Middle Pleistocene lower back and pelvis from an aged human individual from the Sima de los Huesos site, Spain

Abstract

We report a nearly complete lumbar spine from the Middle Pleistocene site of the Sima de los Huesos (SH) that is assigned to the previously published SH male Pelvis 1 [Arsuaga JL, et al. (1999). Nature 399: 255-258]. The "SH Pelvis 1 individual" is a unique nearly complete lumbo-pelvic complex from the human Middle Pleistocene fossil record, and offers a rare glimpse into the anatomy and past lifeways of Homo heidelbergensis. A revised reconstruction of Pelvis 1, together with the current fossil evidence, confirms our previous hypothesis that the morphology of this pelvis represents the primitive pattern within the genus Homo. Here we argue that this primitive pattern is also characterized by sexual dimorphism in the pelvic canal shape, implying complicated deliveries. In addition, this individual shows signs of lumbar kyphotic deformity, spondylolisthesis, and Baastrup disease. This suite of lesions would have postural consequences and was most likely painful. As a result, the individual's daily physical activities would have been restricted to some extent. Reexamination of the age-at-death agrees with this individual being over 45 y old, relying on the modern human pattern of changes of the articular surfaces of the os coxae. The presence of degenerative pathological lesions and the advanced age-at-death of this individual make it the most ancient postcranial evidence of an aged individual in the human fossil record. Additional nonpathological SH lumbopelvic remains are consistent with previous hypotheses, suggesting a less-pronounced sagittal spinal curvature in Neandertals compared with Homo sapiens. human evolution | Sierra de Atapuerca | spino-pelvic morphology | paleopathology P resent knowledge of the evolution of the pelvic region and es-

Stature estimation from complete long bones in the Middle Pleistocene humans from the Sima de los Huesos, Sierra de Atapuerca (Spain)

“…The biomechanical restrictions associated with such a wide pelvis would have been compensated for with a long femoral neck (Arsuaga et al , 1995), iliac flaring (Arsuaga et al , 1999;Bonmati et al, 2010 ), thick cortical bone and different cross sectional properties of long bones and heavy musculature. Increases in body mass generate greater stresses in the pelvic region and more power is required to move the body, i.e., more muscles and therefore more energy.…”

The evolution of the human pelvis: changing adaptations to bipedalism, obstetrics and thermoregulation

“…These changes are accompanied by shortening and flaring of the ischia, which result in a wider subpubic angle and a greater distance between the ischial spines (figure 2). When looked at as a canal with a superior inlet and inferior outlet, the changing shape of the human birth canal is clear: although there is variation [37], in general, the human female pelvis is wide mediolaterally at its inlet, whereas the midplane and outlet are wider anteroposteriorly (figure 2; [1,35]). The contrasts between the human pelvis and that of apes, in combination with the relatively large body size and cranial size of human neonates, have a profound effect on human infant delivery: we experience a birth process that is unusual, if not unique [1,24,34].…”

“…Again, these two aspects of pelvic breadth are probably linked biomechanically [2,60]. The birth canal is broad both at the inlet, partly because of long superior pubic rami, and at the outlet; the shape of the midplane is not clear owing to poor preservation of the iliac spines in the relevant fossils [2,37,60,74,116,119].…”

“…Pelvic anatomy in H. heidelbergensis (sometimes referred to as 'Archaic H. sapiens' 4 ) is known primarily from high-latitude individuals from Europe and Asia (figure 3; [37,97,116,119,120]). These pelvises are very large overall and remarkably wide: the specimens from Atapuerca (Spain) and Jinniushan (China), for example, have the largest bi-iliac breadths in the human fossil record, and are wider than the average for any modern human population studied by Ruff [2].…”

“…Except for a few uniquely derived characteristics, particularly in the cross-sectional shape of the superior pubic ramus (see [100,120] for reviews), recent work has shown that most of the features of the Neanderthal pelvis that were once thought to be distinctive are in fact retained primitive traits [37,100,[119][120][121]123,128].…”