American Journal of Physical Anthropology

doi: 10.1002/ajpa.22950pmid: N/A

doi: 10.1002/ajpa.22849pmid: N/A

Hamada, Yuzuru; San, Aye Mi; Malaivijitnond, Suchinda

doi: 10.1002/ajpa.22862pmid: 26354607

ABSTRACT Objectives Hybridization between rhesus (Macaca mulatta) and long‐tailed (M. fascicularis) macaques has become a focal point of interest. The majority of such studies have evaluated their genetics, but not their morphological characters. Materials and Methods We analyzed morphological characters of eight free‐ranging populations of Indochinese rhesus and long‐tailed macaques distributed at the proposed hybrid zone (15.75–21.58° N) in comparison with one population each of Chinese and Indian‐derived rhesus macaques and three populations of Sundaic long‐tailed macaques. Results Chinese and Indian rhesus macaques had a heavier body mass, longer crown‐rump length, shorter relative facial length and relative tail length, and a greater contrast of reddish and yellowish dorsal pelage color than the Sundaic long‐tailed macaques for which the latter three parameters could be used to visually discriminate between the two species. Although the morphological characters of Indochinese rhesus and long‐tailed macaques were intermediate between the Chinese/Indian rhesus and Sundaic long‐tailed macaques, they were more similar to their respective conspecifics. The species‐specific characters of a shorter tail (<70%) and a bipartite pelage color pattern were retained in the Indochinese rhesus macaques while the longer tail (>90%) and no bipartite pattern was found in the Indochinese long‐tailed macaques. No morphological cline was observed across the species and the variations were abrupt to some extent. Discussion The hybridization between rhesus and long‐tailed macaques may be results of multiple contacts and isolations over a long period of time, thus their evolutionary history should not be drawn solely by genetic or morphological analysis. Am J Phys Anthropol 159:189–198, 2016. © 2015 Wiley Periodicals, Inc.

Chalk, Janine; Wright, Barth W.; Lucas, Peter W.; Schuhmacher, Katherine D.; Vogel, Erin R.; Fragaszy, Dorothy; Visalberghi, Elisabetta; Izar, Patrícia; Richmond, Brian G.

doi: 10.1002/ajpa.22865pmid: 26381730

Spradley, Jackson P.; Glander, Kenneth E.; Kay, Richard F.

doi: 10.1002/ajpa.22877pmid: 26426839

ABSTRACT Objectives Two factors have been considered important contributors to tooth wear: dietary abrasives in plant foods themselves and mineral particles adhering to ingested food. Each factor limits the functional life of teeth. Cross‐population studies of wear rates in a single species living in different habitats may point to the relative contributions of each factor. Materials and Methods We examine macroscopic dental wear in populations of Alouatta palliata (Gray, 1849) from Costa Rica (115 specimens), Panama (19), and Nicaragua (56). The sites differ in mean annual precipitation, with the Panamanian sites receiving more than twice the precipitation of those in Costa Rica or Nicaragua (∼3,500 mm vs. ∼1,500 mm). Additionally, many of the Nicaraguan specimens were collected downwind of active plinian volcanoes. Molar wear is expressed as the ratio of exposed dentin area to tooth area; premolar wear was scored using a ranking system. Results Despite substantial variation in environmental variables and the added presence of ash in some environments, molar wear rates do not differ significantly among the populations. Premolar wear, however, is greater in individuals collected downwind from active volcanoes compared with those living in environments that did not experience ash‐fall. Discussion Volcanic ash seems to be an important contributor to anterior tooth wear but less so in molar wear. That wear is not found uniformly across the tooth row may be related to malformation in the premolars due to fluorosis. A surge of fluoride accompanying the volcanic ash may differentially affect the premolars as the molars fully mineralize early in the life of Alouatta. Am J Phys Anthropol 159:210–222, 2016. © 2015 Wiley Periodicals, Inc.

