The relevance of late MSA mandibles on the emergence of modern morphology in Northern Africa

Abstract

North Africa is a key area for understanding hominin population movements and the expansion of our species. It is home to the earliest currently known Homo sapiens (Jebel Irhoud) and several late Middle Stone Age (MSA) fossils, notably Kébibat, Contrebandiers 1, Dar-es-Soltane II H5 and El Harhoura. Mostly referred to as “Aterian” they fill a gap in the North African fossil record between Jebel Irhoud and Iberomaurusians. We explore morphological continuity in this region by quantifying mandibular shape using 3D (semi)landmark geometric morphometric methods in a comparative framework of late Early and Middle Pleistocene hominins (n = 15), Neanderthals (n = 27) and H. sapiens (n = 145). We discovered a set of mixed features among late MSA fossils that is in line with an accretion of modern traits through time and an ongoing masticatory gracilization process. In Northern Africa, Aterians display similarities to Iberomaurusians and recent humans in the area as well as to the Tighenif and Thomas Quarry hominins, suggesting a greater time depth for regional continuity than previously assumed. The evidence we lay out for a long-term succession of hominins and humans emphasizes North Africa’s role as source area of the earliest H. sapiens.

Geometric Morphometric Analysis of Mandibular Symphysis Growth between 12 and 15 Years of Age in Class II Malocclusion Subjects

“…In particular, subjects within the hyperdivergent subgroup showed a narrower and elongated symphysis compared with the hypodivergent subgroup. This is in agreement with previous quantitative findings [ 31 , 32 ] and would suggest that hyperdivergent individuals can be more exposed to iatrogenic injuries such as gingival recession or dehiscence, in particular for the treatment of mandibular crowding and for the dentoalveolar compensation of class II using intermaxillary elastics or auxiliaries. As a consequence, these patients are more likely to be treated with orthodontic extraction to correct the arch length discrepancy or the sagittal discrepancy [ 33 , 34 ].…”

Mugharet el'Aliya: Affinities of an enigmatic north African Aterian maxillary fragment

“…This would suggest a degree of regional continuity within North African MSA industries. A similar hypothesis of a regional continuity was proposed for the Northwest African MSA associated hominin fossil record (Bergmann et al, 2022; Hublin, 2000; Hublin et al, 2017; Nespoulet et al, 2008). The hominin fossils from the late Middle Pleistocene and Late Pleistocene associated with Northwest African MSA technology show anatomical similarities, whereas later populations in the region associated with the LSA seem to differ morphologically (Harvati & Hublin, 2012; Hublin, 2000; Hublin et al, 2017; Nespoulet et al, 2008; Scerri, 2017).…”

“…The hominin fossils from the late Middle Pleistocene and Late Pleistocene associated with Northwest African MSA technology show anatomical similarities, whereas later populations in the region associated with the LSA seem to differ morphologically (Harvati & Hublin, 2012; Hublin, 2000; Hublin et al, 2017; Nespoulet et al, 2008; Scerri, 2017). However, recent re‐evaluation of mandibular morphology suggests an extension of the regional continuity into both the LSA and the Middle Pleistocene by linking MSA individuals from Jebel Irhoud and the Aterian to an LSA sample of Iberomaurusians and late Early/Middle Pleistocene individuals, respectively (Bergmann et al, 2022). In addition to similar mandibular morphologies, individuals from Jebel Irhoud and the Aterian show a comparable combination of the same primitive retentions, including large overall size and megadonty, and modern features as well as similarities with the samples from Qafzeh and Skhul (Ferembach, 1976; Freidline et al, 2021; Harvati & Hublin, 2012; Hublin et al, 2012; Hublin et al, 2017; Hublin & Tillier, 1981; Hublin & Tillier, 1988).…”

Early presence of Homo sapiens in Southeast Asia by 86–68 kyr at Tam Pà Ling, Northern Laos

“…Three-dimensional (3D) surface models of the comparative sample were created from either computed tomography (CT) scans using Avizo v. 7.1, surface scans (NextEngine, Minolta Vivid 910, and Breuckmann optoTOPHE), or photogrammetry. For the latter, between 40 and 90 2D photographs were taken with a Nikon D600 (4512 × 3008 pixels) and processed with Agisoft PhotoScan Professional v. 1.2.0 (Agisoft LLC, St. Petersburg) 65 , 70 . Error tests evaluating differences in imaging techniques are within the acceptable range of error in osteometry 65 .…”

“… 105 – 107 and refs. 65 , 70 . Virtual reconstructions were also performed on the Minatogawa A mandible, which has some damage along the anterior alveolar region, and the Tam Pà Ling specimens 1, 2, and 6.…”