I apologize if this isn't an acceptable answer because i don't necessarily see you point but I might as well swing right? That would only barely make sense if everyone was an agricultural worker of some kind, for example how would that effect an unintelligent industrial worker on an intellectual level, or anyone that isn't in the farming industry at that, I'm also confused as to how this actually backs your point, you were saying that a vegan diet would make people smarter, this seems like a bit of a stretch.

Farmer< Sustainable/efficient green farm worker.