Assessing human morphology using statistical shape analysis

Body size is often hypothesized to facilitate or constrain morphological diversity in the cranial, appendicular, and axial skeletons. However, how overall body shape scales with body size (i.e., body shape allometry) and whether these scaling patterns differ between ecological groups remains poorly investigated. Here, we test whether and how the relationships between body shape, body size, and limb lengths differ among species with different locomotor specializations, and describe the underlying morphological components that contribute to body shape evolution among squirrel (Sciuridae) ecotypes. We quantified the body size and shape of 87 squirrel species from osteological specimens held at museum collections. Using phylogenetic comparative methods, we first found that body shape and its underlying morphological components scale allometrically with body size, but these allometric patterns differ among squirrel ecotypes: chipmunks and gliding squirrels exhibited more elongate bodies with increasing body sizes whereas ground squirrels exhibited more robust bodies with increasing body size. Second, we found that only ground squirrels exhibit a relationship between forelimb length and body shape, where more elongate species exhibit relatively shorter forelimbs. Third, we found that the relative length of the ribs and elongation or shortening of the thoracic region contributes the most to body shape evolution across squirrels. Overall, our work contributes to the growing understanding of mammalian body shape evolution and how it is influenced by body size and locomotor ecology, in this case from robust subterranean to gracile gliding squirrels.

Body size is a fundamental trait that impacts many aspects of species biology and ecology. It is, in turn, influenced by a suite of environmental factors, and often decreases with warming. Although environmental conditions can also impact body shape, which is another functional trait that influences locomotion, resource acquisition and potentially physiological processes, such responses are poorly understood and rarely quantified. We experimentally tested the independent and combined effects of environmental temperature, resource level and interspecific competition on the body shape and size responses of two model protist species. We also tested the degree to which these individual‐level phenotypic responses are associated with population densities and species coexistence. Body shape was strongly influenced by resource competition, whereas body size changes were mainly driven by environmental temperature. In both species, lower resource levels resulted in body shape elongation, suggesting that relatively more elongate individuals with potentially higher swimming speed were advantaged in the resource scarce environment. However, competition had contrasting influence on the body shape of the two species. Competition decreased the population densities of Blepharisma japonicum, which exhibited relative body shape elongation, similar to the response at low resource levels. In contrast, competition increased the population densities of Paramecium aurelia, which exhibited reduced elongation similar to body shape response at high resource levels. Hence, body shape responses could be indicative of changes in resource availability, aiding our understanding of competitive hierarchies and species interactions. Coexistence was observed in all treatment combinations, likely because body size of both species decreased similarly under warming, potentially maintaining constant per capita competitive intensity. These findings, along with recent research on phytoplankton, diverse pelagic invertebrates, and birds highlight the importance of body shape and morphology across different taxonomic groups. Hence, we call for body size and shape to be considered in concert when investigating ecological consequences of climate warming. A free Plain Language Summary can be found within the Supporting Information of this article.

Phenotypic variations in fish body and scale shape were investigated among the three populations of Aphanius dispar (Ruppell, 1829)in Southern Iran through the use of landmark-based geometric morphometric analyses. This species is widely distributed in the region, and therefore, considerable morphological variations exist among the geographically allopatric populations. Based on the Principle Component Analysis (PCA), variation in body shape of the females is prominently related to the dorsal fin region, while in the males it is related to the dorsal fin and caudal peduncle. Moreover, the shape variations in the scales are obviously linked to the tip of anterior portion of the scales, and the left and right boundaries between anterior and posterior regions of the scales. The lateral sides of the fish scales in site I are concave, while they are laterally convex in sites II and III. The observed variation seen in the fish body shape and scales among the three studied sites are probably caused by the different ecological conditions of their habitats particularly variation in water flow.

