ancient birth control
Placing oneself on a vegan/ fruitarian diet will cause brain damage. Period. Ask a paleontologist or archaelogist what ancient birth control Man consumed.
There is a reason "experts" recommend these diets: to keep the plantation's property docile and limited in thinking potential. It makes good order takers.
Now the plantation needs to keep its property at an adequate number (see Georgia guidestones) and the herd needs culling and involuntary birth control. Let's turn the men into its.....