Where Did Giving People "The Finger" Actually Come From? Well Here Is The Answer

I started a new social series today. I am calling it "Barstool WTF".  It's time that I fully embrace the fact that I am a nerd. I love knowing where shit comes from and why we do and say the things we do. There's a never ending list of saying and symbols that we do without even thinking about why. I always think about the why and I love re-telling it in bars or on podcasts and maybe people don't like shit like that, but I do. I figured something called "WTF" should start off with a video explaining why the finger means "fuck you". Open to suggestions. You guys hit me up.