US neuroscientist Sapolsky's new book 'Monkeylove'

Human behavior shaped by genes, environment, society and more

Even trivial preferences — food, music — have deeper explanations

A son covers his ears as his father sings. Photo is for illustrative purposes only. [123rf]
A son covers his ears as his father sings. Photo is for illustrative purposes only. [123rf]

Every time a man in his late 40s — call him A — gets behind the wheel, he reaches for the same playlist: pop ballads from the 1990s, including Lee Moon-sae's "Yetsarang," Kim Gun-mo's "Areumdaun Ibyeol" and Jo Sung-mo's "Asinayo." "K-pop is hugely popular around the world these days, but I still love '90s ballads the most," A said, giving a thumbs-up. The songs A first heard in his mid-teens are ones he has never stopped loving, three decades on.

A is far from alone. Musical taste is often locked in before a person turns 20. In his new book "Monkeylove," Robert M. Sapolsky — a Stanford University professor of neuroscience and the author of "Behave" and "Determined" — argues that human behavior is shaped not only by genes but also by the state of the body and brain, the environment, and cultural background. Drawing on scientific research and theory, Sapolsky unpacks the reasons behind everyday human behavior in an accessible and entertaining way.

Why does musical taste differ so sharply across generations? Because, as A's case illustrates, taste tends to solidify before age 20, after which new music becomes hard to absorb. To investigate when in the human life cycle cultural preferences take hold, Sapolsky surveyed more than 40 American radio stations that play music from a single era. The research found that people first encounter the popular music they will enjoy for the rest of their lives before the age of 20. It also found that when a new genre emerges, people aged 35 or older have a greater than 95 percent chance of never listening to it.

New release
New release

What about food preferences? Using a similar method, Sapolsky contacted more than 50 sushi restaurants in the American Midwest — sushi being a relatively recent arrival in the United States — and analyzed customer patterns. The research found that a person must try a food before age 28 to develop a lasting taste for it, and that anyone 39 or older has a 95 percent chance of never touching that food for the rest of their life. For fashion choices such as tongue piercings, the window opens only for those who start before 18, and the odds of adopting the trend drop sharply after 23. In other words, the window for embracing new things closes at 23 for fashion, 35 for popular music and 39 for food.

When a major disaster strikes, why do people risk their lives and spend enormous sums to recover the bodies of victims, even when the chance of finding survivors is gone? Sapolsky examines recovery operations such as the search of the sunken Russian submarine Kursk and the Ground Zero effort after the Sept. 11 attacks, and concludes that recovering remains and holding funeral rites is not simply for the dead. Such rituals serve the living — providing a space to affirm, and rebuild, a sense of community, solidarity and social bonds.

Sapolsky also analyzes the emotions and behavior of animals closely related to humans, arguing that our animal nature influences how we act. Baboons, for instance, share the human preference for kind males. Female baboons, the book notes, choose to mate not with males that win fights against rivals, but with those that form friendships and protect young from predators. The common assumption that dominant males win female preference does not hold even in the animal world, Sapolsky suggests.

The book also gathers 18 essays Sapolsky contributed to The New Yorker, Discover and Science, among other publications. Ranging from why humans love, cooperate and compete, to why people willingly absorb a personal loss to punish a cheater but balk at opening their wallets for a good cause, to whether stress really does shrink the brain, the essays draw questions from overlooked habits and received wisdom to illuminate the complex world of human behavior.

"Monkeylove" / By Robert M. Sapolsky / Translated by Kim Hee-jeong / Munhakdongne


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