American Journal of Physical Anthropology

Stoinski, Tara S.; Perdue, Bonnie; Breuer, Thomas; Hoff, Michael P.

doi: 10.1002/ajpa.22301pmid: 23907657

Life history is influenced by factors both intrinsic (e.g., body and relative brain size) and extrinsic (e.g., diet, environmental instability) to organisms. In this study, we examine the prediction that energetic risk influences the life history of gorillas. Recent comparisons suggest that the more frugivorous western lowland gorilla shows increased infant dependence, and thus a slower life history, than the primarily folivorous mountain gorilla to buffer against the risk of starvation during periods of food unpredictability. We further tested this hypothesis by incorporating additional life history data from wild western lowland gorillas and captive western lowland gorillas with the assumption that the latter live under ecological conditions of energetic risk that more closely resemble those of mountain gorillas and thus should show faster life histories than wild members of the species. Overall, we found captive western lowland and wild mountain gorillas to have faster developmental life histories than wild western lowland gorillas, weaning their infants approximately a year earlier and thus reducing interbirth intervals by a year. These results provide support that energetic risk plays an important role in determining gorilla life history. Unlike previous assertions, gorillas do not have substantially faster life histories, at least at the genus level, than other great apes. This calls for a re‐evaluation of theories concerning comparative ape life history and evolution and highlights the need for data from additional populations that vary in energetic risk. Am J Phys Anthropol 152:165–172, 2013. © 2013 Wiley Periodicals, Inc.

Commendador, Amy S.; Dudgeon, John V.; Finney, Bruce P.; Fuller, Benjamin T.; Esh, Kelley S.

doi: 10.1002/ajpa.22339pmid: 23996514

Ecological and environmental evidence suggests that Rapa Nui was among the most marginally habitable islands in Eastern Polynesia, with only a fraction of the biotic diversity found on archipelagos to the west, and capable of sustaining many fewer cultigens traditionally transported by Polynesian colonizers. However, archaeological evidence for human dietary adaptations under such restrictions is limited. Little is known about the particulars of the subsistence base and dietary changes on Rapa Nui that may be associated with a hypothesized late prehistoric decline in the quality and diversity of food sources. To better understand prehistoric Rapa Nui diet we examined stable carbon and nitrogen isotope compositions of human teeth along with archaeological faunal material thought to comprise the Rapa Nui food web. Our results indicate that contrary to previous zooarchaeological studies diet was predominantly terrestrial throughout the entire sequence of occupation, with reliance on rats, chickens and C3 plants. While a few individuals may have had access to higher trophic level marine resources, this is evident only later in time (generally post–AD 1600). A decline in δ15N through time was observed, and may be attributed to declines in available terrestrial proteins; however, presently we cannot rule out the effect of changing soil and plant baseline δ15N. Our results also suggest differential access to higher trophic level marine resources among contemporaneous populations, but more research is required to clarify this observation. Am J Phys Anthropol 152:173–185, 2013. © 2013 Wiley Periodicals, Inc.

Polychronis, Georgios; Christou, Panagiotis; Mavragani, Maria; Halazonetis, Demetrios J.

