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TRAUMA sometimes experienced during childbirth has been a problem faced by our ancestors for almost 4 million years. New evidence of pelvic damage in an ancient female skeleton shows we might be able to find signs of such injuries in the fossil record.

Humans are unique among hominids in having a birth canal that is nearly identical in size to the neonatal head. Inevitably, natural variation means some women have a pelvis that proves slightly too small for the job of childbirth. Yet ancient evidence of birth trauma is rare, says at the University of Toronto in Canada. She has now found an example of stress injury to the pelvis in the skeleton of a 2000-year-old female found in South Africa.

The female’s pelvis was unusually narrow, which appears to have led to injury to the pubic symphysis, a joint running down the midline of the pelvis, during childbirth (). “Resulting deterioration of her joints probably caused a lot of pain, yet she stayed active,” says Pfeiffer. “This suggests that her group had knowledge of pain-numbing substances.”

Early last year at Boston University used estimates of neonatal hominin body mass to suggest that childbirth first became difficult around 4 million years ago. “It is a paper like this that will make me look at all of the casts I have of these pelvises to see if there are [signs of childbirth trauma],” he says. Female pelvises from the fossil record include those of the 3.2-million-year-old Lucy (Australopithecus afarensis) and one from a near-complete 2-million-year-old skeleton of Australopithecus sediba.