Eyelash length disparity between sexes has been observed, with males often exhibiting longer upper eyelashes. This physical characteristic involves the greater projection of the cilia extending from the upper eyelid margin in the male population compared to the female. These structures, composed primarily of keratin, serve to protect the eye from debris and environmental irritants.
The possession of comparatively elongated eyelashes potentially provides enhanced ocular protection. A longer length may offer a greater barrier against particulate matter, reducing the likelihood of corneal abrasion and infection. Historically, such enhanced protection could have been advantageous in environments with high dust or debris levels, possibly contributing to evolutionary selection.