Neonatal postcrania from Mezmaiskaya, Russia, and Le Moustier, France, and the development of Neandertal body form

Abstract

Neandertal and modern human adults differ in skeletal features of the cranium and postcranium, and it is clear that many of the cranial differences-although not all of them-are already present at the time of birth. We know less, however, about the developmental origins of the postcranial differences. Here, we address this deficiency with morphometric analyses of the postcrania of the two most complete Neandertal neonates-Mezmaiskaya 1 (from Russia) and Le Moustier 2 (from France)-and a recent human sample. We find that neonatal Neandertals already appear to possess the wide body, long pubis, and robust long bones of adult Neandertals. Taken together, current evidence indicates that skeletal differences between Neandertals and modern humans are largely established by the time of birth. body proportions | climatic adaptation | Homo neanderthalensis | infracranial | ontogeny

Early development of the Neanderthal ribcage reveals a different body shape at birth compared to modern humans

“…In addition, the morphological differences in the Neanderthal thorax found at birth, paralleling their adult state, would show a body shape characterized by shorter, deeper, and (slightly) wider trunks compared to MH of the same size. This would be consistent with previous authors on Neanderthal postcranial anatomy that proposed that perinatal individuals such as M1, LM2, or La Ferrassie 6 would be characterized by a very large ilium relative to femur length, similar to what is observed in adults ( 44 – 46 ).…”

“…The relatively short thoracic spine, which is related to relatively shorter vertebral bodies, was already noticed in the D1 individual (45), and despite the limited adult Neanderthal fossil record, it has been proposed as a specific feature of the adult thoracic vertebrae (21) or the thoracic spine as a whole (26). Our results are also consistent with previous research on body form of LM2, M1 (44), and D1 (45) that hypothesized that perinatal Neanderthals already had a wide body, with a long pubis and robust long bones. Last, this is in concert with the results from the Neanderthal La Ferrassie 6, where the authors hypothesized that the elongation of the Neanderthal pubis was a feature expressed early in ontogeny (46).…”

Bone functional adaptation does not erase neutral evolutionary information

“…Skeletal remains of an infant (estimated to be around 6 months of age at death) from Kiik‐Koba, Crimea, also possessed significant diaphyseal robusticity and AP curvature of arm and leg bones, as well as other characteristic features like proximal tibial retroversion (Vlček, ). Neonates from Le Moustier, France, and Mesmaiskaya, Russia, confirm that, at birth, Neanderthal skeletons already possessed many of the characteristic features seen in adults, including the marked diaphyseal robusticity that distinguished them from modern humans (Weaver et al, ). This prompted researchers to conclude that these “could not have developed in response to mechanical loading associated with adult/older‐subadult behaviors” and must therefore stem from either some intrinsic factor (perhaps shaped by selection) or from intrauterine environment (Weaver et al, , pp.…”

“…Neonates from Le Moustier, France, and Mesmaiskaya, Russia, confirm that, at birth, Neanderthal skeletons already possessed many of the characteristic features seen in adults, including the marked diaphyseal robusticity that distinguished them from modern humans (Weaver et al, ). This prompted researchers to conclude that these “could not have developed in response to mechanical loading associated with adult/older‐subadult behaviors” and must therefore stem from either some intrinsic factor (perhaps shaped by selection) or from intrauterine environment (Weaver et al, , pp. 6474).…”

One hundred years of paleoanthropology: An American perspective

“…The creation and use of this taxon highlights a persistent problem: a frequent ignoring of the human fossil record <1 myr among those who work on Pliocene and Early Pleistocene hominin remains. A parallel situation exists within the Late Pleistocene, with the common use of later Holocene modern humans as the only comparative samples for the Neandertals and other late archaic humans, rather than considering the Middle and Upper Paleolithic foragers together (e.g., Trinkaus, vs. Trinkaus, ; Weaver et al, vs. Trinkaus, Mednikova, & Cowgill, ). The use of late Holocene (often cadaver‐based) skeletal samples to represent all H. sapiens , in both Plio‐Pleistocene and later Pleistocene analyses, is further exacerbated by marked decreases in skeletal hypertrophy during the Holocene (Ruff et al, ).…”