Why do we have chins?

[sunbear]

Some of us have more chins than others, but why do we have chins? Other creatures get along without them.

[Satan]

Ther're a natural biproduct of the kind of FACE we have, and the type of body it's perched upon.

All mamals with similar structures - mostly simian beings - have chins, or a semblance of a chin to my knowledge.

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Yer pal,
Satan

[sunbear]

They do? Chimpanzees have a sort of round jaw, for instance.

[Therealbubba]

Chin/Jaw Jaw/Chin. One in the same. I just checked both of our cats, and they've got chin/jaws too. Helps with chewing and talking/meowing. I suppose you could have a jaw and no chin if your mouth was located in the middle of your face, between the nose and eyes, but nature saw fit to do it the way it is now.

Therealbubba

[Doobieous]

Well, from what i heard on a TV show on the Discovery Channel once, all mammals and mammal like animals (me thinks) have chins, but humans are the only ones with forward protruding chins. Don't know the reason, but that's what I've heard.

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'The beginning calls for courage; the end demands care'

[sunbear]

Ok, so now we are looking for forward protuding chins.
Some links to primates that I found. Should show the weak chins of apes: http://www.skullsunlimited.com/PhiladelphiaZoo.htm http://www.neanderthal.de/ http://www.primates-online.com/
I think that had the best side view of an ape http://www.bergen.org/Smithsonian/prigal.html

[handy]

No none knows why we have chins.

Frankly, I'd be more interested in why they call them chins.

[JBENZ]

Quote:
Frankly, I'd be more interested in why they call them chins.

Easy one...'cause they'd already used "wang" for something else.

Browsing the Peking phone book.



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JB
Lex Non Favet Delictorum Votis

[manhattan]

We have chins so we have something to keep up when misfortune befalls us. As JBENZS alluded to, the old expression, "Keep your wang up," became, uh, problematic when the English language developed slang.

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Livin' on Tums, Vitamin E and Rogaine

[Temujin]

My WAG is that we have chins because chins were an attribute that the opposite sex found attractive. Slowly, over the millenia, selective breeding creating humans with larger chins.

Or maybe that's what happened with wangs ...

[Lissa]

My WAG is that we have chins because chins were an attribute that the opposite sex found attractive. Slowly, over the millenia, selective breeding creating humans with larger chins.

Then Jay Leno ought to be voted Sexiest Man Alive.

[sunbear]

Oh oh..where's this going..and where is Dr.Fidelius with a good WAG?

[Markxxx]

If we didn't have chins the people who make chin staps would be unemployed. :)

[aseymayo]

Okay, I give. I've tried looking it up with no result. What the hell is neotony?

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Bluecher!

[sunbear]

Lumpy has an original idea. There were hominids with much larger jaws at about the time of homo erectus.They died out soon, brains too small..etc.

[bill422]

Neotony is the concept of organisms becoming sexually mature while maintaining juvenile characteristics. Mudpuppy salamanders are the classic example. As an amphibian they have the tadpole stage, then begin to mature (lose the gills, get lungs, live out of water etc.) but they are able to reproduce before they mature physically, and in fact never "completely" mature in the sense that other amphibs do.

Humans are similar in that we maintain the juvenile/infant characteristics of a typical primate which include relatively hairless, larger brainsize, and flattened faces. A part of being more infant like (when compared to other primates) is we get the advantage of prolonged parental care, and an extended period where our brains are developing and able to learn more complex things.

Part of maintaining this infant/juvenile primate appearance in the adult form (neotony) is that our faces don't protrude past our chins.

The reason we have chins is to distinguish we "common plebleans" from members of the British Royal Family.

Or other primates.(See Chimp reference above)

We hope this slander has made your day a little <strike>more surreal</strike> brighter.

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YO-HO, ME HEARTIES! ALL HANDS ON DECK FOR THE MUSICAL BATTLE AT SEA!

[Lissa]

Sealemon88: Or maybe that's what happened with wangs ...
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Oh, don't I wish.

Actually, for their body size, humans do have one of the largest penises of all the species. IIRC, either human males have the largest penises (adjusting for body size) or the chimpanzees do. Damn, I'm always forgetting these things.

[bill422]

Why forward protruding chins?

Neotony.

(Longer answer available upon request)

[John W. Kennedy]

Pigs and humans alone have chins (it's not just the forward jutting -- there's a reinforcing bone there that other critters don't have).

The only obvious connection would be an omnivorous diet, since one rarely sees pigs boxing.

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John W. Kennedy
"Compact is becoming contract; man only earns and pays."
-- Charles Williams

[NanoByte]

But human fetuses, as well as others, don't have as much chin as a young human adult, and an old human adult is more likely to have a more pronounced chin than a young one.

