Human teeth development changed sometime during the industrial revolution when women were expected to work outside the home and breastfeeding norms were shortened from 3-4 years to more like 1 year. Or that's at least one interesting hypothesis from someone looking at old skulls.
Do you have anything supporting that? My observation has been the kid loses interest somewhere between 1-2 years- the moms aren't cutting them off. Solid food is generally much more interesting.