Briefly explain why, according to Collapse, changes on Mangareva Island after 1450 had such disastrous consequences for the inhabitants of Pitcairn and Henderson Islands. And why does Diamond think that this is a relevant lesson for our society today?
The answer to this can be found in Chapter 3 of Collapse. There, Diamond tells us that the people of Mangareva deforested their island and caused an ecological catastrophe there. When that happened, the people of Pitcairn and Henderson were deprived of a very important trading partner and were no longer able to survive on their islands.
In this book, one factor in Diamond’s “framework” of things that can cause a society to collapse is a change in the circumstances of a friendly neighbor that trades with your country. If you depend on a friendly neighbor for something very important, you are in a lot of trouble if that neighbor stops being willing and able to trade with you. That is what happened to the people of Pitcairn and Henderson.
Both of these islands had severe limitations in terms of their ability to sustain human populations. But the human populations on those islands overcame those limitations, in part, by trading with Mangareva. In particular, Pitcairn and Henderson needed oyster shells from Mangareva to use for making tools. When Mangareva’s population outgrew its carrying capacity, Mangareva dropped into civil war and famine. This prevented it from trading as much as it had and made Pitcairn and Henderson essentially uninhabitable.
Diamond says this is important for us because it shows how interconnected we are and how much trouble one society can get into if another society collapses. Because of our globalized economy, the fates of other societies can strongly affect the fate of our own.