# Chins, evolution, and pointless survival
**URL:** https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947
**Category:** In My Humble Opinion
**Created:** [July 31, 2019, 7:26pm UTC](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947 "2019-07-31T19:26:46Z")
**Posts on this page:** 16
**Page:** 2
### Author:  [@Max\_S](https://boards.straightdope.com/u/Max_S)
#### Post date: [August 1, 2019, 1:52pm UTC](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947/21 "2019-08-01T13:52:50Z")
> [@CalMeacham](#):
>
> In other words, survival of the chin isn’t pointless. A pointed chin has a point.
“Chin-tastic!” ~Crimson Chin
~Max
---
### Author:  [@dropzone](https://boards.straightdope.com/u/dropzone)
#### Post date: [August 1, 2019, 2:47pm UTC](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947/22 "2019-08-01T14:47:37Z")
> [@CalMeacham](#):
>
> I submit that the flaw in your argument isn’t that it got _one_ caveman laid, but a whole succession of them, where they were chosen by discriminating cavewomen over competing Chinless Wonders. And that, in fact, the trend continued long after cavemen days. That’s how sexual selection works. If it didn’t, eventually the Chinless Wonders would eventually be successful enough to make chinlessness as common as prominent chins.
What flaw? May I remind you:
> [@dropzone](#):
>
> …my best guess is that one guy had one, the ladies swooned, and lots of little Cary Grants were born. Then one of those evolutionary bottlenecks reduced the human population to mostly members of the Cary Grant tribe and Bob’s your uncle, here we are, sharing a feature with the only advantage of getting one caveman laid.
The implication being that subsequent generations of cavegirls found it hot and wanted a boy just like the boy that married dear, old mom.
> [@Toxylon](#):
>
> [Male chins do offer a survival advantage](https://www.bbc.com/news/science-environment-27720617)
Interesting Just So Story, and those become testable hypotheses. I like it, but it needs testing. **Toxylon** , hold my beer. **Cal** , stand right here. 😃
---
### Author:  [@Earl\_Snake-Hips\_Tucker](https://boards.straightdope.com/u/Earl_Snake-Hips_Tucker)
#### Post date: [August 1, 2019, 2:59pm UTC](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947/23 "2019-08-01T14:59:21Z")
I have nothing to add to the discussion, but will just offer that every time I see this thread title, I do a double-take, because I think it says
“China, evolution, and pointless survival”
Yeah, I need reading glasses, but I’m putting it off as long as I can.
---
### Author:  [@MrDibble](https://boards.straightdope.com/u/MrDibble)
#### Post date: [August 1, 2019, 4:13pm UTC](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947/24 "2019-08-01T16:13:10Z")
> [@CalMeacham](#):
>
> I agree with Desmond Morris ( who, before he started writing books about humans, was an animal behaviorist ) that the human nose and cleft chin represents a powerful penis-and-scrotum mimic
How does that work when the default male state seems to be “bearded”?
---
### Author:  [@lingyi](https://boards.straightdope.com/u/lingyi)
#### Post date: [August 1, 2019, 6:25pm UTC](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947/25 "2019-08-01T18:25:53Z")
When I read the title my first thought seriously was: “What does the millions of Chins have to to do with evolution and pointless survival?” 😕 I thought it was going to some rant about how the Chinese are taking over the world! :smack:
---
### Author:  [@Mcmechanic](https://boards.straightdope.com/u/Mcmechanic)
#### Post date: [August 2, 2019, 3:39am UTC](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947/26 "2019-08-02T03:39:09Z")
It seems like I remember watching a documentary about how the jaw/chin moved forward after proto-humans started cooking food,and something about this allowed the brain to increase in size do to the lack of having to have bigger jaw muscles? Something along those lines.
---
### Author:  [@lingyi](https://boards.straightdope.com/u/lingyi)
#### Post date: [August 2, 2019, 5:07am UTC](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947/27 "2019-08-02T05:07:32Z")
Ahh…I remember seeing that too!
A quick google search for “cooked food increased brain development” and “cooked food decreased mouth size” brought up the folloiwng:
Here’s an article talking directly about mouth and teeth size possibly being linked to cooked food.
"The Shape of the Matter
Over the course of the last few thousand years, the human jaw has changed shape dramatically. One of the broadest trends has been a steady decline in the size of the jaw. From around 35,000 years ago to about 10,000 years ago human jaws and teeth decreased in size by about one percent every 2,000 years. For the last ten thousand years, that pace has increased to roughly one percent every 1,000 years. In pace with our shrinking teeth and jaw, the structure of human teeth has changed as well, as thickening enamel and adaptations in technology have cut back our reliance on strong, well-ordered teeth.
