In 1975 police took fingerprints from six chimpanzees and two orangutans housed at zoos in England. They weren’t just looking for a unique souvenir; they were testing to see if any unsolved crimes could be the fault of these banana-eating miscreants.

While these primates ended up being as innocent as they seemed, the police did determine that their fingerprints were indistinguishable from a human’s without careful inspection.

A few years later, in 1996, a different type of mammal came under police suspicions: a koala!

While it makes sense that orangutans and chimpanzees would have fingerprints like us, being some of our closest relatives, koalas are evolutionarily distant from humans. It turns out that fingerprints are an excellent example of convergent evolution, or different species developing similar traits independently from each other.

Another example of convergent evolution is seen in the bony structure supporting both birds' and bats' wings.

Fingerprints are thought to serve two purposes. First, they aid in grip, allowing an animal to better hold onto rough surfaces like branches and tree trunks. Second, they increase the sensitivity of our touch and allow us a finer level of perception regarding the textures and shapes of the things we hold.

Why this is useful for humans is obvious. Our hands are made to grasp, hold and manipulate objects. Whether it’s some nuts we foraged for or our Xbox controller, we humans spend all day every day relying on our sensitive sense of touch.

For koalas, it’s not really so different. They are incredibly picky eaters, showing strong preferences for eucalyptus leaves of a certain age. It seems that their fingerprints allow them to thoroughly inspect their food before they chow down.

Police aren’t exactly worried about koala bank robbers, but it is possible that koala fingerprints could be found incidentally at a crime scene and be mistaken for a human's, making it pretty difficult to find a match.

To read about how fingerprints form, how parts of them are genetic, and why identical twins have different ones, click here!

@AdaMcVean

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