>> Optimal foraging theory pretty much rules out the use of things like grains
>> in all but the leanest of times.

I believe that there's a big difference between flax seed and grains.
Grains are inedible raw, and when dried are hard. They have a lot of
starch and are low in oil.

Flax seed is excellent uncooked, easily gathered, and is rich with a
good oil. It gives a good return in calories compared to unimproved
grains. Ever seen teff? Almost as fine as dust. Yet in Ethiopia it's
considered a food crop.

When unimproved grains fall to the ground it's a drawback, especially
since they're so small. Flax stays in the seed casing, where it can be
found easily. Also, flax provides a good fiber for cordage.

Most of these questions can never be answered, but it's easy to imagine
our distant hunter-gatherer forbears liking flax. It also grows in
northern climates, and tolerates heavy wet ground, which is why it used
to be a major crop in Oregon, before the synthetics replaced linen.

Susan Kline