What does the way you greet someone ('Sup?) say about you?

How did 'Hello?' become the word you say when you answer the phone? Why was the handshake invented? How do animals greet each other? For free home activities sign-up at www.WhoSmarted.com See Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.