We're all too familiar with tears welling up in our eyes--brought on by stress, sadness, or even laughter. But why exactly does feeling things make liquid come out of our eyes? And why is that uniquely human? After all, we're the only species that sheds emotional tears.
To unravel the science behind sobbing, I spoke with expert Dr. William H. Frey, who also serves as director of the Alzheimer's Research Center at the HealthPartners Institute for Education and Research in St. Paul, Minn. He explained that not all tears are the same.
Check out the video above and/or click on the link below to learn more. And don't forget to leave your thoughts in the comments section at the bottom of the page. Come on, talk nerdy to me!