Domestication as the evolution of interspecies cooperative breeding.

We propose that domestication is the result of interspecies cooperative breeding. Considering domestication as an outcome of cooperative breeding can explain how domestication occurs in both plants and animals, encompass cases of domestication that do not involve humans, and shed light on why humans are involved in so many domesticatory relationships. We review the cooperative breeding model of human evolution, which posits that care of human infants by alloparents enabled the evolution of costly human brains and long juvenile development, while selecting for tolerance of strangers. We then explore how human cooperation in the protection and provisioning of young plants and animals can explain the evolution of domestication traits such as changes in development; loss of aggressive, defensive, and bet-hedging aspects of the phenotype; and increased fertility. We argue that the importance of cooperative breeding to human societies has made humans especially likely to enter into interspecies cooperative breeding relationships.

Technical note: Artificial Resynthesis Technology for the experimental formation of dental microwear textures.

Dental microwear formation on the posterior dentition is largely attributed to an organism's diet. However, some have suggested that dietary and environmental abrasives contribute more to the formation process than food, calling into question the applicability of dental microwear to the reconstruction of diet in the fossil record. Creating microwear under controlled conditions would benefit this debate, but requires accurately replicating the oral environment. This study tests the applicability of Artificial Resynthesis Technology (ART 5) to create microwear textures while mitigating the challenges of past research. ART 5 is a simulator that replicates the chewing cycle, responds to changes in food texture, and simulates the actions of the oral cavity. Surgically extracted, occluding pairs of third molars (n = 2 pairs) were used in two chewing experiments: one with dried beef and another with sand added to the dried beef. High-resolution molds were taken at 0, 50, 100, 2500, and 5000 simulated chewing cycles, which equates to approximately 1 week of chewing. Preliminary results show that ART 5 produces microwear textures. Meat alone may produce enamel prism rod exposure at 5000 cycles, although attrition cannot be ruled out. Meat with sand accelerates the wear formation process, with enamel prism rods quickly obliterated and "pit-and-scratch" microwear forming at approximately 2500 cycles. Future work with ART 5 will incorporate a more thorough experimental protocol with improved controls, pH of the simulated oral environment, and grit measurements; however, these results indicate the potential of ART 5 in untangling the complex variables of dental microwear formation.

Oral pathological conditions of an Early Epipaleolithic human from Southwest Asia: Ohalo II H2 as a probable case of intentional dental ablation.

OBJECTIVE: To describe the oral pathological conditions of Ohalo II H2, an Early Epipaleolithic human from southwest Asia. MATERIALS: The dentognathic skeleton of Ohalo II H2 and relevant comparative data from similar chronological and/or geographic contexts. METHODS: Gross and x-ray observations of oral pathological conditions and occlusal wear were made following published protocols. A differential diagnosis of antemortem tooth loss is provided. RESULTS: Ohalo 2 has two carious lesions on the right M3, pulpal exposure of left M1, and mild to moderate anterior alveolar bone loss. The right I1 was lost antemortem, and there is probably agenesis of the left M3. CONCLUSIONS: The pathological conditions noted are not exceptional for a Late Upper Paleolithic forager. However, the antemortem missing right I1 is most parsimoniously explained by intentional dental ablation. SIGNIFICANCE: Ohalo 2 could represent the oldest example of dental ablation from the Late Pleistocene circum-Mediterranean world - predating the earliest examples from both North Africa and southwest Asia by several thousand years. The similarity of the Ohalo 2 ablation pattern with later Natufians provides further evidence of potential long-term behavioral trends related to the embodiment of social identities through international body modification within the Epipaleolithic of southwest Asia. LIMITATIONS: The pre-Natufian (∼23,000-14,500 cal BP) human fossil record is relatively sparse, making comparisons with the Natufian (∼14,500-11,500 cal BP) phases of the Epipaleolithic difficult. SUGGESTIONS FOR FURTHER RESEARCH: Documentation of oral pathological conditions for other pre-Natufian fossils would provide greater resolution of the temporospatial patterning of oral health and embodied social identities during the Epipaleolithic of southwest Asia.

Biocultural diversity in Late Pleistocene/Early Holocene Africa: Olduvai Hominid 1 (Tanzania) biological affinity and intentional body modification.

