why do we have them?
To keep the economy going. Without them rich women wouldn’t be able to employe servants to paint them while they eat bon bons…OK the flames begin 
That’s easy. They probably were a means of self-defense in early hominids, and later on just kind of evolved into aids for picking up things and for climbing around. Or, as my mother would say, they help protect the ends of your fingers and toes. Take your pick!
Well, before we evolved from monkees…
Sorry to steal your flames, Markxxx. 
Peace,
mangeorge
I only know two things;
I know what I need to know
And
I know what I want to know
Mangeorge, 2000
Well these things are hinderances more than help. Cutting your nails too close hurts like heck. If you were to fight like an animal it’s likely you’d rip your nails off the nail bed and it’d hurt like heck.
But on the other hand, how would you ever pick your nose or sratch your back without fingernails?