1.2m year-old pelvis found in Ethiopia
The fossil of a wide-hipped Homo erectus
found in Ethiopia suggests females of the
pre-human species swayed their hips as
they walked and gave birth to relatively
developed babies with big heads,
researchers said on Thursday.
14 November, 2008
A prehistoric pelvis discovered in Ethiopia has given researchers new clues about how early humans developed, a study released on Thursday says.
The 1.2 million-year-old pelvis, the first nearly intact female pelvis discovered from that period in human history, shows that Homo erectus was squatter than previously thought and capable of birthing large-brained babies.
That could mean that humans evolved to experience an extended childhood later than previously believed, because babies born with larger brains are less dependent upon their parents.
"As far as the fossil pelvis of ancestral hominids goes, all we've had is Lucy (dated at 3.2 million years and also found in Ethiopia), and she is very much farther back in time from modern humans," said lead author Sileshi Semaw of Indiana University Bloomington.
"This discovery gives us more accurate information about the Homo erectus female pelvic inlet and therefore the size of their newborns."
Semaw and his team reconstructed the pelvic bone fragments discovered in the Gona Study Area in Afar, Ethiopia, in 2001.
They determined that the birth canal was more than 30 per cent larger than earlier estimates based on a 1.5 million-year-old juvenile male pelvis found in Kenya.
The specimen was also shorter and had a broader body shape than expected.
Researchers had believed that early humans evolved to become taller and narrower because that body type helped them to maintain a constant body temperature during endurance running.
However, that body type led to a narrow pelvis, making it more difficult to produce larger-brained offspring, which could explain how humans evolved to have such long childhoods, according to an article accompanying the study.
This discovery, published in the journal Science, will help researchers better determine when that shift happened. - AAP via Yahoo!7 News