We lived upon glaciers last ice age (except for tropical people and probably those in the southern hemisphere) if we weren't hyper carnivores then we couldn't have lived in Europe, we couldn't have crossed to the Americas. We ate animals that could eat the plants that could grow on the ice and the mountain tops poking through the glaciers, there was no fruit, no grain, no root vegetables, no beans, no cruciforms. There hasn't been enough time since then for us to become herbivores, though we inherited much ability to eat many plants from the herbivorous apes we evolved from