Koalas have fingerprints almost identical to ours | Nova

In the mid-1990s, Maciej Henneberg was working with koalas at a wildlife park near Adelaide, Australia, when he noticed something strange: the animals seemed to have fingerprints.

As a biological anthropologist and forensic scientist, Henneberg recognized that this made the koala unique, the only non-primates with fingerprints. “It seems that no one bothered to study it in detail,” he said. He told The Independent In 1996, shortly before the publication of a press article Announcing the discovery. Henberg’s research indicated that even careful analysis under a microscope can’t help distinguish the swollen, coiled cusps on koalas’ toes from our own. The fingerprints were so similar to humans, that he feared they could be easily confused by investigators. (However, he admitted to The Independent that it was “extremely unlikely to find prints of koalas at the crime scene”).

While Henneberg’s discovery didn’t help solve any koala cold cases, it did add fuel to a decades-long debate about the purpose of fingerprints and how humans evolved to possess them.

When it comes to fingerprints, we know more about them How We develop them from why. Scientists divide the intricate vortex of these unique patterns into larger categories: loops, spurs, and arcs. They call the rest of the figures – places where lines separate, split in two, or create concentric islands – “fine details”. While the general essence of your fingerprint is something you inherit from your parents, these details come from the environment you were raised in as a fetus, including the composition of your amniotic fluid, how you were positioned, and what you touched in the womb. This is why everyone has slightly different fingerprints, even identical twins.

But what makes fingerprints useful from an evolutionary point of view? Prior to the discovery of Koala Heinberg, conventional wisdom held that fingerprints increase friction, and help humans understand things better. However, a host of recent studies suggest that it’s more complicated than that.

In 2009, biologist Roland Ennos published a study Which suggests that when we come into contact with something, the skin on our fingertips behaves like rubber. This means that the friction between the skin and the surface increases in proportion to the total area of ​​contact. And because the skin is riddled with loops, braids, and arches, it actually doesn’t come into contact with this surface unless it’s smooth, which means that fingerprints may in fact be discount friction.

But lately, study Based on Ennos’ conclusions, he suggested that while fingerprints may not build friction on their own, they may help maintain grip by working in tandem with sweat glands. Researchers have found that when they come into contact with hard, impermeable surfaces, our fingers release moisture. Moisture builds friction by softening the skin on our fingertips, with the help of tiny grooves in the fingerprints, which direct the liquid in a way that allows for maximum evaporation. (This is important because if sweat collects a lot, it can lead to slippage.) The new flexible leather also allows for other built-in protection, since pressure on the surface eventually clogs the sweat-making pores, allowing evaporation to catch up. And helping to maintain friction is very important.

“This dual mechanism of moisture management has provided primates with an evolutionary advantage in both dry and wet conditions—giving them manipulative and locomotive capabilities not available to other animals,” said co-author Mike Adams. He said in a press release in time.

Fingerprints may also provide extreme sensitivity in our fingertips. Physicists at the Ecole Normale Superior in Paris found that the edges of fingerprints Vibrations may be amplified Made by rubbing the tip of a finger against a rough surface, to deliver those vibrations to the nerve endings in our fingers. This kind of insight is becoming increasingly important as designers prostheticsAnd the adaptive techniquesand touch screens seek to understand how our fingers work and Sense of touch Help us interact with the world.

But our last common ancestor with koalas was, by some accounts, more than 100 million years ago, when marsupials separated from the rest of the mammals. So how did we come to share this special trait? The answer is what is called “convergent evolution,” when unrelated organisms evolve identical characteristics in response to similar evolutionary pressures.

There are only so many ways for animals to climb tall trees, live on cliffs, navigate underwater, or accomplish any of the specific tasks required by narrow evolutionary niches. The wings of bats and birds evolved separately. As Live Science points out, sharks and dolphins come from lineages that diverged hundreds of millions of years apart, but both developed smooth skin and sharp fins to help them hunt down prey. And since marsupials diverged long ago, there is also a parallel pathway to them in Australia that evolved convergently with our placental mammalian cousins. Follicular moles down, for example, are unrelated to moles in other parts of the world. However, both are blind and boast feet that are very similarly adapted to life dug underground.

Koalas are notorious for being picky eaters who look for eucalyptus leaves at a certain age. As Henberg noted in his 1997 paper, koalas may also need to grasp in ways similar to humans, at the same time, “climbing perpendicular to the smaller branches of eucalyptus trees, extending a hand, picking up a handful of leaves and bringing them to the mouth.” He felt that the koala’s fingerprints must have arisen as an adaptation to this task, which is relatively recent, having neither wombat nor kangaroos (both koala cousins). Friction and sensitivity prints may help them stick to trees at the same time and do the job. The delicate act of picking certain papers and discarding others – but hopefully not near the crime scene.

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