Cooking has had one of the largest effects on the development of human dentition. In the distant past, when much of our diet was raw fruits and vegetables, we needed strong and straight teeth. These helped us push our way through the tough, large particles that made up our diet. Cooking has reduced our need for this ability dramatically. At its simplest, the primary goal in cooking food is to break down tough fibers in meats and vegetables, rendering our meals proportionally easier to digest. As a result, the evolutionary pressure to keep our teeth well-ordered has dropped away."
Source: [https://www.ecpi.edu/blog/evolution-teeth-how-smarts-skill-changed-human-mouth](https://www.ecpi.edu/blog/evolution-teeth-how-smarts-skill-changed-human-mouth)
And this article discusses how eating cooked food may coincide with the increase of brain size:
“Fossils show the teeth and digestive tract of Homo erectus decreased in size around the same time brain size increased. This evidence likely means our ancestors started eating softer, higher-quality foods (although not necessarily cooked). New archaeological research has also continued to push back the earliest known date for the control of fire.”
Source: [https://www.scientificamerican.com/article/food-for-thought-was-cooking-a-pivotal-step-in-human-evolution/](https://www.scientificamerican.com/article/food-for-thought-was-cooking-a-pivotal-step-in-human-evolution/)
My Google-fu is STRONG! 😛
Must be all the cooked food I eat! LOL!
---
### Author:  [@Guinastasia](https://boards.straightdope.com/u/Guinastasia)
#### Post date: [August 2, 2019, 5:13am UTC](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947/28 "2019-08-02T05:13:10Z")
Don’t want to have TOO much of a protuding chin. Surely you’ve heard of the [Habsburg jaw](https://allthatsinteresting.com/habsburg-jaw)?
---
### Author:  [@Mcmechanic](https://boards.straightdope.com/u/Mcmechanic)
#### Post date: [August 2, 2019, 5:59am UTC](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947/29 "2019-08-02T05:59:17Z")
> [@lingyi](#):
>
> Ahh…I remember seeing that too!
>
> A quick google search for “cooked food increased brain development” and “cooked food decreased mouth size” brought up the folloiwng:
>
> Here’s an article talking directly about mouth and teeth size possibly being linked to cooked food.
>
> "The Shape of the Matter
>
> Over the course of the last few thousand years, the human jaw has changed shape dramatically. One of the broadest trends has been a steady decline in the size of the jaw. From around 35,000 years ago to about 10,000 years ago human jaws and teeth decreased in size by about one percent every 2,000 years. For the last ten thousand years, that pace has increased to roughly one percent every 1,000 years. In pace with our shrinking teeth and jaw, the structure of human teeth has changed as well, as thickening enamel and adaptations in technology have cut back our reliance on strong, well-ordered teeth.
>
> Cooking has had one of the largest effects on the development of human dentition. In the distant past, when much of our diet was raw fruits and vegetables, we needed strong and straight teeth. These helped us push our way through the tough, large particles that made up our diet. Cooking has reduced our need for this ability dramatically. At its simplest, the primary goal in cooking food is to break down tough fibers in meats and vegetables, rendering our meals proportionally easier to digest. As a result, the evolutionary pressure to keep our teeth well-ordered has dropped away."
>
> Source: [https://www.ecpi.edu/blog/evolution-teeth-how-smarts-skill-changed-human-mouth](https://www.ecpi.edu/blog/evolution-teeth-how-smarts-skill-changed-human-mouth)
>
> And this article discusses how eating cooked food may coincide with the increase of brain size:
>
> “Fossils show the teeth and digestive tract of Homo erectus decreased in size around the same time brain size increased. This evidence likely means our ancestors started eating softer, higher-quality foods (although not necessarily cooked). New archaeological research has also continued to push back the earliest known date for the control of fire.”
>
> Source: [https://www.scientificamerican.com/article/food-for-thought-was-cooking-a-pivotal-step-in-human-evolution/](https://www.scientificamerican.com/article/food-for-thought-was-cooking-a-pivotal-step-in-human-evolution/)
>
> My Google-fu is STRONG! 😛
>
> Must be all the cooked food I eat! LOL!
I’m but a gnawer(is that a word?) of rawhide scraps compared to your skills, lol
---
### Author:  [@Riemann](https://boards.straightdope.com/u/Riemann)
#### Post date: [August 2, 2019, 7:23am UTC](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947/30 "2019-08-02T07:23:52Z")
> [@dropzone](#):
>
> Most people think that evolution is all about the “survival of the fittest.” This is incorrect. It is about the “survival of what didn’t kill the organism or cause the organism to be killed.” As a result animals, including modern humans, are mish mashes of advantageous features and features which have no advantage and no real purpose, but don’t get in the way.
I think “incomplete” is more accurate than “incorrect”. Evolution _by natural selection_ is indeed all about survival of the fittest (adaptation). But your point is that evolution is not just about natural selection. Evolutionary traits may also arise randomly, through genetic drift. They may evolve by drift if they are neutral to fitness; they may even evolve by drift if they _do_ “get in the way”, if they confer _lower_ fitness. This is more likely to happen in small populations, in which random fluctuations in allele frequencies have a greater effect; natural selection is more likely to remove deleterious traits in large populations.
