Terry L. Hunt, anthropology professor at the University of Hawaii at Manoa, proposes a new explanation (PDF) for the environmental degradation of Easter Island.

What Hunt believes happened is that people brought rats with them, and the population of rats mushroomed (“the rat population could have exceeded 3.1 million”). The rats fed on the island’s palm nuts, and that’s what led to the deforestation.

His theory undermines the validity of Easter Island as a 1:1 parable for the consequences of population and deforestation; he thinks it’s unlikely that the local population grew to as many as 15,000 people, or that it was man’s deforestation of the islands (for building and fuel) that rendered it inhabitable.

The article is a long one with a lot of detail on how Hunt came to his conclusions. Reluctantly, btw.