A new study has revealed an unexpected aspect of human evolution: the pelvic anatomy of Neanderthals appears to be closer to that of modern women than to that of modern men. According to the researchers, this does not mean that Neanderthals had a primitive or unusual pelvis. Instead, it suggests that the male human pelvis underwent substantial evolutionary changes on the path to modern humans.
The research was conducted by the Department of Anatomy and Anthropology at Tel Aviv University, led by Professor Yoel Rak, in collaboration with research teams from Spain, the Technion, Bar-Ilan University and Ono Academic College. The findings were published in the scientific journal Scientific Reports.
The researchers examined two nearly complete male Neanderthal pelvises: one discovered at Kebara Cave in Israel and another from Sima de los Huesos in Spain. They then compared them with dozens of pelvises from modern humans.
The results were striking. Despite the Neanderthals’ robust build and larger overall body size, the proportions and individual measurements of their male pelvises showed greater similarities to those of modern women than to those of modern men.
The evolutionary change that occurred in men
The most significant difference concerns the position of the hip joints. In modern men, these joints are positioned farther forward within the pelvic ring compared with both women and male Neanderthals.
This distinctive geometry appears to influence how the pelvis functions during walking. With every step, the body’s center of mass moves slightly downward before rising again. The anatomy of the modern male pelvis allows the muscles at the front of the thigh to act somewhat like springs.
During movement, these muscles can store part of the mechanical energy and release it during the next phase of the stride. According to the researchers, this mechanism may reduce the energy required for walking and make long-distance movement more efficient.
The evolutionary shift was accompanied by other anatomical changes, including a thicker pubic bone and a deeper anterior section of the pelvis.
Why did the female pelvis follow a different path?
The obvious question is why the female pelvis did not undergo the same evolutionary changes.
The researchers’ main explanation is linked to childbirth. The female pelvis must maintain a sufficiently wide birth canal to allow the delivery of babies with relatively large brains and skulls.
These reproductive demands appear to have constrained anatomical changes that might otherwise have further optimized the mechanics of walking. In other words, evolution had to strike a balance between efficient locomotion and the physical requirements of childbirth.
As a result, reproductive pressures may have acted as an evolutionary constraint, keeping the female pelvis closer to an older anatomical form that is also represented by male Neanderthals.
A new perspective on human evolution
The findings offer a different way of looking at the evolution of the human pelvis. Rather than viewing Neanderthal pelvic anatomy as an unusual or primitive configuration that requires a special explanation, the study suggests that it may largely represent an ancestral form from which the modern human pelvis evolved.
The evolutionary question therefore shifts. Instead of asking only why Neanderthals had this particular pelvic structure, researchers can now focus on how and why the pelvis of modern men evolved into a more specialized mechanism for efficient walking.