Scientists have a scary theory about why human vision evolved to be so good

Most humans have an incredible talent without even realizing it. It turns out we are really, really good at spotting snakes.

We're so good at it that scientists think snakes and their venom fangs may have actually helped make the eyesight of modern humans as sharp as it is.

That's the idea behind Snake Detection Theory, which we first read about in the book "Venomous: How Earth's Deadliest Creatures Mastered Biochemistry" by Christie Wilcox.

Lynne Isbell, an anthropologist, first came up with the theory after a close encounter with a cobra - an encounter that would have been much closer and more dangerous if her eyes hadn't quickly yelled "snake!" at her brain.

Since then, Isbell and other scientists have done a range of studies to see if Snake Detection Theory might be right.

They've shown monkeys pictures of monkey faces, monkey hands, and snakes and seen how quickly they respond. They've shown children color and greyscale pictures of snakes and flowers. They've shown adults pictures of snakes, crocodiles, spiders, and slugs to see if our visual aptitude in this area might actually involve fear or disgust more generally instead of snakes particularly.

Even with all of these tests, snakes seem to be special.

So next time you see a snake, you'll probably see it quickly. And once you're sure it isn't venomous and your heart rate sinks a bit, maybe take a moment to thank its ancestors for helping your ancestors develop the excellent (or at least serviceable) vision most humans have today.