Pollen analysis suggests that the islanders were the agents of their own ruin. They used up the resources that brought them success. They used up all the trees. One particular tree was vital to the islanders' way of life.
The tall Chilean palm was ideal for building homes and sea-going canoes, and for providing logs to transport works of art.
This was not an easy job. Rapa Nui is famed for its huge stone statues - some of the largest images of humans ever carved. About 1,000 of these stern and tight-lipped giants, mostly sculpted between 1200 and 1500, litter the land. The largest is 20 metres long, weighs 270 tonnes, and never made it out of the quarry. The statues are only of heads and chests, so the impression is that some colossal child has left its models half-buried in the island's soil.
The figures are astonishing, but they cost the life of the over-harvested Chilean palm, which became extinct around 1400. Its loss meant the islanders could no longer build canoes and go fishing. Deprived of their favourite food, the porpoise, they started eating birds. Soon these were extinct, too. Deprived of nature's seed scatterers, the forests, already scoured for firewood and building material, also disappeared. Then the streams dried up and water became scarce. Crops declined as the topsoil blew away.
With no trees left the islanders were forced to burn grass as fuel. This meant they could no longer make rope, another essential for house building and statue transport. Not surprisingly, quarrels broke out and then fighting. By the time Europeans arrived in 1722, there was little left of a once-civilised society, except its art, of course - the art that helped kill the trees.