Fingerprints are the traces of an impression from epidermal ridges on the fingers of humans. When fingertips brush across an uneven surface these ridges help us better perceive texture, and they also assist in gripping wet surfaces. Many animals lack fingerprints (cats and dogs do NOT have fingerprints). They occur occasionally in other animals whose lifestyle involves climbing or grasping wet objects, but these are usually unique prints that do not look like human fingerprints. Interestingly the Australian koalas (marsupials) have fingerprints that are very similar in their microscopic morphology, organization into patterns and pattern uniqueness to an individual, to those of humans. The presence of fingerprints in humans and Koalas is an example of: