6 Traits Humans Inherited From Fish

ThinkStock
ThinkStock

What’s so fishy about human anatomy? A lot! Just look at these gifts from our aquatic ancestors.

1. Embryos

Look closely at any mammal, bird, or amphibian embryo—they all look the same. That’s because they all inherited genes from a common, fishy ancestor. During the middle stage of development—called the phylotypic period—a special combination of those genes becomes active, while some get turned off. Those active genes become the blueprints for your body.

2. Our Voice

Fish can’t talk, but they do have gills—and that’s where our voices come from. Just like fish, human embryos have gill arches (bony loops in the embryo’s neck). In fish, those arches become part of the gill apparatus. But in humans, our genes steer them in a different direction. Those gill arches become the bones of your lower jaw, middle ear, and voice box.

3. Sense of Hearing

How did gills become part of the ear? Just look at the fossil evidence. The ancient fish Eusthenopteron lived about 370 million years ago. It had a problem, though: A small part of the jawbone—the hyomandibula—poked into its gills. A few million years later, that same pesky bone formed a cavity by the ear of Eusthenopteron’s descendents. There, it started amplifying sound—travel down the fossil record even further, and you’ll see that the bone had become the stape, the part of the ear that helps us hear.

4. Hernias

Fish gonads sit near the heart. In human embryos, the gonads form deep in the chest—just like in fish. However, since we’re warm-blooded, these gonads need to go somewhere cool. After 12 weeks, they start to descend, and for men, they break through the body wall and form testicles. But breaking through the body wall leaves behind a weak spot, which is why it’s relatively easy for humans to get hernias.

5. Fingers

Fish don’t have fingers, but they do have the gene that makes fingers possible. In the 1980s, scientists discovered a special gene called “sonic hedgehog,” which helps animals form digits. When scientists mutated sonic hedgehog in various animals, the creatures all grew extra fins and fingers (people with polydactylism—that is, six fingers—suffer from a sonic hedgehog overload). A surge in sonic hedgehog helped ancient fish crawl onto land.

6. Our Faces

You know that groove above your upper lip, just below the nose? That’s the philtrum. It’s there because, as an embryo, your face looked kind of fishy. Your eyes started at the side of your head and your nostrils and lips grew at the top (you looked a little like an eel). After a couple of months, those features migrated: Your eyes squeezed inward while your lips and nose dropped. The transformation left behind a tiny divot above your upper lip, and gave men everywhere a place to grow terrible mustaches.

Not-So-Fancy Feast: Your Cat Probably Would Eat Your Rotting Corpse

Tycson1/iStock via Getty Images
Tycson1/iStock via Getty Images

Cat enthusiasts often cite the warmth and companionship offered by their pet as reasons why they’re so enamored with them. Despite these and other positive attributes, cat lovers are often confronted with the spurious claim that, while their beloved furry pal might adore them when they’re alive, it won’t hesitate to devour their corpse if they should drop dead.

Though that’s often dismissed as negative cat propaganda spread by dog people, it turns out that it’s probably true. Fluffy might indeed feast on your flesh if you happened to expire.

A horrifying new case study published in the Journal of Forensic Sciences offers the fresh evidence. The paper, first reported by The Washington Post, documents how two cats reacted in the presence of a corpse at Colorado Mesa University’s Forensic Investigation Research Station, or body farm, where the deceased are used to further forensic science for criminal investigations.

The study’s authors did not orchestrate a meeting between cat and corpse. The finding happened by accident: Student and lead author Sara Garcia was scanning surveillance footage of the grounds when she noticed a pair of cats trespassing. The cats, she found, were interested in the flesh of two corpses; they gnawed on human tissue while it was still in the early stages of decomposition, stopping only when the bodies began leaching fluids.

The cats, which were putting away one corpse each, didn’t appear to have a taste for variety, as they both returned to the same corpse virtually every night. The two seemed to prefer the shoulder and arm over other body parts.

This visual evidence joins a litany of reports over the years from medical examiners, who have observed the damage left by both cats and dogs who were trapped in homes with deceased owners and proceeded to eat them. It’s believed pets do this when no other food source is available, though in some cases, eating their human has occurred even with a full food bowl. It’s something to consider the next time your cat gives you an affectionate lick on the arm. Maybe it loves you. Or maybe it has something else in mind.

[h/t The Washington Post]

7 Animals That Appear to Fly (Besides Birds, Bats, and Insects)

renacal1/iStock via Getty Images
renacal1/iStock via Getty Images

The only animals that can truly fly are birds, insects, and bats. Other animals manage to travel through the air by gliding from great heights or leaping from the depths. Here are a few.

1. Devil Rays

The devil rays, in the genus Mobula, are related to manta rays. Their wingspan can grow up to 17 feet wide, making them the second-largest group of rays after the mantas. These muscular fish can leap several feet out of the water, but no one is quite sure why they do it.

2. Colugos

These tree-dwelling gliders are sometimes called flying lemurs, but they're neither true lemurs nor do they fly. These mammals in the genus Cynocephalus are native to Southeast Asia and are about the size of a house cat. Colugos can glide up to 200 feet between trees using their patagium, or flaps of skin between their front and hind legs that extend to their tail and neck (colugos are even webbed between their toes). In the air, they can soar gracefully through the forest, but on the ground, they look like an animated pancake.

3. Flying Fish

Flying fish

There are about 40 different species of flying fish in the family Exocoetidae, although they don't fly so much as they leap from the water with a push of their powerful pectoral fins. Most of the species live in tropical waters. Fish have been observed skipping over the waves for as long as 45 seconds and 650 feet. Scientists suspect that flying fish leap into the air to escape predators.

4. Paradise Tree Snake

The paradise tree snake (Chrysopelea paradisi) lives in the rain forests of Southeast Asia. It glides from the treetops by flattening its body out to maximize surface area, wiggling from side to side to go in the desired direction. Though the idea of a flying snake may be terrifying, C. paradisi is not harmful to humans.

5. Flying Geckos

Flying geckos, a group of gliding lizards in the genus Gekko, live in the wet forests of Southeast Asia. In addition to patagia that let them parachute from tree branches, the geckos have remarkably mutable skin that camouflages them against tree trunks extremely well.

6. Wallace's Flying Frog

Wallace's flying frog (Rhacophorus nigropalmatus) is found in Malaysia and Indonesia. This frog has long webbed toes and a skin flap between its limbs which allows it to parachute—float downward at a steep angle—from the treetops. Although Wallace's flying frogs prefer to live in the forest canopy, they must descend to ground level to mate and lay eggs.

7. Flying Squirrels

Flying squirrels in the subfamily Sciurinae include dozens of species. They are native to North America and Eurasia. When it leaps from a tall tree, a flying squirrel will spread its patagium until it resembles a kite or parachute. The squirrel can steer by moving its wrists and adjusting the tautness of its skin.

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