Although the first arrivals were hunter-gatherers, early evidence shows that people managed the forest environment to provide food. The gardens of the New Guinea highlands are ancient, intensive permacultures, adapted to high population densities, very high rainfalls (as high as 10,000mm/yr (400in/yr)), earthquakes, hilly land, and occasional frost. There are indications that gardening was being practised at the same time that agriculture was developing in Mesopotamia and Egypt.