Eyelash Morphology is Unrelated to Markers of Immunocompetence and Health

Some researchers have suggested that longer eyelashes may serve as a sexually selected cue to underlying immunocompetence, based on findings that individuals with longer eyelashes are rated as more attractive and healthier. Yet no prior research has directly tested whether eyelash morphology is associated with health symptoms or biological markers of immune function. In the present study, participants (N= 163, ages 18–38) provided eyelash samples(measured for total length and lash length-to-eye-width ratio), self-reported health data, saliva samples (assayed for immunoglobulin A and cortisol), and blood samples (assayed for serum lysozyme and lactoferrin). Results indicate no significant associations between eyelash morphology and any of the measures of underlying health and immunocompetence. Together, these findings do not support the hypothesis that eyelash morphology has been sexually selected as a reliable cue of underlying immunocompetence, but that it may provide a cue to age.