[quote]I'm talking about change in bone structure.[/quote] Human jaw size has become progressively smaller over the years, especially in western countries (this is why wisdom teeth are often removed; there's not enough room). Some people are even born that don't produce wisdom teeth. This is due to changes in diet/ improved food processing. We eat less raw and/or tough foods, and therefore require less teeth. Therefore, our bone structures can change without intervention by man. [spoiler]Unless you think the government shortens the jaws of newborns for the fun of it. In which case, I would call you crazy.[/spoiler] EDIT: I'd also like to add that humans have become taller overall as well. Just to throw that out there.