>> why do we assume that humans domesticated grains first ?
>
>Actually, we don't have to assume that at all.  Whether they
>cultivated them first or not, the question remains: Why did they
>cultivate them at all, if they did not previously eat them?

it is more important that you think because grains are not very appealing ,
taste wise to somebody who based his diet on meats but to somebody already
fruit sugar addicted grain have value and become more so in comparaison of
fruits because of its opioid slowly replacing them ( the same phenomenon
could have happen in other part of the world from tuber cultivation also)

you didn't read the adress i gave . You got there a convincing ( to me )
theory.
.http://www.multimania.com/xbeluga/originsofagriculture.html

give me my daily bread ... or tortilla ( i was talking yesterday with a
mexican friend)
peoples are ready for incredible effort to get their drug. even tilling the
land and sowing , even building fortified village to protect their harvest.
Now with the wheat lobby just few dollars are needed to get the fix.
I have seen that drug effect of grains  in me and horses( they go crazy when
you come with a pail)

jean-claude