Fossils show women smaller than males

By Tim Cocks

NAIROBI (Reuters) - Homo erectus, long viewed as a crucial evolutionary link between modern humans and their tree-dwelling ancestors, may have been more ape-like than previously thought, scientists unveiling new-found fossils said on Thursday.

Revealing an ancient skull and a jawbone from two early branches of the human family tree -- Homo erectus and Homo habilis -- a team of Kenyan scientists said they were surprised to find that early female hominids were much smaller than males.

The skull was the first discovery of a female Homo erectus.

It suggests mankind's upright ancestors may have been physiologically closer to modern gorillas and chimpanzees, which also exhibit big differences in size between males and females, than had been supposed.

"Prior to the discovery of the new specimens, scientists did not know that Homo erectus males were far larger than the females," said Dr Emma Mbua, one of the team.

"This sexual dimorphism is considered a primitive character because it occurs in other apes," she said, standing in front of the bones at Kenya's National Museum.

She said this could also mean the sexual behaviour of Homo erectus was more like that of apes, where individuals, especially males, mate with several partners, sometimes in a few hours, than that of its more monogamous human successors.

The fossils, discovered in east Africa's Rift Valley, regarded as the "cradle of humankind", challenge the idea that human prototypes evolved one after the other in a linear fashion from Homo habilis to Homo erectus, ending with modern humans.