Humans have a lot of pro-social tendencies.

It is hard to get animals which normally pay little attention to each other to do things together. One can teach dolphins to jump simultaneously out of the water precisely because they show similar behavior spontaneously, but try to make two domestic cats jump together and you will fail.

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

We are territorial, power-hungry and even more brutal than chimpanzees.

The sturdiest pillars of human morality are compassion and a sense of justice.

Although elephants are far more distantly related to us than the great apes, they seem to have evolved similar social and cognitive capacities.

If you are a cooperative animal you need to watch what you get. If you, or even a whole community, invest in something but then a few individuals receive a much larger return, it's not a good arrangement. If it happens consistently, it's time to look for an arrangement that is more beneficial. That's why we're so sensitive to how rewards are being divided.