American Journal of Physical Anthropology

Matthews, Luke J.; Rosenberger, Alfred L.

doi: 10.1002/ajpa.20859pmid: 18500746

The classifications of primates, in general, and platyrrhine primates, in particular, have been greatly revised subsequent to the rationale for taxonomic decisions shifting from one rooted in the biological species concept to one rooted solely in phylogenetic affiliations. Given the phylogenetic justification provided for revised taxonomies, the scientific validity of taxonomic distinctions can be rightly judged by the robusticity of the phylogenetic results supporting them. In this study, we empirically investigated taxonomic‐sampling effects on a cladogram previously inferred from craniodental data for the woolly monkeys (Lagothrix). We conducted the study primarily through much greater sampling of species‐level taxa (OTUs) after improving some character codings and under a variety of outgroup choices. The results indicate that alternative selections of species subsets from within genera produce various tree topologies. These results stand even after adjusting the character set and considering the potential role of interobserver disagreement. We conclude that specific taxon combinations, in this case, generic or species pairings, of the primary study group has a biasing effect in parsimony analysis, and that the cladistic rationale for resurrecting the Oreonax generic distinction for the yellow‐tailed woolly monkey (Lagothrix flavicauda) is based on an artifact of idiosyncratic sampling within the study group below the genus level. Some recommendations to minimize the problem, which is prevalent in all cladistic analyses, are proposed. Am J Phys Anthropol, 2008. © 2008 Wiley‐Liss, Inc.

Inoue, Eiji; Inoue‐Murayama, Miho; Vigilant, Linda; Takenaka, Osamu; Nishida, Toshisada

doi: 10.1002/ajpa.20865pmid: 18512686

In chimpanzees (Pan troglodytes), high‐ranking males are expected to have high reproductive success and females typically emigrate upon reaching maturity. Although high average relatedness among males in the same social groups has been assumed, previous reports have indicated that relatedness among males is not necessarily significantly higher than that among females. The paternity of 11 offspring and the relatedness of 50 individuals in the M group of chimpanzees at Mahale Mountains National Park, Tanzania, were investigated using DNA analyses. We determined the fathers of 10 offspring. Two different alpha males sired a total of five offspring, whereas the other males had low reproductive success. The proportion of paternal half‐sibling pairs among the 10 offspring was 15.6%. The average relatedness among mature males was significantly higher than that among mature females. The existence of an old male and the long tenure of one alpha male may have contributed to this significant difference. The average dyadic relatedness among mature natal individuals was significantly higher than that in natal‐immigrant pairs in which the individuals came from different groups. The average relatedness among immigrant females was similar to that in pairs of natal and immigrant females, suggesting that the immigrants came from various groups. Thus, female transfer acts to maintain low average relatedness within the group. A comparison of our results to those from other study sites suggests that although the average relatedness among adult males does not reach the level of half‐siblings, under some circumstances it can exceed the relatedness of females. Am J Phys Anthropol, 2008. © 2008 Wiley‐Liss, Inc.

Marivaux, Laurent; Beard, K. Christopher; Chaimanee, Yaowalak; Jaeger, Jean‐Jacques; Marandat, Bernard; Soe, Aung Naing; Tun, Soe Thura; Kyaw, Aung Aung

doi: 10.1002/ajpa.20866pmid: 18524008

The postcranial anatomy of the Asian sivaladapid adapiforms is still virtually undocumented, whereas dental remains of these primates have been known for several decades. Little is known about their positional behavior as a result. In this article, we describe a partial left femur of a medium‐sized primate preserving its entire proximal portion and a significant length of its shaft. This fossil was recently recovered from the fossiliferous locality of Thamingyauk in the late middle Eocene Pondaung Formation (central Myanmar). This femur is considered to pertain to the same individual as two tarsal elements (fragmentary talus and calcaneus) from the same locality (same location), and attributed to a medium‐sized sivaladapid adapiform primate (Kyitchaungia takaii). This new postcranial element provides the first documentation of femoral anatomy among Sivaladapidae from Asia. The mechanical implications deriving from the musculoskeletal interpretation of this bone indicate an animal that probably engaged in a kind of active arboreal quadrupedalism with some degree of proficiency in leaping. Even though many musculoskeletal aspects suggest that branch walking and running were important parts of its locomotor repertoire, in other details it appears that relatively complex movements at the hip joint were actually possible and probably associated with climbing or some hindlimb suspensory activities. Am J Phys Anthropol, 2008. © 2008 Wiley‐Liss, Inc.

