I have often noticed how primate groups in their entirety enter a similar mood. All of a sudden, all of them are playful, hopping around. Or all of them are grumpy. Or all of them are sleepy and settle down. In such cases, the mood contagion serves the function of synchronizing activities.

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

To neglect the common ground with other primates, and to deny the evolutionary roots of human morality, would be like arriving at the top of a tower to declare that the rest of the building is irrelevant, that the precious concept of "tower" ought to be reserved for the summit.

Empathy probably started out as a mechanism to improve maternal care. Mammalian mothers who were attentive to their young's needs were more likely to rear successful offspring.

If we look straight and deep into a chimpanzee's eyes, an intelligent self-assured personality looks back at us. If they are animals, what must we be?

There's actually a lot of evidence in primates and other animals that they return favors.

Humanity is actually much more cooperative and empathic than [it's] given credit for.