Body Size Estimation Research Articles

Ontogenetic scaling of disc width with total length in west African batoids

AbstractMorphological scaling describes changes in the size or shape of one morphological character (e.g. mass, length, width, area etc.) as another increases in size. Understanding how morphological characters scale with body size can shed light on how natural selection influences morphology, and the nature of ecomorphological relationships through ontogeny. Batoids (Elasmobranchii: Batoidea) are a highly specialised lineage of cartilaginous fishes displaying extreme dorsoventral flattening. Despite this, little is known about morphological scaling in batoids compared to sharks. In this study we test the relationship between disc width and total length in five batoid species (Torpedo torpedo, Mobula tarapacana, Fontitrygon margarita, Raja parva, Rhinobatos irvinei) representing four orders that differ in both ecology and morphology, measured from artisanal fisheries in Western and Central Ghana. Whilst a lack of existing ecological data presents some limitations, our results are broadly consistent with ecomorphological theory previously applied to sharks. Moreover, we find that for some lineages (including some myliobatiform taxa) total length may represent a valid proxy for estimating overall body size. This finding has applications for body size and shape estimation in partially processed batoids obtained from fishing camps, and extinct taxa known only from incomplete or fragmented remains.

Visual body size estimation in adolescent anorexia nervosa: Behavioural and neurophysiological data suggest intact visual perception and biased emotional attention

Body image disturbance is a key symptom of anorexia nervosa (AN). AN patients report body dissatisfaction and overestimate their own body size in several tasks. This study aimed to clarify whether this overestimation arises from deficits in visual perception. To this end, 36 adolescent restrictive-type AN patients and 42 matched healthy controls performed metric and depictive body size estimation (BSE) tasks. Magneto- and electroencephalography were measured during the size estimation of 66 computer-generated body pictures varying in size from underweight to overweight. AN patients versus controls showed overestimation across self-referential metric and depictive BSE tasks, but similar performance in a depictive BSE task without self-reference and similar early neurophysiological responses. Starting mid-latency (200 ms), AN patients showed relatively more neural activity in response to underweight body pictures and less neural activity in response to higher-weight body pictures in distributed brain regions. A secondary comparison of AN patients with slight vs. distinct overestimation during self-referential BSE uncovered relatively stronger neural responses to body pictures corresponding to the estimated body mass index. These results suggest that body image disturbances in adolescent restrictive-type AN patients depend on self-reference and do not represent a deficit of visual perception, but rather biased emotional attention.

Features are more than just filling in the blanks on body size scales

ABSTRACT Despite widespread misperceptions of body size and shape, the specific visual features influencing such judgments remain unclear. This study assessed the contribution of internal body features (e.g., colour, shading) to the accuracy of female body size judgements and whether that contribution varies with body size. Using a bodyline task, 100 female participants evaluated images of female bodies, either depicted as real bodies including internal features (feature stimuli) or images of bodies as silhouettes only (silhouette stimuli). The results showed greater overall errors in body size estimation for silhouettes compared to full feature images. However, the direction of error differed for large and small bodies: small silhouettes were judged larger than their full-feature counterparts, while large silhouettes were judged smaller. These findings emphasize the importance of internal body features in shaping perceptions of female body size and highlight the complexity of judgement accuracy across different body sizes.

Quantifying body size estimation accuracy and body dissatisfaction in body dysmorphic disorder using a digital avatar

BackgroundA core feature of body dysmorphic disorder (BDD) is body image disturbance. Many with BDD misperceive and are dissatisfied with the sizes and shapes of body parts, but detailed quantification and analysis of this has not yet been performed. To address this gap, we applied Somatomap 3D, a digital avatar tool, to quantify body image disturbances by assessing body size estimation (BSE) accuracy and body dissatisfaction. MethodsSixty-one adults (31 with BDD, 30 healthy controls) created avatars to reflect their perceived current body and ideal body by altering 23 body part sizes and lengths using Somatomap 3D. Physical measurements of corresponding body parts were recorded for comparison. BSE accuracy (current minus actual) and body dissatisfaction (ideal minus current) were compared between groups and in relation to BDD symptom severity using generalized estimating equations. ResultsIndividuals with BDD significantly over- and under-estimated certain body parts compared to healthy controls. Individuals with BDD overall desired significantly thinner body parts compared to healthy controls. Moreover, those with worse BSE accuracy had greater body dissatisfaction and poorer insight. ConclusionIn sum, this digital avatar tool revealed disturbances in body image in individuals with BDD that may have perceptual and cognitive/affective components.

