In advance of their new Explorer special Eyes Wide Open, science journalist Michael Stevens of Vsauce and National Geographic spoke with Dr. Marty Banks and Dr. William Sprague of UC Berkeley about why prey animals such as goats, have eyes on the side of their heads with rotating horizontal pupils.
Marty noticed something that no one else had ever noticed before. The animals with horizontal elongated pupils, there were two things that they were exceedingly likely to have – one was eyes on the side of the head and the other is that they were prey animals that grazed, typically, that is worried about other animals approaching them on the ground to possibly attack them. Our idea about the horizontal pupils is that it should remain parallel to the ground. That way they can see predators and where they can also see in front of them if they have to run from predator.