Light Eaters by Zoë Schlanger


I heard Zoë Schlanger, a long time science writer, interviewed on Fresh Air and found her an unusually appealing speaker. Her writing is equally appealing; she explains unfamiliar concepts clearly and in an entertaining way.

In the last 15 years there has been a revival of plant behavior research that has brought revelations about the attributes of plants that could be called “intelligence.” In 1973 the best seller The Secret Life of Plants, a “mix of real science, flimsy experiments, and unscientific projection” captured our imagination. One chapter told that plants feel and hear and that they preferred Beethoven to rock and roll. Another chapter described what was reported to have happened when an ex-CIA agent hooked a polygraph machine to his houseplant and had malevolent thoughts about the plant. The needle went wild, which indicated the plant not only was conscious, but also could read a human mind. Scientists tried to reproduce some of the described results and were not able to. The result was that the scientific world rejected any research that reminded anyone of this book for decades. In the meantime the scientific world and our culture has come to view non-human animals differently; we now know they have traits that remind us of ourselves.

A look at the chapter titles of this book tells us that scientists have published works about plants that reflect a world view much closer to that book. A few of these chapter titles are:  The Communicating Plant, Alive to Feeling, An Ear to the Ground, Conversations with Animals, The Social Life of Plants. The scientists the author interviewed were very conservative about using human terms to describe what plants do, but it’s hard to deny how sophisticated their behavior is.

There were countless observations that were revelatory and fascinating. My favorite involves one of the ways plants discourage insects or caterpillars from eating their leaves:

One devilish case has been found in the humble tomato. The tomato plant will inject something into its leaves that makes the caterpillar look up from their chewing, and turn to eye their fellow caterpillars. Soon the leaf becomes irrelevant, the caterpillars begin to eat each other.

Another means of protecting themselves is to emit a chemical that summons predators of the insect that is eating them. Some plants manufacture their own insect repellant and in the case of oregano, that is the rich oil that makes the plant appealing to humans.

The author does not have a narrow focus on her topic. One scientist she spoke to, Sonia Sultan, a plant evolutionary ecologist, made a point that a person’s or a plant’s genes are only one factor in their development. I want to remember the experiments that she described about genes, lung cancer, smoking, and broccoli. A person without genes that protect them from lung cancer are much more likely to get lung cancer the more they smoke. The bit I want to remember is that those who lack that protective gene are much less likely to get lung cancer the more broccoli (or other cruciferous vegetables) they eat. The point of this was that while genes are important in learning how living things operate, other factors are also important. Even more, I want to remember the role of broccoli in this story.

I made so many clips on the audiobook that if I don’t stop looking at them, I’ll just reproduce the book here. I cannot recommend it highly enough.

Zoë Schlanger, Light Eaters, Harper, 2024, 290 pages (I listened to the audiobook). Available in the public library.

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