

That random mutation didn’t happen, basically.
Evolution is a purely subtractive process. It doesn’t design things in, it just subtracts away poorly-designed creatures (and all hypothetical offspring) until only things equipped to survive are left. And obviously, there are things to eat that aren’t grass.
Edit: Herbivores can be smart, even the grazers. Look at elephants.
I can’t believe how many other replies heap that fallacy on top of teleological evolution. Apes are mostly herbivorous anyway, WTF.


Plants are selected to not be great to eat, basically. Cellulose in particular is almost impossible to biochemically break back down (but not completely), and is a pretty good structural material, too.
Seeds are often still palatable once you get through the shell, basically because turning into a baby plant is an already tough design constraint. Some plants still have tricks - notice that it’s the spiciest part of a hot pepper.