The way we narrow our eyes in disgust or open them wide in fear originated as responses to danger, finds a new study from Cornell University.

When eyes open wide, we take in more light and the field of vision expands to help identify a threat. When we squint in displeasure, the eyes are more able to focus on the source of the problem — your partner, for example, who left dishes in the sink.

PHOTOS:  Animal Superpower — The Eyes Have It 

“These opposing functions of eye widening and narrowing, which mirror that of pupil dilation and constriction, might be the primitive origins for the expressive capacity of the face,” said Cornell University neuroscientist Adam Anderson. “And these actions are not likely restricted to disgust and fear, as we know that these movements play a large part in how perhaps all expressions differ, including surprise, anger and even happiness.”

Evolution Is Happening Right Before Your Eyes

Anderson says we tend to think of our reactions being driven by what we’re seeing. But, in fact, emotions can change the way we see things.

“Emotions influence vision at the very earliest moments of visual encoding,” he said. “We know that the eyes can be a powerful basis for reading what people are thinking and feeling, and we might have a partial answer to why that is.”

Photo: iStock