• OK, it's on.
  • Please note that many, many Email Addresses used for spam, are not accepted at registration. Select a respectable Free email.

What are wisdom teeth for?

~~~

Active Member
Local time
Today, 01:55
Joined
Mar 21, 2010
Messages
359
#1
From what I have read they are viewed as vestigial. People used to think that the tonsils were not that useful once. I'm wondering if anyone has some other reasonably possible explanation(s) for the use of wisdom teeth? What about for eating bone? (For the avoidance of doubt: assume evolution is a premise.)
 

Roran

The Original Nerdy Gangsta
Local time
Yesterday, 20:55
Joined
Apr 12, 2011
Messages
431
Location
North Carolina, USA
#2
Slaughtering those with underdeveloped immune systems by inflicting crippling infections
 
Local time
Today, 01:55
Joined
Apr 19, 2012
Messages
454
Location
Florida
#3
Before dental hygiene we'd need another pair of biters by the time we were 18 or so... I guess we'd have been dead by about 40 so that last set should last us.

Also I've read they were for eating grizzlier things like bone and hair and crap like you suggest. This would seem to me to go along with our appendix which may have been for digesting or at least filtering out the grizzlier crap. Obviously wildly speculative as you asked for.

My opinion is that human meat intake probably used to increase around 16 or 18 or so when the men started really pulling their weight hunting and the women got pregnant and needed more fats and proteins. Wisdom teeth coming in at this age might ensure being able to eat the meat without rotted teeth. Just a guess
 

nanook

a scream in a vortex
Local time
Today, 02:55
Joined
Aug 16, 2011
Messages
1,933
Location
germany
#4
if we didn't feed on depleted industrial trash, we would have larger chins, as people in other parts of the world do, and those teeth wouldn't threaten us so much. explains maybe why we don't grow the teeth earlier in life: the chin has to grow first. why does it take so long, to grow the chin? a large chin is also a sign of power (like the power to secure enough nutrition). so maybe nature does not want childs or adolescents to have chins as big as grown ups do. maybe the teeth would even come earlier, if the chin grew faster, but then when it's grown out and it's still not large enough for the teeth, they come anyway, because maybe they don't know how large the chin is, they only know that growth has come to it's limit (hormons). what are the teeth good for? chewing i guess. more chewing. bamboo sticks or meat? dunno. maybe the human species is evolving towards the goal of being able to chew the bible.
 

snafupants

Prolific Member
Local time
Yesterday, 19:55
Joined
May 31, 2010
Messages
5,026
#5
if we didn't feed on depleted industrial trash, we would have larger chins, as people in other parts of the world do, and those teeth wouldn't threaten us so much. explains maybe why we don't grow the teeth earlier in life: the chin has to grow first. why does it take so long, to grow the chin? a large chin is also a sign of power (like the power to achieve enough nutrition). so maybe nature does not want childs or adolescents to have chins as big as grown ups do. maybe the teeth would even come earlier, if the chin grew faster, but then when it's grown out and it's still not large enough for the teeth, they come anyway, because maybe they don't know how large the chin is, they only know that growth has come to it's limit (hormons). what are the teeth good for? chewing i guess. more chewing. bamboo sticks or meat? dunno. maybe the human species is evolving towards the goal of being able to chew the bible.
Have you been reading Dr. Weston Price?
 

Polaris

Radioactive vision
Local time
Yesterday, 13:55
Joined
Oct 13, 2009
Messages
2,001
#7

snafupants

Prolific Member
Local time
Yesterday, 19:55
Joined
May 31, 2010
Messages
5,026
#8
i cant read anyone who is a Dr, unless it's psychology. but yes, i became aware of his work, through the nutrition paradigm.
So I should nix Dr. Dre from your reading list? I found a book by Ramiel Nagel (Cure Tooth Decay) pretty helpful regarding teeth and even holistic health; Ramiel is basically a disciple of Weston. The book, in essence, highlights the important of fat-soluble vitamins and nutrients and minerals in our typically deprived diets. Good read. I would urge anyone to peruse Ramiel's book, especially if you're struggling with gum or tooth problems.
 

EditorOne

Prolific Member
Local time
Yesterday, 20:55
Joined
Mar 24, 2008
Messages
2,697
Location
Northeastern Pennsylvania
#9
I'm not sure teeth in our distant ancestors were subject to the same decay-inducing conditions we have now.
 
Local time
Yesterday, 20:55
Joined
Jan 7, 2012
Messages
5,026
#10
From what I have read they are viewed as vestigial. People used to think that the tonsils were not that useful once. I'm wondering if anyone has some other reasonably possible explanation(s) for the use of wisdom teeth? What about for eating bone? (For the avoidance of doubt: assume evolution is a premise.)
This is best summed up using a poor example written by someone without an understanding of evolution (everything in green is a derivative of selection):

"Research now indicates that the reasons for most third molar problems today are not due to evolutionary changes but other reasons. These reasons include a change from a coarse abrasive diet to a soft western diet, lack of proper dental care, and genetic factors possibly including mutations."

It's quite the facepalm material.



Anyway, the bone-eating theory is wrong (I couldn't think of a way to sugar coat it).

