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’s a post with those quotes and links to the original studies they reference.
Later in the chapter, Sapolsky discusses a phenomenon that Scientist W.D Hamilton describes as the “Green Beard Effect.”*
There are various ways that the green-beard effect works in humans.
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.**
In this final quote, Sapolsky explains why evolution may have selected for the green beard trait in the first place.
*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.