Evolution of Cooperation, Animals’ Sensory Systems, and Other New Books – Scientific American

The Social Instinct: How Cooperation Shaped the World
by Nichola Raihani
St. Martin’s Press, 2021 ($29.99)

Society is built on a foundation of cooperation, with lessons on its importance starting as early as Sesame Street. It may be tempting to look at our ability to cooperate—however imperfectly—as evidence that humans have transcended our baser instincts. But in her energetic analysis, psychologist Nichola Raihani recontextualizes cooperation within the framework of evolution and reveals the competition for survival that still bubbles below its surface.

According to Raihani, cooperation is “not just about what we do, but who and what we are.” As multicellular beings, we literally embody cooperation. As individuals, we gravitate toward others. The same instincts that lead us to live in tight-knit family groups drive us to help those who are not part of our immediate circles, even when our assistance will never be reciprocated. While this may not seem to square with “survival of the fittest,” Raihani accounts for this evolutionary puzzle and illuminates how cooperation has shaped such disparate phenomena as cancer, monogamy, menopause, hatred toward vegans, and people leaving dirty dishes in the office sink.

Raihani explains the breathtaking intricacies of natural selection yet does not shy away from addressing the field’s current controversies (such as whether human societies should share the status of “superorganisms” with bee and ant colonies) or touching on its outermost frontiers, including the “mind-bendingly bonkers” possibilities of microchimerism, the presence of cells of two individuals in one body. She compares human behaviors