Mangareva, Pitcairn, and Henderson are the only habitable islands in the remote region of the South Pacific known as Southeast Polynesia.
There is ample evidence that these islands traded extensively with each other. In particular, Mangareva supplied the two smaller islands with oyster shells and basalt stone suitable for making a range of different utensils. Mangareva quite likely also provided the two other islands with a variety of crops and with pigs. Of vital importance, due to the small populations of Pitcairn and Henderson, Mangareva would have been a source of marriage partners for them.
Diamond lists nine different factors that can contribute to deforestation on islands in the Pacific. Mangareva exhibited most of these including a location at a relatively colder high latitude and lesser fallout from atmospheric dust to supplement the soil. As a result, when Mangareva's inhabitants eventually felled the forest in the interior of the island, it led to permanent deforestation. Soil erosion followed, limiting the area available for their gardening.
Critically, deforestation also removed the larger trees needed to construct canoes for fishing. Existence on the island descended into a nightmare of hunger and war, and trading with Pitcairn and Henderson ceased. The population of the two smaller islands, deprived of goods and partners from Mangareva, dwindled to nothing.
Diamond points out that our time's increasing globalization and dependence on foreign trade mirrors on a vastly larger scale the situation of the islands in Southeast Polynesia. He states that we are affected by "many economically important but ecologically fragile areas" just as Henderson and Pitcairn were.