Wish I'd read this book 30 years ago.**SPOILER ALERT** Discussion of the main themes and revelatory points follows.First, the book is extremely well written. Complex subjects are analyzed and explained clearly and concisely, and wonderful examples and metaphors are frequently offered to emphasize points.The authors also display a delightful sense of humor at various points during exploration of topics most people don't feel comfortable discussing openly.The thing that blew me away the most was his discussion of how agriculture changed the world more than any other single event or series of events. With the advent of farming, human societies invented concepts of land ownership and private property. This led to the formation of hierarchical societies, which was necessary to wage war for land and other limited resources--a circumstance that did not exist among hunter-gatherer societies, they say, because no one claimed to own the land or anything else. There simply were no wars for land or resources among prehistoric people; they lived in a world of abundance and would have had no reason to organize to control territory; nor did they store food; they were "immediate return" hunter-gatherers, meaning they consumed what they found or acquired daily.I can't find any flaws with the theories or logic.Another reader did, however, writing: “ ‘If human sexuality developed primarily asa bonding mechanism in interdependent bands where paternity certainty was anonissue, then the standard narrative of human evolution is toast.’ If the standardnarrative of human evolution is, in fact, ‘toast,’ how does their competing worldviewbetter help explain contemporary human sexual relations?” The book answers thisquestion with the detailed discussion of agriculture referenced above, noting themany social, cultural and legal consequences that resulted from land ownership,hoarding of food, farming, and the need to preserve and pass on private property toheirs.The authors further argue that monogamy is simply a cultural construct that arose with agriculture as the logical consequence of abandoning communal living. Once everyone stopped cooperating mutually for each other's survival and farming began, a psychological shift from abundance to scarcity occurred, as resources suddenly became limited, had to be cultivated, hoarded, and sold, rather than gathered communally and distributed equally.Sexuality followed the same path. By imposing monogamy, men could have some reassurance of their paternity, which became increasingly important, because fathers passed property to their children (unlike in communal times), so paternity certainty became vital to ensure that property was passed to true heirs, not another man's children.The whole thing is amazing and forces one to reexamine the merit and utility of monogamy, among various other cultural beliefs.Fun and fantastic read.