Morphological Continuity of the Face in the Late Middle and Late Pleistocene Hominins from Northwestern Africa: A 3D Geometric Morphometric Analysis

Abstract

Facial morphology comprises some of the most distinctive features of early modern humans. The rich fossil record of Morocco allows assessing changes in facial morphology from the late Middle Pleistocene through the Late Pleistocene. Specimens associated with the Aterian industry in Morocco were originally thought to be relatively recent (40–20 ka), but could be much older (35–90 ka). Predating this population are the late Middle Pleistocene specimens of Irhoud. Later in the same geographical area, larger samples are represented by the Iberomaurusian series. We conducted a 3D geometric morphometric analysis of the facial shape of the Aterian specimen Dar es-Soltan II-5, with the aim of deciphering the affinities of this specimen with earlier North African and Levantine fossils, later Upper Paleolithic Eurasian specimens, as well as later North African populations. We used a large comparative sample (n = 191) comprising seven geographic populations of recent humans, Iberomaurusians from Afalou and Taforalt (n = 22), and Middle and Late Pleistocene Eurasian and African fossils. The 3D coordinates of 19 facial landmarks were collected. Specimen landmark configurations were processed with Generalized Procrustes Analysis. Principal Components, Canonical Variates, and cluster analyses were performed and Procrustes distances and Mahalanobis squared distances were calculated. Both Irhoud 1 and Dar es-Soltan II-5 are similar to the early anatomically modern humans from Qafzeh, and the Iberomaurusian sample is closely connected to the Upper Paleolithic European sample.