Let me just point out a few things:
* Most early hominids had bigger, stronger teeth and jaws than modern humans.
* Hit it really hard with a rock and most hard things become soft things. This was probably the first scientific discovery of the hominids.
* Fire makes most hard foods softer.
* Acid does the same for some.
* And fermentation. Although we no longer think it's a good idea to nail ducks to a wall for 2 weeks before eating them.
* It's amazing what people will eat when they get hungry enough.