Is there any credence to the notion that the modern Western diet is largely responsible for the high rate of tooth problems in modern humans?
Yes. Specifically the introduction of sugar to the western diet in the 16th Century. Before then, the only sweetener in common use was honey, and there wasn’t very much honey in the average diet. Medieval man had pretty good teeth, decay-wise - although the diet was more gritty and that tended to wear teeth down.
You misunderstood the point of evolution. Evolution doesn’t do what’s best, it does what works. Something can be faulty and as long as it doesn’t interfer with reproduction, evolution doesn’t back up and start over.
This is best seen in the ability to eat food. Our food pipe and wind pipe cross. From a design standpoint this is a STUPID thing. But evolution gave us a cough reflex. Those with the mutation to cough lived to reproduce. Those without it, choked to death.
As other posters have noted, humans start reproducing around 13 years old. (Rather they CAN start). Most people start having teeth troubles around 30. That leaves them 15+ years to reproduce. That’s a lot of reproduction.
Elephants are a good example. They’re huge, virtually nothing can kill an adult elephant. Yet it only has so many sets of teeth. In the wild when the last ones fall out, the elephants starve to death. Indeed in zoos old elephants can be kept alive much longer by giving them mushy food after their last teeth fall out. They live much longer in zoos, 'cause in the wild they’d starve. Bad for elephants but good for things that eat elephants and can’t kill one, but can eat one if it’s already dead.
This is an ancestral mammalian trait. Mammals grow a set of baby teeth, then the adult teeth come in, and then they’re done. Mammals differ from their reptile ancestors in that our teeth are specialized for different roles–incisors, canines, premolars, and molars. Most other species have only one sort of tooth.
Note that some animals like the elephants mentioned earlier delay the growth of adult molars so they only use one set at a time, then the next one set grows, then the next set, and when the last set grows that’s it.
Other species have continuously growing teeth, such as rodent incisors. But other species don’t. Never look a gift horse in the mouth, because a horse’s teeth wear down throughout it’s life eating tough grass, and an old horse will have it’s teeth worn down to nubbins. And when those nubbins wear away, the horse will starve to death unless you give it mash that it can eat without chewing.
I’d have to hunt for a legitimate cite but my History of Native Americans instructor mentioned in passing that anthropologists can get a good idea on when corn was domesticated in N. America by the increased amount of rot in the teeth of skeletons.
It might not have been rot, but rather wear caused by eating lots of stone-ground grain. If a very large proportion of your diet is stone-ground grain you can wear your teeth to nubs over decades.
I should know better. Forget it.