10 Strange Things Evolution Left on Your Body

Evolution has given the human body some odd parting gifts, like the appendix. People just don't eat as much tree bark as they used to.

Scroll to the end to watch the video.

The human body has been a work in progress for about the last six million years, so it’s understandable if over that time we’ve outgrown some of our components. Our tonsils, once intended to be the all-natural wall nasty pathogens need to penetrate in order to call our bodies home, are now usually infection culprits themselves. When was the last time you heard tonsils being name-dropped if it wasn’t in reference to having them removed? Much like the appendix, which humans did at one point rely on to help digest a diet much heavier on the greenery, tonsils are now something that have become a cottage industry for surgeons. When in doubt, grab a scalpel and start slicing.

Appendix

Source: Nagaraju raveender / Wikimedia

This is the classic useless organ, at least according to popular thought. It’s hard to determine what its purpose is or once was since it’s not something that appears universally in other animals. Some have it, some don’t. We do.

An appendix, when it appears, usually appears in herbivores, so the common opinion is that it once helped us digest plants back when we ate a lot of mostly indigestible plants. We can afford to be a bit pickier about what we eat these days, so we don’t need an organ like that anymore. If, in fact, we ever did.

Recent studies show it might not be as vestigial as we once thought, since it appears to have a function during the fetal and early human stages as a source of endocrine cells that produce hormones and other compounds that help with the immune system.

Its classification as a useless bit of our bodies dates back to Charles Darwin himself, who listed a number of body parts in his seminal work “The Decent of Man” that he considered “rudimentary” and an argument supporting his theory of evolution.

Whatever the appendix is for, we do know that we can live without it. And for some people who get stricken with appendicitis, we need to be without it if we want to keep living.

Ear wiggling

Source: Travis Isaacs / Flickr

Some people can wiggle their ears, some people can’t. We all have the muscles for it, or traces of them anyway, but we can’t call control them.

Ear wiggling is believed to be a genetic thing, which suggests that it’s either a new mutation that the species is trying on for size, or an old one we don’t need anymore. The fact that so many other animals do have much more defined muscles attached to their ears and a large amount of control over the movement of these muscles, which help with directional sound detection, suggests that it’s probably not new.

It’s commonly believed that around 10 to 20 percent of the population can do it, but there is some evidence to suggest that it’s something that can be learned. But then again, maybe it can only be learned by people who have the genes to do it in the first place.

Since it’s not something that really matters to modern day homo sapiens, nobody is rushing to toss a lot of research money at the question.

Corner of the eye

That little fold of tissue in the corner of your eye is called the plica semilunaris. It’s all we have left of what  was once a really cool organ that would make staring contests so much more interesting.

It’s called the nictitating membrane, or third eyelid, and some animals like reptiles, birds, and sharks still have them. It’s translucent and slides in from the side either partially or all of the way over the eye, and serves to protect and moisten the delicate squishy bits. Because it’s translucent, animals that have a functioning nictitating membrane can see through it.

All that’s left now is that little fold there in the corner, along with some useless muscles that tell us what it once was, back when people had really cool lizard-shark eyes.

Palmaris longus

Most of us, about 85-90%, have a muscle in our forearm for which we have no need and no use. It’s called the palmaris longus, and there are a number of mammals who have it, such as lemurs and monkeys.

What do these animals have in common? They all use their forearms to move around. Well, all except us, although we used to, a log long long long time ago.

But we don’t now, so this truly is a vestigial feature. And that’s why only some of us still have it. In a small percentage of modern humans, the palmaris longus just doesn’t exist. That’s evolution in action.

How do you know if you’re part of the 10-15% without it? Touch your pinky finger to your thumb and look for the raised tendon in your wrist. That tendon connects to the muscle, so if you see it, you’re more monkey.  If you don’t see it, congrats. You’ve evolved.

Male nipples

Source: Zureks / Wikimedia

Why do men have nipples? They really are useless, unless you plan on serving up some milk to a baby.

See, nipples first appear in the womb, where for the first few weeks of development we are all female. We all have wombs and other lady bits, including nipples. But after a few months those of us who are XY in the chromosomal department start producing testosterone, which changes the embryo into a boy. Lady bits become manly bits, all except the nipples. For whatever reason, those stick around.

One could argue that men have nipples because evolution is random. If we were designed, men probably wouldn’t have nipples. They’d be a loose thread that a careful creator would snip off to be clean an efficient. Or maybe men have nipples because we were all designed, and that wise creator knew that someday some boys would want to become girls, and pre-existing nipples would make the gender switch a whole lot easier. Or maybe men have nipples because the spaghetti monster in the sky just has a wacky sense of humour. Who knows.

Maybe once upon a time we all had a bunch of nipples lined up on our chests. You now, like dogs have. It might seem crazy, but during those turbulent first weeks in utero, we all have multiple sets of nipples which disappear before we’re born.

