RIO DE JANEIRO, BRAZIL - Dutch primatologist Carel van Schaik was able to observe an orang-utan for the first time in 1994 using tools it had developed in order to feed itself.
During an expedition to Gunung Leuser National Park in northwestern Sumatra, the expert noticed that some specimens used sticks to open a type of fruit with sweet and nutritious pulp, but which has thorns that can embed in the skin and cause great pain.
From an anthropological point of view, the use of tools represents a cultural aspect, since the whole group takes part in behavior that has . . .