Automatic digest processor wrote:
>
> 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?

I don't know of any research on the subject but would like to offer some
speculations and consideration.

Grains are little self-contained units that require no special storage
conditions beyond a reasonable dryness.  They remove themselves from
their husks with the most minimal of processing once dehydrated.  They
are tidily portable and virtually any mobile person, children included,
can easily carry enough for several days eating.  Dehydrated, they
provide a rather dense source of nutrients with merely the addition of
water to make them edible.  Or, they can be ground and used for other
kinds of foods.  You can see the crop you will get and can plan
accordingly.  Grains can be harvested several times during a temperate
climate growing season and the straw has other uses as well including
thatching, bedding and fodder.  Grasses can grow on thin soil.

Tubers are wet and therefore heavy.  To transport them, they either need
to be carried with all their water still in them or they need to be
processed to remove the water and that adds labor and time to the
pre-preparation.  Tuber developement and therefore crop size can't be
tracked during the growing season because they're buried.  Storing
tubers can be a tricky process in a very low technology society.
Currently, I'm of the impression that tubers produce less available
tonnage per unit of ground than grains; it may be that in the
technological past that could have been different.  Tubers require
plowing, burial of cuttings and weeding.  Plowing is mandatory in most
soils to get maximum yields.  Tubers can be harvested only once in a
single growing season.  Tops of tuberous plants don't offer many other
uses and are, in some cases, toxic.  Tubers require friable soils for
good growth and yields.

Bob Pastorio