Traits that are not adaptive in themselves may also be indirect by-products of other adaptive traits. And there’s a word for this, coined by Gould & Lewontin, an _evolutionary spandrel_.
> **[Spandrel (biology)](https://en.wikipedia.org/wiki/Spandrel_(biology))**
>
> In evolutionary biology, a spandrel is a phenotypic trait that is a byproduct of the evolution of some other characteristic, rather than a direct product of adaptive selection. Stephen Jay Gould and Richard Lewontin brought the term into biology in their 1979 paper "The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme". Adaptationism is a point of view that sees most organismal traits as adaptive products of natural selection. Gould and Lewontin so Th...
> [@markn\_1](#):
>
> No, it’s about “traits which lead to reproduction”. Any traits that allow the organism to survive at the expense of reproductive fitness will not be selected for. Any traits that do lead to reproductive success at the expense of overall fitness WILL be selected for. The classic example is the peacock’s tail, which reduces the bird’s overall fitness but attracts the peahens like crazy.
I know what you mean, but your terminology is a bit off here. There’s only one kind of fitness. Evolutionary fitness is, by definition, reproductive success (greater genetic contribution to subsequent generations). So you can’t talk about “reproductive fitness” vs “overall fitness”. It would be better to say “reproductive success” vs “survival”.
But you’re talking about adaptive traits here, about natural selection and sexual selection. Dropzone’s main point is that some traits are _not_ adaptive at all.
---
### Author:  [@Riemann](https://boards.straightdope.com/u/Riemann)
#### Post date: [August 2, 2019, 7:36am UTC](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947/31 "2019-08-02T07:36:46Z")
> [@Max\_S](#):
>
> Not entirely true. Selection of mates is a huge factor in natural selection, and seems to be the relevant one here.
>
> There are theories as to the ontogeny of the human chin, one says it facilitates speech, one says it makes it easier to chew, and another says it helps with balance when we are upright. People who speak better have an advantage both for survival and reproductive purposes. People who chew better might whine less about their gums, and therefore be slightly more attractive as a mate. We could speculate all day here, and if you are really interested I’m sure we could dig up some cites.
But you also can’t just dismiss the possibility that the chin is not adaptive at all (although I concede that seems unlikely).
---
### Author:  [@Ashtura](https://boards.straightdope.com/u/Ashtura)
#### Post date: [August 2, 2019, 4:59pm UTC](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947/32 "2019-08-02T16:59:01Z")
> [@MrDibble](#):
>
> How does that work when the default male state seems to be “bearded”?
The beard is probably so the chinless dudes can get laid too. 😃
---
### Author:  [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)
#### Post date: [August 2, 2019, 8:12pm UTC](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947/33 "2019-08-02T20:12:55Z")
My WAG: As the teeth got smaller and the jaws adapted, the chin simply didn’t follow since there was no selective advantage in doing so.
---
### Author:  [@Mcmechanic](https://boards.straightdope.com/u/Mcmechanic)
#### Post date: [August 3, 2019, 2:07am UTC](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947/34 "2019-08-03T02:07:59Z")
I just find it hard to believe that early humans were choosing mates based on chins. We’re they sitting around at le club Savanna flirting with only the big chins? Seeing how the ideal image of beauty has changed over just the last hundred years, doesn’t seem like an aesthetic feature would change the whole trajectory of human development.
---
### Author:  [@rsat3acr](https://boards.straightdope.com/u/rsat3acr)
#### Post date: [August 3, 2019, 2:10pm UTC](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947/35 "2019-08-03T14:10:22Z")
> [@Guinastasia](#):
>
> Don’t want to have TOO much of a protuding chin. Surely you’ve heard of the [Habsburg jaw](https://allthatsinteresting.com/habsburg-jaw)?
It isn’t really a protruding chin but rather a mid face deficiency. One can tell by the profile, normal is convex theirs is flat or concave. Like Jay Leno, a flat face, the chin is where it should be, the area in the middle third of the face is not far enough out.
---
### Author:  [@Trancephalic](https://boards.straightdope.com/u/Trancephalic)
#### Post date: [August 3, 2019, 2:40pm UTC](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947/36 "2019-08-03T14:40:47Z")
> [@Hari\_Seldon](#):
>
> My WAG: As the teeth got smaller and the jaws adapted, the chin simply didn’t follow since there was no selective advantage in doing so.
Chins do strike me as a remnant of a muzzle, like those still present in our chimp brothers. That is, they’re more atavistic than the more derived receding chins in other homo species. We as humans seem to have a hard time thinking we’re not the furthest from primitive as any great ape gets.
[Previous page](https://boards.straightdope.com/t/chins-evolution-and-pointless-survival/837947.md?page=1)