Cautionary tales on the use of proxies to estimate body size and form of extinct animals.

Body size is of fundamental importance to our understanding of extinct organisms. Physiology, ecology and life history are all strongly influenced by body size and shape, which ultimately determine how a species interacts with its environment. Reconstruction of body size and form in extinct animals provides insight into the dynamics underlying community composition and faunal turnover in past ecosystems and broad macroevolutionary trends. Many extinct animals are known only from incomplete remains, necessitating the use of anatomical proxies to reconstruct body size and form. Numerous limitations affecting the appropriateness of these proxies are often overlooked, leading to controversy and downstream inaccuracies in studies for which reconstructions represent key input data. In this perspective, we discuss four prominent case studies (Dunkleosteus, Helicoprion, Megalodon and Perucetus) in which proxy taxa have been used to estimate body size and shape from fragmentary remains. We synthesise the results of these and other studies to discuss nuances affecting the validity of taxon selection when reconstructing extinct organisms, as well as mitigation measures that can ensure the selection of the most appropriate proxy. We argue that these precautionary measures are necessary to maximise the robustness of reconstructions in extinct taxa for better evolutionary and ecological inferences.

Testing the validity of online psychophysical measurement of body image perception.

This body image study tests the viability of transferring a complex psychophysical paradigm from a controlled in-person laboratory task to an online environment. 172 female participants made online judgements about their own body size when viewing images of computer-generated female bodies presented in either in front-view or at 45-degrees in a method of adjustment (MOA) paradigm. The results of these judgements were then compared to the results of two laboratory-based studies (with 96 and 40 female participants respectively) to establish three key findings. Firstly, the results show that the accuracy of online and in-lab estimates of body size are comparable, secondly that the same patterns of visual biases in judgements are shown both in-lab and online, and thirdly online data shows the same view-orientation advantage in accuracy in body size judgements as the laboratory studies. Thus, this study suggests that that online sampling potentially represents a rapid and accurate way of collecting reliable complex behavioural and perceptual data from a more diverse range of participants than is normally sampled in laboratory-based studies. It also offers the potential for designing stratified sampling strategies to construct a truly representative sample of a target population.

Body length changes for Atlantic salmon (Salmo salar) over five decades exhibit weak spatial synchrony over a broad latitudinal gradient.

Understanding the factors that drive spatial synchrony among populations or species is important for management and recovery of populations. The range-wide declines in Atlantic salmon (Salmo salar) populations may be the result of broad-scale changes in the marine environment. Salmon undergo rapid growth in the ocean; therefore changing marine conditions may affect body size and fecundity estimates used to evaluate whether stock reference points are met. Using a dataset that spanned five decades, 172,268 individuals, and 19 rivers throughout Eastern Canada, we investigated the occurrence of spatial synchrony in changes in the body size of returning wild adult Atlantic salmon. Body size was then related to conditions in the marine environment (i.e., climate indices, thermal habitat availability, food availability, density-dependence, and fisheries exploitation rates) that may act on all populations during the ocean feeding phase of their life cycle. Body size increased during the 1980s and 1990s for salmon that returned to rivers after one (1SW) or two winters at sea (2SW); however, significant changes were only observed for 1SW and/or 2SW in some mid-latitude and northern rivers (10/13 rivers with 10 of more years of data during these decades) and not in southern rivers (0/2), suggesting weak spatial synchrony across Eastern Canada. For 1SW salmon in nine rivers, body size was longer when fisheries exploitation rates were lower. For 2SW salmon, body size was longer when suitable thermal habitat was more abundant (significant for 3/8 rivers) and the Atlantic Multidecadal Oscillation was higher (i.e., warmer sea surface temperatures; significant for 4/8 rivers). Overall, the weak spatial synchrony and variable effects of covariates on body size across rivers suggest that changes in Atlantic salmon body size may not be solely driven by shared conditions in the marine environment. Regardless, body size changes may have consequences for population management and recovery through the relationship between size and fecundity.