Morphological diversity was analyzed in pumpkinseed sunfish (Lepomis gibbosus) between a lake (40.5 ha) and a pond (4 ha) at the Huyck Preserve and Biological Research Station in upstate New York. The hypotheses were (1) fish from the lake and pond would differ in body shape due to different biotic/abiotic factors in each water body, and (2) there would be a difference in variance in body shape between the lake and the pond due to differences in the availability of niches. Body shape variation was examined using geometric morphometrics, and parametric statistics were used to identify differences in body shape, and differences in the variance in body shape, between fish from the pond and the lake. Fish from the pond were, on average, slightly deeper bodied for a given body size; however, there was substantial overlap in variation, so this variation may not be ecologically significant even though it is statistically significant. The variance in components of body shape also differed between the pon...

This study examines variations in body shape and bust-related measurements, focusing on bust, waist, and hip dimensions while also considering the influence of BMI and ethnicity. Employing a quantitative approach, it analyzes anthropometric data of 2,750 women aged 26–45 from the SizeUSA database. The sample includes the following ethnicities: White, Black, Asian, non-Mexican Hispanic, and Mexican Hispanic. Variations in body measurements, BMI, and bra cup sizes across these groups are statistically analyzed using analysis of variance, cluster analysis, and chi-square tests. Body shape analysis reveals three shape clusters; Triangle shape (larger hips compared to upper body with moderate bra cup size), Rectangle shape (smaller waist–hip differences with a moderate cup size), and Inverted Triangle shape (larger upper body compared to hips with a large cup size). Each ethnic group exhibited distinct body shape patterns as follows: The Triangle group comprised a higher percentage of Black and White populations. The Rectangle group comprised a predominantly Asian population, while the Mexican Hispanics and non-Mexican Hispanics dominated the Inverted Triangle group. This study highlights trends in bra cup sizes across weight categories and suggests potential correlations between the former and body shape types. It contributes insights into the relationships among ethnicity, BMI, and bust-related measurements; identifies specific body shape clusters and bra size distributions; and offers valuable information in designing inclusive and well-fitted foundation garments for a diverse population.

Phylogenomics reveals habitat-associated body shape divergence in Oryzias woworae species group (Teleostei: Adrianichthyidae)

1. Climate change has been occurring at unprecedented rates and its impacts on biological populations is beginning to be well documented in the literature. For many species, however, long‐term records are not available, and trends have not been documented. 2. Using museum specimens from southern USA, we show that the stream‐dwelling beetle Gyretes sinuatus has shown an 8% increase in body size and change in body shape (fineness ratio) from 1928 to 1988. Any directional morphological change observed over time could be an indicator of a microevolutionary response. 3. During these 60 years, there have also been changes in temperature, precipitation, and location of collection sites. Unlike the global trend, mean annual temperature in the region has decreased, and furthermore, total annual precipitation has increased. By investigating how these various ecological and geographical variables may affect body size and shape, we can examine which pressures may promote larger and/or thinner beetles. 4. Results indicate that mean annual temperature was the most predictive variable for the change in size and shape. We suggest there is an adaptive role for temperature on body size and shape of stream dwelling organisms. 5. We found that museum specimens can be invaluable resources of information when collection date and location information is available. We promote the use of such specimens for future studies of the morphological response to climate change.

A key question in ecological speciation is to understand the causes and consequences of phenotypic divergence among populations. In this work, we analyzed the body shape and size variation in Jenynsia lineata across different coastal habitats along the Atlantic coast of South America. We hypothesized that J. lineata presents morphological variations to inhabit contrasting environments and that these adaptations are sex specific. We analyzed 13 populations from five coastal habitats, using linear and geometric morphometry, and tested the correlation of body shape variation with environmental variables to understand which environmental factors may influence body shape and size variation. Jenynsia lineata showed differences in body shape and size among populations, and these differences are specific to each sex. While females showed a variation in the caudal peduncle correlated with water current, we did not find such trait variation and correlation in males. Alternatively, individuals from marine rocky pools have a convex body curvature along the dorsal profile and larger body sizes, in both sexes. With these results, we describe the shape and size morphological variation of J. lineata and discuss this uncommon habitat-dependent sexual dimorphism in a Neotropical livebearer fish.

