A reconstruction of the 1.2 million-year-old pelvis discovered in 2001 in the Gona Study Area at Afar, Ethiopia, that has led researchers to speculate early man was better equipped than first thought to produce larger-brained babies. The actual fossils remain in Ethiopia. Credit: Scott W. Simpson, Case Western Reserve University

Ask any woman who has given birth and she'll be happy to wax lyrical about the bad fit between the modern human pelvis and a baby's big head.

Ask any anthropologist and he or she will also be happy to explain, in similar gory detail, that painful labor is the product of an evolutionary compromise to accommodate upright walking in a species that also has an oversized brain.

That compromise came, anthropologists used to believe, about 2.4 million years ago when our already bipedal ancestorHomo habilis experienced a huge leap forward in brain size.

But a recent announcement in the journal Science of a 1.2 million-year-old Homo erectus pelvis uncovered by University of Indiana paleoanthropologist Sileshi Semaw in the Afar region of Ethiopia in 2001 suggests that painful labor is a relatively modern affliction.
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