Estimating body volumes and surface areas of animals from cross-sections.

Body mass and surface area are among the most important biological properties, but such information is lacking for some extant organisms and most extinct species. Numerous methods have been developed for body size estimation of animals for this reason. There are two main categories of mass-estimating approaches: extant-scaling approaches and volumetric-density approaches. Extant-scaling approaches determine the relationships between linear skeletal measurements and body mass using regression equations. Volumetric-density approaches, on the other hand, are all based on models. The models are of various types, including physical models, 2D images, and 3D virtual reconstructions. Once the models are constructed, their volumes are acquired using Archimedes' Principle, math formulae, or 3D software. Then densities are assigned to convert volumes to masses. The acquisition of surface area is similar to volume estimation by changing math formulae or software commands. This article presents a new 2D volumetric-density approach called the cross-sectional method (CSM). The CSM integrates biological cross-sections to estimate volume and surface area accurately. It requires a side view or dorsal/ventral view image, a series of cross-sectional silhouettes and some measurements to perform the calculation. To evaluate the performance of the CSM, two other 2D volumetric-density approaches (Graphic Double Integration (GDI) and Paleomass) are compared with it. The CSM produces very accurate results, with average error rates around 0.20% in volume and 1.21% in area respectively. It has higher accuracy than GDI or Paleomass in estimating the volumes and areas of irregular-shaped biological structures. Most previous 2D volumetric-density approaches assume an elliptical or superelliptical approximation of animal cross-sections. Such an approximation does not always have good performance. The CSM processes the true profiles directly rather than approximating and can deal with any shape. It can process objects that have gradually changing cross-sections. This study also suggests that more attention should be paid to the careful acquisition of cross-sections of animals in 2D volumetric-density approaches, otherwise serious errors may be introduced during the estimations. Combined with 2D modeling techniques, the CSM can be considered as an alternative to 3D modeling under certain conditions. It can reduce the complexity of making reconstructions while ensuring the reliability of the results.

Body evaluation in men: the role of body weight dissatisfaction in appearance evaluation, eating, and muscle dysmorphia psychopathology.

Body image dissatisfaction is a significant concern among men, influencing appearance evaluation, eating behaviors, and muscle dysmorphia psychopathology. However, research on these correlations is notably deficient in men, largely because body image concerns are unevenly distributed between genders. Therefore, this study aims to assess the various dimensions of concerns about body image in men and explore their associations with characteristics such as sexual orientation. A cross-sectional study was conducted with 251 adult men from fitness centers in the Veneto Region, Italy. Participants completed self-report questionnaires, including the Eating Attitudes Test (EAT-26), the Appearance Schemas Inventory-Revised (ASI-R), and the Muscle Dysmorphic Disorder Inventory (MDDI). Body weight perception and dissatisfaction were evaluated using a Figure Rating Scale (FRS) with 12 male biometric silhouettes. Participants were divided into three subgroups based on the experienced levels of body weight dissatisfaction: those who rated a smaller body (BWsmaller), those who rated a larger body (BWlarger) more highly relative to their own estimated body size, and those who reported implicit neutrality with their current weight (BWneu). BWsmaller participants reported higher levels of eating-related concern, while BWlarger participants exhibited higher levels of muscle dysmorphia. Additionally, the BWlarger group showed the highest degree of quantitative perceptual underestimation of their body weight. Sexual orientation was found to have an impact on body weight dissatisfaction, with bisexual men more likely to desire an increase in weight and gay men more likely to desire a decrease. Body weight dissatisfaction significantly impacts appearance evaluation, eating behaviors, and muscle dysmorphia psychopathology in males. Tailored interventions that consider individual differences can support the well-being of men. The study provides useful insight into male body image issues, warranting further exploration to inform effective interventions and promote positive body image and mental health in this population.

Reconstructing an ancient fish: Three-dimensional skeletal restoration of the head of Mawsonia (Sarcopterygii, Actinistia) using CT scan, and an adjusted model for body size estimation in fossil coelacanths.

