Some snakes sure seems friendly enough. But we’re hard-wired to be alarmed when we see them. (Astrid Riecken/For The Washington Post)

Scared of snakes? Blame your ancestors.

Scientists may be closer to explaining why ophidiophobia (fear of snakes) ranks among humans’ top fears and seems to be shared with other primates.

Researchers looked into the brains of Japanese macaques — they’re a kind of monkey — and found that the part of their brain that controls visual attention responded more strongly and quickly to images of snakes than to images of other objects.

The results, published in the journal Proceedings of the National Academy of Sciences, appear to support a theory that early primates developed advanced perception as an evolutionary response to being prey.

“The characteristics we have help us to see them better than other mammals can see them,” said Lynne Isbell, an evolutionary biologist and an author of the paper. “Mammals in general are really good at picking up movement. But snakes lie in wait. . . . It’s crucial to see them before they see us and to avoid them.”

— From news services