Easter Island deforestation: humans and rats

[snore]

http://www.americanscientist.org/tem...true&print=yes

By the time the second round of radiocarbon results arrived in the fall of 2005, a complete picture of Rapa Nui's prehistory was falling into place. The first settlers arrived from other Polynesian islands around 1200 A.D. Their numbers grew quickly, perhaps at about three percent annually, which would be similar to the rapid growth shown to have taken place elsewhere in the Pacific. On Pitcairn Island, for example, the population increased by about 3.4 percent per year following the appearance of the Bounty mutineers in 1790. For Rapa Nui, three percent annual growth would mean that a colonizing population of 50 would have grown to more than a thousand in about a century. The rat population would have exploded even more quickly, and the combination of humans cutting down trees and rats eating the seeds would have led to rapid deforestation. Thus, in my view, there was no extended period during which the human population lived in some sort of idyllic balance with the fragile environment.

It also appears that the islanders began building moai and ahu soon after reaching the island. The human population probably reached a maximum of about 3,000, perhaps a bit higher, around 1350 A.D. and remained fairly stable until the arrival of Europeans. The environmental limitations of Rapa Nui would have kept the population from growing much larger. By the time Roggeveen arrived in 1722, most of the island's trees were gone, but deforestation did not trigger societal collapse, as Diamond and others have argued.

There is no reliable evidence that the island's population ever grew as large as 15,000 or more, and the actual downfall of the Rapanui resulted not from internal strife but from contact with Europeans.

It's an interesting article that argues that deforestation was caused principally by rats eating the seeds of the palm trees. These rats came along with the polynesians that colonized the island.

[Karl Martell]

I am having difficulty believing that a society of 3000 people could build all those moai, actually... there are, what, 50? 60? of them, and they seem to have required a lot of work. Also, considering that the islanders had gone through social upheaval (change of cults, overthrow of moai) prior to the European arrival suggests to me that there was indeed a demographic crisis which involved a decline of the population from a previous, higher point to the 3000 or so that were there when the Euros arrived.