Mawsonia constitutes one of the most conspicuous fossil coelacanth taxa, due to its unique anatomy and possible maximum body size. It typifies Mesozoic coelacanth morphology, before the putative disappearance of the group in the fossil record. In this work, the three-dimensional cranial anatomy and body size estimations of this genus are re-evaluated from a recently described specimen from Upper Jurassic deposits of Uruguay. The 3D restoration was performed directly on the material based on anatomical information provided by the living coelacanth Latimeria and previous two-dimensional restorations of the head of Mawsonia. The montage was then scanned with computed tomography and virtually adjusted to generate an interactive online resource for future anatomical, taxonomic and biomechanical research. In general terms, the model constitutes a tool to improve both the anatomical knowledge of this genus and its comparison with other coelacanths. It also facilitates the evaluation of possible evolutionary trends and the discussion of particular features with potential palaeobiological implications, such as the anterior position of the eye and the development of the pseudomaxillary fold. Regarding the body size, a previous model for body size estimation based on the gular plate was submitted to OLS, RMA, segmented linear and PGLS regressions (including the evaluation of regression statistics, variance analysis, t-tests and residual analysis). The results point to a power relationship between gular and total lengths showing a better support than a simple linear relationship. The new resulting equations were applied to the studied individual and are provided for future estimates. Although an isometric evolutionary growth cannot be rejected with the available evidence, additional models developed with other bones will be necessary to evaluate possible hidden evolutionary allometric trends in this group of fishes, thus avoiding overestimates.

Correction: Body size estimation method for seasonally growing farmed yellowtail Seriola quinqueradiata in an aquaculture net cage using a stereo camera

Correction: Body size estimation method for seasonally growing farmed yellowtail Seriola quinqueradiata in an aquaculture net cage using a stereo camera

Using scale-derived estimates of body size in analyses of Atlantic salmon life-history variation: a cautionary note

Measurements of individual body length at different life stages are critical in understanding fish ecology and evolution. Such data can be obtained via back-calculation from measurements of fish scales or by using the size of the scale as a direct proxy for body length. Using data from Atlantic salmon, we test key assumptions associated with each approach and their implications for investigating how variation in growth earlier in life is associated with age at maturity. The scaling of scale size approximated isometry and was similar among individuals who matured at different ages—validating a key assumption of back-calculation. However, we observed that individuals genetically predisposed to delay maturation have smaller scales for their body size—challenging a key assumption of the “direct scale-size” approach. Depending on the method of body length estimation, the relationship between body length growth earlier in life and age at maturity was observed to differ. Thus, when using scale material to study the relationship between growth and maturation in salmon, we recommend back-calculation and an assumed allometric scaling coefficient.

Coupled social and ecological change drove the historical extinction of the California grizzly bear (Ursus arctos californicus).

Large carnivores (order Carnivora) are among the world's most threatened mammals due to a confluence of ecological and social forces that have unfolded over centuries. Combining specimens from natural history collections with documents from archival records, we reconstructed the factors surrounding the extinction of the California grizzly bear (Ursus arctos californicus), a once-abundant brown bear subspecies last seen in 1924. Historical documents portrayed California grizzlies as massive hypercarnivores that endangered public safety. Yet, morphological measurements on skulls and teeth generate smaller body size estimates in alignment with extant North American grizzly populations (approx. 200 kg). Stable isotope analysis (δ13C, δ15N) of pelts and bones (n = 57) revealed that grizzlies derived less than 10% of their nutrition from terrestrial animal sources and were therefore largely herbivorous for millennia prior to the first European arrival in this region in 1542. Later colonial land uses, beginning in 1769 with the Mission era, led grizzlies to moderately increase animal protein consumption (up to 26% of diet), but grizzlies still consumed far less livestock than otherwise claimed by contemporary accounts. We show how human activities can provoke short-term behavioural shifts, such as heightened levels of carnivory, that in turn can lead to exaggerated predation narratives and incentivize persecution, triggering rapid loss of an otherwise widespread and ecologically flexible animal.

Body size estimation from isolated fossil bones reveals deep time evolutionary trends in North American lizards.

