How can someone play with kids for self interest? It just happens to be natural thing to any organism?
On surface, it may not look like a selfish act but when you see deeper, this is how it is supported:
Most of us play with kids for own self-interest. Short term self interest is to get relief from career stress. Long term self-interest is the expectation of kid taking care of you in old age.
Selfish acts does not serve the benefits well.
Try selfless play. Play is very critical for child growth.
Societies and tribes whom you consider barbaric, know the child development much better than us! Learn from them! I loved this pic very much! Showing the selfless play!