Why do we have creases on our fingers, and do they have a primary use?

Transverse finger creases represent the necessary skin folding near the joints during finger flexion. Most of us have two creases at each finger joint but this person with exceptionally long fingers has 1) extra creases (skin folds) between the PIP and DIP joints of the ulnar three fingers, 2) exceptionally wide PIP joint creases on the index finger, and 3) an extra crease distal to the long finger DIP joint!