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?

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.

I've argued that many of what philosophers call moral sentiments can be seen in other species. In chimpanzees and other animals, you see examples of sympathy, empathy, reciprocity, a willingness to follow social rules. Dogs are a good example of a species that have and obey social rules; that's why we like them so much, even though they're large carnivores.

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.

We justify the inequalities by saying some people are just better and smarter than others and the strong should survive and the poor can die off.

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

In humans, the family prevents infanticide. Next to language, the core family, consisting of a mother, a father and children, is the greatest difference between us and other primates.