According to an article by Bob Holmes for New Scientist, a new study by Terry Hunt finds that humans decimated Easter Island on arrival:
Archaeologists had thought that humans first arrived at the island around 800 AD, based on radiocarbon dating of kitchen scraps and cooking fires. Since the first signs of severe deforestation do not appear until the 13th century, this suggests the Easter Islanders lived several centuries without serious impact on their environment.
Not so, says Terry Hunt, an archaeologist at the University of Hawaii at Manoa. Hunt and Carl Lipo of California State University at Long Beach, US, radiocarbon-dated charcoal from the earliest human traces in a new excavation on the island. The site, Anakena, is Easter Island’s only sandy beach and has long been regarded as the likeliest spot for first colonists to settle. To their surprise, the wood dated no earlier than 1200 AD – several hundred years more recent than they had expected.