Just think of the trust that often exists in soldiers. Within their own unit, you could say they have to trust each other. A spirit of camaraderie builds up and, in the end, they will risk their lives for each other. They may even go so far as to dehumanise the other, enemy group - a mechanism you can also observe in chimps.
Jane GoodallWe have language and they do not. Chimps communicate by embracing, patting, looking - all these things. And they have lots of sounds. But they cannot sit and discuss. They cannot teach about things that are not present, as far as we know.
Jane Goodall