Genuine Puzzles In Biology?

Actually, it's just not the fear of snakes that's deeply ingrained in us. It's pretty much fear of anything that doesn't look like us. The farther away in appearance the thing is to us, the more "scary" it looks to us.This is why people instinctively fear harmless things like certain kinds of arthropods. Take the spider for example. It looks totally alien compared to us, and there are more arachnophobes out there than we can count. Would you want to hold something like this in your hand? Snakes look alien to us because there's no limbs. And before nitpickers come snooping around, yes I am aware of the vestigial limbs. But generally speaking, the snake is a total alien to us, which is probably why we instinctively fear it.