Humans are the only species to cry with tears, and a new Spanish study focused on their function. Researchers asked 30 women to look at photos of crying people, then at the same faces with the tears digitally removed. The participants’ gaze was tracked using eye-tracking technology.
The result: Women appeared to look more often and longer at tearful faces, especially at the tears themselves. They also judged tearful faces to be more emotionally intense and sincere than the others.
Research has already shown that emotional tears have an important social function, acting as a “cry for help.” In addition, they stimulate solidarity and mutual aid. According to the Spanish researchers, tears facilitate the reading of emotions, which makes them evolutionarily useful for a hypersocial animal like humans.