Until now, the purpose of eyelashes was thought to only be that of protecting the eyes against dust and small debris, but a new study has revealed that the purpose of eyelash length is that of protecting the eyes from frying out. The results of the study were published in the Journal of the Royal Society Interface.
David Hu, lead author of the study and researchers at the Georgia Institute of Technology, was prompted to research eyelashes after seeing his newborn child’s eyelashes. Joined by graduate students and colleagues, he set out to find why eyelashes are the length they are.
The researchers measured the lashes of various mammals and then proceeded to make an artificial eye with lashes which they placed inside a wind tunnel. They also measured the eyelashes of 22 species of mammals that were preserved at the American Museum of Natural History and found that the measurements showed the constant relation to the eye size.
The next step was to create mathematical models of airflow over the eyelashes and after careful examination of the results, they determined that lashes are almost always about one third as long as the eye is wide. This measurement appears to be ideal for diverting the airflow around the eye and helping reduce evaporation. The experiments in the wind tunnel corroborated the mathematical data.
Steven Vogel, professor at Duke, studies related issues in biomechanics and catalogued the results of the study as being terrific. He continued to say that now people know why eyelashes are the length they are.
Guillermo Amador, study co-author and a graduate student at Georgia Tech, stated:
[We] expected that longer eyelashes would be better. Instead, it seems like nature has come to this optimal eyelash length to help protect the eye, and making eyelashes any longer doesn’t really benefit them.
In humans, eyelashes have an additional role in seduction and sex, or to put it bluntly, in performing mating rituals. Dr. Hu said that, while that may be true for some species, the changing airflow around the eyes is so important that the proportion of the eyelash length to eye width does not change, from elephants to rabbits to humans.
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