Koalas Have Fingerprints Almost Identical to Ours

Picture a researcher at a desk by the window, leaning over a brass microscope and studying a fingerprint on a slide. There are loops, whorls and arches, the familiar swirl of ridges that we tend to think of as a uniquely human signature. Nothing about it looks unusual. It could belong to anybody. It might, however, belong to a koala. And telling the two apart is harder than you might expect.

According to Earth.com, the biological anthropologist Maciej Henneberg of the University of Adelaide discovered the resemblance in the mid-1990s. Under the microscope, koala prints show the same ridge patterns as human ones: loops, whorls and arches. McGill University’s Office for Science and Society describes koala fingerprints as nearly indistinguishable from ours, and Henneberg noted that the likeness was so close that an investigator could, in theory, confuse the two.

What makes this so strange is how distantly related we are. Earth.com notes that humans and koalas last shared a common ancestor more than 100 million years ago, before fingerprints existed in either lineage. Our closest relatives, such as chimpanzees and orangutans, also have fingerprints, McGill points out, but many other species do not. And the koala’s own cousins, wombats and kangaroos, lack them, which suggests that koalas evolved the trait on their own.

Biologists call this convergent evolution, which McGill describes as different species developing similar traits independently from each other. The two lines arrived at the same design because they faced a similar problem. McGill explains that fingerprints aid grip, allowing an animal to hold on better to rough surfaces like branches and tree trunks, and that they also increase the sensitivity of touch. Earth.com adds that koalas use their fingers for delicately selecting eucalyptus leaves and for grasping branches.

That leads to a delightful and mostly theoretical worry. McGill’s article notes that a koala fingerprint could, in principle, turn up at a crime scene and be mistaken for a human one, which would make finding a match very difficult. Henneberg himself was more reassuring. As Earth.com quotes him, it is extremely unlikely that koala prints would be found at the scene of a crime. Koalas, it seems, have better things to do with their fingers than burgle houses.

So the next time you look at the whorls on your own fingertips, it is worth remembering that you share the pattern with an animal whose family split from ours long before either line had fingerprints at all. Nature does not always invent a good idea only once. Sometimes it arrives at the same answer twice, on opposite branches of the tree of life, because the problem of holding on to things and feeling what you are holding is much the same everywhere.