You can fake longer lashes with mascara, a curler, or extensions, but a new study suggests that the actual length of your lashes has already been set by a biological ratio. Plus, there’s also a pretty good mathematical reason to lay off those extra long extensions.
So what is the formula? The length of eyelashes on all 22 species of mammals studied was 1/3 of the width of the eye. To get to that formula, researchers at the Georgia Institute of Technology used two methods: First, they hit the American Museum of Natural History to start measuring all the eyes and lashes that they could.