A protruding strut of bone. A sticky-outy bit. A chin.

January 29, 2016 7:03 AM

We're the only animals with chins, and no one knows why. "I always get entertaining emails from lay people trying to help me so let me thank you in advance for what I'm about to receive."
posted by Metroid Baby (73 comments total)

Elephants also have chins.
posted by humanfont at 7:05 AM on January 29, 2016 [8 favorites]

Also chins are probably a byproduct of domestication syndrome. This results in a shortened jaw and rounder faces. As humans formed larger social groups natural selection favored less agressive individuals, resulting in a kind of self-domestication of humans. The chin got left behind as your jaw got smaller. Also you probably had to have your wisdom teeth removed because your mouth is too small.
posted by humanfont at 7:11 AM on January 29, 2016 [1 favorite]

It's an obvious evolutionary disadvantage when dealing with angry old ladies...

Warning: goofy mouth- and chin-related horror movie gross out... no blood though.
posted by Huck500 at 7:11 AM on January 29, 2016 [1 favorite]

I'll thank you not to make assumptions about the number of chins I may or may not have. It goes from 0 to about 7 depending on how I hold my head. #notallhumans
posted by phunniemee at 7:15 AM on January 29, 2016 [11 favorites]

A guy in a fedora once hit on me in a bar by telling me I had a really cute chin.

We're married now.

(No, I made that part up. I refused to let him buy me a drink and left the bar to go home and read a book.)
posted by sallybrown at 7:16 AM on January 29, 2016 [42 favorites]

I will believe to my dying day that my cat has a chin - after all, don't I often say "oooh, who wants me to pet her little cat chin?" Also she has eyelashes. And little tiny back leg elbows.

Say what you will, so-called "Science".
posted by Frowner at 7:18 AM on January 29, 2016 [24 favorites]

It's more that we've got receding mouths.

Everything else has sticky-out mouths in order to be able to bite things out there, but we don't need to bite things like that because we've got better ways of killing things and we can stuff food right down into our face with our hands.
posted by Segundus at 7:19 AM on January 29, 2016 [26 favorites]

we've got better ways of killing things and we can stuff food right down into our face with our hands

kind of want this on a t-shirt now tbh
posted by phunniemee at 7:23 AM on January 29, 2016 [26 favorites]

I was totally going to cite The Three Little Pigs as proof that pigs have chins but then I looked at the article and it smacked me down in the first four sentences.
posted by XMLicious at 7:23 AM on January 29, 2016 [2 favorites]

Obviously chins are related to our increased brain capacity. When our brains are in contemplative mode, we need something to either stroke, or rest our massive craniums upon. In the case of the former, to create sensory 'white noise', and in the latter, to relieve the brain of distracting corporeal concerns by resting the head upon chin upon fist, and this lets our brains get on with the task of thinking.
posted by Capt. Renault at 7:25 AM on January 29, 2016 [11 favorites]

I would have thought the reason we have chins was clear. Without chins, would we have Bruce Campbell?
posted by mwhybark at 7:27 AM on January 29, 2016 [11 favorites]

Elephants also have chins.

The author of The Atlantic article, Ed Yong, posted a well-reasoned rebuttal to the idea that elephants have chins similar to humans this morning.
posted by zarq at 7:28 AM on January 29, 2016 [2 favorites]

Band name? Lotsa Chin and the Spandrels.
posted by notyou at 7:28 AM on January 29, 2016 [5 favorites]

I would have thought the reason we have chins was clear. Without chins, would we have Bruce Campbell?

To counter: would we have Jay Leno?
posted by Etrigan at 7:29 AM on January 29, 2016 [7 favorites]

I remember running into the hypothesis that breasts stick out in humans because our faces are flatter which means that suckling at a flat surface is more difficult. I'm at work, so I'm a little scared to try and google it right now.

I don't know if it's true, but I tend to like it more than any evolutionary psychology story about breasts replicating buttocks, but that may just be me. (Also, breasts don't really do that unless you stick them in a push-up bra, but that's neither here nor there.)

Anyway, the idea that breasts evolved as a response to chins makes it so that chins were actually a disadvantage during this period. And if they're spandrels, not features, makes me wonder why they would have stuck around. Which makes me wonder about the original hypothesis about breasts.

/tangent
posted by Hactar at 7:30 AM on January 29, 2016 [9 favorites]

Yeah, but infant chins are kinda tucked out of the way behind the cherubic cheeks and mouths and stuff, so maybe not a factor.
posted by notyou at 7:32 AM on January 29, 2016 [1 favorite]

Fun fact: the Russian word for 'chin' is подбородок, literally 'the thing under [под] your beard [борода].'

/a guy with a beard
posted by languagehat at 7:34 AM on January 29, 2016 [25 favorites]

Sheepshead wrasse is a fish with a jaw that slopes forward...and ends in a prominent knob... Why does that not count as a chin?
posted by midmarch snowman at 7:46 AM on January 29, 2016 [1 favorite]

Pampush doubts that chins are adaptations at all. He thinks it's more likely that they are spandrels—incidental features that have no benefits in themselves, but are byproducts of evolution acting upon something else.

Spandrels?
posted by leotrotsky at 7:49 AM on January 29, 2016

Spandrels.
posted by peeedro at 7:52 AM on January 29, 2016

Spaniels.
posted by Rock Steady at 7:56 AM on January 29, 2016 [6 favorites]

S'mandrills.
posted by phunniemee at 8:00 AM on January 29, 2016 [3 favorites]

Spangles.
posted by flabdablet at 8:05 AM on January 29, 2016 [3 favorites]

It's natural selection. Paleo-Dude-Bros who could survive a sock on the jaw, & go on to breed, out-produced the weak-chinned degenerates who fell before their mighty fists.
posted by Devils Rancher at 8:06 AM on January 29, 2016

All humans have chins but only a chosen few have butt chins, and we the butt-chinned shall lead the downtrodden of the world into a new glorious age.
posted by roger ackroyd at 8:10 AM on January 29, 2016 [5 favorites]

I believe the good people at the Super Furry Animals have already addressed the purpose of chins.

To counter: would we have Jay Leno?
He also doesn't have a spine. Or a funny bone. In brief: he'd be a worm.
posted by lmfsilva at 8:20 AM on January 29, 2016

we the butt-chinned

This was originally how the US Constitution started but the notoriously small-chinned James Madison made them change it.
posted by dephlogisticated at 8:22 AM on January 29, 2016 [9 favorites]

People would look pretty weird without chins

They really tie the face together
posted by Ray Walston, Luck Dragon at 8:32 AM on January 29, 2016 [1 favorite]

Not all of us.
posted by gottabefunky at 8:33 AM on January 29, 2016 [1 favorite]

It's a little-known fact that humans didn't start to evolve chins until Adapa U-an, a pre-ancient military defense contractor, was given the job of figuring out how to keep the soldiers' helmets from falling off, and invented the chin strap.
posted by sfenders at 8:34 AM on January 29, 2016 [2 favorites]

The Search for Animal Chin.
posted by gottabefunky at 8:37 AM on January 29, 2016

🤔
posted by bonje at 8:40 AM on January 29, 2016 [2 favorites]

I will believe to my dying day that my cat has a chin - after all, don't I often say "oooh, who wants me to pet her little cat chin?"


Norma had a chin, but she also had butt cheeks and a semi-prehensile tail, so.
posted by louche mustachio at 8:52 AM on January 29, 2016

Add another thing to the list of google searches I hadn't expected to need: "elephant chin"

Now I need to come up with a great theory for the chin and present it at next year's BAHFest.
posted by numaner at 8:57 AM on January 29, 2016

I like the idea that we need a shelf to rest our heavy brains on when we are sitting/squatting, thus chin. A smoothly-sloping skull works for four-legged animals because their whole mandible can be rested on something (like my lap, you sweet widdle puppy you).
posted by muddgirl at 9:03 AM on January 29, 2016 [1 favorite]

More than you ever wanted to know about the human chin:

The human chin revisited: what is it and who has it? (PDF)

Even if you don't want to slog though all the technical language and discussion it is worth it for all the pictures of fossil chins. Also, according to this paper Elephant chins are not the same as ours:

Morphologically, the primary implication of our observations is that a bulging symphyseal region is not equivalent to a chin. When humans and elephants can both be described as having chins, it is probably time to reconsider the applicability of the term. Consequently, we recommend that the term ‘‘chin’’ no longer be used in discussions of mandibular morphology and its phylogenetic and systematic significance. If, however, one feels the need to retain this term, it should be restricted in usage only to extant H. sapiens and those fossils displaying the constellation of symphyseal features of this species.
posted by AElfwine Evenstar at 9:03 AM on January 29, 2016 [2 favorites]

Pffft. Next you'll be trying to tell me that tardigrades don't have real chins either.
posted by flabdablet at 9:19 AM on January 29, 2016

We simply couldn't think without chins.
posted by Alter Cocker at 9:33 AM on January 29, 2016

Spandrels?

