CLOSE
Original image
ThinkStock

7 Traits Humans Inherited From Reptiles

Original image
ThinkStock

We may not always look it, but humans are repurposed reptiles. Believe it or not, but all of these traits reflect your inner lizard.

1. Our Yolk Sacs

When we’re embryos, a relic of our egg-laying past hangs in the womb with us—a yolk sac. Just like bird and reptile eggs, this sac provides embryos with nutrients. Yolk sacs developed about 300 million years ago when the first amphibians moved onto land. Along with the amniotic sac, it prevented their eggs from drying out.

2. Resilient Skin

It may not look like it, but our skin developed thanks to a reptilian battle with the elements. 300 million years ago, reptiles evolved a new kind of skin to deal with the dry air on land: a watertight barrier of dead skin cells, which rested atop a layer of fresh, living cells. We inherited that same layering system.

3. The Hair On Our Heads (And Elsewhere)

Sorry mammals, but reptiles beat you to the punch and grew hair first. Animals like thrinaxodon—a burrowing reptile that lived 245 million years ago—evolved whiskers to feel around in the dark. Within 20 million years, animals got hairier and hairier, and the first mammals appeared.

4. Ears and Sense of Hearing

Three bones in our middle ear help amplify sound. Amazingly, two of those bones are part of a reptile’s jaw. The fossil record indicates that over 200 million years ago, those two jawbones started receding back into ancient reptiles’ heads. Hadrocodium, a small mouse-like creature that descended from reptiles some 190 million year ago, was one of the first critters to inherit the special three-boned ear.

5. Big Brains

As late reptiles and early mammals developed whiskers and a better sense of hearing, their brains had to process more information. Because of this, their brains started to grow.

6. Our Teeth

Most modern reptiles have long, sharp, peg-shaped chompers (think crocodiles). They don’t have canines—those are strictly found in mammals. But it wasn’t always that way. The dog-like lizard gorgonopsid was one of the first ancient reptiles to flaunt long, saber-toothed canines. By the time the shrew-like tritheldonts appeared 230 million years ago, reptiles were chewing on plants and developing molar-like teeth. Teeth became more complex, setting the stage for humans—and dentists.

7. The Genes That Make Us Us

Of course, we don’t inherit reptile teeth, skin, and bones directly. We simply inherit the genes that make them possible. One gene has a lot to do with all of these transformations—EDA. EDA controls how many teeth you have, what those teeth look like, how hairy you are, and how soft and sweaty your skin is. It’s believed that mutations to EDA in ancient reptiles helped us inherit our body’s current blueprints.

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

Original image
ThinkStock
9 Reasons to Love the Amazing Snow Monkey
Original image
ThinkStock

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

Original image
ThinkStock
6 Traits Humans Inherited from Monkeys
Original image
ThinkStock

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

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios