The leader of the hitherto uncontacted Biami in central New Guinea lists the nearby rivers. Counting gestures vary between tribal groups, so the ones he used might reveal which people he traded with. (© David Attenborough)
The leader of the hitherto uncontacted Biami in central New Guinea lists the nearby rivers. Counting gestures vary between tribal groups, so the ones he used might reveal which people he traded with. (© David Attenborough)