A Neanderthal pelvis — the basin-shaped ring of bones at the base of the spin — discovered decades ago may help explain an unusual feature of modern human anatomy: why the pelvises of men and women are shaped so differently.
Reconstruction of a Neanderthal. Image credit: Neanderthal Museum.
“Until the discovery of the nearly complete male Neanderthal pelvis in the early 1980s (in Kebara Cave, Israel, very little was known about the anatomy of the Neanderthal pelvis as a whole,” said Ono Academic College’s Professor Ella Been and her colleagues.
“The few detached pelvic fragments that were already available hinted at significant differences between the Neandertal pelvis and that of modern humans (primarily males).”
In a new study, the authors compared the pelvis of a Neanderthal individual known as Kebara 2, along with another Neanderthal pelvis from Sima de los Huesos in Spain, with 63 modern human male pelvises and 28 female pelvises.
They found that, in several important respects, male Neanderthals more closely resemble modern human females than males.
The key difference is the position of the hip joints, or acetabula. In modern human males, the joints sit farther forward on the pelvic rim. This shift is accompanied by a shorter and thicker superior pubic ramus, the section of bone extending toward the front of the pelvis.
In Neanderthal males, the hip joints sit farther back, leaving a longer, thinner ramus, a configuration that is also found in modern human females.
The researchers propose that the forward position of the hip joints in modern human males may have turned the pelvis into a kind of shock absorber.
“During every step of bipedal walking, the body’s center of mass drops downward,” said Tel Aviv University’s Professor Yoel Rak.
“This drop traumatizes the joints and requires energy to raise the body again in preparation for the next step.”
“According to the new model, the distinctive geometry of the male pelvis enables the thigh muscles to cushion the drop of the body’s center of mass, store potential energy during the step, and then release that energy immediately afterward– effectively ‘springing’ the body upward into the next step.”
“In this way, the pelvis functions as a natural shock-absorber and energy-return system.”
“It may reduce energy expenditure, improve walking efficiency, and thereby provide a significant advantage during long-distance travel on foot.”
“The change in the position of the hip joints also required additional structural adaptations, including the thickening of the pubic bone and deepening of the anterior portion of the pelvis to withstand the new mechanical loads.”
The scientists also suggest that this adaptation may have emerged after the evolutionary split between Neanderthals and Homo sapiens.
They argue that modern human females retained the more ancestral pelvic configuration because changes that would narrow or deepen the pelvis could interfere with the demands of childbirth.
“Our study demonstrates that questions about human evolution are not confined to the distant past,” Professor Been said.
“Understanding the evolution of our walking mechanism can contribute to contemporary research in biomechanics, musculoskeletal medicine, rehabilitation, and injury prevention.”
“The perspective provided by the Neanderthals helps us better understand the modern human body.”
The results were published on July 31 in the journal Scientific Reports.
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Y. Rak et al. Neandertal pelvis reveals specialized walking apparatus in human males. Sci Rep, published online July 31, 2026; doi: 10.1038/s41598-026-59915-8
