Q:

Bending your little finger without bending ring finger

It is possible to bend each finger without bending any other, except one for most people. It is more difficult for the ring finger, but when I try to bend my little finger independently my ring finger bends as well. I don't know if this is because of the muscle or  bone configuration, but I'm interested in the answer.

Is it possible to bend the little finger independently, and if so why is it so hard to do so?

A:

This does not have to be the case always, For example if you are a pianist you need all your finger to work independently.
OK, So coming to the main question.
In simple words, They are all interconnected. See the image [Source: Google Images]

They share flexor tendons (The flexor tendons allow you to bend your fingers) , If you try to move one, other is objected to come along.
Yes it is possible, As I mentioned before if you are a pianist, you don't have much choice. It is possible by little bit training.

A:

To shed some light on why this is happening in the first place, it may be helpful to understand the innervation of the muscles on these fingers. 
There are two nerves that innervate the little finger, both branches of the superficial ulnar nerve. One of them is exclusive to the little finger, but the other (the common palmar digital nerve) actually branches again and innervates both sides of the gap between your little finger and ring finger. This explains why contracting your little finger muscles causes some (but not complete) contraction of your ring finger. 
These connections can be modified and trained with practice, like many other movements we can improve with practice. 

Iannotti, Joseph P, and Parker, Richard. Netter Green Book Collection : The Netter Collection of Medical Illustrations: Musculoskeletal System, Volume 6, Part I - Upper Limb, Volume Vol. 6 : Musculoskeletal System, Volume 6, Part I - Upper Limb (2). Saint Louis, US: Saunders, 2012. ProQuest ebrary. Web. 29 November 2016.

