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8 Times Very Different Animals Evolved Very Similar Traits

Koalas and humans (specifically, Australian Prime Minister Tony Abbott and U.S. President Barack Obama). Image credit: Andrew Taylor/G20 Australia via Getty Images

Ever show up at a party dressed to the nines only to find that someone else was wearing the same outfit as you? Awkward! But don’t be too embarrassed. Something like this happens in nature all the time. Different creatures sometimes face very similar problems and environmental pressures, like getting from point A to point B or protecting themselves from predators that hunt a certain way. Faced with the same challenges, two (or more) groups of organisms may arrive at the same solution independently and develop adaptations that are similar in form or function but weren’t found in their last common ancestor.

This phenomenon is called convergent evolution (say that to your next dress twin), and you can see it all over. Here are just a few examples.

1. HUMANS HAVE FINGERPRINTS … AND SO DO KOALAS.

While the pattern of dermal ridges on your fingertips is unique to you, the ridges in general are not. Some of our primate relatives like chimpanzees and gorillas have them, too. We all got them from a common ancestor, but another animal developed them all on its own: the koala. Koalas have dermal ridges that form whorls, loops and arches just like ours, and the researchers that first noted them say that they’re very similar in form to those of humans— similar enough that even under a microscope, koala and human fingerprints are hard to tell apart. Moreover, just like human fingerprints, koala fingerprints seem to be unique to individuals. (Note to koalas: You had better not find yourself in a crime scene.)

The scientists think that koalas’ ridges developed fairly recently in their evolutionary history, as most of their close relatives don’t have them, and suggested they might be an adaptation for grasping and manipulating the koala’s favorite food, eucalyptus leaves. Though to be fair, scientists are still trying to figure out why we have fingerprints, even though they don’t appear to improve our grip.

2. BATS, BIRDS, AND FLYING BUGS: THREE DIFFERENT SOLUTIONS FOR WINGS

A barn owl at British Wildlife Centre, Surrey, England. Image credit: Peter Trimming via Wikimedia Commons // CC BY 2.0

One of the clearest examples of convergence is flight in birds and bats. The two groups aren’t closely related; they descend from non-flying ancestors and developed the ability to fly independently. In both cases, their forelimbs morphed over time into wings, but in different ways. Bats took to the air using a membrane (called the patagium) attached to their body, arms, and elongated fingers, while birds’ wings consist of feathers extending all along a forelimb whose finger bones fused together to create a different shape. Flying insects, meanwhile, developed their wings in a whole other way. With no internal skeleton to tweak like birds and bats, their wings came from modifications to their exoskeletons.

3. BATS AND WHALES: REAL-LIFE DAREDEVILS

Bats share another adaptation with a different, much larger animal. Both bats and the toothed whales echolocate, meaning that they emit high-pitched sounds and listen for the echoes in order to navigate and hunt. Bats produce their echolocation calls with their larynx and emit them through their mouth or nose, while whales pass air through their nasal passage to push vibrations out from a fatty tissue called the melon.

Interestingly, this same tactic has evolved in two very different environments: the sea and the sky. Even more amazing is that echolocation arose independently in each group and is done in different ways, but works thanks to the same genetic mutations. Two studies (independently conducted and appearing in the same issue of the same journal—talk about convergence) showed that bats and whales have experienced the same changes to a gene involved in sound processing, allowing them each to better hear the ultrasonic frequencies used for echolocation.

4. SHREWS AND LIZARDS: MASTERS OF THE SAME POISON

A Mexican beaded lizard. Image credit: Ltshears via Wikimedia Commons // Public Domain

The Northern short-tailed shrew and the Mexican beaded lizard are two animals you wouldn’t want to be bitten by. Both are venomous, and the toxins in their saliva can cause respiratory failure. While the species rely on two different toxins to give their bites some bite, both poisons evolved from the same digestive enzyme through very similar changes. In both species, the enzyme went through “almost identical” alterations, giving rise to two distinct toxins that do the same job.

5. CROSSING KINGDOMS: CATERPILLARS AND PLANTS

A bird's-foot trefoil in southern Sweden. Image credit: Fredrik Lähnn via Wikimedia Commons // Public Domain

Convergent evolution isn’t just limited to two types of animal. It can also happen with species that are in entirely different kingdoms of life. This is the case for a plant called the bird's-foot trefoil and the burnet moth caterpillar that feeds on it. Both the plant and the caterpillar protect themselves from predators with cyanide. The trefoil uses a trio of genes to convert a pair of amino acids into two cyanides. The caterpillars can absorb the plant’s poisons when they eat its leaves and use them to protect themselves, but researchers have found that caterpillars that don’t feed on trefoils contain the same toxins—which means they also make them themselves.

