A more general pattern appears to be along the lines of Monocotelydons[1] vs other types of plants that bear edible fruits. I forget where I read this but it appears that monocots are going to be the dominant class of plants across the globe, hand-in-hand with climate change.

Another interesting parallel in eating seeds is between seeds from angiosperms like pine seeds and those from grasses like wheat. Two very different types of plants, but primates ate the same part of each.

Also, did humans evolve to carry gluten digesting genes over time, hence a subpopulation that cannot handle gluten?

[1]http://en.m.wikipedia.org/wiki/Monocotyledon