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Phys.org reports that Polynesian rats (Rattus exulans) may have played a larger role in the deforestation of Rapa Nui than previously thought. Some 15 million Rapa Nui palm trees (Paschalococos disperta) are estimated to have covered Easter Island before the arrival of Polynesians around A.D. 1200. When Europeans arrived in 1722, they observed just a few isolated trees, grasses, and shrubs. Terry Hunt of the University of Arizona and Carl Lipo of the University of Birmingham developed an ecological model of the island and found that a single pair of rats, feasting on nutritious palm nuts, could grow into a...

Rat DNA clues to sea migration This carving shows Pacific rats on the face of a Polynesian ancestor Scientists have used DNA from rats to trace migration patterns of the ancestors of today's Polynesians. People are thought to have arrived in Polynesia, comprising the Pacific islands of Fiji, Tonga and Samoa, by boat some 3,000 years ago. Rat data suggests the journey was more complex than the popular "Express Train" theory, which proposes a rapid dispersal of people from South Asia. Details appear in Proceedings of the National Academy of Sciences. Elizabeth Matisoo-Smith and Judith Robins from the University of...