Professor Holly Dunsworth is a biological anthropologist who looks to fossil, anatomical, and metabolic evidence to reconstruct ape and human evolution, and she’s changing what the world knows about evolution – and human pregnancy.

Her early research on the feet of fossil apes led her to examine the evolution of bipedalism – or upright walking on two legs. That study got her thinking about human growth and reproduction, because two traits that set humans apart from other primates – big brains and the ability to walk upright  – could be at odds with one another when it comes to childbirth. After all, big brains (and the big heads that encase them) are hard to push through the human birth canal, but a wider pelvis might compromise our ability to walk upright.

Her study led her to publish a research paper challenging the long-held belief that the length of a human pregnancy is determined by the size of the mother’s birth canal and, ultimately, the width of her pelvis. Professor Dunsworth’s paper on what anthropologists call the “obstetric dilemma,” concludes that the length of human pregnancy is limited primarily by a mother’s metabolism, not the size of her birth canal.

“What we found is that babies are born when they’re born because mother cannot put any more energy into gestation and fetal growth,” she explained. “Mom’s energy is the primary evolutionary constraint, not her hips,” she said.

The resulting media attention thrust her into the limelight in unexpected ways. She’s been featured in the popular British science television program Horizon, quoted in numerous news stories, invited to speak at prominent venues around the globe, and generated a tremendous following on Twitter.

She hopes the attention will carry over into several new projects, including a book for general audiences about the evolution of reproduction and a children’s book about how dogs evolved from wolves, written from the perspective of her mutt Elroy.

“When I wake up in the morning, I want to change the way people think about evolution,” she said. With every bipedal step she takes, Professor Dunsworth is making progress toward accomplishing that goal.