Some believed Eyelashes are dust catchers, snaring things that would otherwise drift into the eye. Some others believed, they are sensors, acting like a cat's whiskers, to warn the eye of wind-borne grit or other dangers, according to another hypothesis. Some suggested that eyelashes are for expression, to enhance the impact of the eye for communication or sexual allure. A team of biologists said that, eyelashes direct airflow around the eye to shield it from airborne particles, bacteria, viruses and mites and prevent the protective coating of tears on the eyeball, a mix of mucus, oil and water, from drying out.
Unlike the hairs in the nose and airway, which act as physical traps, eyelashes act as "a passive dust-controlling system," the study headed by researcher David Hu at the Georgia Institute of Technology in the American city Atlanta, found. "They reduce evaporation and particle deposition by upto 50 percent." Hu's team measured the lashes of 22 mammal species, from hedgehogs to humans. In all of them, the length of the eyelash was about one-third of the width of the eye, which is optimal for minimising airflow over the eye surface without obstructing vision. The findings were published in the Journal of the Royal Society Interface.