The primate laugh is given in playful contexts, and as such has a strong similarity to the human laugh.

Humans have a lot of pro-social tendencies.

Wild groups of chimpanzees attack their enemies like gangs. What they completely lack, precisely because of their strong territorial behavior, is a friendly relationship with their neighbors.

I am personally not against keeping animals at zoos, as they serve a huge educational purpose, but treating them well and with respect seems the least we could do, and with 'we' I mean not just zoo staff, but most certainly also the public.

Future benefits rarely figure in the minds of animals.

A chimpanzee who is really gearing up for a fight doesn't waste time with gestures but just goes ahead and attacks.

The intuitive connection children feel with animals can be a tremendous source of joy. The unconditional love received from pets, and the lack of artifice in the relationship, contrast sharply with the much trickier dealings with members of their own species.