Apicella, Coren L.; Tobolsky, Victoria A.; Marlowe, Frank W.; Miller, Kathleen W.

doi: 10.1002/ajpa.22864pmid: 26354727

ABSTRACT Objectives The ratio between the length of the second and the length of the fourth digit (2D:4D) is sexually dimorphic such that males of many species possess a lower ratio than females, particularly in the right hand. Still, men and women often exhibit overlapping 2D:4D ranges and the ratio is highly variable between populations. In order to further explore populational variability, we chose to analyze 2D:4D in the Hadza, a population of hunter‐gatherers living in Tanzania. Materials and Methods Data were collected separately by two researchers over the course of three years (1998, 2001, 2006) from 152 adult participants (male: n = 76, female: n = 76). Independent samples t‐tests were used to explore sex differences, paired samples t‐tests were used to explore directional effects within each sex, and linear regression and one‐way ANOVA were used to test possible age effects. Results In none of the years, or pooled (n = 152), did we find evidence that adult men have a lower 2D:4D than adult women. If anything, the data suggest that women in this population have a significantly lower right hand 2D:4D than men (P < 0.001, d = 0.57). In contrast, left hand 2D:4D did not exhibit a sex difference (P = 0.862, d = 0.03). Discussion These findings challenge the current view that lower 2D:4D in men is a uniform characteristic of our species. Cross‐populational variance in 2D:4D may be related to known patterns of hormonal variation resulting from both genetic and environmental mechanisms, though this relationship merits further investigation. Am J Phys Anthropol 159:223–232, 2016. © 2015 Wiley Periodicals, Inc.

Quinn, Elizabeth A.; Diki Bista, Kesang; Childs, Geoff

doi: 10.1002/ajpa.22871pmid: 26397954

ABSTRACT Objective The physiological challenges of high altitude have led to population‐specific patterns of adaptation. These include alterations to child growth and reproduction, including lactation. However, while breastfeeding has been investigated, nothing is known about milk composition in high altitude adapted populations. Materials and Methods Here, we investigate milk macronutrient composition, volume, and energy in a sample of 82 Tibetans living at high and low altitude in rural villages (Nubri Valley, Nepal) and at low altitude in Kathmandu, Nepal. Milk samples were collected in the morning using hand expression, frozen, and assayed for fat, protein, and total sugars. Reproductive histories and health recalls were also collected. Results Milk fat averaged 5.2 ±2.0 g/100 mL, milk sugar 7.37 ± 0.49 g/100 mL, and milk protein 1.26 ± 0.35 g/100 mL for a mean energy density of 81.4 ± 17.4 kcal/100 mL. There were no associations between altitude of residence and milk composition; however, overall milk fat was high compared to reference populations. Within the three groups, milk fat was positively associated with infant age (B = 0.103; p < 0.001) and maternal triceps skinfold thickness (B = 0.095; p < 0.01) while milk sugar was significantly and inversely associated with maternal parity and triceps skinfold thickness. Discussion Milk fat, and consequently milk energy, may be increased in high‐altitude adapted Tibetans when compared to populations living at low altitude. The association between milk fat and maternal adiposity suggests that milk composition may be sensitive to maternal adiposity in this sample, likely reflecting increased metabolic costs of producing a high‐fat milk. Am J Phys Anthropol 159:233–243, 2016. © 2015 Wiley Periodicals, Inc.