Varela, Héctor H.; O'Brien, Tyler G.; Cocilovo, Jose A.

doi: 10.1002/ajpa.20867pmid: 18512687

The peopling of the south‐central Andean region can be determined by exploring a combination of cultural, economic, and biological factors that influence the structure of populations and determine particular dispersals of gene frequencies. Quantitative characters from 1,586 adult crania of both sexes from northern Chile, northwestern Argentina, and the Cochabamba valleys in Bolivia were analyzed employing multivariate statistical analyses. Biological distances, representing phenotypic variation between these regions and their subregions, were studied within a population genetics framework. An analysis of Mahalanobis D2 distances establishes two principle directions of interaction: the first between the Cochabamba valleys and northern Chile, and the second between the Cochabamba region and northwestern Argentina. The Chile and Argentina regions are shown to be less related to each other than each is to the Bolivian region. A higher mean genetic divergence is found for the entire region (FST = 0.195); with northwestern Argentina having the highest spatial isolation (FST = 0.143) and northern Chile the lowest (FST = 0.061). These results allow us to propose a populating model based on the dispersion of several lines from a common ancestral population similar to those who inhabited the Cochabamba valleys. These lines differentiated themselves in time and space according to the effective size and the rate of gene flow, eventually producing the human groups which inhabited the valleys of northern Chile and northwestern Argentina. Am J Phys Anthropol, 2008. © 2008 Wiley‐Liss, Inc.

Hanihara, Tsunehiko; Yoshida, Kohzo; Ishida, Hajime

doi: 10.1002/ajpa.20869pmid: 18615574

In and after the latest Neolithic period in Japan (∼B.P. 2,300 years), there were two distinct waves of migration from eastern Asia. One is well known as successive episodes in which indigenous inhabitants of main‐island Japan were intruded on by new arrivals with advanced technology, and of a different genetic stock. Another migration of people and culture, identified as the Okhotsk culture, reached the northeastern part of Hokkaido. As opposed to main‐island Japan, the morphological continuity from the Neolithic to recent inhabitants in Hokkaido (Ainu) is notable, so that the evidence of admixture easily could have escaped notice. In this study, the effects of gene flow from an outside source on the pattern of among‐group variation of Hokkaido Ainu are examined by means of two models. One is the R‐matrix model comparing observed and expected craniometric variation for estimating differential external gene flow into a region. The other is a simple simulation model that estimates admixture in a population with two parental populations. The two approaches give similar results. The results suggest the possibility of admixture between the migrants from Northeast Asia, the Okhotsk culture people, and the indigenous inhabitants in Hokkaido during the 5th to 12th centuries A.D., at least in northeastern Hokkaido. Such gene flow may have a certain degree of effect on the genetic structure of recent Ainu. The findings further suggest morphological heterogeneity in Northeast Asia during the Holocene that has relevance for understanding the morphological heterogeneity seen through time in the New World. Am J Phys Anthropol 2008. © 2008 Wiley‐Liss, Inc.

Prowse, Tracy L.; Saunders, Shelley R.; Schwarcz, Henry P.; Garnsey, Peter; Macchiarelli, Roberto; Bondioli, Luca

doi: 10.1002/ajpa.20870pmid: 18615573

This study integrates isotopic, palaeopathological, and historical evidence to investigate infant and young child feeding practices in a Roman period (1st to 3rd centuries AD) skeletal sample from the Isola Sacra necropolis (Rome, Italy). Stable isotope analysis of bone collagen from 37 rib samples indicates that transitional feeding began by the end of the first year and weaning occurred by 2–2.5 years of age. Both δ15N and δ13C data clearly show the trophic level effect associated with breastfeeding. Childhood diet is investigated using dental pathology data in the deciduous dentitions of 78 individuals aged between 1 and 12 years. The presence of calculus, caries, and tooth wear in young children suggests that individuals were provided complementary foods and other items that impacted their dental health at an early age. The isotopic and dental data are generally consistent with the historical evidence from the Roman period with respect to the general timetable of weaning and the character of complementary foods. This is the first study to integrate isotopic and deciduous dental pathology data to explore infant and young child feeding practices in the Roman world. Am J Phys Anthropol 2008. © 2008 Wiley‐Liss, Inc.

Vlak, Dejana; Roksandic, Mirjana; Schillaci, Michael A.

doi: 10.1002/ajpa.20875pmid: 18613093

Using Schutkowski's method for juvenile sex determination (Schutkowski H. 1993. Am J Phys Anthropol 90:199–205), we evaluated the morphology of the greater sciatic notch of 56 ilia (23 females and 33 males) from a documented skeletal collection housed at the Bocage Museum in Lisbon (Portugal). After applying Schutkowski's original methodology and comparing the results with previous studies, we used age‐adjusted metrical variables to describe greater sciatic notch depth, breadth, and angle. Although results of both morphological and metrical analyses did not reveal a statistically significant level of sexual analyses dimorphism, we found a strong correlation between pelvic morphology and age at death. On the basis of the obtained results, we argue that Schutkowski's morphological method does not predict sex accurately in all populations and that recorded correlation of iliac features with age needs to be further explored in the context of the ontogeny of sexual dimorphism. Am J Phys Anthropol 2008. © 2008 Wiley‐Liss, Inc.

