The Neanderthal cervical spine revisited

Recent studies have challenged the long-held notion that Neanderthals possessed a more stable and less lordotic cervical spine than modern humans. To investigate this hypothesis further, we conducted the first three-dimensional geometric morphometric analysis focused on the Neanderthal cervical spine, examining 43 classic Homo neanderthalensis cervical vertebrae alongside 243 Homo sapiens cervical vertebrae from diverse populations, including the whole cervical spine (C1-C7). The Neanderthal sample comprises specimens from well-known individuals such as La Ferrassie 1, La Chapelle-aux-Saints 1, Kebara 2, Shanidar 2, Regourdou 1, and the Krapina group, ensuring completeness for a detailed analysis. Our results reveal a distinct morphological difference-that is greater in the lower levels-in the Neanderthal cervical spine, including a craniocaudally shorter and mediolaterally wider shape, longer spinous processes, and horizontally oriented articular facets. Contrary to earlier hypotheses, the study challenges the notion of reduced cervical lordosis in Neanderthals, proposing instead a potentially greater lordotic curvature than in modern humans, as evidenced by articulated mean forms and Cobb angle measurements. These findings suggest robust neck musculature adaptations in Neanderthals, potentially reflecting biomechanical responses to support the head and inhibit joint displacement. The study also highlights implications for respiratory biomechanics, with differences in the orientation of transverse processes (attachment site of the scalene muscle) potentially influencing neck muscle length and function, which could affect respiratory capacity in Neanderthals. In summary, our comprehensive examination sheds new light on the morphology and functional implications of the Neanderthal cervical spine, offering valuable insights into the intricate adaptations of Neanderthals and their implications for functional morphology and evolutionary biology.