The language of art is powerful to those who understand it, and puzzling to those who do not. What we do know is that here was the modern human mind at work, spinning symbolism and abstraction in a way that only Homo sapiens is capable of doing.

Ritual disposal of the dead speaks clearly of an awareness of death, and thus an awareness of self.

Humans become human through intense learning not just of survival skills but of customs and social mores, kinship and social laws-that is, culture.

Natural selection operates according to immediate cirumstances and not toward a long-term goal. Homo sapiens did eventually evolve as a descendant of the first humans, but there was nothing inevitable about it.

As every parent knows, children go through an adolescent growth spurt, during which they put on inches at an alarming rate. Humans are unique in this respect: most mammalian species, including apes, progress almost directly from infancy to adulthood.

It seems inconceivable that a species of human could possess fully modern language and not be fully modern in all other ways, too. For this reason, the evolution of language is widely judged to be the culminating event in the emergence of humanity as we know it today.

Spoken language clearly differentiates Homo sapiens from all other creatures. None but humankind produces a complex spoken language, a medium for communication and a medium for introspective reflection.

The world's five thousand extant languages are products of our shared ability, but the five thousand cultures they create are separate from each other.

We are bipedal apes, and it should not be surprising to see that fact reflected in the way our ancestors lived.

Culture represents a novelty in the world of nature, and it could have added an effective, unifying edge to the forces of natural selection.