Abstract: Language, with its complex recursive structure, is almost certainly a uniquely human capacity. I argue that it evolved over the past 2 million years during the Pleistocene epoch, as part of a cognitive adaptation to deforestation and predation from dangerous killer animals on the African savanna. Rather than postulate any specific genes for language, I suggest that there was systematic selection for increase in brain size, allowing for more complex social cognition, including the “grammaticalization” of communication through learning and cultural pressures. Parallel to this development, the medium of communication changed gradually from a manual mode to a facial and then vocal mode, culmination in a mutation of the FOXP2 gene that gave our own species, Homo sapiens, the capacity for autonomous speech. This final switch may explain the so-called “human revolution,” leading to the dominance of humans on the planet, and the demise of other species of the genus Homo.

Key words: language, grammaticalization, the medium of communication