The importance of body size versus weight distribution for cancer risk is unclear. We investigated associations between measures of body size and shape and the risk of developing cancer. The study population consisted of 26,607 participants from the Alberta’s Tomorrow Project cohort. Two main measures of body shape and size were examined: i) body mass index (BMI) and ii) waist circumference (WC). Incident cancers were identified via linkage to the Alberta Cancer Registry. Cox proportional hazards models were used. Males and females classified as obese (BMI ≥ 30 kg /m−2) have a 33% and 22% increased risk of all-cancer, respectively, than their normal weight counterparts. Similar all-cancer risk increases are observed for those above sex-specific WC guidelines. Mutual adjustment for WC attenuates the association between BMI and all-cancer risk, especially among females. Central adiposity appears to be a stronger predictor of all-cancer risk than body size.

Understanding human body type and shape variations is of fundamental importance in various ergonomic applications in a wide range of industries. This article provides a comprehensive analysis of the body types in various countries using the most recent national sizing standards. A set of integrated and internationally compatible size tables are then derived, which provide a valuable reference for analysis of body shape variation. This study covered both female and male sizing standards of the US, Europe, China, Japan and some other countries. The statistical analysis showed that size frequency varies from various countries with significant differences in body types and shapes. The standards of China and Japan covered the smaller body dimensions and sizes, as reflected in the relatively narrow torso and hips. The Europe and US standards covered the relatively large body dimensions and size ranges; the body shapes are plumper and wider than those of other countries.

Understanding the ecological pressures that generate variation in body shape is important because body shape profoundly affects physiology and overall fitness. Using Fundulus, a genus of fish that exhibits considerable morphological and physiological variation with evidence of repeated transitions between freshwater and saltwater habitats, we tested whether habitat salinity has influenced the macroevolution of body shape at different stages in development. After accounting for phylogenetic inertia, we find that body shape deviates from the optimal streamlined shape in a manner consistent with different osmoregulatory pressures exerted by different salinity niches at every stage of ontogeny that we examined. We attribute variation in body shape to differential selection for osmoregulatory efficiency because: (1) saline intolerant species developed body shapes with relatively low surface areas more conducive to managing osmoregulatory demands and (2) inland species that exhibit high salinity tolerances have body shapes similar to saline tolerant species in marine environments.

Detailed statistical models of body size and shape are valuable for wide range of statistical analyses. Most body shape models represent a single posture, usually standing. Previous efforts to model both posture and body shape have parameterized posture using joint angles. This paper presents a statistical model of body shape in supported seated postures using a posture measured derived from surface landmarks rather than internal joint locations and angles. This method is not limited by a particular kinematic linkage deformation and so is particularly well suited to model the effects on body shape of posture changes in complex linkages such as the spine or shoulder.Keywordsbody shapelaser scanninganthropometryposture

Posture normalisation of 3D body scans

Example-based statistical framework for parametric modeling of human body shapes

The phenotypic expression of adult body size and shape results from synergistic interactions between hereditary factors and environmental conditions experienced during growth. Variation in body size and shape occurs even in genetically relatively homogeneous groups, due to different occurrence, duration, and timing of growth insults. Understanding the causes and patterns of intrapopulation variation can foster meaningful information on early life conditions in living and past populations. This study assesses the pattern of biological variation in body size and shape attributable to sex and social status in a medieval Italian population. The sample includes 52 (20 female, 32 male) adult individuals from the medieval population of Trino Vercellese, Italy. Differences in element size and overall body size (skeletal height and body mass) were assessed through Monte Carlo methods, while univariate non-parametric tests and Principal Component Analysis (PCA) were employed to examine segmental and overall body proportions. Discriminant Analysis was employed to determine the predictive value of individual skeletal elements for social status in the population. Our results highlight a distinct pattern in body size and shape variation in relation to status and sex. Male subsamples exhibit significant postcranial variation in body size, while female subsamples express smaller, nonsignificant differences. The analysis of segmental proportions highlighted differences in trunk/lower limb proportions between different status samples, and PCA indicated that in terms of purely morphological variation high status males were distinct from all other groups. The pattern observed likely resulted from a combination of biological factors and cultural practices.