Two Neanderthal pelvises suggest the strange hip belongs to the modern human male

A team from the Department of Anatomy and Anthropology at Tel Aviv University has published a comparison in Scientific Reports that reverses the direction of a long-standing inference: measured against dozens of modern human pelvises, two nearly complete male Neanderthal pelvises came out looking like modern human females rather than modern human males ^[1][3][4]. If that holds, the specimen needing a special functional explanation is not the Neanderthal one, which is how the problem has been framed for years, but ours ^[5][15].

The study was led by Professor Yoel Rak, with collaborators in Spain and at the Technion, Bar-Ilan University and Ono Academic College ^[2]. The Neanderthal side of the comparison is one pelvis from Kebara Cave in Israel and one from Sima de los Huesos in Spain ^[3]. Both are described as male, which means no Neanderthal female enters the sample at all ^[16]. Despite their size and robust construction, both resembled modern human females across most measurements and proportions ^[4].

The measurement doing the work is the position of the hip joints on the pelvic ring. In modern human males they sit farther forward than in either modern human females or male Neanderthals ^[7]. The researchers argue that this forward shift set up a different mechanical arrangement, with the anterior thigh muscles attached to the front of the pelvis acting as a spring while body weight bears on the posterior part ^[8]. Rak's account of the gait cycle is that the body's centre of mass drops with every step, loading the joints and demanding energy to lift the body again ^[9]. Under the proposed model, male pelvic geometry lets the thigh muscles cushion that drop, store potential energy and return it into the next step ^[10]. The team also reports associated structural changes consistent with heavier loading in that region: a thickened pubic bone and a deepened anterior pelvis ^[12].

The sex difference is explained as a constraint problem rather than a separate adaptation. Childbirth requires a relatively shallow pelvis and a wide enough birth canal, so on this reading the female pelvis could not take on the full set of modifications and stayed closer to the ancestral configuration, the same general configuration the authors find in male Neanderthals ^[13][6].

Two things are worth keeping separate. The morphometric result is a set of measurements on real specimens. The shock-absorber account is presented as a model, and the efficiency payoff is stated as something that may reduce energy expenditure and may help over long distances, not as a measured saving ^[17][11]. No gait-laboratory or metabolic data appears in the published account of the work.

Ella Been of Ono Academic College, a co-author, frames the downstream interest as clinical rather than purely palaeontological, pointing to biomechanics, musculoskeletal medicine, rehabilitation and injury prevention ^[14].

Watch whether the pattern survives a larger fossil sample, particularly any Neanderthal pelvis identified as female, since the ancestral-retention claim currently rests on two male individuals ^[3][16]. Watch, too, for anyone putting the energy-return prediction on a force plate: a model that claims a stride-by-stride saving is testable in living people, and the size of that saving is what decides whether this is a real selective story or a tidy description of a shape difference ^[10][11].