1. You Are a Contact Sport
Biology in Motion
"No man is an island." We are naturally social creatures but must develop enough experience and understanding of the World to interact effectively. The symbiosis of dependence and altruism provides a cycle of nurturing and learning for all involved.
The developmental pathways are based on the capabilities of our physical nature,  flesh, bones & brain and our bio-psycho-social environment. Each cell must interact with the World and control its metabolism but the nervous system (brains) takes in a World of stimuli and create reflective/modeled images of how "things work."
The development of language allow abstract concepts which afford a more complex model and longer view.