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

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

Analyse morphométrique et microscopique du maxillaire de la grotte de Coupe-Gorge (350 ka) à Montmaurin (Haute-Garonne, France)

La grotte de Coupe-Gorge fait partie du complexe karstique des grottes de Montmaurin dans lesquelles des restes humains fossiles ont été retrouvés, parmi lesquels un fragment de maxillaire droit adulte. Récemment daté à 343-328 ka par ESR-U/Th, ce spécimen vient compléter le registre fossile aux côtés de Steinheim ou Swanscombe, permettant d’aborder la question de l’émergence de la lignée néandertalienne en Europe. Dans cette étude, le maxillaire de Coupe-Gorge a été analysé en morphométrie ..

The undescribed juvenile Maxilla from Contrebandiers Cave, Morocco - A study on Middle Stone Age facial growth

In 2009, renewed excavations at the Middle Stone Age (MSA) site of Contrebandiers Cave, Morocco, yielded a skull and partial skeleton of a child dated to Marine Isotope Stage 5. While much of the cranium was found shattered, the midface remained largely intact. In this study, we virtually reconstructed the maxilla and quantified its shape using three-dimensional geometric morphometric methods and compared it to an extensive sample of non-adult and adult Eurasian Neanderthals and Homo sapiens spanning the Middle Pleistocene to Holocene. We used developmental simulations to predict the adult shape of the Contrebandiers maxilla by simulating development along three ontogenetic trajectories: Neanderthal, African, and Levantine early H. sapiens and Holocene H. sapiens. Our results confirm the H. sapiens-like morphology of the Contrebandiers fossil. Both shape and size align it with other North African MSA fossils and Late Pleistocene humans from Qafzeh, Israel. Interestingly, the evaluation of the ontogenetic trajectories suggests that during late ontogeny the facial growth pattern of the Contrebandiers and the Qafzeh children is more similar to that of Neanderthals than it is to recent humans. This suggests that the unique facial growth pattern of Homo sapiens post-dated the MSA. This study is an important step in addressing ontogenetic variability in the African MSA, a period characterized by the origins, emergence, and dispersal of our species, but poorly understood because of the fragmentary and scant human fossil record

Human midfacial growth pattern differs from that of Neanderthals and chimpanzees

Present-day humans have small and retracted midfaces, while Neanderthals possess large and forwardly projected midfaces. To understand the ontogenetic patterns underlying these characteristic morphologies, we compared maxillary growth and development from birth to adulthood in present-day humans (Homo sapiens; n = 128), Neanderthals (Homo neanderthalensis; n = 13), and chimpanzees (Pan troglodytes verus; n = 33) using macroscopic (i.e., geometric morphometrics) and microscopic (i.e., surface histology) approaches. Using geometric morphometrics to quantify macroscopic patterns of growth and development, we found that the midfaces of present-day humans are on average already smaller at birth than those of Neanderthals and grow more slowly after birth. In particular, we find an early cessation of growth around adolescence, which is unique to our species. Microscopically, this is reflected in reduced amounts of bone resorption, indicative of decreased cellular activities linked to bone development. Greater amounts of bone formation in the infraorbital and nasal regions and faster growth rates are responsible for the large Neanderthal midface. These results highlight the importance of postnatal ontogeny (especially in late stages) for explaining facial differences between Neanderthals and present-day humans, as well as part of the gracilization process characteristic of present-day humans

A shared pattern of midfacial bone modelling in hominids suggests deep evolutionary roots for human facial morphogenesis

Midfacial morphology varies between hominoids, in particular between great apes and humans for which the face is small and retracted. The underlying developmental processes for these morphological differences are still largely unknown. Here, we investigate the cellular mechanism of maxillary development (bone modelling, BM), and how potential changes in this process may have shaped facial evolution. We analysed cross-sectional developmental series of gibbons, orangutans, gorillas, chimpanzees and present-day humans (n = 183). Individuals were organized into five age groups according to their dental development. To visualize each species's BM pattern and corresponding morphology during ontogeny, maps based on microscopic data were mapped onto species-specific age group average shapes obtained using geometric morphometrics. The amount of bone resorption was quantified and compared between species. Great apes share a highly similar BM pattern, whereas gibbons have a distinctive resorption pattern. This suggests a change in cellular activity on the hominid branch. Humans possess most of the great ape pattern, but bone resorption is high in the canine area from birth on, suggesting a key role of canine reduction in facial evolution. We also observed that humans have high levels of bone resorption during childhood, a feature not shared with other apes

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

The timing of the first arrival of Homo sapiens in East Asia from Africa and the degree to which they interbred with or replaced local archaic populations is controversial. Previous discoveries from Tam Pà Ling cave (Laos) identified H. sapiens in Southeast Asia by at least 46 kyr. We report on a recently discovered frontal bone (TPL 6) and tibial fragment (TPL 7) found in the deepest layers of TPL. Bayesian modeling of luminescence dating of sediments and U-series and combined U-series-ESR dating of mammalian teeth reveals a depositional sequence spanning ~86 kyr. TPL 6 confirms the presence of H. sapiens by 70 ± 3 kyr, and TPL 7 extends this range to 77 ± 9 kyr, supporting an early dispersal of H. sapiens into Southeast Asia. Geometric morphometric analyses of TPL 6 suggest descent from a gracile immigrant population rather than evolution from or admixture with local archaic populations

Variation in paranasal pneumatisation between Mid-Late Pleistocene hominins

There is considerable variation in mid-late Pleistocene hominin paranasal sinuses, and in some taxa distinctive craniofacial shape has been linked to sinus size. Extreme frontal sinus size has been reported in mid-Pleistocene specimens often classified as Homo heidelbergensis, and Neanderthal sinuses are said to be distinctively large, explaining diagnostic Neanderthal facial shape. Here, the sinuses of fossil hominins attributed to several mid-late Pleistocene taxa were compared to those of recent H. sapiens. The sinuses were investigated to clarify differences in the extent of pneumatisation within this group and the relationship between sinus size and craniofacial variation in hominins from this time period. Frontal and maxillary sinus volumes were measured from CT data, and geometric morphometric methods were used to identify and analyse shape variables associated with sinus volume. Some mid

A late Middle Pleistocene Denisovan mandible from the Tibetan Plateau

Denisovans are members of a hominin group who are currently only known directly from fragmentary fossils, the genomes of which have been studied from a single site, Denisova Cave in Siberia. They are also known indirectly from their genetic legacy through gene flow into several low-altitude East Asian populations and high-altitude modern Tibetans6. The lack of morphologically informative Denisovan fossils hinders our ability to connect geographically and temporally dispersed fossil hominins from Asia and to understand in a coherent manner their relation to recent Asian populations. This includes understanding the genetic adaptation of humans to the high-altitude Tibetan Plateau, which was inherited from the Denisovans. Here we report a Denisovan mandible, identified by ancient protein analysis, found on the Tibetan Plateau in Baishiya Karst Cave, Xiahe, Gansu, China. We determine the mandible to be at least 160 thousand years old through U-series dating of an adhering carbonate matrix. The Xiahe specimen provides direct evidence of the Denisovans outside the Altai Mountains and its analysis unique insights into Denisovan mandibular and dental morphology. Our results indicate that archaic hominins occupied the Tibetan Plateau in the Middle Pleistocene epoch and successfully adapted to high-altitude hypoxic environments long before the regional arrival of modern Homo sapiens