Why aren't babies afraid of snakes?

Presenter: The emotion of fear is a vital survival mechanism, designed to protect our body's inner balance, a first line of defence against potential threats, even before they’ve struck. The strange thing is, we aren't born with it. For the first few months of our lives, we're quite literally fearless. Our ability to identify things that can threaten our survival is something we learn from those around us. That's why some of our fears are rational ...:

Woman 1: I'm terrified of sharks.

Woman 2: Very quick-moving rodents.

Teenage girl: I'm really, really scared of spiders.

Presenter: ... but others are not:

Girl: Monsters.

Boy 1: Vampires.

Teenage boy: Giant squids.

Boy 2: /dɔk/. Very, very big /dɔk/. (It is not clear whether he is saying 'dark', 'duck' or 'dog'.)

Presenter: You're scared of the dark or a duck?

Boy 2: A duck.

Presenter: A duck?!

Boy 2: (laughs)

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