Nov 15, 2008

Science - Ancestors had babies with big heads

WASHINGTON: The fossil of a wide-hipped Homo erectus found in Ethiopia suggests females of the pre-human species swayed their hips as they walked Wide at the Waist: The fossil of a wide-hipped Homo erectus female, in Ethiopia.
and gave birth to relatively developed babies with big heads, researchers said.

The finding transforms thinking about some early human ancestors and evolution and suggests that helpless babies came along relatively late in the human lineage.

“We could look at this pelvis and then, using a series of measurements, we can calculate ... how big the baby’s head could be at birth,” said Scott Simpson, a paleontologist at Case Western Reserve University who worked on the study.

Writing in Science, Simpson and colleagues said the size and shape of the 1.2 million-year-old pelvis indicates that Homo erectus females had hips wider than those of modern human females and their infants were born with heads about 30% larger than previously calculated. “What this means is the offspring were not as helpless as a modern human,” he said.

“It is not coming out walking and talking. But it was probably capable of more advanced behaviour at a younger age like grasping, like sitting up ... than we would see in a modern human.”

An extended childhood is a particularly human characteristic. Helpless babies require intensive care, not from the mothers but from an extended group, which may have spurred the development of human society and culture. Homo erectus, Latin for “upright man”, arose in Africa 1.8 to 2 million years ago, migrating to Asia and Europe before becoming extinct about half a million years ago.

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