State of origin

Archaeology continues to turn up fossil evidence that humans may not have evolved only on Africa's savannahs.

- Bob Brockie

Scientists have long supposed that early humans evolved on African savannahs. But that idea has become questionable.

The traditional theory suggests our chimp-like ancestors used their long arms and short legs to climb and swing through the African jungles. On the ground, they walked on all fours and on their knuckles. Between 200,000 and 300,000 years ago, the African climate dried out and many forested parts turned into open grassland, especially in east Africa.

As forests disappeared and apemen moved on to the savannahs, they underwent a suite of skeletal changes. They adapted to their new home by evolving longer legs and walking upright. Bipedalism allowed the earliest humans to see over the tall grass in search of prey or predators. Longer legs enabled them to walk or run long distances and develop "adroit movements, swiftness and stealth" (to quote an early theorist). It freed up apemen's arms and hands. They evolved longer opposable thumbs and shorter, straighter fingers - all the better for throwing objects, clubbing prey (or each other) and for handling objects with dexterity.

About 200,000 years ago, their brains started to grow dramatically, and some 100,000 to 50,000 years ago, Homo sapiens developed the power of complex speech.