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6 Traits Humans Inherited From Fish

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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.

Want to learn more about your aquatic ancestors? Tune in to Your Inner Fish tonight at 10 pm Eastern/9 pm Central on PBS’s Think Wednesday lineup.

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9 Reasons to Love the Amazing Snow Monkey
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Snow monkeys (also known as Japanese macaques) are a cute, fun-loving bunch. Adorable as they may be, there’s much more to this primate than just a pretty face.

1. They Are Social Creatures (Very Social)

Snow monkeys live in groups called “troops,” which can include up to 500 of the primates (although it’s usually closer to 100). Things get crowded, but are largely kept in order because…

2. Female Snow Monkeys Run the Show

While males end up leaving the troops around the age of four, their female counterparts stick around for their entire lives. The females are responsible for socialization and are to thank for keeping the multiple families within each troop in line.

3. They’re Big on Collaborative Grooming

Snow monkeys groom each other for more than just cleanliness—it’s also their way of hanging out and being social. In fact, almost one-third of a snow monkey’s day is spent grooming other members of the troop (compared to the 1% of the day they spend cleaning themselves).

4. They Know How to Chill

Snow monkeys are world-famous spa-lovers. They spend tons of time bathing in hot springs with their friends and family and, like humans, dig the aprés ski lifestyle.

5. They Monkey Around

When not grooming or bathing, snow monkeys have been observed having some rambunctious fun—they occasionally roll and throw snowballs around.

6. They Are Real Chatterboxes

Snow monkeys have multiple coos and calls for different situations. They have calls to alert others that it’s grooming time, ones to welcome new monkeys into the troop, and coos to calm aggressive individuals during squabbles. They often respond to these calls with their own coos and have little conversations throughout the day.

7. They Speak With Accents

Studies have shown that snow monkeys in one region will have differently pitched coos than those of troops miles away.

8. They Can Handle a Winter

With a range that extends as far north as the tip of the Japanese island of Honshu, snow monkeys live further north than any other primate except humans. Snow monkeys can handle temperatures that dip below 15 degrees F, but they probably complained about this year’s extra-cold winter, too.

9. They Are Smart, With a Capital “S”

Scientists once observed a female snow monkey washing dirt off a sweet potato before she ate it. Soon, her companions picked up on this behavior and began to clean their own food as well, behavior that’s only observed in raccoons, humans, and snow monkeys. They also appear to be foodies – the snow monkeys began seasoning the potatoes in seawater to give the food a tasty kick.

Want to learn more about the amazing snow monkey? Tune in to Nature tonight at 8 pm Eastern/7 pm Central on PBS’s Think Wednesday lineup.

All images courtesy of Thinkstock

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6 Traits Humans Inherited from Monkeys
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Humans didn’t evolve from modern monkeys, but if you trace the branches of our family tree far enough, you’ll realize that we share a common ancestor. Here’s what they left us with.

1. Coccyx, Our Former Tail

Why does falling on your tush hurt so much? Because the tailbone is a remnant of your long-lost tail. (For about four weeks, human embryos have a tail. In rare cases, people are born with them!) The tail disappeared millions of years ago when hominids started walking upright and no longer needed it for balance. However, its absence has left the bottom of our spinal columns exposed. That’s why your coccyx is so easy to bruise and break.

2. Our Complex Hands

Primates are the only mammals with opposable thumbs. Notharctus, a lemur-like monkey that lived 50 million years ago, was the first ape to develop human-like hands: A thumb, long fingers, and nails instead of claws. Why? They were—and still are—perfect for clinging to tree branches!

3. The Ability to See Colors

For millions of years, our ancestors were red-green colorblind. But thanks to receptors called “opsins,” everything went technicolor around 23 million years ago. Most colorblind animals have two sets of opsin genes. Humans, however, have three—and that third gene makes all the difference. Scientists posit that millennia ago, an opsin gene duplicated and mutated and was a huge advantage. (Scientists have confirmed this hypothesis by planting a third opsin gene in the retina of colorblind squirrel monkeys. The experiment gave them human-like color-vision.)

4. Our Crummy Sense of Smell

You can’t have it all. As our sense of vision got better, our sense of smell got worse. We have thousands of genes for smell, but nearly 600 of them don’t work anymore.

5. The Ability to Take a Stroll

For about 365 million years, most animals walked on all fours. But around 4.4 million years ago, a woodland primate called ardipithecus stood up and walked with an awkward wobble. After a couple million years, australopithecus emerged (its most famous member is “Lucy”). Just like humans', its knees bent inward, making walking more natural.

6. Our Bad Backs

Walking came with a cost: it ruined our backs. In order to stay balanced, our ancestors developed an “S-shaped” spine, which—as we all know—leads to kinks, knots, sciatica, and all sorts of pain. But all that aching might be worth it. Standing freed up our hands and gave us a chance to make tools.

Want to learn more about our monkey relatives? Tune in to Your Inner Fish tonight at 10 pm Eastern/9 pm Central on PBS’s Think Wednesday lineup.


All images courtesy of Thinkstock

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