I have read about exactly the same issues with alopecia occurring a thousand years ago in Europe. Of course, grains like wheat were staples of the diet at that time and the gluten was helping to induce the baldness. I have wondered whether there was baldness prior to agricultural cultivation of grain crops. They were eating nightshade vegetables and fruits but I'm unsure whether they have the same virulence against hair growth which gluten does. There were also likely to have been many more cases of malnutrition induced hair loss back then so it's likely that there may have been a bit of a transitional period between hair loss induced by malnutrition and allergy as the dominant cause of the condition.