Hassan, Hisham Y.; Underhill, Peter A.; Cavalli‐Sforza, Luca L.; Ibrahim, Muntaser E.

doi: 10.1002/ajpa.20876pmid: 18618658

We study the major levels of Y‐chromosome haplogroup variation in 15 Sudanese populations by typing major Y‐haplogroups in 445 unrelated males representing the three linguistic families in Sudan. Our analysis shows Sudanese populations fall into haplogroups A, B, E, F, I, J, K, and R in frequencies of 16.9, 7.9, 34.4, 3.1, 1.3, 22.5, 0.9, and 13% respectively. Haplogroups A, B, and E occur mainly in Nilo‐Saharan speaking groups including Nilotics, Fur, Borgu, and Masalit; whereas haplogroups F, I, J, K, and R are more frequent among Afro‐Asiatic speaking groups including Arabs, Beja, Copts, and Hausa, and Niger‐Congo speakers from the Fulani ethnic group. Mantel tests reveal a strong correlation between genetic and linguistic structures (r = 0.31, P = 0.007), and a similar correlation between genetic and geographic distances (r = 0.29, P = 0.025) that appears after removing nomadic pastoralists of no known geographic locality from the analysis. The bulk of genetic diversity appears to be a consequence of recent migrations and demographic events mainly from Asia and Europe, evident in a higher migration rate for speakers of Afro‐Asiatic as compared with the Nilo‐Saharan family of languages, and a generally higher effective population size for the former. The data provide insights not only into the history of the Nile Valley, but also in part to the history of Africa and the area of the Sahel. Am J Phys Anthropol, 2008. © 2008 Wiley‐Liss, Inc.

Guatelli‐Steinberg, Debbie; Sciulli, Paul W.; Betsinger, Tracy K.

doi: 10.1002/ajpa.20878pmid: 18615561

Previous researchers hypothesized that tooth types forming during early childhood should be less sexually dimorphic than those forming during later childhood, if sex hormone concentration differences between males and females increase progressively throughout childhood and can affect tooth size. Descriptive tooth size data have recently been cited in support of this hypothesis, particularly with respect to differences in sexual dimorphism among the tooth types of tooth classes. The present study tests this hypothesis for the mesiodistal dimension of human permanent teeth using published data for incisor, premolar, and molar tooth classes from seven diverse populations. The sample size for each tooth type per population was at least 50. This study also tests a modification of this hypothesis which takes into account the postnatal testosterone surge in males and the low levels of sex hormones in both sexes prior to puberty. Predictions are developed for both the original and modified hypotheses. The “D” statistic, the total area of nonoverlap between the phenotypic distributions of males and females, is used to quantify sexual dimorphism. Comparison of D values for different tooth types within tooth classes across these seven populations does not strongly support either hypothesis. These results suggest that gross changes in sex hormone concentrations during development are not related to population‐wide patterns of sexual dimorphism among the tooth types of human permanent tooth classes, as recent studies indicate. This finding is consistent with other studies which suggest that sex hormones have only a minor role in generating crown size sexual dimorphism. Am J Phys Anthropol 2008. © 2008 Wiley‐Liss, Inc.

Smith, Lindsey W.; Link, Andres; Cords, Marina

doi: 10.1002/ajpa.20879pmid: 18613091

The adaptive function of cheek pouches in the primate subfamily Cercopithecinae remains unresolved. By analyzing the circumstances of cheek pouch use, we tested two hypotheses for the evolution of cercopithecine cheek pouches proposed in earlier studies: (1) cheek pouches reduce vulnerability to predation, and (2) cheek pouches increase feeding efficiency by reducing competition. We studied two groups of wild blue monkeys (Cercopithecus mitis stuhlmanni) in the Kakamega Forest, Kenya, conducting focal observations of feeding individuals. Monkeys were less exposed while emptying their cheek pouches than filling them, supporting the predation‐avoidance hypothesis. We investigated several measures of competitive threat, but only one supported the competition‐reduction hypothesis: when the nearest neighbor's rank increased, subjects were more likely to increase than to decrease cheek pouch use. Overall, our findings supported the predation‐avoidance hypothesis more strongly than the competition‐reduction hypothesis. We suggest that variation in cheek pouch use may reflect differing behavioral strategies used by cercopithecines to mitigate competition and predation, as well as factors such as resource size and distribution, home range size, and travel patterns. Am J Phys Anthropol 2008. © 2008 Wiley‐Liss, Inc.