Enamel covers teeth, is the hardest tissue in the vertebrate body and has a complex multiscale structure from nanometres to millimetres1. The structure comprises thin, long hydroxyapatite (Ca5(PO4)3OH) nanocrystals2, 50-70 nm wide, many micrometres long, parallel and bundled into approximately 5-µm-wide rods. The rods undulate and cross into a microscale 'decussation pattern' that toughens enamel by deflecting cracks3,4. However, the crystallographic orientation of enamel nanocrystals is poorly understood. Here we show that the misorientation angle of adjacent nanocrystals varies markedly across 12 primate teeth spanning 9 species, 17.8 million years of evolution and diverse diets. Using a method called Polarization Enabled Large Input of Crystal Angles at the Nanoscale (PELICAN)5, we compare nanocrystals in the same (pre)molar locations and show that misorientation increases with food hardness in extant and fossil non-human apes and monkeys. We compare misorientation across three major dietary shifts in human evolution: the transition to meat-eating about 2.0-1.5 million years before present6,7, to agriculture (about 12,000 years before present)8,9, and the Industrial Revolution (about 250 years before present)10. We show that over the past 1.6 million years, in the human lineage misorientation increased with time, especially when meat and stone-ground grains were introduced into human diets, but not with the Industrial Revolution. Thus, besides macro-changes, teeth adapted to dietary change at the nanoscale and crystallographically. This observation suggests that misorientation may contribute to enamel's resilience; thus, bioinspired materials may consider small misorientation angles for added resilience.

OBJECTIVE:This study provides new dental phenotypic data on the Aurignacian mandible Les Rois 2 (southwestern France). A former study of its dental morphology concluded that its taxonomic assignment to either Homo sapiens or Homo neanderthalensis was "uncertain" and could reflect a recent Neanderthal ancestry of this specimen. An alternative explanation was that Aurignacian people from Les Rois were H. sapiens displaying plesiomorphic features, extending the biological variation seen among modern populations. Here, we propose a reassessment of Les Rois 2 taxonomic status through the study of its dental morphological features. MATERIAL AND METHODS:Our analyses include micro-tomographic data of a large comparative sample of H. neanderthalensis, Pleistocene and Holocene H. sapiens. We analyze dental metrics, 3D dental tissue proportions (AET and RET), Enamel Dentin Junction (EDJ) nonmetric trait variations, and lower premolar EDJ size and shape with 3D geometric morphometrics. RESULTS:The Les Rois 2 specimen displays dental features placing it at the limit of the range of variation of Holocene populations, but consistent with the morphology of Late Pleistocene H. sapiens. Our analyses also show that Les Rois 2 lacks the derived H. neanderthalensis morphological trait. DISCUSSION:Our study shows that the taxonomic attribution of Les Rois 2 is more consistent with H. sapiens than with H. neanderthalensis, while acknowledging that the specimen displays plesiomorphic features rare among recent H. sapiens populations. These findings highlight the larger phenotypic variation displayed by Early Upper Paleolithic populations and contribute to a better understanding of the morphology of Aurignacian makers.

OBJECTIVE:This study follows up on our recent morphological analysis of the juvenile maxilla from Mugharet el'Aliya, Morocco. Although this specimen shows a reportedly archaic morphology, likely due to its large size, 3D shape analyses indicated affinities with early Homo sapiens. Here, we conducted an in-depth comparative investigation of the associated dentition to further clarify this individual's phylogenetic and taxonomic affinities. MATERIALS AND METHODS:Our analyses were based on three kinds of data: (a) external crown dimensions and non-metric features, analyzed via summary statistics; (b) CT scan data enabling the study of internal structures (enamel-dentine junction) via geometric morphometrics; and (c) high-resolution replicas of the external surface of the upper canine enabling the study of perikymata numbers via probability functions. The comparative samples included Middle Pleistocene (Chibanian) Europeans and Africans, Neanderthals, and early and later H. sapiens. RESULTS:Mugharet el'Aliya showed the greatest similarities in external and internal tooth morphology with early and later H. sapiens. Perikymata counts cluster the upper canine with H. sapiens. However, its canine and fourth premolar are megadont at a level generally atypical for H. sapiens. DISCUSSION:Our analyses of the dentition of the Mugharet el'Aliya individual support our previous findings on the morphological analysis of the maxilla, placing this fossil closest to H. sapiens. Our study further strengthens the evidence connecting fossils from the North African Aterian to those from Western Asia, especially Qafzeh. We also provide the first comparative analysis of a permanent upper canine from the Aterian fossil record.

