Rapid growth in a Neandertal infant from Amud Cave in Israel.

Abstract

Neandertal infants are rarely found, with only a few individuals documented in the literature. Therefore, their growth and development remain poorly understood. Amud 7 is the articulated skeleton of an infant Neandertal discovered in Amud Cave, northern Israel.^1,2 The cave was excavated in the 1960s¹ and the 1990s^{2,3,4,5,6,7,8,9,10,11} and has yielded several human remains with distinct Neandertal affinities,^{1,9,10,11,12,13,14} as well as Middle Paleolithic stone tool assemblages,^{15,16,17,18,19,20,21} dated to approximately 51-56 thousand years old.^22,23 Nearly 111 skeletal pieces of Amud 7 were found in situ, of which only the cranial bones were thoroughly described.^24,25,26,27 It is the most complete Neandertal infant assigned to the 6- to 14-month age range. As such, it plays a significant role in our understanding of Neandertal paleobiology. The skeleton exhibits distinct Neandertal affinities in both cranial and postcranial remains, and its morphological features shed light on Neandertal phylogeny, growth, and development. Most notably, the infant exhibits signs of unusually rapid somatic growth, suggesting that Neandertals had a distinct developmental strategy in early life. Other rare Neandertal infants show the same pattern of accelerated early somatic and endocranial growth, suggesting a consistent difference in how our evolutionary relatives developed. Simultaneously supporting faster somatic growth and brain development would have resulted in high energetic demands. These findings emphasize the diversity of developmental strategies among hominin species and demonstrate that Neandertals might have followed a different developmental path, distinguishing them from H. sapiens.