A new statistical approach could give camel breeders a clearer way to measure an animal’s overall body size, replacing a scattered collection of individual measurements with a single biologically meaningful trait. In a study of dromedary camels in southern Iran, researchers used confirmatory factor analysis to define what they call a latent body-size phenotype—a hidden characteristic inferred from several observable features. The method could help livestock scientists compare animals more consistently, improve genetic evaluations and design breeding programs around a trait that is difficult to measure directly.
Body size is one of the most important characteristics in livestock production, but it is not a single visible feature. A camel’s overall size is reflected in its height, length, chest dimensions and abdominal proportions, all of which are related but not identical. Measuring each trait separately can create analytical complications: an animal may be tall but relatively narrow, or deep-bodied without being especially long. Treating these measurements as independent can therefore obscure the shared biological signal that breeders actually want to capture. The Iranian study addressed this problem by modeling body size as a latent construct, a statistical variable that cannot be observed directly but can be estimated from correlated measurements.
The analysis used records from 136 dromedary camels raised in southern Kerman province, Iran. The group included eight males and 128 females, reflecting a strongly female-dominated sample typical of many managed breeding populations. Researchers selected six morphometric traits as observable indicators of the hidden body-size phenotype: height at the hump, body length, height at the withers, thoracic depth, abdominal girth and abdominal depth. Together, these measurements describe the animal’s vertical development, longitudinal frame and body capacity. Rather than simply adding the measurements or averaging standardized values, the researchers tested whether the six traits could be explained by a common underlying factor.
That test was performed using confirmatory factor analysis, or CFA, a technique designed to evaluate a prespecified relationship between observed variables and an unseen construct. In this case, the researchers proposed that a single latent factor—body size—would account for the correlations among the six measurements. CFA differs from exploratory factor analysis because the structure is defined in advance and then tested against the data. Each measurement receives a factor loading, which indicates how strongly it reflects the latent trait after accounting for the relationships among the other measurements. A high loading suggests that the measurement is a particularly informative indicator of overall body size, while a lower loading suggests a weaker connection.
The model was fitted using robust maximum likelihood estimation in the lavaan package for the R statistical computing environment. The use of robust estimation is important because biological measurements may not perfectly follow the assumptions of conventional statistical models, including the assumption that the data are normally distributed. The researchers assessed the model with several complementary fit indices. The comparative fit index was 0.94 and the Tucker–Lewis index was 0.91, values indicating that the proposed structure represented the observed relationships reasonably well. The root mean square error of approximation was 0.06, while the standardized root mean square residual was 0.05. Taken together, these results showed acceptable agreement between the model and the measurements collected from the camels.
All six traits made statistically significant contributions to the latent body-size factor. Their standardized factor loadings ranged from 0.66 to 0.87, indicating that every selected measurement carried substantial information about the shared phenotype. In practical terms, the model suggests that the dimensions of a camel’s frame are not merely a collection of unrelated features. They contain a common biological signal that can be estimated mathematically. A latent score derived from that signal could provide a more stable summary of body size than any one measurement alone, especially when animals differ in shape or proportions.
The distinction matters because body-size measurements are often used in breeding and management decisions. Height at the hump may be relevant to structural development, body length can relate to frame and conformation, and thoracic depth, abdominal girth and abdominal depth can provide information about body capacity. Yet selecting animals on the basis of one dimension could unintentionally favor an extreme body shape rather than a generally larger or more functionally useful animal. A composite latent phenotype could reduce that risk by weighting the measurements according to their observed relationships. It could also make statistical comparisons more efficient by reducing multiple correlated traits to a unified outcome.
The researchers’ approach may eventually be valuable for genetic evaluation, although the study itself defined the phenotype rather than demonstrating its heritability or predicting production performance. In a future breeding analysis, each camel’s latent body-size score could potentially be linked with pedigree or genomic information to estimate genetic differences among animals. Such a framework might help identify whether the shared body-size signal is transmitted reliably to offspring and whether it is genetically associated with traits such as growth, reproductive performance, endurance or meat production. Those questions remain open and would require larger, more balanced datasets collected across herds, environments and age groups.
The composition of the current sample is an important consideration when interpreting the findings. With 128 females and only eight males, the model primarily reflects variation among female camels from one region. The results therefore provide evidence that the six measurements can form a coherent body-size construct in this population, but they do not establish that the same factor structure will apply identically to males, other breeds or camels raised under different environmental conditions. Age, nutrition, pregnancy status and management may also influence body dimensions. Validation in larger populations would be needed before the method could become a standard tool for national breeding programs or international comparisons.
Even with those limitations, the study illustrates how modern statistical modeling can turn familiar field measurements into a more informative biological indicator. The central idea is not to discard traditional measurements, but to understand how they work together. By confirming that six dimensions share a measurable underlying signal, the analysis offers a framework for summarizing camel conformation without pretending that any single dimension defines size on its own. For a species central to transport, food production, livelihoods and cultural traditions across arid regions, a more precise approach to evaluating body size could make breeding decisions more systematic. The latent phenotype may ultimately give camel science a common language for comparing animals—and a new way to see the biology hidden inside a tape measure.
Subject of Research: Defining a latent body-size phenotype in dromedary camels using six morphometric traits and confirmatory factor analysis.
Subject of Research: Biology
Article Title: Defining a latent body size phenotype from morphometric traits in dromedary camels (Camelus dromedarius) using confirmatory factor analysis
Article References: Ehsaninia, J. (2026). Defining a latent body size phenotype from morphometric traits in dromedary camels (Camelus dromedarius) using confirmatory factor analysis. Discover Animals, 3(1), Article 79. https://doi.org/10.1007/s44338-026-00242-7
Image Credits: AI Generated
DOI: 10.1007/s44338-026-00242-7
Keywords: dromedary camels, Camelus dromedarius, body size, morphometric traits, confirmatory factor analysis, latent phenotype, livestock breeding, camel genetics, animal science, Iran
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SCIENMAG. (August 27, 2026). Researchers Identify Hidden Body-Size Trait in Dromedary Camels Using Statistical Analysis. https://scienmag.com/researchers-identify-hidden-body-size-trait-in-dromedary-camels-using-statistical-analysis/
SCIENMAG. “Researchers Identify Hidden Body-Size Trait in Dromedary Camels Using Statistical Analysis.” Scienmag, 27 August 2026, https://scienmag.com/researchers-identify-hidden-body-size-trait-in-dromedary-camels-using-statistical-analysis/. Accessed 27 August 2026.
SCIENMAG. “Researchers Identify Hidden Body-Size Trait in Dromedary Camels Using Statistical Analysis.” Scienmag. August 27, 2026. https://scienmag.com/researchers-identify-hidden-body-size-trait-in-dromedary-camels-using-statistical-analysis/
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