Dermal ridges cover the palms and fingers of some animals, and these ridges form patterns known as fingerprints. The fingerprints of humans are unique; no individual person has exactly the same fingerprints as any other human. Perhaps unsurprisingly, unique fingerprints occur in most other primates, and sometimes occur in even more distantly related animals, such as koalas.
Common Among Clingers
Finger and palm prints likely evolved to allow the ancestors of modern primates to grasp items like branches. Hands with fingerprints achieve a better grip than hands without fingertips do. While monkeys and all other primates have very similar fingerprints -- presumably inheriting them from the group’s common ancestor -- koalas are marsupials that have developed these ridges independently of the primates. Additionally, other arboreal animals have evolved dermal ridges on their feet or tails to allow them better gripping ability. This means that this adaptation has arisen multiple times.
Tom Brakefield/Stockbyte/Getty Images