Thinking About Anything

There was this show, I cant remember the name of the show, but it told how things came to be. It was interesting because it told how language came to be and many more. But I had never thought about how things came to be the way there are now. In this show, I guess, it was an overall history lesson. How language was created, why people have flat/sharp teeth and many more. But what I want to  know from you is, what are the reasons that you do the things you do and why is that we have not noticed this before?