Babies love to imitate. I remember I was reading once about this experiment where a couple decided to raise their child alongside a chimpanzee
so they could figure out which of the human/ape differences were innate (it was the 1930s, all right, parents were weird back then) and they eventually shut down the experiment because they found that rather than the ape picking up human behavior, the son was imitating the ape. Human babies are just really great at imitating even though they mostly just look like drooling potatoes.
What's really great is when it comes to speech. I knew about babies babbling and all that, but until I had these particular babies I never realized that they'll have entire conversations with you in potato-speech (or at least mine do. I have no idea if I have freak babies). It'll be like this:
YOU: Hello, baby! How are you!
BABY: Ua ua ua ua ua ua.
YOU: That's interesting!
BABY: Ggggggg ua ua ua.
YOU: Is that so?
BABY: *nods thoughtfully*
After a while I realized that the baby isn't just practicing speech, it thinks it's participating in a real, equal conversation
. It hears all these adults around it talking, and of course it can't understand because it's a baby, so it just hears a bunch of meaningless syllables. So even though it can't physically produce anything more than meaningless syllables, it totally thinks it's joining in and beating the adults at their own game.
What's REALLY great is when you have twins, occasionally they'll get caught in this meaningless-syllable feedback loop and start having a conversation with each other:
BABY 1: Ua ua ua ua ua ua.
BABY 2: Gggggggggg UA UA
BABY 1: Guh Guh uauauaua?
BABY 2: *nods thoughtfully*
It's like seeing two spambots on Twitter getting into a conversation with one another.