Another example of how humans have coevolved with our tools:
Until around 250 years ago in the West, archaeological evidence suggests that most human beings had an edge-to-edge bite, similar to apes. In other words, our teeth were aligned liked a guillotine, with the top layer clashing against the bottom layer. Then, quite suddenly, this alignment of the jaw changed: We developed an overbite, which is still normal today. The top layer of teeth fits over the bottom layer like a lid on a box.
This change is far too recent for any evolutionary explanation. Rather, it seems to be a question of usage. An American anthropologist, C. Loring Brace, put forward the thesis that the overbite results from the way we use cutlery, from childhood onwards.
There is a pretty substantial if still-controversial literature on cooking and and its effect on humans (though some recent discoveries-- the discovery of cooking fires from a million years ago at least helps establish that cooking is very very old), but now a study about cooking and brain size in primates adds to the plausibility of the argument.