India, Jan. 27 -- It was the abundance specifically of medium and large grazers in fertile savannas, concentrated near water in the dry season, that enabled the evolutionary transformation of a relatively puny ape into a feared hunter in Africa

That humans originated in Africa is widely accepted . But it's not generally recognised how unique features of Africa's ecology were responsible for the crucial evolutionary transitions from forest-inhabiting fruit-eater to savanna-dwelling hunter.

These were founded on earth movements and aided physically by Africa's seasonal aridity, bedrock-derived soils and absence of barriers to movements between north and south.

These features promoted extensive savanna grasslands marked by erratic rainfal...