ABSTRACT
Homo neanderthalensis has a unique combination of craniofacial features that are distinct from fossil and extant ‘anatomically modern’ Homo sapiens (modern humans). Morphological evidence, direct isotopic dates1 and fossil mitochondrial DNA from three Neanderthals2,3 indicate that the Neanderthals were a separate evolutionary lineage for at least 500,000 yr. However, it is unknown when and how Neanderthal craniofacial autapomorphies (unique, derived characters) emerged during ontogeny. Here we use computerized fossil reconstruction4 and geometric morphometrics5,6 to show that characteristic differences in cranial and mandibular shape between Neanderthals and modern humans arose very early during development, possibly prenatally, and were maintained throughout postnatal ontogeny. Postnatal differences in
cranial ontogeny between the two taxa are characterized primarily by heterochronic modifications of a common spatial pattern of development. Evidence for early ontogenetic divergence together with evolutionary stasis of taxon-specific patterns of ontogeny is consistent with separation of Neanderthals and modern humans at the species level.