Spandrels.

My level 9 gnome wizard is named Proscenium Spandrel.
posted by NMcCoy at 9:36 AM on January 29, 2016 [1 favorite]

More examples of the No True Chin" fallacy.
posted by GenjiandProust at 9:50 AM on January 29, 2016 [3 favorites]

Paleo-Dude-Bros who could survive a sock on the jaw, & go on to breed, out-produced the weak-chinned degenerates who fell before their mighty fists.

This concept was documented in the movie Chinny Chinny Bang Bang
posted by maxwelton at 9:53 AM on January 29, 2016 [2 favorites]

Spaniards
posted by briank at 9:59 AM on January 29, 2016

Castleton snobs.
posted by AndrewInDC at 10:07 AM on January 29, 2016

More than you ever wanted to know about the human chin:

The human chin revisited: what is it and who has it? (PDF)


TL;DR : while the authors shed little light on the exact evolutionary purpose of the chin, they are clear in stating that its presence is a chief factor in determining the split between neanderthal specimens and H. sapiens (before dna was available), i.e neanderthals din't have chins.
posted by OHenryPacey at 10:19 AM on January 29, 2016 [1 favorite]

I will believe to my dying day that my cat has a chin - after all, don't I often say "oooh, who wants me to pet her little cat chin?"

Thank you. I feel better knowing that I'm not the only person who immediately leapt to the "But... my cat!" argument.
posted by mudpuppie at 10:33 AM on January 29, 2016 [2 favorites]

Metafilter: better ways of killing things

Metafilter: kind of want this on a t-shirt now tbh

Metafilter: We've Got Spandrels
posted by nebulawindphone at 10:41 AM on January 29, 2016 [1 favorite]

So British'll have something to keep. Duh.
posted by Mental Wimp at 10:50 AM on January 29, 2016

Where is MetaFilter's Own Stan Chin during all of this???
posted by oneswellfoop at 10:52 AM on January 29, 2016

oneswellfoop: Where is MetaFilter's Own Stan Chin during all of this???

By day, he's a mild-mannered Metafilter commenter. But when night falls....
posted by zarq at 11:01 AM on January 29, 2016

I assume we have it because we're the only primate that talks. I think it has a role in providing more strength and control to the jaw area to help us talk more clearly. Clearly we need an experiment where monkeys strap on giant fake Jay Leno chins and then try to talk like us. In fact I think I saw something like that on TV last night.
posted by w0mbat at 11:06 AM on January 29, 2016 [2 favorites]

I remember running into the hypothesis that breasts stick out in humans because our faces are flatter which means that suckling at a flat surface is more difficult. I'm at work, so I'm a little scared to try and google it right now.

Why don't the nipples stick out like monkeys and apes?
posted by sebastienbailard at 11:57 AM on January 29, 2016

The "hands evolved for punching" scientists talked about the evolution of face shape and suggested that the face also evolved for punching: Our faces may have gotten flatter because a sticking-way-out ape jaw gives a punch much more leverage to overcome the strength of the neck muscles. Overcoming the neck muscles and rotating the head with a punch causes the brain to bounce around in the skull and can knock you unconscious.

So that could explain why our faces got flatter... but not why the chin kept sticking out, just waiting to be mentioned in every boxing commentary ever.
posted by clawsoon at 12:29 PM on January 29, 2016 [1 favorite]

When human males get aggressive they often just out their chins (and puff out their chests). Which is really weird. Since the human chin is a handy knock out button.

In boxing the tough guys that were used to physically intimidating people on the street we had work very hard get them off that reaction and tuck their chins in the ring.

Seems like an evolutionary bug, maybe?
posted by innocentsabored at 12:30 PM on January 29, 2016 [1 favorite]

Clawsoon beat me to it. Strange, huh?
posted by innocentsabored at 12:31 PM on January 29, 2016

Or chin-jutting is like stotting, an "honest signal" that says you can take a punch so it's not even worth fighting you in the first place.

