Cats are, of course, adorable: We love them, we snuggle them, we wear sweaters emblazoned with them. And that includes their adorable little eyes. Which science just proved evolved to make them more efficient killing machines!
The efficiency of domesticated cats as environment-wrecking predators is nothing new, but it did lead scientists to wonder why cats, alligators, and other ambush predators had vertical slits for pupils, while herbivores like sheep have horizontal slits for pupils. It turns out that the angle of the slit affects vision; for example, with a horizontal slit, a sheep’s eye lets in more light from the sides, improving its peripheral vision.
Cats and other ambush predators, on the other hand, have vertical slits because it helps them spot the distance to prey and keep prey focused. Interestingly, predators and other animals that are higher off the ground, like your dog, don’t need this advantage, which is why they have round pupils and eyes just like us.
In other words, when you look into your cat’s eyes, you’re looking right into the eyes of a scientifically certified killing machine. Better give them a scratch, just in case.