Koalas Have Fingerprints Just Like Yours

If a koala touched a glass, it would leave fingerprints. And not just any fingerprints: ridges, loops and whorls arranged almost exactly like yours. When anatomists at the University of Adelaide described them in 1996, they noted that even under an electron microscope it is hard to tell a koala's fingertip from a person's.

The astonishing part is the kinship — or rather, the lack of it. The last common ancestor of koalas and humans lived more than a hundred million years ago, long before primates or eucalyptus trees existed. Our close relatives, chimpanzees and gorillas, do share fingerprints with us; but the koala arrived at its own independently. It's what biologists call convergent evolution: two utterly separate roads leading to the same solution.

What are they for? The leading hypothesis: for climbing and, above all, for feeling. A koala picks eucalyptus leaves one by one, and those tiny ridges sharpen its sense of touch the way a tyre's tread grips the road.

In Australia they joke that a koala could contaminate a crime scene. Technically, it isn't entirely a joke.