Fine, that is micro-evolution, the survival of the fittest within the given parameters of the species.
So how did we develop an Achilles Tendon if ape chromosomes don't produce it?
Ours is just longer and ‘springier’.
If a critter spends most of its time in the trees running isn’t much needed. Therefore apes and monkeys don’t need to be spring loaded.
It becomes important on open savannas. Our ancestors needed to outrun predators and chase down prey. They needed the energy recovery/efficiency that a springy tendon provided. The ones that had that edge were more likely to live long enough to reproduce.