A group researchers from Georgia Tech have found that eyelashes of mammals grow to just the right length in order to funnel debris and dust from the eye without drying them out.
The research started with measuring the eyelashes of 22 different species of mammals preserved at the American Museum of Natural History. What they found was pretty remarkable – in every instance, eyelashes were always about one-third as long as the eye is wide. Some of the mammals that were measured included panda, camel, kangaroo, possum, elephant, and leopard.
The team then used a wind tunnel and placed a dish of water the size of an eye and a circle of mesh around it to mimic eyelashes into the tunnel. They were able to show that the actual length of mammalian eyelashes worked better in preventing evaporation or debris landing in the eye than either shorter or longer eyelashes.
Lead author of the study, Guillermo Amador, explained, “As [the eyelashes] get longer you get less evaporation and less deposition. But, if they get too long they start to channel more airflow towards the eye and that increases the evaporation and increases the deposition of the particles.”
So, although those fake eyelashes may be fun for a costume party or a special night, wearing them all the time may increase your chances of infection and irritation due to dust and dryness.