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.

This Wall Chart Shows Almost 130 Species of Shark—All Drawn to Scale

Pop Chart Lab
Pop Chart Lab

Shark Week may be over, but who says you can’t celebrate sharp-toothed predators year-round? Pop Chart Lab has released a new wall print featuring nearly 130 species of selachimorpha, a taxonomic superorder of fish that includes all sharks.

The shark chart
Pop Chart Lab

Called “The Spectacular Survey of Sharks,” the chart lists each shark by its family classification, order, and superorder. An evolutionary timeline is also included in the top corner to provide some context for how many millions of years old some of these creatures are. The sharks are drawn to scale, from the large but friendly whale shark down to the little ninja lanternsharka species that lives in the deep ocean, glows in the dark, and wasn’t discovered until 2015.

You’ll find the popular great white, of course, as well as rare and elusive species like the megamouth, which has been spotted fewer than 100 times. This is just a sampling, though. According to World Atlas, there are more than 440 known species of shark—plus some that probably haven't been discovered yet.

The wall chart, priced at $29 for an 18” x 24” print, can be pre-ordered on Pop Chart Lab’s website. Shipping begins on August 27.

Can You Really Suck the Poison Out of a Snakebite?

iStock
iStock

Should you find yourself in a snake-infested area and unlucky enough to get bitten, what’s the best course of action? You might have been taught the old cowboy trick of applying a tourniquet and using a blade to cut the bite wound in order to suck out the poison. It certainly looks dramatic, but does it really work? According to the World Health Organization, approximately 5.4 million people are bitten by snakes each year worldwide, about 81,000 to 138,000 of which are fatal. That’s a lot of deaths that could have been prevented if the remedy were really that simple.

Unfortunately the "cut and suck" method was discredited a few decades ago, when research proved it to be counterproductive. Venom spreads through the victim’s system so quickly, there’s no hope of sucking out a sufficient volume to make any difference. Cutting and sucking the wound only serves to increase the risk of infection and can cause further tissue damage. A tourniquet is also dangerous, as it cuts off the blood flow and leaves the venom concentrated in one area of the body. In worst-case scenarios, it could cost someone a limb.

Nowadays, it's recommended not to touch the wound and seek immediate medical assistance, while trying to remain calm (easier said than done). The Mayo Clinic suggests that the victim remove any tight clothing in the event they start to swell, and to avoid any caffeine or alcohol, which can increase your heart rate, and don't take any drugs or pain relievers. It's also smart to remember what the snake looks like so you can describe it once you receive the proper medical attention.

Venomous species tend to have cat-like elliptical pupils, while non-venomous snakes have round pupils. Another clue is the shape of the bite wound. Venomous snakes generally leave two deep puncture wounds, whereas non-venomous varieties tend to leave a horseshoe-shaped ring of shallow puncture marks. To be on the safe side, do a little research before you go out into the wilderness to see if there are any snake species you should be particularly cautious of in the area.

It’s also worth noting that up to 25 percent of bites from venomous snakes are actually "dry" bites, meaning they contain no venom at all. This is because snakes can control how much venom they release with each bite, so if you look too big to eat, they may well decide not to waste their precious load on you and save it for their next meal instead.

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