They're generated by underwater landslides and earthquakes Known as tsunamis, they can flatten coastlines Yet these destructive forces may have also brought life to some islands As tsunamis strike the coast, rafts of vegetation could be cast adrift Perhaps animals were caught up in those rafts too Could this have been the answer to how these animals made it to Fiji? After all, they are the hardest of their kind and could have survived long sea journeys Fiji's first animals washed up tens of millions of years ago But humans were slow off the block They only arrived here three and a half thousand years ago Their history remains thin on the ground The ruins of Nan Madol are one of only two ancient cities ever found in the Pacific With archaeological evidence so scarce, the origins of the first people in the central Pacific were hotly debated Were they Papuans From New Guinea, native Indians from the Americas, or another race of people from Asia