New findings in Papua Highlands reveal that people were already there at least as early as 49,000 years ago, living 2000 meters above sea level and using characteristic waisted axes (left), which they probably used to fell down trees and make convenient clearings.
Previous research by the same team had located sites as old as 41,000 years near the coast.
Starch grains found on the axes are from yam (Dioscorea sp.), a tuber that does not grow at such high altitudes. Other vegetable remains found at the sites are charred nut shells from Pandamus sp., a high altitude tree that is used through Oceania for a variety of purposes: food, medicine, housing material, clothing, etc. Bones fragments from unidentified animals have also been found.
Lead researcher Glenn Summerhayes suggests that clearing was done on purpose, so medicinal plants could grow. He also suggests that some sort of clothing must have been used in order to ward off pneumonia (temperatures at such altitudes vary along the day between the nice 20 degrees Celsius at noon to freezing point at night).
Ref. G. Summerhayes et al., Human Adaptation and Plant Use in Highland New Guinea 49,000 to 44,000 Years Ago. Science 2010. Pay per view.