why do we own finger nail?

why do we own finger nail?
Nice answer Tony. The article does not answer the question.
We hold finger nails because we are mammals. All mammals developed claws or nail as a survival trait. They are used as weapons, or to comfort climb surfaces, etc. They also provide extra support when holding or grasping things.
For humans we do not use our nails as much as we are tool users and most of the things we could use our nail for, we have tools (cleaning teeth, digging, climbing). Sometimes my own nail come in handly to pick up things (small pins) or to open out packages without using a blade.
Go to Wikipedia.com and type Nail (anatomy)
To tear hefty off of meat!