Lizards play vital roles in extant ecosystems. However, their roles in extinct ecosystems are poorly understood because the fossil record of lizards consists mostly of isolated bones. This makes it difficult to document changes in lizard morphology and body size over time, which is essential for studies of lizard paleoecology and evolution. It is also difficult to compare available fossil lizard data with existing sources of extant lizard data because extant studies rarely measure individual bones. Furthermore, no previous study has regressed measurements of individual bones to body length across crown lizard groups, nor tested those regressions on fossil skeletons. An extensive dataset of individual bone measurements from extant lizards across crown taxonomic groups is here employed to develop novel methods for estimating lizard body size from isolated fossil elements. These methods were applied to a comparably large dataset of fossil lizard specimens from the robust Paleogene record (66-23 Ma) of the Western Interior of North America. This study tests the hypothesis that anatomical proportions have been conserved within higher-level crown lizard groups since the Paleogene and can therefore be used to reconstruct snout-vent length (SVL) and mass for fossil specimens referred to the same groups. Individual bones demonstrated strong correlation with SVL in extant as well as fossil lizard specimens (R2 ≥ 0.69). Equations for mass estimation from individual bones were derived from the SVL regressions using published equations for calculating lizard body mass from SVL. The resulting body size estimates from regression equations for the entire fossil dataset revealed that lizards reached greatest maximum body size in the middle Paleogene, with the largest size class dominated by anguid lizards that exceeded 1 meter in SVL and 1.5 kg in body mass. Maximum body size decreased to under 400 mm and below 1.5 kg in the late Paleogene. No association was found between changes in maximum lizard body size and marine isotope proxies of global temperature through the Paleogene. This is the first study to investigate body size evolution across lizard clades over a deep time interval and for a large geographic region. The proposed methods can be used to generate body size regressions and provide estimates of body size for isolated lizard bones referred to any crown group.

Playing With Spatial Frames: Altering the Body Matrix Through Multisensory Egocentric and Allocentric Body Illusions

The multifaceted nature of body experience, encompassing affective, cognitive, and perceptual components, plays a critical role in the development and persistence of conditions such as anorexia nervosa (AN). Recent research attempted to address such disturbance to improve therapeutical effectiveness, using mirror exposure (ME) and body‐swapping (BS) techniques in immersive virtual reality (VR). Procedures from a third‐person perspective—as mirror‐like experiences—were primarily used to address bodily cognitive and affective components, whereas first‐person ones—as BS—were used to correct distorted body perception. This study investigated the effect of spatial reference frame on body self‐consciousness and body perception during BS. Data revealed two main findings: Even though embodiment was significantly enhanced when participants engaged with a virtual body from a first‐person viewpoint, both egocentric and allocentric perspectives influenced body size estimation (BSE), suggesting that both spatial perspectives critically form and sustain body self‐perception. We discussed predictive coding theory to explain spatial perspective influence on body experience, highlighting the potential therapeutic benefits of incorporating first and third‐person perspectives on body illusions (BIs) for more effective interventions targeting body‐related disturbances.

Reconstructing patterns of domestication in reindeer using 3D muscle attachment areas

The use of reindeer has been a crucial element in the subsistence strategies of past Arctic and Subarctic populations. However, the spatiotemporal occurrence of systematic herding practices has been difficult to identify in the bioarchaeological record. To address this research gap, this study proposes a new virtual anthropological approach for reconstructing habitual physical activity in reindeer, relying on the protocols of the “Validated Entheses based Reconstruction of Activity” (VERA) method. Following blind analytical procedures, we focused on eight muscle attachment sites (“entheses”) in 36 reindeer free ranging in the wild, 21 specimens in captivity (zoo), and eight racing reindeer (habitual runners). Importantly, our analyses accounted for the effects of variation by subspecies, sex, age, and estimated body size. Our results showed clear differences across activity groups, leading to the development of discriminant function equations with cross-validated accuracies ranging from approximately 88 to 100%. The reliability of our functions was additionally confirmed using a blind test involving six zoo individuals not included in the initial dataset. Our findings support the use of the proposed approach for identifying domestication-related activities in zooarchaeological contexts, introducing a valuable tool for locating suspected domestication hotspots and elucidating the nature of past human-reindeer interactions.

