From Adriaan Kortlandt
D. W Ewer is mistaken when he proposes that a spoken language had a selective advantage when early humans wanted to communicate with companions who were out of sight in a tall grass savanna or a forest (Letters, 15 April).
When I surveyed chimpanzee paths in the rainforest in Eastern Zaire, accompanied by Mbuti Pygmies, I noticed that they used bird calls as a means of communication at a distance and avoided speaking. Their aim apparently was not to reveal the presence of human hunters to their game, mainly antelopes.
