3D reconstruction of spinal posture of the Kebara 2 Neanderthal

Abstract

Spinal posture has vast biomechanical, locomotor and pathological implications in hominins. Assessing the curvatures of the spine of fossil hominins can provide important information towards the understanding of their paleobiology. Unfortunately, complete hominin spines are very rarely preserved in the fossil record. The Neanderthal partial skeleton, Kebara 2 from Israel, constitutes a remarkable exception, representing an almost complete spine and pelvis. The aim of this study is, therefore, to create a new 3D virtual reconstruction of the spine of Kebara 2. To build the model, we used the CT scans of the sacrum, lumbar and thoracic vertebrae of Kebara 2, captured its 3D morphology, and, using visualization software (Amira 5.2©), aligned the 3D reconstruction of the original bones into the spinal curvature. First we aligned the sacrum and then we added one vertebra at a time, until the complete spine (T1-S5) was intact. The amount of spinal curvature (lordosis and kyphosis), the sacral orientation, and the coronal plane deviation was determined based on the current literature or measured and calculated specifically for this study based on published methods. This reconstruction provides, for the first time, a complete 3D virtual reconstruction of the spine of an extinct hominin. The spinal posture and spinopelvic alignment of Kebara 2 show a unique configuration compared with that of modern humans, suggesting locomotor and weight-bearing differences between the two. The spinal posture of Kebara 2 also shows slight asymmetry in the coronal plane. Stature estimation of Kebara 2 based on spinal length confirms that the height of Kebara 2 was around 170 cm. This reconstruction can now serve as the basis for a more complete reconstruction of the Kebara 2 specimen, which will include other parts of this remarkable fossil, such as the pelvis, the rib cage and the cervical spine.