What’s more, the caterpillars produce the toxin in almost the same way as the plant. Scientists found that the caterpillars use a different group of three genes to turn the same starter chemicals into the same cyanides using the same chemical reactions. This is, the researchers say, the first example of identical biosynthetic pathways evolving convergently in two different kingdoms.

6. BUTTERFLIES AND THEIR JURASSIC-ERA LOOKALIKES, LACEWINGS

Structural diversity among lacewings. Image credit: composite image via Wikimedia Commons from Yang et al. in BMC Evolutionary Biology // CC BY 2.0

Tens of millions of years before butterflies appeared, another animal was doing a pretty good impression of them. Kalligrammatid lacewings were insects that flitted around Europe, Asia, and South America during the Mesozoic Era. They weren’t the ancestors of butterflies, but were strikingly similar to them in shape, coloration and, scientists think, ecology. Looking at lacewing fossils earlier this year, scientists found that one species, Oregramma illecebrosa, had patterns on its wings very similar to those of the modern owl butterfly. The researchers think they served the same purpose: mimicking the eyes of a larger creature to scare off predators. The two groups of bugs also evolved similar-looking long proboscises for getting the same food—nectar from plants. Even though the flowering plants butterflies feed on didn't exist back in the lacewings’ day, they seem to have hit on the same tool for tapping a different set of plants during a very different time.

7. GECKOS AND GECKOS: ADHESIVE TOES ARE A MUST

Convergent traits don’t always show up in organisms that are as wildly different as bats and dolphins or caterpillars and plants. Sometimes multiple members of the same lineage independently develop a new trait that their common ancestors didn’t have. Scientists used to think that the adhesive toes many geckos use to scale vertical surfaces evolved once in their common ancestor, but it turns out that the wall-crawling lizards all developed the trait on their own time and time again. Recent research suggests that adhesive toes evolved at least 11 separate times across the geckos’ family tree. The adaptation appears to have been ditched almost as often; it was independently lost on nine occasions.

8. TWO CRICKETS, TWO HAWAIIAN ISLANDS, ONE SILENCE

Pinned cricket of the speciesTeleogryllus oecanicus from the collection of the Zoologische Staatssamlung München. Image credit: via Franziska Walz via Wikimedia Commons

In another case of convergent evolution happening in the same group, two populations of the same cricket species converged on the same trait in different ways. About 10 years ago, field crickets on the Hawaiian island of Kauai started to go quiet. It’s not that they were just choosing to stay mum; they’d lost the ability to chirp because males were being born without sound-producing structures on their wings. A few years later, crickets on the island of Oahu similarly went silent. At first, scientists thought that the trait—dubbed “flatwing”—had spread because of quiet crickets making their way from one island to the other, but a look at the crickets’ genes revealed convergent evolution in action. The two populations had stopped chirping independently, with two different genetic mutations leading to two different, modified wing shapes and the same outcome—silence. But why go quiet? The crickets are sometimes targeted by a parasitic fly, which follows the cricket’s chirp to find them and lay its eggs inside them, eventually killing the host. The silent treatment seems to protect the crickets from the fly.

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Animals
Why Tiny 'Hedgehog Highways' Are Popping Up Around London
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Hedgehogs as pets have gained popularity in recent years, but in many parts of the world, they're still wild animals. That includes London, where close to a million of the creatures roam streets, parks, and gardens, seeking out wood and vegetation to take refuge in. Now, Atlas Obscura reports that animal activists are transforming the city into a more hospitable environment for hedgehogs.

Barnes Hedgehogs, a group founded by Michel Birkenwald in the London neighborhood of Barnes four years ago, is responsible for drilling tiny "hedgehog highways" through walls around London. The passages are just wide enough for the animals to climb through, making it easier for them to travel from one green space to the next.

London's wild hedgehog population has seen a sharp decline in recent decades. Though it's hard to pin down accurate numbers for the elusive animals, surveys have shown that the British population has dwindled by tens of millions since the 1950s. This is due to factors like human development and habitat destruction by farmers who aren't fond of the unattractive shrubs, hedges, and dead wood that hedgehogs use as their homes.

When such environments are left to grow, they can still be hard for hedgehogs to access. Carving hedgehog highways through the stone partitions and wooden fences bordering parks and gardens is one way Barnes Hedgehogs is making life in the big city a little easier for its most prickly residents.

