Modern human men evolved unique hip 'spring' for efficient walking, Israeli-led study finds

A Tel Aviv University-led study published in Scientific Reports challenges decades-old assumptions about the Neanderthal pelvis. Researchers found that the modern human male pelvis, not the Neanderthal's, is the evolutionary innovation. The male hip joints shifted forward, creating a built-in 'spring' mechanism that cushions the body's center of mass drop during walking, stores energy, and releases it for efficient long-distance travel. Neanderthal pelvises and modern female pelvises share an ancestral configuration, with childbirth constraints keeping the female pelvis closer to that ancestral form.

A new Tel Aviv University-led study, published in Scientific Reports, overturns a long-held anthropological assumption about the human pelvis. Researchers led by Prof. Yoel Rak compared two nearly complete male Neanderthal pelvises—one from Israel's Kebara Cave and one from Spain's Sima de los Huesos—with dozens of modern human pelvises. They found that the Neanderthal pelvis closely resembles the modern human female pelvis in most measurements, not the modern human male pelvis. The study argues that the modern human male pelvis, not the Neanderthal's, is the true evolutionary innovation. The male hip joints shifted forward, creating a built-in 'spring' mechanism that cushions the drop of the body's center of mass during walking, stores potential energy in the thigh flexors, and releases it to propel the body into the next step. This adaptation reduced energy expenditure and improved walking efficiency, providing an advantage for long-distance travel. The researchers note that childbirth constraints—requiring a shallow pelvis and wide birth canal—kept the female pelvis closer to the ancestral configuration shared with Neanderthals. The study highlights that even in human macroscopic anatomy, previously unrecognized structures and mechanisms can still be discovered.