Jared Diamond's account of the collapse of Easter Island society is well known by now — how the Islanders decimated their ecosystem and drove themselves to the brink of starvation by using up the island's natural resources at a furious rate. But that's not the only possible explanation for how Easter Island lost its tree cover and ended up with a much-reduced population. In fact, some anthropologists say there's not really any hard evidence that the Islanders were practicing slash-and-burn agriculture, clearing the land with fire.
Instead, this other theory blames the little creature pictured above — the Polynesian rat, an invasive species that stowed away on canoes and chewed its way through the roots, sprouts, and seeds of Easter Island's trees. Instead of willfully destroying themselves, this scenario has the islanders desperately adapting to a quickly changing environment. It's not that the changes had nothing to do with people — the rats got there with human help, after all — but the angle of the story changes somewhat, becoming less about the destructive aspects of human nature and more about the lengths humans will go to in order to survive.
Image: Cliff from Arlington, via CC license