>>21210450Not terribly knowledgeable, but I believe he is referring to the overbites that we all have from using cutlery to eat (rather than chomping away at everything and wearing our teeth down).
"After analysing 19,000 skulls, anthropologist Charles Loring Brace concluded that the appearance of the overbite in Britain 250 years ago coincided with the time when it first became normal to cut food into little pieces with a knife and fork. Before then, eating involved gripping one end of a chunk of food in your teeth and tearing it off with your hand. If you eat like that, your incisors will be worn down and your other teeth will grow to meet perfectly. If you use forks, though, the incisors keep growing and give you an overbite."
http://qi.com/infocloud/cutlery 
