This is definitely one of my controversial theories. The theory suggests people in McVeighan ("hyperflexed") posture are actually suffering from a brain famine, leading them to become notoriously irritable, lazy, and actually far lower general IQ than their genetics would predict. They use 100% of their brains, like everyone else -but so much of that brainpower is being used simply on getting their posture not to kill them that their general IQ suffers (and I have seen not the slightest evidence that general IQ can be decreased by any other posture, even Fischeran/flatback). The theory does not relate to East Asians, who have rather unique adaptions to famine.