doi: 10.1002/ajpa.22340pmid: 24009105

Dental casts of 160 Greek subjects (80 males, 80 females) were scanned by a structured‐light scanner. The upper and lower right first molar occlusal surface 3D meshes were processed using geometric morphometric methods. A total of 265 and 274 curve and surface sliding semilandmarks were placed on the upper and lower molar surfaces, respectively. Principal component analysis and partial least square analysis were performed to assess shape parameters. Molars tended to vary between an elongated and a more square form. The first two principal components (PCs), comprising almost 1/3 of molar shape variation, were related to mesiodistal–buccolingual ratios and relative cusp position. Distal cusps displayed the greatest shape variability. Molars of males were larger than those of females (2.8 and 3.2% for upper and lower molars respectively), but no shape dimorphism was observed. Upper and lower molar sizes were significantly correlated (r2 = 0.689). Allometry was observed for both teeth. Larger lower molars were associated with shorter cusps, expansion of the distal cusp, and constriction of the mesial cusps (predicted variance 3.25%). Upper molars displayed weaker allometry (predicted variance 1.59%). Upper and lower molar shape covariation proved significant (RV = 17.26%, P < 0.0001). The main parameter of molar covariation in partial least square axis 1, contributing to 30% of total covariation, was cusp height, in contrast to the primary variability traits exhibited by PC1 and PC2. The aim of this study was to evaluate shape variation and covariation, including allometry and sexual dimorphism, of maxillary and mandibular first permanent molar occlusal surfaces. Am J Phys Anthropol 152:186–196, 2013. © 2013 Wiley Periodicals, Inc.

Willis, Anna; Oxenham, Marc F.

doi: 10.1002/ajpa.22343pmid: 24000119

The purpose of this article is to present new oral health data from Neolithic An Son, southern Vietnam, in the context of (1) a reassessment of published data on other Neolithic, Bronze, and Iron Age Southeast Asian dental series, and (2) predictions of the Neolithic Demographic Transition (NDT). To this end, frequencies for three oral conditions (caries, antemortem tooth loss, and alveolar lesions) were investigated for seven Southeast Asian adult dental series from Thailand and Vietnam with respect to time period, age‐at‐death and sex. A clear pattern of elevated rates for oral disease in the Neolithic followed by a marked improvement in oral health during the Bronze and Iron Ages was observed. Moreover, rates of caries and antemortem tooth loss for females were almost without exception higher than that for males in all samples. The consensus view among Southeast Asian bioarchaeologists that oral health did not decline with the adoption/intensification of agriculture in Southeast Asia, can no longer be supported. In light of evidence for (1) the low cariogenicity of rice; (2) the physiological predisposition of females (particularly when pregnant) to poorer oral health; and (3) health predictions of the NDT model with respect to elevated levels of fertility, the most plausible chief explanation for the observed patterns in oral health in Southeast Asia is increased levels of fertility during the Neolithic, followed by a decline in fertility during the subsequent Bronze and Iron Ages. Am J Phys Anthropol 152:197–208, 2013. © 2013 Wiley Periodicals, Inc.

Quinn, Elizabeth A.

doi: 10.1002/ajpa.22346pmid: 23996600

Maternal reproductive investment includes both the energetic costs of gestation and lactation. For most humans, the metabolic costs of lactation will exceed those of gestation. Mothers must balance reproductive investment in any single offspring against future reproductive potential. Among mammals broadly, mothers may differentially invest in offspring based on sex and maternal condition provided such differences investment influence future offspring reproductive success. For humans, there has been considerable debate if there are physiological differences in maternal investment by offspring sex. Two recent studies have suggested that milk composition differs by infant sex, with male infants receiving milk containing higher fat and energy; prior human studies have not reported sex‐based differences in milk composition. This study investigates offspring sex‐based differences in milk macronutrients, milk energy, and nursing frequency (per 24 h) in a sample of 103 Filipino mothers nursing infants less than 18 months of age. We found no differences in milk composition by infant sex. There were no significant differences in milk composition of mothers nursing first‐born versus later‐born sons or daughters or between high‐ and low‐income mothers nursing daughters or sons. Nursing frequency also showed no significant differences by offspring sex, sex by birth order, or sex by maternal economic status. In the Cebu sample, there is no support for sex‐based differences in reproductive investment during lactation as indexed by milk composition or nursing frequency. Further investigation in other populations is necessary to evaluate the potential for sex‐based differences in milk composition among humans. Am J Phys Anthropol 152:209–216, 2013. © 2013 Wiley Periodicals, Inc.

