Abstract Human breasts are larger and more enduring than reproductively necessary. It is thus unclear why this costly, yet conspicuous phenotype has been selected for, or what information they might… Click to show full abstract
Abstract Human breasts are larger and more enduring than reproductively necessary. It is thus unclear why this costly, yet conspicuous phenotype has been selected for, or what information they might convey about the underlying quality of the female. Following previous research on fluctuating asymmetry, we postulated that breast symmetry would predict a marker of mucosal immunity (salivary immunoglobulin-A; sIgA). Anthropometric breast measurements were provided by 97 young women. Controlling for Body Mass Index (BMI), breast size, and volume, results demonstrated that breast asymmetry predicted lower sIgA, whereas size and volume did not. Results support the hypothesis that symmetrical female breasts are a cue to underlying immunocompetence.
               
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