Frans de Waal, Granta (UK); W. W. Norton (US)

When primatologist Frans de Waal died in 2024, he left a huge scientific legacy. His work was a fixture in this magazine for decades, and he wrote a small library of books, including The Age of Empathy, Are We Smart Enough to Know How Smart Animals Are? and .

Many of de Waal’s ideas were controversial, but are now so widely accepted we often treat them as given. For instance, the idea that some animals engage in social manoeuvring can be traced to his foundational , published in 1982. Then there are his ideas about bonobos, the apes that, along with chimps, are our closest living relatives. They live in female-dominated societies, and often use sex, not violence, to resolve conflict – something de Waal promoted vigorously in .

De Waal’s last book, Minds I’ve Met: From denying to embracing the inner lives of animals, was begun before his death, but not completed. He left “documents and audio files with instructions and suggestions”. The two last chapters and the epilogue were completed by his wife Catherine Marin, psychologists Stephanie Preston and Sarah Brosnan, and anthropologist Peter Verbeek.

The book blends science and memoir, retelling key episodes in de Waal’s career and placing them in the context of our changing understanding of animals. For much of the 20th century, science treated animals as little more than automata: “Animal minds were denied,” explains de Waal. This was reflected in an “arcane, castrated vocabulary for animal behaviour”. De Waal says he was told that the phrase “ape laughter” was anthropomorphic, that he should call it “vocalized panting” instead. In reality, de Waal argues, animals can think, experience emotions and display empathy – which they often act on.

The story begins in the 1960s, when de Waal was a biology student at the then Catholic University of Nijmegen in the Netherlands. During a summer job in an animal research lab, he worked with young male chimps set the task of discriminating between two shapes just by feeling them with their hands. At first, they performed “nearly flawlessly”. But after about 20 trials, their attention drifted, and they wanted to play with him. This, he decided, was not because they were stupid, but because the task was easy and repetitive: they were “bored out of their minds”.

De Waal says he was told ‘ape laughter’ was anthropomorphic – that he should call it ‘vocalized panting’

Such anecdotes help de Waal show how blinkered scientists often were to research animals. For behaviourists, these animals were little more than stimulus-response machines, and any attempt to glimpse their internal states was pointless.

One of their techniques was to underfeed lab animals, keeping them below 80 per cent of their normal weight, so hunger would motivate them to perform in experiments. On one occasion, behaviourists tried a similar regime on captive apes, who became “morose, grumpy, and hostile”, refusing to perform and flinging “smelly stuff” at researchers. Their caretakers secretly fed them at night. B. F. Skinner complained that “tender-hearted colleagues frustrated efforts to reduce chimpanzees to a satisfactory state of deprivation”.

The phrase “satisfactory state of deprivation” is one of the more obscene things I have read lately.

Happily, many researchers fought back. Among them were Wolfgang Köhler, who found evidence of chimps solving problems, and Jane Goodall, who described wild chimps with personalities and strong bonds. We see how researchers, including de Waal, found evidence that many animals empathise with the experiences of others, and that this may be at the root of many of the moral intuitions of humans.

Inevitably, given how it was created, stumbles at the end. The final chapter rushes through animal culture to fairness and delayed gratification. After the richness and depth of the earlier chapters, it feels scattered and unsatisfying. The rest of the book, however, is terrific: readable, often funny, illuminating, occasionally shocking. Mixing memoir and science is always challenging, but de Waal pulls it off. The only thing is, I now want a full biography.

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