Intrapopulational body size variation and cranial capacity variation in middle pleistocene humans: The Sima de los Huesos sample (Sierra de Atapuerca, Spain)

Abstract

A sexual dimorphism more marked than in living humans has been claimed for European Middle Pleistocene humans, Neandertals and prehistoric modern humans. In this paper, body size and cranial capacity variation are studied in the Sima de los Huesos Middle Pleistocene sample. This is the largest sample of non-modern humans found to date from one single site, and with all skeletal elements represented. Since the techniques available to estimate the degree of sexual dimorphism in small palaeontological samples are all unsatisfactory, we have used the bootstraping method to asses the magnitude of the variation in the Sima de los Huesos sample compared to modern human intrapopulational variation. We analyze size variation without attempting to sex the specimens a priori. Anatomical regions investigated are scapular glenoid fossa; acetabulum; humeral proximal and distal epiphyses; ulnar proximal epiphysis; radial neck; proximal femur; humeral, femoral, ulnar and tibial shaft; lumbosacral joint; patella; calcaneum; and talar trochlea. In the Sima de los Huesos sample only the humeral midshaft perimeter shows an unusual high variation (only when it is expressed by the maximum ratio, not by the coefficient of variation). In spite of that the cranial capacity range at Sima de los Huesos almost spans the rest of the European and African Middle Pleistocene range. The maximum ratio is in the central part of the distribution of modern human samples. Thus, the hypothesis of a greater sexual dimorphism in Middle Pleistocene populations than in modern populations is not supported by either cranial or postcranial evidence from Sima de los Huesos.

Exploring bone volume and skeletal weight in the Middle Pleistocene humans from the Sima de los Huesos site (Sierra de Atapuerca, Spain)

“…Although, as mentioned above, the five SH bones analyzed here are sexed as males, it is important to note that the femoral RBV shows no statistical difference between males and females in recent H. sapiens (Seeman, 1997), including the sample used in the present study. Moreover, the degree of size variation (interpreted as mainly reflecting sexual dimorphism) in most postcranial dimensions in the SH hominins is similar to that found in recent humans (Lorenzo et al 1998). Therefore, it is plausible to suggest that our results for the RBV in male SH bones likely characterize female bones from this sample as well.…”

Postcranial morphology of the middle Pleistocene humans from Sima de los Huesos, Spain

“…Using a randomization method, relying on bootstrapping, the size variation in the SH hominins was studied as a proxy for their level of sexual dimorphism (33,34), including additional anatomical parts that were previously underrepresented (SI Appendix, Tables S5-S7). Contrary to previous suggestions that middle Pleistocene humans were more dimorphic (35,36), the SH hominins do not show an unusual degree of size variation compared with MH.…”

Determining sex by bone volume from 3D images: discriminating analysis of the tali and radii in a contemporary Spanish reference collection

“…hominids [15,16], and on variability within populations [17]. More recently, there was a notable study of correlations between the different volumes of cranial regions and face size [18], as well as studies on differences in volumes among different regions of the brain based on sex [19].…”