Staring is a precursor to attacks; animals which responded to other animals getting ready to attack them by posturing as if they were ready to counterattack avo

Staring is a precursor to attacks; animals which responded to other animals getting ready to attack them by posturing as if they were ready to counterattack avoided many fights. Over time, this interaction was offloaded into specialized hardware analyzing gaze -- the one more interested in fighting was the one who stared longer, and that interaction became associated with dominance in social groups. This was accelerated as the system became more advanced, and more gestures could be recognized as implicit confrontations (and their resolutions).