As the forehead grew forward, the jaws grew smaller, but that may have been partially because of attraction based selection and because processed/cooked food is easier to chew so less need for strong chompers.
Africans have slightly bigger jaws and teeth because they have more fibrous roots and whatnot in their diet. Japanese lower jaws have been getting a tad narrower because they eat less tough foods than they had traditionally. In that case, what they chew growing up affects size. Australian Aboriginals may have retained more archaic features (incl larger jaws) or reaquired them out of necessity, tho the former seems more likely.
Or do you mean because of where the muscle attachments are on the skull? That's interesting.
Yeah, cooked meat rather than raw, easier to digest. Using tools enabled more access to rich bone marrow also. One day someone will propose seafood fits this notion even more, as that's what the swimming ape ate.
Snag on the vegheads, they have shorter gut tracks for a reason,,,
