Book review: Hierarchy in the Forest: The Evolution of Egalitarian Behavior, by Christopher Boehm.
This book makes a good argument that a major change from strongly hierarchical societies to fairly egalitarian societies happened to the human race sometime after it diverged from Chimpanzees and Bonobos. Not due to any changes in attitudes toward status, but because language enabled low-status individuals to cooperate more effectively to restrain high-status individuals, and because of he equalizing effects of weapons. Hunter-gatherer societies seem rather consistently egalitarian, and the partial reversion to hierarchy in modern times may be due to the ability to accumulate wealth or the larger size of our societies.
He provides a plausible hypothesis that this change enabled group selection to become more powerful than in a typical species, but that doesn’t imply that group selection became as important as within-group selection, and he doesn’t have a good way of figuring out how important the effect was.
He demonstrates that humans became more altruistic, using a narrow biological definition of altruism, but it’s important to note that this only means agreeing to follow altruistic rules. He isn’t able to say much about how well people follow those rules when nobody notices what they’re doing.
Much of the middle of the book recounting anthropological evidence can be skipped without much loss – the most important parts are chapters 8 and 9.