[h/t Atlas Obscura]

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Stones, Bones, and Wrecks
New Program Trains Dogs to Sniff Out Art Smugglers
Penn Vet Working Dog Center
Penn Vet Working Dog Center

Soon, the dogs you see sniffing out contraband at airports may not be searching for drugs or smuggled Spanish ham. They might be looking for stolen treasures.

K-9 Artifact Finders, a new collaboration between New Hampshire-based cultural heritage law firm Red Arch and the University of Pennsylvania, is training dogs to root out stolen antiquities looted from archaeological sites and museums. The dogs would be stopping them at borders before the items can be sold elsewhere on the black market.

The illegal antiquities trade nets more than $3 billion per year around the world, and trafficking hits countries dealing with ongoing conflict, like Syria and Iraq today, particularly hard. By one estimate, around half a million artifacts were stolen from museums and archaeological sites throughout Iraq between 2003 and 2005 alone. (Famously, the craft-supply chain Hobby Lobby was fined $3 million in 2017 for buying thousands of ancient artifacts looted from Iraq.) In Syria, the Islamic State has been known to loot and sell ancient artifacts including statues, jewelry, and art to fund its operations.

But the problem spans across the world. Between 2007 and 2016, U.S. Customs and Border Control discovered more than 7800 cultural artifacts in the U.S. looted from 30 different countries.

A yellow Lab sniffs a metal cage designed to train dogs on scent detection.
Penn Vet Working Dog Center

K-9 Artifact Finders is the brainchild of Rick St. Hilaire, the executive director of Red Arch. His non-profit firm researches cultural heritage property law and preservation policy, including studying archaeological site looting and antiquities trafficking. Back in 2015, St. Hilaire was reading an article about a working dog trained to sniff out electronics that was able to find USB drives, SD cards, and other data storage devices. He wondered, if dogs could be trained to identify the scents of inorganic materials that make up electronics, could they be trained to sniff out ancient pottery?

To find out, St. Hilaire tells Mental Floss, he contacted the Penn Vet Working Dog Center, a research and training center for detection dogs. In December 2017, Red Arch, the Working Dog Center, and the Penn Museum (which is providing the artifacts to train the dogs) launched K-9 Artifact Finders, and in late January 2018, the five dogs selected for the project began their training, starting with learning the distinct smell of ancient pottery.

“Our theory is, it is a porous material that’s going to have a lot more odor than, say, a metal,” says Cindy Otto, the executive director of the Penn Vet Working Dog Center and the project’s principal investigator.

As you might imagine, museum curators may not be keen on exposing fragile ancient materials to four Labrador retrievers and a German shepherd, and the Working Dog Center didn’t want to take any risks with the Penn Museum’s priceless artifacts. So instead of letting the dogs have free rein to sniff the materials themselves, the project is using cotton balls. The researchers seal the artifacts (broken shards of Syrian pottery) in airtight bags with a cotton ball for 72 hours, then ask the dogs to find the cotton balls in the lab. They’re being trained to disregard the smell of the cotton ball itself, the smell of the bag it was stored in, and ideally, the smell of modern-day pottery, eventually being able to zero in on the smell that distinguishes ancient pottery specifically.

A dog looks out over the metal "pinhweel" training mechanism.
Penn Vet Working Dog Center

“The dogs are responding well,” Otto tells Mental Floss, explaining that the training program is at the stage of "exposing them to the odor and having them recognize it.”

The dogs involved in the project were chosen for their calm-but-curious demeanors and sensitive noses (one also works as a drug-detection dog when she’s not training on pottery). They had to be motivated enough to want to hunt down the cotton balls, but not aggressive or easily distracted.

Right now, the dogs train three days a week, and will continue to work on their pottery-detection skills for the first stage of the project, which the researchers expect will last for the next nine months. Depending on how the first phase of the training goes, the researchers hope to be able to then take the dogs out into the field to see if they can find the odor of ancient pottery in real-life situations, like in suitcases, rather than in a laboratory setting. Eventually, they also hope to train the dogs on other types of objects, and perhaps even pinpoint the chemical signatures that make artifacts smell distinct.

Pottery-sniffing dogs won’t be showing up at airport customs or on shipping docks soon, but one day, they could be as common as drug-sniffing canines. If dogs can detect low blood sugar or find a tiny USB drive hidden in a house, surely they can figure out if you’re smuggling a sculpture made thousands of years ago in your suitcase.

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