I used to think babies just cried all the time for no reason.  But in my very limited experience, crying seems to be their only way of communicating.  It's sort of like the beginning part of a video game where you only have one skill or one emote unlocked.  Since it's all you have, you use it for everything, even when it's not particularly appropriate or effective.  You melee an enemy, then try to melee a door because you haven't figured out the "open door" command.  Or you dance to say hi to a fellow gamer, then dance to warn them about the enemy behind them.  It's actually kind of amazing how a single action can communicate hunger, discomfort, gas, dirty diaper, etc. #lifestyle