A long long time ago I studied Archaeology in University college Cork. One of the things which has for some reason lodged in my brain was that the advent of Plantago Landceolata (Plantain), or as we call them in Cork “Soldiers”, was the indication that man started to farm as well as hunt (they being weeds of cultivation and needing ground cleared for cultivation to flourish).
This happened roughly the late Mesolithic, the end of the Paleolithic, but before the Neolithic sometime between 10,00 and 8,000 BC (as we used to say then)
Anyway as wheat is reckoned to have been the first crop farmed we, that is man, have been eating wheat, bread and its derivitates for certainly the last 10,000 years, and it appears thriving on it.