Based ENTIRELY on the first statement...
I once had an accident at work that resulted in having my thumb nail ripped off completely. In addition to a few other injuries which healed after a few months, it took nearly 6 months to regrow my nail. During which time I learned having a finger nail helps give your finger "meat" something to press against, instead of literally trying to pick something up essentially with your bone.
I mean the saying is about monkeys and a chimp is an ape, so...