Snakes on the brain

This one is harmless, but your brain may be freaking out anyway.

Nebraska.gov

Primates have incredibly complex and accurate visual systems. There’s no shortage of evolutionary reasons why good vision might have evolved among primates; it may have helped our ancestors locate colorful fruits in trees, catch insects, or identify other group members. But one idea in particular taps into what is still a major fear for humans: snakes.

According to “Snake Detection Theory,” these slithering creatures have played a major role in the evolution of our brains, and, more specifically, our visual systems. Over more than 50 million years, primates have had a complicated relationship with snakes as predators, competitors, and prey. Since both snakes and primates flourish in tropical regions, there have been plenty of opportunities for primates and snakes to interact—and adapt to each other's presence—on an evolutionary time scale. Snakes are hard to spot, so if their threat was strong enough, natural selection might have favored primates with keen eyesight and quick reaction times.

Of course, until there’s solid evidence that we have snakes to thank for our keen vision, it’s just a lot of evolutionary hand waving. But in this week’s issue of PNAS, an international group of researchers lend some solid support to the Snake Detection Theory.