OBJECTIVES: The dentition of Olduvai Hominid 1 (OH1) exhibits an anomalous pattern of dental wear that was originally attributed to either intentional cultural modification (filing) or plant processing behaviors. A differential diagnosis of the wear and assessment of the biological affinity of OH1 is presented. MATERIALS AND METHODS: Macroscopic and microscopic observations of all labial and buccal tooth surfaces were undertaken to assess wear patterns. A multivariate analysis of mandibular morphology of OH1 compared to other Late Pleistocene, Holocene, and recent modern humans was used to ascertain biological affinity. RESULTS: The morphological variation of the OH1 mandible is closely aligned with variation in penecontemporaneous fossils from Africa and outside that of recent humans. The concave wear facets exposing dentin on the labial surfaces of all three preserved mandibular incisors is confirmed. Substantial loss of labial/buccal surfaces was documented on the surfaces of all in situ maxillary and mandibular canines, premolars, and molars ranging from distinct facets with well-defined edges, to blunting or "polishing" around areas of maximum buccal curvature. The wear on both the anterior and postcanine teeth closely resemble that caused by adornments ("labrets") worn in lower-lip and buccal facial piercings known from bioarchaeological and ethnographic contexts. The wear pattern suggests that the OH1 wore three facial piercings-two buccal/lateral and a medial one in the lower lip. DISCUSSION: Our findings suggest that the expression of social identities through intentional body modification is more diverse than previously documented elsewhere in Africa during the Late Pleistocene (i.e., ablation) and Early Holocene (i.e., ablation, chipping, and filing).

Anterior tooth-use behaviors among early modern humans and Neandertals.

Early modern humans (EMH) are often touted as behaviorally advanced to Neandertals, with more sophisticated technologies, expanded resource exploitation, and more complex clothing production. However, recent analyses have indicated that Neandertals were more nuanced in their behavioral adaptations, with the production of the Châtelperronian technocomplex, the processing and cooking of plant foods, and differences in behavioral adaptations according to habitat. This study adds to this debate by addressing the behavioral strategies of EMH (n = 30) within the context of non-dietary anterior tooth-use behaviors to glean possible differences between them and their Neandertal (n = 45) counterparts. High-resolution casts of permanent anterior teeth were used to collect microwear textures of fossil and comparative bioarchaeological samples using a Sensofar white-light confocal profiler with a 100x objective lens. Labial surfaces were scanned, totaling a work envelope of 204 x 276 µm for each individual. The microwear textures were examined for post-mortem damage and uploaded to SSFA software packages for surface characterization. Statistical analyses were performed to examine differences in central tendencies and distributions of anisotropy and textural fill volume variables among the EMH sample itself by habitat, location, and time interval, and between the EMH and Neandertal samples by habitat and location. Descriptive statistics for the EMH sample were compared to seven bioarchaeological samples (n = 156) that utilized different tooth-use behaviors to better elucidate specific activities that may have been performed by EMH. Results show no significant differences between the means within the EMH sample by habitat, location, or time interval. Furthermore, there are no significant differences found here between EMH and Neandertals. Comparisons to the bioarchaeological samples suggest both fossil groups participated in clamping and grasping activities. These results indicate that EMH and Neandertals were similar in their non-dietary anterior tooth-use behaviors and provide additional evidence for overlapping behavioral strategies employed by these two hominins.

Anterior dental microwear textures show habitat-driven variability in Neandertal behavior.

The causes of Neandertal anterior tooth wear patterns, including labial rounding, labial scratches, and differential anterior-posterior wear, have been debated for decades. The most common explanation is the "stuff-and-cut" hypothesis, which describes Neandertals clamping down on a piece of meat and slicing a portion close to their lips. "Stuff-and-cut" has been accepted as a general aspect of Neandertal behavior without fully assessing its variability. This study analyzes anterior dental microwear textures across habitats, locations, and time intervals to discern possible variation in Neandertal anterior tooth-use behavior. Forty-five Neandertals from 24 sites were analyzed, represented by high-resolution replicas of permanent anterior teeth. The labial surface was scanned for antemortem microwear using a white-light confocal profiler. The resultant 3D-point clouds, representing 204 × 276 µm for each specimen, were uploaded into SSFA software packages for texture characterization. Statistical analyses, including MANOVAs, ANOVAs, and pairwise comparisons, were completed on ranked microwear data. Neandertal descriptive statistics were also compared to 10 bioarchaeological samples of known or inferred dietary and behavioral regimes. The Neandertal sample varied significantly by habitat, suggesting this factor was a principal driving force for differences in Neandertal anterior tooth-use behaviors. The Neandertals from open habitats showed significantly lower anisotropy and higher textural fill volume than those inhabiting more closed, forested environments. The texture signature from the open-habitat Neandertals was most similar to that of the Ipiutak and Nunavut, who used their anterior teeth for intense clamping and grasping behaviors related to hide preparation. Those in more closed habitats were most similar to the Arikara, who did not participate in non-dietary behaviors. These Neandertal individuals had a broad range of texture values consistent with non-dietary and dietary behaviors, suggesting they varied more in anterior tooth-use behaviors and exploited a wider variety of plant and animal resources than did those from open habitats.