Coccyx

Source: BodyParts3D is made by DBCLS

The coccyx is a little triangular structure of bone at the bottom of your spine, commonly known as the tailbone. Common wisdom has it that it doesn’t really do anything except hurt like hell when you fall on your ass, but that’s not entirely true. It’s actually a place where various muscles, ligaments, and tendons can attach, and helps us sit properly.

Now you may have noticed that humans don’t have tails, but this little anatomical anomaly suggests that we once did. It’s another one of Charles Darwin’s rudimentary features of human anatomy, and even today our opinion of the coccyx is clouded by the effect of Darwinian thought on modern science. Maybe it had nothing to do with an actual tail, maybe it is just an anchor point at the base of the spine, but it’s hard to shake off an idea planted by Mr. Darwin.

Wisdom teeth

Source: Coronation Dental Specialty Group

For most modern humans, wisdom teeth are just something to get rid of. Our jaws just aren’t big enough to fit all those extra chompers in there. And since our diet no longer consists of raw meat that needs to be chewed up a lot, we don’t need them.

Back in the day, having a third set of molars was handy. Along with raw meat, our ancestors ate lot of really tough food like leaves and nuts and plant roots. An inordinate amount of time was spent chewing, and all that grinding of hard stuff in their mouths was greatly aided by wisdom teeth.

As for why they’re called “wisdom” teeth, most experts think it either stems from the Dutch “verstandskiezen,” which means “far standing tooth,” or from the Latin “dens sapientiae” which literally means wisdom tooth. Maybe because they usually appear around the age 17-25 years, or around the time people get old enough to gain a little wisdom.

Body hair

Fans of vestigial body parts like to say that back before we all ran around wearing sweaters and using electric baseboard heating in our caves, humans were cold a lot of the time. And in these bad old days, a nice later of body hair would not have been something to wax away, it would have been a good thing. A warm thing.

And maybe that’s true, but it’s also overlooking a lot of other things body hair does for us. Our hair can’t feel anything, thank goodness, or trips to the salon would require general anaesthetic. But the follicles at the base of the hair are rich with nerve connections, and we actually do a lot of our feeling through the hairs on our skin.

Our various hairs also do a lot other things, like help radiate pheromonal scent, keep water out of your eyes, filter gunk and bugs from your nose and ears, cushion your head, regulate heat, and even communicate things like gender and health.

So…maybe not so vestigial after all.

Goosebumps

Connected to the whole body hair thing is the physical reaction to cold and stress we call goosebumps. It’s caused by an itty bitty muscle at the base of the hair follicle called the arrector pili. It literally makes your hair stand on end.

You see it in animals all the time, like cats, dogs, and other primates like chimpanzees. When they feel threatened they’ll make their fur stand up. The idea is to make themselves seem bigger and serve as a warning that there’s trouble a-brewing so you’d better back the eff off. And if they’re cold, it helps trap a layer of insulating air under the fur to keep a little warmer.

For a 21st Century human, there’s not a lot of need for that kind of behaviour. Even for a human long ago, it didn’t do much. Odds are this is a vestigial carry-over from pre-human days, from an ancestor that is even further back up the evolutionary chain. Like a chimp.

Shrinking brain

Source: _DJ_

One thing we humans pride ourselves on is our big sophisticated brain. It took millions of years for our brains to get big enough for us to invent things like fire and Netflix, but the undeniable evidence shows that over the past 20 thousand years or so, our wonderful brains have been steadily shrinking in size.

So, are we getting dumber, or what? Er…maybe?

The fossil record shows that Cro-Magnon man had a bigger brain than we do. Since we’ve evolved into modern humans, we’ve lost about a tennis ball sized chunk of grey matter. But, when you consider that Cro-Magnon had a much bigger physique, with loads more muscle, that sort of makes sense. Big animals tend to have bigger brains, and the ratio of brain size to body size for Cro-Magnon is the same as it is for us.

But here’s the thing: on the evolutionary scale, 20,000 years is nothing. It’s a sneeze. And to change that much, that fast…well, it’s significant.

Some suggest it could be because our switch to an agrarian lifestyle actually meant we had worse nutrition, so our smaller brains are because of chronic malnutrition until we really figured out this whole farming business.

Other look at the evidence and see a correlation between population density and brain size, and draw the conclusion that as we started living in big groups we didn’t need to be as clever to survive.

Of course, we aren’t the only creatures to have lost brain size. When you look at all the animals we have domesticated, every single one has lost 10-15 percent of the brain size they had in the wild. So maybe human beings have become more domesticated too. Less wild. Less violent. Less…animalistic. Maybe a smaller brain means a more civilized temperament.

But we like the more upbeat hypothesis that our brains are smaller because they can be. Today’s human brain just works better than our Cro-Magnon ancestors’, so we are able to do more with less. And because the brain is such an energy hog, using up a whopping 20% of the calories we burn on a daily basis, a smaller brain is just more efficient.

Which is great, except for one thing. When you look at the relationship in modern humans between IQ and brain size, you find that smarter people really do have bigger brains.

Well ain’t that just a kick to the coccyx.

Watch: 10 Unnecessary Things Evolution Has Left on Your Body


Sources