Human beings, it turns out, are ultrasocial learning machines. We’re born to learn, to bond and to play. Maybe it’s not so strange, then, that blushing is the only human expression that’s uniquely human. Blushing, after all, is quintessentially social – it’s people showing they care what others think, which fosters trust and enables cooperation.

— Humankind by Rutger Bregman (Page 69)