Proceedings of the National Academy of Sciences—Mismatched evolutionary constraints between childbirth and locomotion are unlikely to have driven human pelvis shape, according to a study*. The Obstetrical Dilemma Hypothesis suggests that the shape of the human pelvis is an evolutionary compromise between the need to give birth to large-brained babies and to maintain bipedal locomotion. Whether such factors shaped the pelvic morphology of Neanderthals is unclear, given limited fossil evidence. Christoph Zollikofer and colleagues report virtual reconstructions and morphometric analyses of two nearly complete Neanderthal pelvises from a young adult female in Sima de las Palomas del Cabezo Gordo in Spain, as well as a 1.5-year-old infant in Dederiyeh Cave in Syria. The authors compared the reconstructions with age-matched Neanderthals and modern humans. The comparison identified differences in overall pelvis shape between Neanderthals and modern humans that were apparent from an early age. Both species shared patterns of sexual dimorphism in pelvis shape. The morphology of pelvic regions relevant for childbirth was also comparable between species, suggesting similar birth mechanics. However, modern humans and Neanderthals differed in features related to locomotion, including hip joint orientation and muscle movement arm geometry, suggesting that the two species had distinct stances and gaits. According to the authors, pelvis morphology in modern humans and Neanderthals may represent a compromise between childbirth and pelvic floor stability, rather than between childbirth and bipedalism.
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Virtual reconstructions of the Neanderthal pelvises of a 1.5-year-old infant from Dederiyeh Cave, Syria (left), and a young adult female from Sima de las Palomas de Cabezo Gordo, Spain (right), with transparent age- and sex-matched modern human pelvises superimposed. Credit: Marcia Ponce de León and Christoph Zollikofer.
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Article Source: Proceedings of the National Academy of Sciences news release.
*“Insights into Neanderthal development, childbirth, and locomotion from the Palomas and Dederiyeh pelves,” by Christoph P. E. Zollikofer, Marcia S. Ponce de León et al., Proceedings of the National Academy of Sciences, 17-Aug-2026. https://www.pnas.org/cgi/doi/10.1073/pnas.2535303123
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