Knowing how that process has changed over time may shed light on the evolution of humans' superior intelligence, which relies on a long childhood.

ECONOMIST: An ancient child has been discovered

And I decided that it seemed to be possibly connected with some other research I had heard about in cancer more recently in Philadelphia, done by a fellow, Carlo Maley, on the evolution of cancer in humans.

NPR: Startling New Evidence Cancer Is Contagious

The authors conclude that their findings support a theory that females may have played a similarly important role in the evolution of tool technology among early humans.

BBC: Chimps sharpened the spears with their teeth

Two traits were needed, says Mr Seabright, to bring the fruits of co-operation within reach, and evolution had equipped humans with both accidentally, as it were.

ECONOMIST: Economics focus

In terms of what makes us human, the most promising areas for exploration are six regions that show very little variation among humans but more variation in chimps suggesting they were important in the human line of evolution.

BBC: NEWS | Science/Nature | Reading the chimp book of life

Language and music are results of cultural evolution harnessing auditory inputs from our natural environments environments that included the sounds other early humans made.

FORBES: How Language and Music Made Us Human