Objective: Our aim was to evaluate by enamel microstructure analysis two hypotheses that would explain the early dental eruption in the Bakaparticularity, a shorter crown formation time and/or earlier onset of crown formation. Design: Deciduous canines corresponds to the best teeth to perform the analysis of enamel microstructure. Longitudinal ground sections of 21 deciduous canines from 12 individuals were studied with transmitted light microscopy. Cross-striations, striaes of Retzius (SR) and the neonatal line (NNL) enable to establish the prenatal crown formation time (preCFT), the postnatal crown formation time (postCFT), the crown formation time (CFT) as well as the daily secretion rate (DSR) and the enamel extension rate (EER) and their variation along crown formation. Results: The DSR and the EER in the Baka are similar than in other populations with an average DSR of 3.26 mu m and EER of 18.18 mu m. The preCFT was 154 days, the postCFT 265 days and CFT 419 days. Comparison with other population does not show difference in CFT. However, the preCFT and the postCFT differ, the first is higher and the second lower in the Baka than in other populations. Furthermore, the number of prenatal areas of enamel was greater in the Baka. Conclusion: Our analysis suggests that the Baka does not distinguish by a different CFT but the onset of crown formation is earlier than in other groups. Therefore, the early dental eruption in the Baka results from an earlier onset of crown formation.

Indigenous Peoples are exposed to the impacts of the climatic, ecological and socioeconomic changes, yet there is a need for a better understanding of their health and higher involvement of Indigenous Peoples in health promotion design and implementation. Our study brings empirical data on the healthcare system of the Baka, forager-horticulturalists from Cameroon. Using a mixed methods approach, we explored the health issues they encounter, the emic determinants of health and healthcare system, and the different threats towards their healthcare system. We conducted focus group discussions, interviews with experts, and self-reported health recalls with 302 individuals living in two settlements from southeastern Cameroon during two fieldwork periods between June and November 2022. Our insights highlight the prevalence of respiratory and children’s digestive issues, and the occurrence of illnesses implying a combination of symptoms that would deserve further Western biomedical attention. The Baka’s healthcare relies on medicinal plants, knowledge experts, and on the social cohesion of the community, all largely affected by the local social-ecological impacts of global change. Exposure to the market and health facilities does not seem to relate to Baka’s health state and practices but might affect their perception of health. Deforestation, poor water quality, and alcohol (ab)use were reported and observed threats to the Baka’s health and healthcare system. Our work supplies empirical evidence for a better understanding of Baka’s health and healthcare system, helpful in designing health prevention and policies adapted to their reality and culture. Further research and interventions on health should consider the current threats to Baka’s local ecosystems and cultural knowledge. These insights contribute to a higher recognition of the Baka’s, and most broadly, the Indigenous Peoples’ emic perspective on health, and on culturally grounded indicators of the resilience of their healthcare system to current and future challenges.

Many people and organizations misunderstand the concept behind the name Pygmy. This misunderstanding leads them to misinterpretations and erroneous judgements about its use. This article goes back to the origin of the name in order to clarify the meaning that it has today, especially for the Pygmies themselves. The term 'pygmy' originated in ancient Greece where it was employed for a legendary people who, in Greek mythology, were engaged in an unceasing battle against cranes. Although the morphology of the pygmies described by the ancient Greeks cannot be fully characterized, the term 'pygmy' was used for centuries to refer to a population of small stature living close to the Nile. This led scientists and travellers in modern times to refer to populations of small stature living in equatorial Africa as pygmies. The distinction between Pygmies and non-Pygmies in this region matches the presence of two kinds of populations whose identities are defined in contraposition to one another by socio-cultural aspects. Genetic population studies have suggested that the Pygmies split from non-Pygmy populations around 60,000 years BP. Very importantly, the use of the name Pygmy is gratifying to the Pygmies themselves and it appears in the title of almost all Pygmy rights organizations. The name Pygmy thus covers populations sharing a particular phenotype, having a common origin and thus a biological identity, as well as socio-cultural characteristics which are diverse but nevertheless distinguish them from non-Pygmy populations. Furthermore, the name Pygmy has a dual function for the Pygmies themselves, at once asserting their common identity in contraposition to non-Pygmies ("Big-blacks" as they call them) and conveying their claims against those who despise them, who are the same "Big-blacks".