Body size estimation method for seasonally growing farmed yellowtail Seriola quinqueradiata in an aquaculture net cage using a stereo camera

Body size estimation method for seasonally growing farmed yellowtail Seriola quinqueradiata in an aquaculture net cage using a stereo camera

Fossil frogs (Eleutherodactylidae: Eleutherodactylus) from Florida suggest overwater dispersal from the Caribbean by the Late Oligocene

Abstract Establishment of extant terrestrial vertebrate faunas in North America was influenced by a set of factors associated with temporal changes in climate and ecology that operated at different geographic scales. While the biogeography of extant taxa can be inferred from phylogenies, these omit lineages that have gone regionally extinct and for which the only direct evidence is the fossil record. A comprehensive study of anurans from the Late Oligocene of Florida reveals an abundance of fossils referred to Eleutherodactylus. Time-calibrated molecular phylogenies have suggested that this genus originated in the Caribbean in the Early Oligocene and then colonized Central America in the Middle Miocene. Here, we describe the first records of pre-Quaternary fossils referred to Eleutherodactylus from Florida. Results from analysis of inter- and intraspecific variation in anatomy, size, and shape of isolated bones of fossil and extant species suggest that the fossils represent adult individuals with an estimated body size (snout–urostyle length) of 16.8–29.8 mm. We show that Eleutherodactylus was established by the Late Oligocene in North America well before colonizing Central America in the Miocene. We provide, for the first time, evidence of dispersal of amphibians from the Caribbean into North America during the Late Oligocene.

Accuracy of estimating self and other body size among adolescent girls with anorexia nervosa

ABSTRACT This study aimed to analyze body size estimates of others by patients with anorexia nervosa (AN) and to identify any differences with the perception of their own body size. Adolescent females (age, 13–17 years) were enrolled into AN (n = 30) and control(n = 23) groups. The Subjective Body Dimensions Apparatus (SBDA) was used to evaluate body size estimates for oneself (self-estimation) and others (other-estimation). Participants also completed questionnaires assessing eating disorders and depressive symptoms. The AN and control groups scored significantly higher in self-estimation than in other-estimation. However, the AN group showed higher self-estimation scores than the control group for all the body parts and for the global silhouette (p < .001). Patients with more severe eating disorder symptomatology showed more distorted self-estimation (p < .05). No statistically significant differences were found in the other-estimation scores between the groups (p = .714), indicating that AN and control patients estimate the body sizes of others similarly. Eating disorder symptomatology correlates with self-estimation scores but not with other-estimation scores in adolescents with AN. No correlations existed between clinical symptomatology and other-estimation.

Testing visual self-misperception in anorexia nervosa using a symmetrical body size estimation paradigm.

Individuals diagnosed with anorexia nervosa (AN) often report seeing themselves as overweight. While body size estimation tasks suggest that such individuals overestimate their body size, these tasks have failed to establish whether this misestimation stems from visual misperception. Misestimation might, instead, be due to response bias. We designed a paradigm to distinguish between visual and response bias contributions to body size misestimation: the symmetrical body size estimation (s-BSE) paradigm. The s-BSE paradigm involves two tasks. In the conventional task, participants estimate the width of their photographed body by adjusting the size of a rectangle to match. In the transposed task, participants adjust the size of a photograph of their body to match the rectangle. If overestimation stems exclusively from visual misperception, then errors in each task would be equal and opposite. Using this paradigm, we compared the performance of women diagnosed with AN (n = 14) against women without any eating disorder (n = 40). In the conventional task, we replicated previous findings indicating that both women with AN and women without any eating disorder overestimate their body size. In the transposed task, neither group adjusted the bodies to be narrower than the rectangle. Participants with AN set their photographs to be significantly wider. While we replicated previous findings of body size overestimation amongst women with AN and those without any eating disorder, our results are inconsistent with the hypothesis that such overestimation stems exclusively from visual misperception and instead suggest a substantial response bias effect. Women with anorexia nervosa overestimate their own body size. Research has not yet determined whether this overestimation stems from them seeing themselves as larger or other, non-visual factors. We employ a new method for distinguishing these possibilities and find that non-visual factors influence size estimates for women with and without anorexia nervosa. This method can help future research control for non-perceptual influences on participant responses.