As in a Russian doll, however, the outer layers always contain an inner core. Instead of evolution having replaced simpler forms of empathy with more advanced ones, the latter are merely elaborations on the former and remain dependent on them. This also means that empathy comes naturally to us. It is not something we only learn later in life, or that is culturally constructed.

Sometimes I read about someone saying with great authority that animals have no intentions and no feelings, and I wonder, 'Doesn't this guy have a dog?'

Experiments with animals have long been handicapped by our anthropocentric attitude: We often test them in ways that work fine with humans but not so well with other species.

Being both more systematically brutal than chimps and more empathetic than _x000D_ bonobos, we are by far the most bipolar ape. Our societies are never completely peaceful, never completely competitive, never ruled by sheer selfishness, and never perfectly moral.

If you look at human society, it is very easy, of course, to compare our warfare and territoriality with the chimpanzee. But that's only one side of what we do. We also trade, we intermarry, we allow each other to travel through our territory. There's an enormous amount of cooperation.

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.