..drive natural selection within our race?
Play became real training for the day boys joined the adult hunters. Trained hunters brought more food to the troops, with fewer injuries.
Our ancestors learned new skills from every story.
Gatherers need to learn and remember which herbs had natural medicinal properties and which make you sick.
Important is the ability to acquire the experience of others through stories.
Advantage lies in the ability to transmit learned information about how best to farm. Often the teacher demonstrates then follows each attempt of the pupil.
This can sometimes be miming, which we now call apprenticeship.