Gathering Wild Grains

From the book Lost Crops of Africa:  Volume 1: Grains published by the National Academies Press:

"Over large areas of Africa people once obtained their basic subsistence from wild grasses. In certain places the practice still continues—especially in drought years (see boxes, pages 258 and 264). One survey records more than 60 grass species known to be sources of food grains.²

Despite their widespread use and notable value for saving lives during times of distress, these wild cereals have been largely overlooked by both food scientists and plant scientists. They have been written off as ''obsolete"—doomed since hunting and gathering started giving way to agriculture thousands of years ago. Certainly there has been little or no thought of developing wild grains as modern foods.

This deserves reconsideration, however. Gathering grains from grasslands is among the most sustainable organized food production systems in the world. It was common in the Stone Age³ and has been important almost ever since, especially in Africa's drylands. For millennia people living in and about the Sahara, for instance, gathered grass seeds on a grand scale. And they continued to do so until quite recently. Early this century they were still harvesting not insignificant amounts of their food from native grasslands.

However, in previous centuries the grains of the deserts and savannas were harvested in enormous quantities. In the Sahel and Sahara, for example, a single household might collect a thousand kilos during the harvest season.⁴ The seeds were piled in warehouses by the ton and shipped out of the region by the caravan-load. It was a major enterprise and a substantial export from an area that now has no equivalent and is often destitute."

If possible in relatively recent centuries, why not during the stone age?

By the way, in prehistoric sites the evidence points to consumption of sorghum, a gluten-free grain, at about 100,000 years before present. 

If so, then what about leading up to that?  Evolutionary explanations generally involve gradual changes over long periods of time.  A species generally does not change its means of subsistence suddenly, or even over a few millennia.   Adaptation to a new niche (if truly new) generally takes a very long time.

The hypothesis that grains were hardly ever consumed before about ten thousand years ago suffers from lacking a plausible explanation for why and how a species never adapted or even interested in cereal grains would so suddenly (on an evolutionary time scale) adopt a totally new behavior and means of subsistence.

Supposedly gathering grains would be a poor time investment for a forager.  Put to the experimental test, this turns out to be untrue.  From Kislev et al, "Impetus for sowing and the beginning of agriculture: Ground collecting of wild cereals" [1 full text]:

"We found that hand gathering of wild barley and emmer spikelets from the ground in Korazim and Mount of Beatitudes (Israel) is simple and efficient. About 0.25–0.5 kg (0.337 kg on the average) of pure grain could be gathered per hour by a single person, which provides on the average between a half and a whole day of the nutritional requirements for an adult individual."

So, in one to two hours a forager could collect enough wild grain to feed himself for a day, just collecting it off the ground by the handful.  Eight hours of collecting could supply him with grain for a whole week.  A smart forager would quickly come up with ways to make the work easier and more efficient.  Kislev et al continue:

"Our results are in accordance with Harlan, who, after experimental hand stripping of pre-full-ripe ears of wild einkorn at Karacadag, southeast Turkey, claimed that in three weeks, a family group could gather more grain than it could possibly consume in an entire year (28)."

Three weeks investment for more food than you can eat in an entire year doesn't count as optimal foraging?  More from Kislev et al:

"The significance of recognizing the practicality of spikelet gathering from the ground is that the gathering of large-seeded cereals as a staple food is not restricted to early summer. Rather, it can continue throughout the summer into the autumn, July through October, when the first heavy rains arrive and the dispersed grains begin to sprout. In other words, the collecting of grains from the ground would supply hunter-gatherers with a ready source of vegetal food until October, when acorns, their second most important plant resource, matured (29). The availability of acorns in October enabled them to invest part of the harvested grains for sowing. Moreover, stored grains and acorns would have provided nourishment until the following summer. There would then have been no period of vegetal food shortage due to seasonality of the two major harvests that helped support human groups in Western Asia at least from the beginning of the Upper Palaeolithic."

Has the bubble burst yet?

Put this together with evidence that Paranthropus boisei, a human relative dating to 1.4 to 1.9 million years ago,  grazed on grass [2].  Paranthropus and humans both descended from Australopithecus, but the Paranthropus went extinct.  To several scientists working with this information, this new data on Paranthropus suggests a reinterpretation of previously collected data on Australopithecine diet, i.e. that Australopithecus may also have eaten grasses.

Perhaps we can start to put together a plausible path for the incorporation of cereal grains--grass seeds--into human diets.  Perhaps human ancestors used grasses as food more than 2 million years ago. Human evolution might look something like this: the grass-eaters went extinct, but the grass-seed eaters thrived.