NPR science correspondent Dan Charles explains why most of the dairy cows in America are descended from just two bulls, creating a lack of genetic diversity that can lead to health problems.

He also visits a lab at Penn State University where scientists are trying to change that.

This episode was produced by Brent Baughman and edited by Viet Le.

Short Wave Podcast

It’s science for everyone, using a lot of creativity and a little humor. Join host Maddie Sofia for science on a different wavelength.