Scaling of linear anthropometric dimensions in living humans

Abstract

Objectives Some previous studies suggest that humans do not conform to geometric similarity (isometry) in anthropometric dimensions of the upper and lower limbs. Researchers often rely on a single statistical approach to the study of scaling patterns, and it is unclear whether these methods produce similar results and are equally robust. This study used one bivariate and one multivariate method to examine how linear anthropometric dimensions scale in a sample of adult humans. Materials and methods Motion capture marker data from 104 adults of varying height and mass were used to calculate anthropometric dimensions. We analyzed scaling patterns in pooled and separate sexes with two methods: (1) bivariate log–log regression and (2) multivariate principal component analysis (PCA). We calculated 95% highest density/confidence intervals for each method and defined positive/negative allometry as estimates lying outside those intervals. Results Results identified isometric scaling of the upper arm, thigh, and shoulder, positive allometry of the forearm and shank, and negative allometry of the pelvis in the pooled sample using both statistical methods. Patterns of allometry in the pooled sample were similar between methods but differed in magnitude. Sex‐specific results differed in both pattern and magnitude between log–log regression and PCA. Only one measurement (shoulder width) departed from isometry in the sex‐specific log–log regressions. Discussion Our findings suggest that especially in sex‐specific analyses, the pattern and magnitude of allometry are sensitive to statistical methodology. When body mass was selected as the size variable, most human linear anthropometric dimensions in this sample scaled isometrically and were therefore geometrically similar within sexes.

A three‐dimensional musculoskeletal model of the pelvis and lower limb of Australopithecus afarensis

“…This provides some initial indication that the model is extensible to a wide range of A. afarensis adults. Yet, uniform model scaling based on a single element (i.e., maximum tibia length) is an incomplete evaluation of this issue, as some human anthropometric dimensions (e.g., pelvis width) depart from isometric scaling in a pooled‐sex sample (Fox et al, 2021). Differential scaling (i.e., negatively allometric) of pelvis mediolateral diameter, or direct inclusion of the KSD‐VP‐1/1 pelvic remains in future work, may be useful in discriminating between size and sexual dimorphism in the predicted moment arms for A. afarensis .…”

An alternative size variable for allometric investigations in subadults

“…Results of this study demonstrate that FMSB and GM midshaft breadths are the best alternative size variables to stature for subadult allometry research across two geographically diverse samples. Choosing an appropriate size variable is important to identify deviations from isometry (Fox et al, 2021; Jungers et al, 1995; Jungers & German, 1981), as all positive or negative allometric relationships are inferred based on departures from a slope of one for stature in logarithmic space and represent a biological change in relation to size. Thus, the methodology of this research focused more on finding the closest isometric relationship between alternative size variables and stature instead of relying on correlation.…”

Effects of Body Mass on Leg and Vertical Stiffness in Running Humans

“…There are multiple reasons to question the applicability of geometric similarity in humans given the wide range of variation in human body and limb proportions (Nevill et al, 2004; Steudel-Numbers and Weaver, 2006; Sylvester et al, 2008; Kramer and Sylvester, 2013). Although humans may not be perfectly isometric in their limb lengths, it is unclear whether these proportional differences are enough to violate geometric similarity (Fox et al, 2021).…”