_When humans switched to processed foods after the spread of agriculture, they put less wear and tear on their teeth. _
What? When were foods processed thousands of years ago? Also Carrots and fruit are not "soft"
What? When were foods processed thousands of years ago? Also Carrots and fruit are not "soft"
"Processed" doesn't just mean Doritos.
In the Americas they ground up corn instead. In Africa, millet.
In New Guinea they still harvest sago palms. They chop up the insides, extract the starch through several washing cycles, and make a sort of pancake out of it. The palm itself is inedible. Harvesting a palm takes several people all day. In the end they have a portable, storable, easily digestible food.
Around the Pacific, taro has to be cooked and mashed before eating. It's toxic if you don't cook it and discard the water. A lot of greens need to be cooked too due to calcium oxalate.
Wheat grains (without husks) or any other cereal grains, can be eaten easily just by adding an appropriate amount of water (e.g. 4 times their weight) and boiling them, exactly like one would make cooked rice from rice grains.
Making flour and bread (initially unleavened, then leavened) has required considerably more work, not less work, but it has become the preferred way to eat wheat because it was considered much more tasty than boiled grains or porridge.
The varieties of wheat that were available before domestication had seeds from which it was difficult to remove the hulls, so milling them into coarse floor and boiling that into a porridge was actually easier than removing just the husks and boiling the whole grains.
Even in this case, when some kind of flour has been used since the beginning, instead of whole grains, the evolution from coarse floor and porridge to fine floor and bread has increased the amount of work required for eating wheat.
There are two concepts of "work required to eat [something]".
You might be talking about the amount of labor that goes into preparing the food.
Or you might be talking about the amount of labor that goes into digesting the food.
Bread from fine flour may be harder to make, but it's much easier to eat.
Unlike porridge, bread still requires vigorous chewing, especially in the case of the kinds of bread available to the ancients, which were not as fluffy as many modern kinds of bread.
Ancient Rome is an example of a society that has transitioned from eating porridge to eating bread during historical times. While during the late Roman Republic and during the Empire the staple food of the Romans was bread made of (triploid) wheat flour, the staple food of the earlier Romans was "pult" made of "far", i.e. porridge made of emmer wheat.
This transition was also a transition from porridge made by each family at home to flour and bread made by professionals, because that required much more work.
And while cultivated fruits and veggies are not pap-soft, they are significantly less fibrous than seeds, stalks, husks etc that you would get from foraged, unprocessed food. Especially our farmed leaves are much softer than grass, leaves etc, that animals eat.