im p sure it has to do with stuff being easier to eat. we dont have to work with our jaw to tear or crush difficult foods since everything is processed or we have tools to make it easy. our jaws are underused, so they develop to be smaller than theyre supposed to be, and our teeth get crowded

Something else that affects our teeth (though I'm not sure if it affects growth) is sugar consumption. Our ancestors had very little access to sugar or even spices. They ate things like meat and veggies plain. Back in prehistoric times, this meant they wouldn't have to brush their teeth, since the bacteria in their mouths wouldn't have produced plaque.

That's why a lot of human remains of 80-year-olds from 20,000 BC have perfect teeth or only a few missing after those teeth got knocked out by getting hit in the face. If you're ever stranded on a deserted island, you should avoid eating all those coconuts and bananas with every meal.