6 Human Quirks You Didn't Know Have Evolutionary Origins

5 Sighing Prevents Suffocation

You may not be able to do anything about that impossible deadline your boss assigned you or that cute girl in algebra class who will never acknowledge your existence, but you can sigh heavily about both. Which is as good as doing nothing, but more passive-aggressively dramatic. And yet, according to science, all that sighing serves a secondary, arguably more important function: making sure you don't slowly suffocate to death.

Your lungs contain scads of tiny air sacs called alveoli, which exchange carbon dioxide for oxygen, allowing you to continue doing your two favorite things: living and breathing. Thing is, they also tend to collapse over time. Luckily, we also have a built-in mechanism for preventing that: taking an extra-large gulp of air, also known as a sigh. This simple act pops those little bastards right back open and keeps you living, no matter how badly you wish you could die already.

4 You Talk Like That Because Of The Environment

Why does Spanish sound so sexy, while Swedish is fodder for Muppet mockery? The "acoustic adaptation" theory posits that a region's climate has a direct and profound effect on the languages that develop in that area. In essence, the evolution of a place's lingo is influenced by the landscape, temperatures, and even rainfall of the locale, all of which are factors determining which sounds will be used frequently and which won't. The reason is simple physics: Sound waves don't behave the same in the woods as they do in open fields, and they behave differently yet in snowy mountains.

For instance, consonants are easily distorted or lost altogether in a rainforest, making them the weakest link in a language evolving in such an environment. By the time you've figured out what "etch ou fo tha agua" means, you've been eaten by a jaguar. Conversely, the consonant-heavy Germanic languages, such as English, could develop quite nicely in the hills of Europe, where the acoustics are perfect for warning people about marauding Visigoths, who ironically are not easily visible.

3 Shaking Your Head Originally Meant You Were Full

Next to throwing up the horns whenever somebody mentions Slayer, the most universally recognized human gesture is the head shake, which signifies a negative response. But what a strange way to communicate that. What logical relation could there possibly be between turning your head from side to side and denying a proffered Double Down?

That is in fact a pertinent example, because the prevailing theory on the origin of the head shake is food-related. Since babies don't have the whole "language" thing down yet, they simply turn their heads away from food when they're full. This simple denial of food mentally links the gesture to the concept of negation, and it's this relationship which survives into our adult lives, where it can serve many purposes, ranging from "not hungry" to "not right now" to "that is not my German porn, and I will not dignify your accusations with a verbal response."

Related: 5 Iconic Movie Pieces (That Were Meant To Be Cut)

2 Scowling Is Flexing (With Your Face)

Hey, we heard your mom's college nickname was Clappy McCondomTrap. You're a biological curiosity -- the first human conceived not by your father's sperm, but by his tears of regret. Your mom's vagina is like a Slip 'n' Slide, if a Slip 'n' Slide were bigger, floppier, and more prone to misuse.

Are you angry yet? Good!

Look at your face: You're scowling. Why are you doing that, aside from all of our needlessly personal insults about your mother? Researchers from the University of California at Santa Barbara and Griffith University in Australia set out to answer that. While science has long considered the "anger face" to be an ingrained facet of our basic biology, its origins are more enigmatic. So professors Aaron Sell, Leda Cosmides, and John Tooby set out to explain why the contraction of seven distinct muscle groups -- "lowered brow ... raised cheekbones (as in a snarl), lips thinned and pushed out, the mouth raised (as in defiance), the nose flared and the chin pushed out and up" -- is the universal human expression of anger. To do so, they isolated each component of the "anger face" and showed the resulting computer-generated faces to test subjects. And even when shown in isolation -- only the lowered brow or just the thinned lips, for instance -- subjects reported that the expressions made the depicted individual look physically stronger.

1 We Call Our Parents "Mama" And "Dada" Because They're The Easiest "Words" To Say

Unless you've royally screwed up and your baby's first words are "I pwead the fifth," they were probably either "mama," or "dada." And oddly enough, those words sound very similar in every single language, all across the globe. American and European children usually go with "mama" and "papa," Chinese babies prefer "mama" and "baba," while Turkish kids go with "ana" and "baba." You're probably wondering how this is even possible. The answer, of course, is ancient aliens.

Actually, linguistics pioneer Roman Jakobson solved this peculiar phenomenon decades ago. He theorized that babies aren't simply hopelessly unoriginal, but rather desperately trying to get a grip on this whole "articulation" thing. This process mainly involves a buttload of gibberish, but Jakobson discovered that there's a technical side to it as well. Speech sounds are acquired in a specific order, based on their complexity.

This means that, while enunciations which require all sorts of fancy vocal acrobatics, like r and w, are learned relatively late, mmm is the result of an infant seeing what happens when they fire off their vocal cords while keeping their trap shut. Doing the same thing with their mouth wide open results in ah. Getting from m to p requires only the addition of a small puff of air.

So because babies are lazy little idiots, the first sounds they begin repeating are "mama" and "papa," and emotional parents adopt those as their loving nicknames. Also because they're lazy little idiots. We're all lazy little idiots, when you get right down to it.

When he's not busy keeping from going extinct, Guidodo is on Facebook. Bayfman writes about science at night and teaches it in the day. You can email him here.

For more questions brainiacs have found the answers to, check out 8 Simple Questions You Won't Believe Science Can't Answer and 5 Stupid Questions You Won't Believe Scientists Answered.

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