Weitz, Charles A; Garruto, Ralph M.; Chin, Chen‐Ting

doi: 10.1002/ajpa.22873pmid: 26407532

ABSTRACT Objectives This study compares forced vital capacity (FVC) and Forced Expiratory Volume at 1 Second (FEV1) of Tibetans with those of Han who were born and raised at high altitude. Materials and Methods FVC and FEV1 tests were conducted among 1,063 children and adolescents between the ages of 6 and 20 years, and 184 adults between the ages of 21 and 39 years who had lived their entire lives at 3200 m, 3800 m and 4300 m in Qinghai Provence, Peoples Republic of China. Results Even though FVC and FEV1 values of Han born and raised at high altitude are generally lower than those of Tibetans through age 15 in girls and age 16 in boys, differences are largely explained by variation in stature (height‐squared) and chest circumference. Among older adolescents and adults, the FVC and FEV1 values of Tibetans are significantly larger than those of Han born and raised at high altitude; and are much larger than would be predicted, based on stature and chest circumference. Discussion These results indicate that the large FVC and FEV1 values of Tibetan adults develop primarily from an accelerated pattern of lung growth that begins during mid‐to‐late adolescence and possibly extends into young adulthood. This developmental pattern is not only distinct from that of Han born and raised at high altitude, but also from those of Andean Quechua and Aymara. The pace of lung function growth may therefore represent another feature distinguishing the Tibetan from the Andean pattern of adaptation to high altitude hypoxia. Because of this, a search for features in the Tibetan genome related to this lung function growth phenotype might be productive and important. Am J Phys Anthropol 159:244–255, 2016. © 2015 Wiley Periodicals, Inc.

Pampush, James D.; Daegling, David J.

doi: 10.1002/ajpa.22863pmid: 26381610

ABSTRACT Objectives This research theoretically models and empirically records symphyseal surface strain during in vitro human mandibular wishboning (lateral transverse bending) in order to test one aspect of the hypothesis that the chin is an adaptive response to masticatory stresses. From a perspective of optimality, three questions were tested: 1) Do human mandibles function as curved beams during wishboning? 2) Is the presence of a chin associated with lower than predicted curved beam effects? 3) Are there relatively low strain gradients on the lingual and labial symphyseal surfaces respectively? Materials and Methods Based on morphometric criteria, theoretical wishboning strains were calculated for five dentate adult human mandibles. The same mandibles were fitted with strain gauges and subjected to simulated wishboning loads. From the empirically‐recorded strains, relative strains were calculated by dividing all strains by the absolute lowest strain in a given specimen. The theoretical and empirical results were compared in order to address the three related questions guiding this research. Results Human mandibles behave as curved beams during wishboning (question 1). Empirical strain measures showed greater disparity both between and within the labial and lingual symphyseal surfaces than the theoretical models predictions (questions 2 and 3). Discussion Human symphyseal form, with its distinctive chin, is unlikely to be adapted for countering wishboning loads. Chins are associated with larger than expected strain gradients within and between symphyseal surfaces, which runs counter to the optimality criterion typically invoked in assessing trait performance for signs of adaptation. The implications are twofold: 1) wishboning may not, in fact, be a regular feature of human mastication or 2) wishboning may not pose the same structural risks in human jaws as this load does in other anthropoid primates. Am J Phys Anthropol 159:256–266, 2016. © 2015 Wiley Periodicals, Inc.

Yonemoto, Shiori

doi: 10.1002/ajpa.22870pmid: 26408231

ABSTRACT Objective This study aims to determine the impacts of both age and physical activity on entheseal changes at sites of muscle and ligament attachment, and proposes that the influence of age on entheseal changes may depend on specific social systems. Methods Entheseal markers of 193 individuals excavated from archaeological sites in Japan were examined, and archaeological evidence from those sites was used to determine the subsistence activities that those individuals engaged in. Fifteenth‐century samples were either fishermen or Agehamashiki salt manufacturers, while samples from between the late 17th century and the 19th century were peasants, townspeople, or samurai. Nineteen entheses were examined using the scoring method of Hawkey and Merbs (1995) to clarify the degree to which age influenced entheseal severity of a given sample as well as the differences in the degree to which age influenced entheseal changes among samples. Results Results indicated that age influenced entheseal changes; however, the degree to which age influenced entheseal development was dependent on the characteristic physical activities associated with an individual's class and occupation. Furthermore, in certain groups, aging did not significantly impact entheseal changes. Discussion The degree to which age influenced entheseal changes was dependent on characteristic physical activities associated with an individual's class and occupation. This indicated that physical activities and lifestyle, along with age, were major factors that contributed to entheseal changes. Based on these results, it was concluded that entheseal changes could serve as a useful tool in the reconstruction of physical activities of past populations. Am J Phys Anthropol 159:267–283, 2016. © 2015 Wiley Periodicals, Inc.