With a child of my own interested in running a marathon, I researched marathon training programs for youth in the US (there are some!), injury rates and how these compare to high school running programs.
There's also the Tarahumara of Mexico, another culture where running is a normal mode of transportation. Folks may remember the iconic story of some of the Tarahumara running in the Leadville 100-mile mountain race and winning one year... while racing in traditional sandals!