A team of integrative biologists at the University of Texas, Western Washington University and Columbia University Irving Medical Center has found that both wide and narrow hips provide women with certain physical benefits, though they both also have downsides. In their study published in the journal Science, the group compared hip structure among 31,000 people listed in the UK Biobank, with other physical features including those associated with pregnancy and birth.

For many years, evolutionary theorists have debated aspects of what has come to be known as the obstetrical dilemma. Prior research has shown that as humans evolved, their brains grew bigger. But prior research has also shown that as people began to walk upright, their hips grew narrower, creating a conundrum—wider hips are needed to deliver babies with bigger brains.

For this new study, the research team investigated the ways that nature has dealt with the obstetrical dilemma by studying hips and the pelvic floor.