Chins are so they can sell more razor blades or electric shaver combs.

So retire to the laboratory and give people without chins a rough time and see what happens to them that would be less likely to happen to the well-chinned.

Ray (If you didn't have a chin, what would you take it on?)

[bill422]

I respectfully disagree with the pig/human extra bone idea.

All mammals have two bones in their lower jaw the dental bone (the chin) and the mastoid bone (the bone that connects to the skull). Reptiles, conversly have four bones in the lower jaw (the dental bone IS one of the four). This is a primary way paleontologists can distinguish between reptile fossils and mammal fossils.
So all mammals have the dental bone (Pigs and humans don't have an extra "reinforcing" bone). Incidently, I don't remember my pig skulls having a forward protruding dental bone...I'll have to dig them out and look more closely, but I think they didn't.

The whole question of why we have chins is silly. We have them to support our lower teeth, there's no other reason.

The answer to the question of why ours protrude and most others don't is still

Neotony.

[Konrad]

If the question is why are our chins shaped that way then part of the reason may be our brains. In certain humans and most animals the jaw muscles take up a large part of the space inside the skull, but that's ok cause their brains are small. A good example would be the alligator's head.

Another reason is, of course, our diet and posture. Our chins stick out because our head is not pointed along our bodies as most animal's head are. Also if you look at early humans their chins are very different, probably because of changes in diet.

[Sealemon88]

My WAG is that we have chins because chins were an attribute that the opposite sex found attractive. Slowly, over the millenia, selective breeding creating humans with larger chins.
Or maybe that's what happened with wangs ...


Oh, don't I wish.

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You say "cheesy" like that's a BAD thing.

[Lumpy]

A protruding chin is the unique hallmark of Homo Sapiens. Neanderthan man, Homo Erectus, et al, have a rounded chin. I think that it's more a case of the rest of our lower jaw having shrunk and receded, leaving that knob of bone sticking out.

I recently read a fascinating book called "The Face," which postulated that chins (and large noses) are actually on their way out in an evolutionary sense. It's a great book, it talks about why we have the kind of eyes, ears, etc., that we do, what what kind of faces have been found attrative through the years.

The vanishing chin theory, though, leads me to assume that earth will someday become The Planet of the Liza Minnellis. "A planet where Liza Minnellis evolved from man?" "Get your stinkin' false fingernails off me, ya lousy Liza Minnelli!" "Oh my god, it talks--isn't that FABULOUS?"

[NanoByte]

Please note that the hypothesis of my previous post shall be termed the 'Roll-Bar Theory'.

Ray (author of the more general (not generic) theory that heads bounced once in a while tend to work better.)

[sunbear]

Flora: are we still evolving? I thought we pretty much quit, long before recorded history. There are no special environments anymore, we handle all of them. Other than south american natives that evolved for higher altitudes, I can't think of much.

[NanoByte]

Well, getting back to taking it on the chin. How about looking at it this way (no pigs, no Beijing phone directories). As an expert at falling on my face, I say:

Homo's the only mammal that really took to running fast and well on his hind feet, and sapiens honed it up the best,. . .but, if you fall on your face, and you don't have a chin, you can more easily knock out all your teeth. And if you're in the jungle, that might mean you don't eat much anymore. You don't eat, you don't proliferate. QED

Lab test: Ran down a trail yesterday. Fell a time or two, but chickened out of falling on my face. So we can still say: "Needs further study."

Ray (slowly arising and removing the rubble from his stubble)

[Abe]

Evolution is not something that stops happening; it is comprised of a series of (usually) gradual changes that, through reproduction of the individuals possessing these traits, become normal.

As for special environments and the changes that the environment can bring to the human body, the most dramatic examples are the Inuit and Australian aborigines. From what I have read, the Inuit are so physically adapted to extreme cold that they are able to draw blood away from their extremities to prevent it from cooling excessively. The Australian Aborigines are humans, yet they are able to control their temperature internally without sweating (sweating is an excellent cooling technique for other humans, but to Aborigines, who survive on miniscule quantities of water, it would be devastating to bust a sweat and waste precious fluid).

A lot of features are influenced by our ancestors' environment. The epicanthic eye fold most Asians have is thought to help protect from cold. Long noses are an evolutionary benefit that allow to humidify dry air, heat up cold air, and filter pollution (dirt, pollen, etc.) by means of nose hair and turbinate filtration. Long noses take the strain off the rest of our breathing apparatus.

Some people have proposed that we are evolving weaker arms, although I don't know if this is true.

About neotony; isn't it spelled "neoteny"?



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Abe
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"For what is myth, but the deconstructive prose of a missing literary critic who lisps?"
--Harry Harrison