The dawn of dentistry in the late upper Paleolithic: An early case of pathological intervention at Riparo Fredian.

OBJECTIVES: Early evidence for the treatment of dental pathology is found primarily among food-producing societies associated with high levels of oral pathology. However, some Late Pleistocene hunter-gatherers show extensive oral pathology, suggesting that experimentation with therapeutic dental interventions may have greater antiquity. Here, we report the second earliest probable evidence for dentistry in a Late Upper Paleolithic hunter-gatherer recovered from Riparo Fredian (Tuscany, Italy). MATERIALS AND METHODS: The Fredian 5 human consists of an associated maxillary anterior dentition with antemortem exposure of both upper first incisor (I1 ) pulp chambers. The pulp chambers present probable antemortem modifications that warrant in-depth analyses and direct dating. Scanning electron microscopy, microCT and residue analyses were used to investigate the purported modifications of external and internal surfaces of each I1 . RESULTS: The direct date places Fredian 5 between 13,000 and 12,740 calendar years ago. Both pulp chambers were circumferentially enlarged prior to the death of this individual. Occlusal dentine flaking on the margin of the cavities and striations on their internal aspects suggest anthropic manipulation. Residue analyses revealed a conglomerate of bitumen, vegetal fibers, and probable hairs adherent to the internal walls of the cavities. DISCUSSION: The results are consistent with tool-assisted manipulation to remove necrotic or infected pulp in vivo and the subsequent use of a composite, organic filling. Fredian 5 confirms the practice of dentistry-specifically, a pathology-induced intervention-among Late Pleistocene hunter-gatherers. As such, it appears that fundamental perceptions of biomedical knowledge and practice were in place long before the socioeconomic changes associated with the transition to food production in the Neolithic.

Incisor ablation among the late upper paleolithic people of Tam Hang (Northern Laos): Social identity, mortuary practice, and oral health.

OBJECTIVES: A detailed assessment of intentional incisor ablation among the Late Upper Paleolithic people of Tam Hang (northern Laos) was undertaken to understand how this cultural practice, in addition to age and sex, influenced an individual's inclusion in the mortuary context. The covariation of ablation status with occlusal variation and anterior dental pathology was addressed to study the implications of this cultural practice on oral health. MATERIALS AND METHODS: Sex, age, caries, antemortem tooth loss, and occlusal variation were assessed through standard osteological methods for 12 individuals. An observational protocol to identify intentional ablation was developed specifically for this sample. RESULTS: Four ablation states were identified that range from no ablation to the removal of two, three, or four lateral (I2) incisors. The timing of ablation was attributed to ritual extractions during early adolescence. Adult age-at-death was the strongest indicator of inclusion in the main burial context and a child burial was isolated from those of adults. Ablation status does not strongly influence inclusion in the mortuary context. Individuals lacking ablation tended to have a higher incidence of anterior caries, pathological tooth loss, incisor crowding, and canine rotation. CONCLUSIONS: This study identifies the oldest case of intentional incisor ablation in Late Pleistocene Mainland Southeast Asia. We conclude that ablation does not always "compromise" the dentition; instead, it may have unintentional oral health benefits in some contexts. Am J Phys Anthropol 160:519-528, 2016. © 2016 Wiley Periodicals, Inc.

Middle Paleolithic human remains from the Gruta Da Oliveira (Torres Novas), Portugal.

Additional Middle Paleolithic human remains from layers 17, 18, and 22 of the Gruta da Oliveira, Portugal consist of a proximal manual phalanx 2 (Oliveira 5), a partial postcanine tooth (Oliveira 6), a humeral diaphysis (Oliveira 7), a distal mandibular molar (Oliveira 8), and a mandibular premolar (P(3) ) (Oliveira 9). Oliveira 5, 6, and 8 are unremarkable for Late Pleistocene humans. The Oliveira 7 right humerus is moderately robust or the individual had the stocky body proportions of other European (including Iberian) Neandertals. The Oliveira 9 P(3) has a large and symmetrical crown and lacks a distal accessory ridge and accessory lingual cusps, overlapping both Neandertal and recent human ranges of variation. It contrasts with at least recent human P(3) s in having relatively thin enamel. These join the Oliveira 1 to 4 remains in further documenting early MIS 3 Neandertal morphology in western Iberia.