Our lineages have been eating grass seeds for much longer than 10,000 years. Possibly for as long as we've been effective big-game cooperative hunters as demonstrated by the megafauna extinction record, so perhaps back to the middle Paleolithic. While wheat consumption may only date back to the late Paleolithic, millet consumption goes further back. Cattail underground storage organs have been of considerable interest as their distinctive isotopic signature matches that of early H erectus, while their seed starch is present on 30,000 year old tools.
Mercader, J., Bennett, T., & Raja, M. (2008). Middle stone age starch acquisition in the Niassa Rift, Mozambique. Quaternary Research, 70(2), 283-300.
Revedin, A., Aranguren, B., Becattini, R., Longo, L., Marconi, E., Lippi, M. M., ... & Svoboda, J. (2010). Thirty thousand-year-old evidence of plant food processing. Proceedings of the National Academy of Sciences, 107(44), 18815-18819.
Henry, A. G., Brooks, A. S., & Piperno, D. R. (2011). Microfossils in calculus demonstrate consumption of plants and cooked foods in Neanderthal diets (Shanidar III, Iraq; Spy I and II, Belgium). Proceedings of the National Academy of Sciences, 108(2), 486-491.
Hardy, K., Buckley, S., Collins, M. J., Estalrrich, A., Brothwell, D., Copeland, L., ... & Rosas, A. (2012). Neanderthal medics? Evidence for food, cooking, and medicinal plants entrapped in dental calculus. Naturwissenschaften, 99(8), 617-626
Henry, A. G., Brooks, A. S., & Piperno, D. R. (2014). Plant foods and the dietary ecology of Neanderthals and early modern humans. Journal of human evolution, 69, 44-54.
I suspect there are things other than congenital inability to cope with glutens going on with modern gluten intolerance and even Crohn's disease, and they may have similar etiologies of other modern inflammatory epidemics like asthma.
That said, modern gluten intolerance is real - I've made and eaten 80% wheat gluten "sausages", and roughly 8-16 hours after two bratwurst sized servings, the whites of my eyes would become bloodshot with dilated blood vessels, which was confirmed months later with the same results. I experience no adverse effects from normal doses of glutens in whole wheat pasta or bread.
Edited by Darryl, 24 June 2014 - 05:01 PM.