Skeletal assessment and secular changes in knee development: a radiographic approach.

OBJECTIVES: The purpose of this study is to conduct an analysis of ossification patterns in the distal femoral, proximal tibial, and proximal fibular epiphyses, and the patella. The results generated from this analysis will be compared with previous standards published by Elgenmark () and Garn et al. () to determine if clinical and skeletal age assessment standards should be updated for contemporary Americans. MATERIALS AND METHODS: Using the Pediatric Radiology Interactive Atlas (Patricia), a total of 1,317 epiphyses were scored for presence or absence from radiographs of 1,056 white individuals born in or after 1990. Statistical modeling of epiphyseal appearance was conducted for all major percentiles, including the 5th and 95th percentiles through logistic regression. RESULTS: Compared with Elgenmark () and Garn et al. (), our data suggest that the distal femoral and proximal tibial epiphyses show overall earlier ossification, while the proximal fibular epiphysis shows later ossification. When examining the pooled sex 50th percentile for our data, we found that ossification timing differences are 1.2 weeks earlier in the distal femoral epiphysis, 2.1 weeks earlier in the proximal tibial epiphysis, and 1.4 years later in the proximal fibular epiphysis. DISCUSSION: The epiphyses that appear early in life, for example the distal femoral epiphysis, require gestational age information to accurately estimate appearance times. There are considerable differences between the ossification timing patterns presented in this study and those of previous standards, which did not include gestational ages. Several factors may explain the observed differences in the epiphyses of the knee including: the availability of gestational age information, the analysis of longitudinal versus cross-sectional data, differences in socioeconomic status and prenatal care, and secular change. KEYWORDS age estimation, growth standards, ossification, skeletal maturation, subadult/juvenile growth.

Relationships between Eskimos, Amerindians, and Aleuts: old data, new perspectives.

Eskimos and Aleuts have long shown uncertain anthropological relationships to each other and to Amerindians. Various researchers, using different samples, data, and methods, have derived diverse relationships among them. Despite supervising the collection of anthropometric data during various expeditions around the turn of the century, Franz Boas did not use these data to formulate or support his Eskimo wedge theory. The perception of Eskimo biological uniqueness has persisted (Greenberg et al. 1986; Laughlin et al. 1979; Laughlin and Harper 1988), although it has been challenged by Szathmary and Ossenberg (1978), Szathmary (1979), and Ossenberg (1992). Genetic analyses, whether using nuclear or mitochondrial DNA, have not revealed consistent relationships for various reasons. A widely known multidisciplinary study (Greenberg et al. 1986) has failed to show agreement among data sets. As a result, Boas's theory has not been adequately tested to this day. A modern analysis of anthropometric data collected under Boas casts doubt on an Eskimo wedge and the assumed close relationship between language and biology. Compared with other north Pacific populations, the Siberian, Labrador, and MacKenzie Delta Eskimo samples are anthropometrically closest to northeast Siberians, whereas the Aleuts are closest to some Northwest Coast Amerindians. An analysis with additional data collected by Hrdlicka (1930) reflects ethnohistorical relationships and a geographic pattern of population affinities: The Eskimos of southwestern Alaska are similar to Aleuts and selected Amerindian tribes on the Northwest Coast. Despite linguistic similarities, Eskimo and Aleut populations are diverse, with some being more similar to populations from opposite sides of the north Pacific.

Multivariate quantitative genetics of anthropometric traits from the Boas data.

The use of multivariate quantitative trait information to address questions of population relationships and evolutionary issues has a long-standing history in human anthropometry. Previous analyses have usually rested on a number of explicit or implicit assumptions that allow phenotypic information to be used as a proxy for quantitative genetic information. One (usually implicit) assumption is that the additive genetic variance-covariance matrix (G) among traits is proportional to the phenotypic variance-covariance matrix (P). In this study we discuss the implications of this assumption, demonstrating that if it is true that G = h2P, where h2 is some constant of proportionality, then (1) the biological (phenotypic) Mahalanobis distance will be proportional to genetic distance, (2) phenotypic and genetic allometry coefficients will be equal, and (3) evolutionary models will become simplified. We then use a multivariate quantitative genetic analysis of 12 anthropometric traits in 5 tribes to demonstrate that G = h2P for at least a portion of the Boas data.