This is a frustrating book to review. It touches on a lot of interesting subjects, but avoids discussing many of the most thought-provoking implications. It has sections of research picked almost randomly in support of alternately prudent and ridiculous opinions. It's heavy on analysis, yet it doesn't have many clear prescriptions at all. Its subject is vast, yet his focus is often very narrow. I liked many parts of it, but overall it's unquestionably a step down from his past 2, even though it clearly seems to be a more heartfelt book. In the grand continuum of popular science books, it's much closer to the "pop" end, and even given the fact that it's impossible to satisfy all types of popular science readers, I have no idea who the target audience is supposed to be. His subject is the cultural practices of several groups of traditional societies, and the lessons that us Westerners can learn from their practices. In a way it's a return to the first chapter of Guns Germs & Steel, but instead of asking "how did the West get so advanced?", he's asking "are there things we can still learn from the people we've out-developed?"
It's a reasonable question, and anyone who has devoted any thought to the long-term effects of our overweight, overstressed, overmedicated, atomized modern lifestyles ("WEIRD" in his acronym - Western Educated Industrial Rich Democratic) will find some value in his high-level survey of the ways that traditional societies handle various aspects of the human condition like conflict, child-raising, religion, diet, the role of the elderly, and the like. He tends to split his analysis into either anecdote-heavy descriptive passages that involve his pals in New Guinea, or slightly more rigorous conceptual sections that discuss things like the various functions of religion or the types of political changes that occur when societies grow from a few hundred hunter-gatherers to millions of specialized citizens. There's good stuff in both types of sections, but... (as usual, ignore the first half of any sentence that has a "but..." in it).
My problem with the anecdotal sections is that though the narrative format is a good way to make your points more vivid, it's also a good way to make them less rigorous. It's all very well to tell people that "constructive paranoia" (minimizing risks through careful skepticism) is a helpful way to live, but even though he has some neat stories about mysterious forest sorcerers, almost dying in a canoe accident, and running around on remote mountain peaks, my reaction was basically "cool story bro" - are these either generalizable in any way to Western lives, or even anything more than an over-elaborate way to say "watch out for danger"? He also tosses in anecdotes that are simply absurd, like the one about the Kenyan who didn't like American toys because Kenyan toys were more interactive and better at encouraging mechanical creativity. Hence the global leadership and supremacy of Kenyan industry? Ditto again for stories about how much more isolating modern society is than than the constant communication and contact in traditional societies. This is certainly true, but it seems odd to package a criticism of solitary entertainment like TV, video games, or books in the form of a book which can only be appreciated by reading or listening to it alone.
As far as the more data-heavy sections are concerned, I don't think any of the science is outright wrong, but I can see why this book annoys specialists in several scientific fields. Diamond picks really big topics, like The Role of Religion In Society, or The Effects of Increasing Scale On Societal Organization, and sums them up in a few pages of text and maybe a table or two. This is either admirable trans-specialty synthesis, or over-simplification on an epic scale, and the trend was increasingly towards the latter as the book went on. For example, late in the book he talks about the sharp decrease in global language diversity and the disappearance of many traditional languages. I personally am not very sentimental about languages in and of themselves, even English, and so his pathos-filled arguments for the preservation and continuation of languages with just a few thousand speakers didn't do much for me. Suppressing speakers of Breton is bad, I agree, and I think his advocacy of bilingualism is solid, yet the fact that all languages eventually change or die out doesn't really bother me in a metaphysical sense; that my nth generation descendants might be speaking SpaceMandarin instead of NeoEnglish is fine with me. Also, Diamond correctly points out that death rates from all kinds are much higher in traditional societies than modern ones: are there any evolutionary consequences to this? He doesn't say.
Ultimately I wasn't very satisfied with the book. Certainly we should give more thought to whether the vast changes in lifestyle encouraged by modernity are really good for us in the long run, but I found the evidence that Diamond gave insufficient to conclude that New Guinean highlanders have much to teach us. What made Guns Germs & Steel and Collapse such good books to me was their rigorous sourcing, his broad synthesis of those sources, and the careful way his specific claims about imperialism and sustainability emerged from those things. This book is a decent overview of the cultural practices of some groups of traditional societies, but it feels like a huge let-down from those two works, simultaneously too lengthy and too unclear.
Also, the airport frame story technique was almost intolerably Thomas Friedman-esque. Cut that stuff out.