The growth pattern of Neandertals, reconstructed from a juvenile skeleton from El Sidrón (Spain)

Abstract

Ontogenetic studies help us understand the processes of evolutionary change. Previous studies on Neandertals have focused mainly on dental development and inferred an accelerated pace of general growth. We report on a juvenile partial skeleton (El Sidrón J1) preserving cranio-dental and postcranial remains. We used dental histology to estimate the age at death to be 7.7 years. Maturation of most elements fell within the expected range of modern humans at this age. The exceptions were the atlas and mid-thoracic vertebrae, which remained at the 5- to 6-year stage of development. Furthermore, endocranial features suggest that brain growth was not yet completed. The vertebral maturation pattern and extended brain growth most likely reflect Neandertal physiology and ontogenetic energy constraints rather than any fundamental difference in the overall pace of growth in this extinct human.

Immature remains and the first partial skeleton of a juvenile Homo naledi, a late Middle Pleistocene hominin from South Africa

“…The evidence for skeletal association here meets the standards linking immature partial skeletons at other hominin sites with commingled individuals [1,4,8,9]. El Sidrón J1 is an Early Juvenile partial skeleton (H. neanderthalensis) recovered mostly from a 1 m 2 unit, together with multiple elements from at least one younger and one older immature individual.…”

“…Yet such remains provide important evidence about the maturation of extinct hominins. Apart from recent modern humans and Neanderthals (e.g., [1]), only three hominin species are represented by immature partial skeletons at this time: Australopithecus afarensis [2,3], Australopithecus sediba [4,5] and Homo erectus [6][7][8][9]. Augmenting this limited dataset is of great significance in trying to understand the evolution of human growth and development.…”

Bilateral asymmetry of the humerus in Neandertals, Australian aborigines and medieval humans

“…Little is known about the ontogeny of the postcranial skeleton in Neandertals (Cowgill, ), but it has been shown that dental maturation and craniofacial ontogenetic transformations differ between Neandertals and modern humans (Bastir, O'Higgins, & Rosas, ; Smith et al, ). The present study included only adult individuals, but differences in directional asymmetry levels of cross‐sectional properties and in shape may be the result of different levels of mechanical loading during growth, along with different patterns of postcranial maturation (Rosas et al, ), especially given that differences in ontogeny are present between individuals of <1 year of age (Cowgill, ). Additionally, the variability of the humeral properties can also partially explain the differences between the Neandertals and rMHs, especially given that the populations differ in terms of sample size.…”

A catalog of single nucleotide changes distinguishing modern humans from archaic hominins

“…However, given their similar brain sizes (Hofman 1983), humans and Neanderthals might both have needed a long overall maturation time (Ponce de León et al 2017;Rosas et al 2017). Accordingly, notions like neoteny and heterochrony are unlikely to be fine-grained enough to capture differences between these populations, but early differences in infant brain growth between humans and Neanderthals (Gunz et al 2010;Hublin et al 2015) could have rendered our maturational profile distinct during limited developmental periods and within specific brain regions, imposing different metabolic requirements (Bruner et al 2014).…”