If you think about it, doors play a very important part in our lives. Not only do they keep out the coyotes and foxes and the spiders and the ants and the flies and the wasps and the flying ants and the weird crawly bugs that look so ugly that you wonder if maybe they’re the outcasts of the bug world…wait where was I going with this?
Oh yeah, doors also play a big part in how we express and feel emotion.
THINK ABOUT IT:
We slam doors when we’re angry.
We lock (or barricade) doors when we’re trying to say “GO AWAY I NEED SOME SPACE, DAMMIT!”
We close the door gently while smiling after we’ve just tucked in a child (or done some such sentimental thing).
We leave a door wide open when we want to welcome people in.
We nail shut the mail slot when we are trying to say “No more Hogwarts letters allowed in this house!!”
We loudly double lock the door to say “Yeah, and STAY OUT, YOU STUPID KIDS WHO ARE CHASING POKEMON IN MY BUILDING!!”
We get really scared that there is a ghost/spirit/terrifying demon when the door opens on its own.
From this strong evidence, I think we can conclude that the evolution of doors was driven by our need to express complex emotions. I bet some dude was like “Ugh, I hate having to stomp around the house whenever my roommate is home. It’s like, if I just walk normally, he’ll think I’ve forgiven him. Ooh, I know! I’ll just put this board up in between us so that I can slam it and don’t have to maintain the angry charade all the time!” Tada, the door was born, simultaneously expressing emotion and saving generations from the dangers of overexertion (stomping takes a lot of muscle).