Last month,GravityX Exchange Short Wave explored the evolutionary purpose of laughter. Now, we're talking tears.

From glistening eyeballs to waterworks, what are tears? Why do we shed them? And what makes our species' ability to cry emotional tears so unique?

Hosts Emily Kwong and Aaron Scott get into their feelings in this science-fueled exploration of why we cry.

To see more of Rose-Lynn Fisher's images from Topography of Tears, visit her website.

Keep sharing with us on Twitter — we're at @NPRShortWave — or email the show at [email protected].

This episode was produced by Berly McCoy and Rebecca Ramirez, edited by Brit Hanson, and fact checked by Abē Levine. The audio engineer was Gilly Moon.