“Doctors by Nature: How Ants, Apes, and Other Animals Heal Themselves” by Jaap de Roode

Main Index / Reviews Index / Nonfiction Reviews Index / 2026 Reviews Index

Rating: 5/5 Stars.

A fascinating and enjoyable about how animals heal themselves by using drug and medicines found in the world around them. Based on research done by the author, and through interviews and collaborations with other scientists, the book presents a wonderful overview of the different ways animals who are sick treat themselves either by instinct, learning or following others. He also argues that domesticated animals still know how to treat themselves, and the animals might lead better lives if we allow the animals to find their own cures from nature, rather than continually providing artificial means (antibiotics) to cure them. And humans can benefit by seeing what animals use as medicines, and emulate their examples to find new drugs and cures for diseases.

The book starts with a fascinating example. Monarch butterflies know when they are infected by parasites, and compensate by laying their eggs on milkweed that contains more of the chemicals to fight the parasites. This doesn’t help the butterflies directly, but it helps their eggs survive the infection. How do butterflies know to do this? These, and other questions, are studied in the book and possible answers are provided.

From here, the author covers the various ways animals use the environment to cure themselves. Field studies discovered that chimpanzees eat some bitter plants to cure their sickness or to get rid of parasites. While some of this might be cultural (learned by following what other chimpanzees do), some might be biological: animals may tend to eat bitter things because their bodies develop cravings for them. Bitter plants usually contain toxins, so part of the process including learning just how much to eat to fight the disease without poisoning themselves.

Besides eating, animals also learn to use certain plants and other stuff as building material that help fight infections. Some birds, for example, now line their nest with cigarette butts because the nicotine in cigarettes is an insecticide that helps to keep mites away. Other animals like ants and bees, use tree resin to line their nests as a fungicide.

A question the author tackles is why do plants produce toxins. The reason is that plants want to protect themselves from predators who want to eat them. But predators evolve to compensate for the toxins, leading to a never ending battle between plants and animals. This produces a large range of chemicals used by different plants to keep different predators at bay. And some of these chemicals turn out to be useful to animals, and humans, as a way to combat various diseases.

The final chapters of the book look at domesticated animals and how letting them cure themselves naturally (like cows and goats eating medicinal plants in the field, or honey bees lining their nest with antifungal resin), instead of being artificially cured by antibiotics and other means, may be a more cost-effective way of keeping animals healthy. Dogs and cats are also featured, looking at why dogs eat grass and why cats love catnip.

The book offers some answers to these, and may other fascinating questions, about how animals cure themselves, and how we can find more ways to cure our own ills by observing and seeing what animals do. It is also a call for protecting more of the natural environment, for we may well be destroying the very sources of medicine that we may need in the future.

Book read from 2026/10/27 to 2026/10/29.