I don't know. I'm not an expert on the subject, but the account Diamond gives in
Collapse is the same as what I'd heard before, and it's the only one I've ever heard, until now. Benny Peiser takes issue with this account in a paper published in Energy & Environment.
The `decline and fall' of Easter Island and its alleged self-destruction has become the poster child of a new environmentalist historiography, a school of thought that goes hand-in-hand with predictions of environmental disaster. Why did this exceptional civilisation crumble? What drove its population to extinction? These are some of the key questions Jared Diamond endeavours to answer in his new book Collapse: How Societies Choose to Fail or Survive. According to Diamond, the people of Easter Island destroyed their forest, degraded the island's topsoil, wiped out their plants and drove their animals to extinction. As a result of this selfinflicted environmental devastation, its complex society collapsed, descending into civil war, cannibalism and self-destruction. While his theory of ecocide has become almost paradigmatic in environmental circles, a dark and gory secret hangs over the premise of Easter Island's self-destruction: an actual genocide terminated Rapa Nui's indigenous populace and its culture. Diamond, however, ignores and fails to address the true reasons behind Rapa Nui's collapse. Why has he turned the victims of cultural and physical extermination into the perpetrators of their own demise? This paper is a first attempt to address this disquieting quandary. It describes the foundation of Diamond's environmental revisionism and explains why it does not hold up to scientific scrutiny.
Here's the full paper (PDF). Anyone know anything else about this?