I'm not an evolutionary biologist, but it seems to me we've been running around hunting for a lot longer than we've been sitting around writing (/ doing math / other mainly intellectual activity), and thus one is significantly more natural than the other given our history. The human body seems designed to throw spears / rocks / balls. The necessary mental faculties for writing a poem seem more complicated than those needed for doing sports. The proportion of good athletes to good writers.

I'd love to be corrected on this if the opposite is true, that becoming a good athlete is just as difficult as or more difficult than becoming a good writer. I'm just not seeing it.