Neanderthal Pelvis Study Suggests Modern Male Anatomy Is the Real Evolutionary Outlier

A new study from Tel Aviv University's Department of Anatomy and Anthropology suggests the modern human male pelvis, not the Neanderthal pelvis, may be evolution's unusual case, offering a possible explanation for why men and women walk differently. The study, led by Professor Yoel Rak and published in Scientific Reports, also involved researchers from Spain, the Technion, Bar-Ilan University and Ono Academic College.

The researchers compared two nearly complete male Neanderthal pelvises, one from Kebara Cave in Israel and another from the Sima de los Huesos site in Spain, with dozens of modern human pelvises. Despite their large, robust build, the Neanderthal specimens matched modern female pelvises more closely than modern male ones across most measurements, suggesting Neanderthals and modern human females may have kept an ancestral pelvic shape while the modern male pelvis changed.

The key difference lies in the hip joints, which sit farther forward on the pelvic ring in modern human males than in females or male Neanderthals. The researchers propose this shift lets the thigh muscles attached to the front of the pelvis act like a spring, storing energy as the body's centre of mass drops with each step and releasing it to help lift the body into the next step, an arrangement that could lower the energy cost of long-distance walking. The change also required a thicker pubic bone and a deeper front portion of the pelvis.

Because childbirth requires the pelvis to stay relatively shallow while keeping a wide birth canal, the female pelvis could not undergo the same changes and may have remained closer to the ancestral form seen in male Neanderthals. Professor Ella Been of Ono Academic College, a study co-author, said the findings show that questions about human evolution are not confined to the distant past, and that understanding how the human walking mechanism evolved can contribute to biomechanics, musculoskeletal medicine, rehabilitation and injury prevention research.