In his TED talk, The Hidden Power of Smiling, Ron Gutman provides some insights into the proven value of smiling.
We are born smiling. Using 3D ultrasound, we can see developing babies smile in the womb. When born, they continue to smile. A smile is one of the most basic expressions of all humans and it is the fastest way to build trust and rapport during face-to-face interactions.
OK, so why doesn’t Bill Belichick smile? What would he be revealing? Especially with the Media, he knows how to be brief, be good, be gone. Yet he almost never seems happy. I believe this is his strategy. In fact, one study tracked him smiling only 7 times in 114 minutes of media footage!