What lessons can we draw from history? The most straightforward: take environmental problems seriously. They destroyed societies in the past, and they are even more likely to do so now....Diamond gives us several charming historical examples of societies that failed to heed these lessons, and collapsed as a result. We learn all about the environmental depredations of the Easter Islanders, the stubborn unwillingness of the Norse Greenlanders to adapt their culture to a shift in their climate, and the callous insularity of the Mayan kings who did nothing to halt the deforestation and soil erosion that eventually destroyed them.
Other lessons involve failures of group decision-making. There are many reasons why past societies made bad decisions, and thereby failed to solve or even to perceive the problems that would eventually destroy them. One reason involves conflicts of interest, whereby one group within a society....can profit by engaging in practices that damage the rest of society. Another is the pursuit of short-term gains at the expense of long-term survival....
History also teaches us two deeper lessons about what separates successful societies from those heading toward failure. A society contains a built-in blueprint for failure if the elite insulates itself from the consequences of its actions....The other deep lesson involves a willingness to re-examine long-held core values, when conditions change and those values no longer make sense.
But strangely, while Diamond gives us much sparsely-supported speculation about the possible environmental and social causes of some famously mysterious and poorly-understood societal collapses, we hear remarkably little about what's surely the cause of the overwhelming majority of more mundane societal disappearances: conquest by hostile neighboring societies. Certainly far more New World civilizations--that is, just about every one of them in existence in 1492--were destroyed by the European invasion and conquest (together with the resulting epidemics) than by their own poor ecological stewardship of their domains. Likewise, the very cradle of civilizations--the Middle East--was home to innumerable noble civilizations over thousands of years that did just fine till being gobbled up by even nobler ones, and disappearing completely except for a stone relic or two.
Of course, a rule like, "be sure to stay militarily stronger than your neighbors", or, "try to avoid falling so far behind technologically that you're easy pickings for invaders", is both less emotionally satisfying and less fashionable than, say, "be kind to mother Earth". Still, Diamond really ought to allot it more than the mere passing mention he offers, given its overwhelming historical importance.