Quotes About Tribalism, Us/Them Behavior and the “Green Beard Effect” From BEHAVE, by Robert Sapolsky

The quotes below are from Behave: The Biology of Humans at Our Best and Worst, by Robert Sapolsky. I’ve taken inspiration from this book for both teacher trainings and writing workshops, including a recent writing workshop in which all of the exercises were based on behavioral science. For one of the prompts, I read this collection of woven-together quotes about our tribal tendencies, also called Us/Them behavior.

Here are some quotes about tribalism, Us/Them Behavior, and “The Green Beard Effect” that can also make great conversation starters and writing prompts in a language arts class

“As it’s been said, (most often attributed to Robert Benchley), “There are two kinds of people in the world: those who divide the world into two kinds of people and those who don’t.” There are more of the first. And it is vastly consequential when people are divided into Us and Them, in- group and out-group, “the people” (i.e., our kind) and the Others.”—Behave, p. 387

Later in the chapter, Sapolsky discusses a phenomenon that Scientist W.D Hamilton describes as the “Green Beard Effect.”*

“. . . if an organism has a gene that codes for both growing a green beard and cooperating with other green bearders, green bearders will flourish when mixed with non-green bearders.”—p. 342

There are various ways that the green-beard effect works in humans.

“What helps define a particular culture? Values, beliefs, attributions, ideologies. All invisible, until they are yoked with arbitrary markers such as dress, ornamentation, or regional accent.”—p.390

In other words, we often dress, act, talk, and make purchasing decisions that help others in our in-group identify us and identify with us. Think political bumper stickers, or the decision to buy a hybrid vehicle vs. a Hummer. Do these choices change the way we treat people and expect them to treat us? One example Sapolsky uses early in the book is a study from soccer games in Britain, where a research team planted “fans” who pretended to slip and hurt their ankle. If the plant was wearing the home team’s sweatshirt, more fans got up to help.**

“Crucially, we differ as to what counts as a green-beard trait. Define it narrowly, and we call it parochialism. Include enmity toward those without that green-beard trait and it’s xenophobia. Define the green-beard trait as being a member of your species, and you’ve described a deep sense of humanity.”—p.342

In this final quote, Sapolsky explains why human evolution may have selected for the green beard trait in the first place.

“This is how we’ve evolved to collectively raise barns for neighbors, plant and harvest the whole village’s rice crop, or coordinate marching-band members to form a picture of their school’s mascot. And, oh yeah, to reiterate an idea aired previously, “cooperation” is a value-free term. Sometimes it takes a village to ransack a neighboring village.”—p.637


*Hamilton, William D. “The genetical evolution of social behaviour. II.” Journal of theoretical biology 7.1 (1964): 17-52.

**Levine, Mark, et al. “Identity and emergency intervention: How social group membership and inclusiveness of group boundaries shape helping behavior.” Personality and Social Psychology Bulletin 31.4 (2005): 443-453.

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