Imagination doesn't contribute to human survival. So, why do we do it?

So, you come home from work and, when you ask your preschooler if she wants a glass of milk, she replies no, but her friend Cuckoo does. Then she looks pointedly at the empty seat next to her. Do you 

“Pay attention!” It’s every parent, teacher (or boss’s?) reaction to the person sketching stick figures in the margins of a report, or doodling in class. But research shows that the doodler already is paying attention – maybe even more than