Paul, Kathleen S.; Stojanowski, Christopher M.; Butler, Michelle M.

doi: 10.1002/ajpa.22347pmid: 24000131

This article presents an analysis of biological and spatial patterning of an Early Classic (A.D. 250–500) Chatino cemetery at the archaeological site of Charco Redondo, located in the lower Río Verde Valley, Oaxaca, Mexico. The Early Classic was a time of political instability positioned between two phases of state‐level centralization within the coastal valley. The communal cemetery at Charco Redondo adds significantly to the inventory of excavated graves from this time period and provides novel data on mortuary practices during a critical phase in the development of state level polities in the region. Cluster analysis of mortuary data is combined with intracemetery biodistance approaches to reconstruct how the Charco Redondo cemetery was organized with respect to biological relationships. Cluster analysis of mortuary data identified three groupings of burials. Multidimensional scaling of Euclidean distances and Gower coefficients based on 45 odontometric and 13 dental morphological variables suggests a strong relationship between grave characteristics and locations and phenotypic variation. In other words, the cemetery at Charco Redondo appears biologically kin‐structured. The communal nature of the cemetery conflicts with the assumed “household” burial model for this time period. We propose the observed combination of features represents a transitional practice in which aspects of community, kin, and individual identity were signaled simultaneously within the funerary environment during a time of political transition in the Valley. This article highlights the utility of intracemetery biodistance analyses for examining dimensions of kinship, “house,” and community throughout Mesoamerica where overarching models often mask regional variability. Am J Phys Anthropol 152:217–229, 2013. © 2013 Wiley Periodicals, Inc.

Temple, Daniel H.; McGroarty, Jennifer N.; Guatelli‐Steinberg, Debbie; Nakatsukasa, Masato; Matsumura, Hirofumi

doi: 10.1002/ajpa.22348pmid: 23996633

This study reconstructs linear enamel hypoplasia (LEH) prevalence and stress episode duration among Jomon period foragers from Hokkaido, Japan (HKJ). Results are compared to Jomon period samples from coastal Honshu, Japan (HSJ) and Tigara Inupiat from Point Hope, Alaska (PHT) to provide a more comprehensive perspective on the manifestation of stress among circum‐Pacific foragers. LEH were identified macro‐ and microscopically by enamel surface depressions and increased perikymata spacing within defects. Individuals with more than one anterior tooth affected by LEH were labeled as LEH positive. Stress episode durations were estimated by counting the number of perikymata within the occlusal wall of each LEH and multiplying that number by constants reflecting modal periodicities for modern human teeth. LEH prevalence and stress episode duration did not differ significantly between the two Jomon samples. Significantly greater frequencies of LEH were found in HKJ as compared to PHT foragers. However, HKJ foragers had significantly shorter stress episode durations as compared to PHT. This suggests that a greater proportion of HKJ individuals experienced stress episodes than did PHT individuals, but these stress events ended sooner. Similarity in stress experiences between the two Jomon samples and differences between the HKJ and PHT are found. These findings are important for two reasons. First, stress experiences of foraging populations differ markedly and cannot be generalized by subsistence strategy alone. Second, due to significant differences in episode duration, stress experiences cannot be understood using prevalence comparisons alone. Am J Phys Anthropol 152:230–238, 2013. © 2013 Wiley Periodicals, Inc.

Green, David J.

