<An interesting question was recently forwarded to me via email.
Has any source ever seriously examined the question of why humans would have gravitated toward cereal grains as a primary crop for agriculture?  Do these plants yield a superior caloric density or protein content to other vegetation, such as tubers?>

Grains have a higher protein content than many tubers, (wheat about 10g per 100g compared to 2g for potatoes) but I believe that potatoes will support the greater number of people per acre planted. (I just remember this from a lecture, I'm afraid I don't have any references).  

I would imagine that grains are easier and more compact to store and carry around as you are considering a dried product. Tubers are very bulky.

Bronwen Humphreys