The Philosophical Baby: What Children's Minds Tell Us About Truth,… (2009)

This protracted period of immaturity is intimately tied up with the human capacity for change. Our human capacities for imagination and learning have great advantages; they allow us to adapt to more different environments than any other species and to change our own environments in a way that no other animal can. But they also have one great disadvantage - learning takes time. You don't want to be stuck exploring all the new possible ways to hunt deer when you haven't eaten for two days, or learning all the accumulated cultural wisdom about saber-toothed tigers when one is chasing you. It would be a good idea for me to spend a week exploring all the capabilities of my new computer, as my teenage son would, but with the saver-toothed tigers of grant deadlines and classes breathing down my neck, I'll just go on relying on old routines.
      An animal that depends on the accumulated knowledge of past generations has to have some time to acquire that knowledge. An animal that depends on imagination has to have some time to exercise it. Childhood is that time. Children are protected from the usual exigencies of adult life; they don't need to hunt deer or ward off saber-toothed tigers, let alone write grant proposals or teach classes - all of that is done for them. All they need to do is learn. When we're children we're devoted to learning about our world and imagining all the other ways the world could be. When we become adults we put all that we've learned and imagined to use.
     There's a kind of evolutionary division of labor between children and adults. Children are the R&D department of the human species - the blue-sky guys, the brainstormers. Adults are production and marketing. pp 10-11

In Germany there are more avoidant babies than in America, and in Japan there are more anxious babies. (p. 182)