doi: 10.1002/ajpa.22353pmid: 24000155

Primate shoulder morphology has been linked with locomotor habits, oftentimes irrespective of phylogenetic heritage. Among hominoids, juvenile African apes are known to climb more frequently than adults, while orangutans and gibbons maintain an arboreal lifestyle throughout ontogeny. This study examined if these ontogenetic locomotor differences carry a morphological signal, which should be evident in the scapulae of chimpanzees and gorillas but absent in taxa that do not display ontogenetic behavioral shifts. The scapular morphology of five hominoid primates and one catarrhine outgroup was examined throughout ontogeny to evaluate if scapular traits linked with arboreal activities are modified in response to ontogenetic behavioral shifts away from climbing. Specifically, the following questions were addressed: 1) which scapular characteristics distinguish taxa with different locomotor habits; and 2) do these traits show associated changes during development in taxa known to modify their behavioral patterns? Several traits characterized suspensory taxa from nonsuspensory forms, such as cranially oriented glenohumeral joints, obliquely oriented scapular spines, relatively narrow infraspinous fossae, and inferolaterally expanded subscapularis fossae. The relative shape of the dorsal scapular fossae changed in Pan, Gorilla, and also Macaca in line with predictions based on reported ontogenetic changes in locomotor behavior. These morphological changes were mostly distinct from those seen in Pongo, Hylobates, and Homo and imply a unique developmental pattern, possibly related to ontogenetic locomotor shifts. Accordingly, features that sorted taxa by locomotor habits and changed in concert with ontogenetic behavioral patterns should be particularly useful for reconstructing the locomotor habits of fossil forms. Am J Phys Anthropol 152:239–260, 2013. © 2013 Wiley Periodicals, Inc.

Radi, Nico; Mariotti, Valentina; Riga, Alessandro; Zampetti, Stefania; Villa, Chiara; Belcastro, M. Giovanna

doi: 10.1002/ajpa.22354pmid: 23999736

The effectiveness of the so‐called skeletal markers of activity as functional indicators is widely debated. Among them, certain morphological features of the anterior aspect of the femoral head‐neck junction (Poirier's facet, cervical fossa of Allen, etc.) have been considered in relation to some behaviors and specific activities (e.g., squatting, horseback riding, etc.). However, disagreement on terminology and descriptions, the absence of standardized scoring methods and poor knowledge of the variability and distribution of these features make it difficult to interpret their meaning. The aim of this study is to analyze the variability of the anterior aspect of the femoral neck through a new scoring method taking into account three main traits: Poirier's facet, plaque, and cribra (including the Allen's fossa). This method has been applied to a sample of 225 adult individuals of both sexes coming from an identified modern skeletal collection, achieving low intraobserver and interobserver error values. The results highlight some significant trends: plaque, almost always bilateral, appears to be a normal condition of the femur, being present in approximately 90% of the individuals. Cribra is more frequent in females and decreases with age. Poirier's facet shows a very low frequency. This method allows the representation of both the anatomical diversity of the region already described in literature and part of the variability never considered before. Our results suggest caution in considering these features as markers related to specific activities. Am J Phys Anthropol 152:261–272, 2013. © 2013 Wiley Periodicals, Inc.

Littleton, Judith; Scott, Rachel; McFarlane, Gina; Walshe, Keryn

doi: 10.1002/ajpa.22358pmid: 23999884

Often it is assumed that hunter‐gatherer dentitions are dominated by heavy attrition. Recent analyses, however, have shown unexpected variability in the pattern of wear between groups. It had been previously noted that wear differed between neighboring groups on the Murray River, Australia. This analysis extends that geographic scope as well as focusing on wear across the dentition, including the premolars. The samples came from coastal and riverine regions of southern Australia. The analysis used records from the Yorke Peninsula, Adelaide Plains (Gillman site), and Euston regions. These were compared with previously published work from the Adelaide Plains and four locations on the Murray River. The results confirm the overall severity of wear but reveal systematic differences between the samples in terms of the pattern of wear. Heavy wear on the incisors and canines is observed among males from the Euston, Kaurna, Middle A, Murray Mouth, and Yorke Peninsula samples but with marked intra‐individual variability. Extensive premolar wear is noted among females from Kaurna and Middle B samples as well as among males and females from Euston. It is argued that these patterns relate to gendered non‐masticatory use of teeth and reliance upon bulrush (Typha spp.) and related species for both food and fiber among some groups. We argue that analyzing the degree of variability within samples and across all teeth provides a more nuanced understanding of dental wear among hunter‐gatherers. Am J Phys Anthropol 152:273–286, 2013. © 2013 Wiley Periodicals, Inc.