyric poetry. We, too, are animals; our behavior, too, is natural. I sometimes wanted to pull de Waal aside and say, The world that you labor to prove may someday exist already does ... in his frequent use of essentialist fallacies, de Waal seems simply in over his head ... It is a bad habit of essentialists to describe overlapping probability curves as mutually exclusive gendered traits, especially when the trait is suggestible and so the exaggeration self-fulfilling.

A game-changer, potentially no less significant to the field than Foucault’s The History of Sexuality, but in a noncanonical fashion, and void of the usual tropes ... Though the data speak for themselves, de Waal is an extremely attentive listener ... De Waal moves slowly, painstakingly so, and rarely jumps to conclusions. When it turns out that he is wrong — failing to gather enough observations, for instance — he lets the reader know. That, alone, is a prized value in the world of science ... Preferring to stay close to the data, he does not spin theories ... De Waal’s prose is concise and straightforward. His sensitivity to the prevailing zeitgeist that surrounds sex and gender is evident ... mountains of data, uncontaminated by parental or cultural expectations nor limited to self-reports and their all-pervasive biases ... There’s no end, in fact, to the fascinating details that emerge from this book, all carefully tied to supporting explanations, historical context, the prevalence of misinformation, the tendency to censor, the power of mindless biological determinism, and whatever else might be necessary for de Waal to make his point. Humor, and the curious anecdote, are never far behind. None of this, however, rises to the level of a foundational contribution to the study of sex and gender. The value of his book is the mortar that holds it all together: the underlying rationale for comparing human behavior to that of other primates ... The only misstep that I can detect — an exception that proves the rule, perhaps — is an example that de Waal uses to illustrate the ill-advised mind-body divide, the dualism conceit whereby the mind is the lofty tower in contrast with the serviceable body ... a towering achievement. Not simply does it cut through many Gordian knots that persist in the worlds of sex and gender, but de Waal manages to do so without relying on a higher authority such as a beloved theory. His data-based approach may not immediately appeal to audiences that prioritize complex reasoning and nonintuitive departures — readers who may also raise eyebrows about the wisdom of comparing de Waal to a brilliant French philosopher, as I have done — but the value outweighs the risk. We ignore important works at our own peril, especially if our goal is to better understand the many nuances and overt displays of sex and gender. A primatologist of de Waal’s stature has much to contribute to these discussions.

Fascinating ... De Waal shines in his empathetic, Tolstoyan portrait of animal life ... This surprising look at the nature of primates has a lot to say about what it means to be human.

De Waal draws on a long career of investigating chimpanzees and bonobos—both equally close to humans genetically—to argue with wit and clarity against assumptions about sex and gender that generate inequality ... The author enlivens his pages with attentive, sometimes moving portraits of animals he has encountered as well as anecdotes about his own experiences as one of six brothers. Engaging, enlightening, and deeply informative.