PSYCHOLOGY - Determination might be a very human expression

Humans might be using facial expressions of determination as a call for help from others, according to new research. When children and chimpanzees were both given a task that was impossible to solve, children's faces expressed determination or frustration the more they tried to solve the task, but chimpanzees did not. The facial expressions shown by the children -- chin raised and lips pressed together -- could signal effort or frustration, accor ...

http://www.sciencedaily.com/releases/2014/03/140305084614.ht