Common knowledge states that every person’s fingerprint is unique. While this has never been strictly proven, there’s something special about the whorls and ridges at the ends of our fingers. After all, who doesn’t want to be one of a kind?
It’s not exactly true, however, to say that when it comes to fingerprints, humans are exceptional. Way back in time, as the ancestors of the human race developed, they needed to be able to grab an object, such as fruit, and maintain their hold. Grasping required a hand and fingers that could accurately exert pressure and use fine motor control. It also required traction. As a result, fingertips! The ridges, whorls, loops, and arches created an organized skin surface that could precisely grab things and hold on tight.
It’s no surprise, then, that fellow primates, such as chimpanzees and gorillas, also have unique fingerprints. But what is surprising is that koalas have fingerprints, too. Looking at koalas’ fingers and toes, scientists at the University of Adelaide, Australia, found ridges that look remarkably like a human’s, even though some technical differences are plainly visible.
So why would koalas—marsupials from a different branch of the evolutionary tree than our primate ancestors—have raised ridges on the pads of their fingers, just like we do? And why would the close relatives of the koala, including wombats and kangaroos, lack fingerprints? The scientists suspect that the cause is, once again, that need to grasp. Koalas, unlike wombats and kangaroos, eat by grabbing eucalyptus leaves and bringing those leaves to their mouth. As with humans, all that grasping after tasty food meant that koalas eventually evolved fingerprints.