Fish holds insight into the evolution of blinking

Scientists have studied the mudskipper fish for insight into the evolution of blinking in humans.

The study, which was published in Proceedings of the National Academy of Sciences, highlighted the importance of blinking for eye health.

“In humans, for example, the inability to blink regularly can lead to vision loss. However, how and why did blinking first evolve? It has been difficult to tackle this question from the fossil record alone,” the authors shared.

The researchers observed the blinking behaviours of mudskippers – which regularly leave the water to spend time on land and display similar blinking patterns to those observed in tetrapods.

Mudskippers blink more often under high evaporation conditions and when there is a threat of physical injury to the eye. A single blink can clean the mudskipper’s cornea of particulates.

Study author, Brett Aiello, of Seton Hill University, shared that mudskippers blink to protect and clean their eyes as well as maintaining moisture.

“What’s incredible is that they can use their blinks to wet the eyes, even though these fish haven’t evolved any tear glands or ducts. Whereas our tears are made by glands around our eyes and on our eyelids, mudskippers seem to be mixing mucus from the skin with water from their environment to produce a tear film,” he said.

Fellow study author, Thomas Stewart, of Pennsylvania State University, highlighted that mudskippers blink for similar reasons to human ancestors.

“We think that it was likely part of the suite of traits that evolved when tetrapods were adapting to live on land,” he said.