You know that nod of acknowledgement that you give people when you’re walking around? Nod upwards.

A cool little body language tidbit that I’ve picked up is that nodding up denotes self-esteem. It shows that you are at the subconscious level, comfortable in your own skin. In the wild, animalistic world of our pasts, the neck is the most precious and vulnerable part of an animal’s body. An animal’s neck host all sorts of vital pieces required in order to live. The Carotid artery, one of your body's largest arteries; runs right along your wind pipe, the life of your blood. I’m sure you’ve seen documentary videos before of a lion going for a zebra’s throat. The throat is the most important target in the animal world. Animal behaviors have extended into human body language. A person that is confident enough to expose the most vulnerable part of their body to another person’s teeth knows that he is in no danger. And so when you next give that nod of acknowledgement, be like the lion, and nod up.

Edit: incorrect fact