A worthwhile signal to send on the street; not so worthwhile when you're in the ring with someone who's going to fight you anyway.
posted by clawsoon at 12:42 PM on January 29, 2016 [1 favorite]

So let's start a list of what is physically exclusively human :

Chins

Male nonfunctional nipples

That ridged area under our noses

. . . .?
posted by rtimmel at 12:45 PM on January 29, 2016

Damnit, take the Philtrum (the nose thing) off the list. According to Wikipedia, lots of animals have it - it just still serves a function.
posted by rtimmel at 12:48 PM on January 29, 2016

I'm pretty sure my male dog has nonfunctional nipples...
posted by muddgirl at 12:51 PM on January 29, 2016 [2 favorites]

rtimmel: That ridged area under our noses

...is called a philtrum. But it is not unique to humans. Years ago, I read the novelization of the first Superman movie with Christopher Reeve, and the author mentioned that our philtrums are unique to humans, and the reason we are the only animals that can smile. Wrong on both counts.

Our brains are different, obviously.
We have greater finger flexibility than any other primate. We can touch our ring fingers with our thumbs.
We have a descended larynx, which helps allow human speech, and a descended hyoid bone under our tongues which allows us to articulate words when we speak.
posted by zarq at 12:55 PM on January 29, 2016

Huh. The descended larynx is not uniquely human either.

Am learning all sorts of things from this thread.
posted by zarq at 12:57 PM on January 29, 2016

I'm pretty sure my male dog has nonfunctional nipples...

I'm nearly positive that all male mammals have them.
posted by zarq at 1:02 PM on January 29, 2016

So let's start a list of what is physically exclusively human :

That weird dorsal fin thing on my back that expands when I become enraged. you know. Like all men.

Right?



Whut? Another thing my mom lied to me about?
posted by innocentsabored at 1:28 PM on January 29, 2016 [2 favorites]

Male nipples can function if you are determined enough.
posted by humanfont at 1:39 PM on January 29, 2016 [1 favorite]

Or if you have male galactorrhea.
posted by clawsoon at 1:58 PM on January 29, 2016

If dogs didn't have chins, where would their old-age goatees go?

I was totally going to cite The Three Little Pigs as proof that pigs have chins but then I looked at the article and it smacked me down in the first four sentences.

That's what Big Bad Wolf wants you to believe.
posted by Room 641-A at 2:01 PM on January 29, 2016

Male nipples can function if you are determined enough.

It also depends what you want that function to be. I mean, with the right piercing, you always have a place to keep your locker key while you're swimming.
posted by GenjiandProust at 2:34 PM on January 29, 2016 [4 favorites]

Or...Intelligent Design aiming for Kirk Douglas. Duh.
posted by Abehammerb Lincoln at 4:21 PM on January 29, 2016

>while the authors shed little light on the exact evolutionary purpose of the chin

Yeah, there's really no consensus on the purpose of the human chin. Explanations have ranged from functional morphology related to bio-mechanical masticatory stresses to some form of sexual selection. Homo sapiens have highly derived cranial and postcranial morphology so it's really not surprising that something like a chin might be the result of a perfect storm of several functional adaptations acquired over the course of genus Homo's evolution (the last 6 million years).
posted by AElfwine Evenstar at 4:39 PM on January 29, 2016

Zarq: Years ago, I read the novelization of the first Superman movie with Christopher Reeve, and the author mentioned that our philtrums are unique to humans, and the reason we are the only animals that can smile. Wrong on both counts.

This is literally the only thing I remember from reading the Superman novelisation as a lovestruck preteen. I'm appalled to learn it's not true.
posted by tavegyl at 4:39 PM on January 29, 2016 [3 favorites]

Let's start a male nipple club guys

I've got two
posted by Ray Walston, Luck Dragon at 1:45 PM on January 30, 2016

Quit bragging, Ray.
posted by Etrigan at 3:31 PM on January 30, 2016 [2 favorites]

Sorry Ray, you can't be part of male nipple club until you've proven they're nonfunctional.
posted by sebastienbailard at 4:39 PM on January 30, 2016

Does anyone else wish that the first rule of male nipple club was "no one talks about it?"
posted by GenjiandProust at 6:59 PM on January 30, 2016 [2 favorites]