Humans have bunodont dentition adapted for an omnivorous lifestyle and an extremely weak angle of jaw articulation (produces ~150 psi of force) while carnivores like the spotted hyena (which can crush water buffalo femurs using a bite force in excess of 1600 psi) have teeth positiones in such a manner that their upper molar along a curve.

In the picture below, the upper molar isn't labeled. They only have 1, right behind the 4th premolar (A.K.A. carnassial), and it's only used for crushing bone because its use requires a change in mandible articulation, like a pair of vice grips.

http://www.grin.com/object/external_document.277890/1fa82c07bdb194ef93f888b4c49ca0f5_LARGE.png

The job of wisdom teeth was to lighten the load put on our other molars and premolars by a diet composed of more coarse material (vegetation and insects).
 

Jennywocky

guud languager
Local time
Yesterday, 20:55
Joined
Sep 25, 2008
Messages
10,619
Location
Charn
#11
To take a different tact, did they really need to serve any purpose?

There are vestigial elements in the body that basically just haven't been weeded out. Something needn't have provided a quantifiable positive impact on survival in order to linger; sometimes mutations/chance just happens, and if they happen to occur in conjunction with elements with more impact on survival, wouldn't they linger anyway? The only thing nature cannot endure are elements that contribute negatively to survival; depending on the threads within the environment or the impact on the functioning of the body, those negative elements will perhaps kill off the organism before it can reproduce, in turn removing themselves from the gene pool.

The optic nerve in the human eye actually runs into the eye and attaches on the inside. The way it connects I think contributes to the region known as the "blind spot" we all have experienced. It's not a wise engineering move and would be considered a design flaw, only having negative impact over all; but it's not enough to kill the organism, which could survive just fine with it. So it still exists. Would it be erroneous to say wisdom teeth might just be extra random teeth that got into the gene pool but weren't ever really necessary, but have never been weeded out since they don't really have an impact on survival? Just curious.
 

scorpiomover

The little professor
Local time
Today, 01:55
Joined
May 3, 2011
Messages
1,645
#12
The optic nerve in the human eye actually runs into the eye and attaches on the inside. The way it connects I think contributes to the region known as the "blind spot" we all have experienced. It's not a wise engineering move and would be considered a design flaw, only having negative impact over all; but it's not enough to kill the organism, which could survive just fine with it. So it still exists. Would it be erroneous to say wisdom teeth might just be extra random teeth that got into the gene pool but weren't ever really necessary, but have never been weeded out since they don't really have an impact on survival? Just curious.
Considering how much of a big deal dentists and other people make about how much of a problem wisdom teeth are, and how much of a problem it is to have malformed teeth, and how much of an importance a nice smile is considered to affect one's sexual appeal, I would have thought that they would cause quite a high level of natural selection, and sexual selection, against those with the genes for growing wisdom teeth. Then factor in how many people died in war, and disease, and starvation, and there have been plenty of generations to make those selective pressures weed out many with the genes for wisdom teeth.
 
Local time
Yesterday, 20:55
Joined
Jan 7, 2012
Messages
5,026
#13
Would it be erroneous to say wisdom teeth might just be extra random teeth that got into the gene pool but weren't ever really necessary, but have never been weeded out since they don't really have an impact on survival? Just curious.
It is possible, just not in this case. Several species (i.e. numbat, people) have variable numbers of teeth with the same teeth being lost and regained. In our current state this is just a genetic mutation, a trait that's randomly disappearing as opposed to being acted upon by selection (even if one's genetics produce wisdom teeth, we can just pull them out if they cause a problem, thus the genes are maintained in the population). We've stalled the process (for now).

Over time the more derived a lineage becomes and the more specialized its feeding habits, the more teeth it loses. The baseline mammalian number of teeth (50) is seen in marsupials (virginia opossum), and every other advanced order and family have less. When a lineage needs more of a chewing surface instead of sprouting new teeth, the teeth they have just become larger, or the way they grow in changes. This is verified by triangulation with other characteristics (number of digits, locomotion, musculature, skull anatomy, etc).

An example within the order Carnivora is the omnivorous bear (42 teeth) vs a carnivorous lion (30). Tooth number reduction is demonstrated to the extreme in proboscideans (elephants).

"Primative" proboscidean (hyrax):



Highly derived proboscidean (Asian elephant):

 

nanook

a scream in a vortex
Local time
Today, 02:55
Joined
Aug 16, 2011
Messages
1,933
Location
germany
#14
so the voices told me, we are like two different species, with different numbers of teeth, merged into one body, one of them struggeling for dominance - as hormonal conditions change, the former more evolved species has two new energy/awareness centers in the ZNS, 9 instead of 7 and it doesn't have wisdom teeth, those belong to the older 7 centered species, now since we don't really culturally embrace the more evolved species during our lifetime (no propper hormonal feedback), it gets weakened and dies (leaving some functionality in tact but unevolving), after it has established it's most important traits like a rudimentary self-awareness in the mind as opposed to the body, then the older species gets it's way and gives birth to those ancient cow teeth.
 

snafupants

Prolific Member
Local time
Yesterday, 19:55
Joined
May 31, 2010
Messages
5,026
#16
I'm not sure teeth in our distant ancestors were subject to the same decay-inducing conditions we have now.
Contingent on the region and culture, you would basically be correct in that skeptical assumption. The test's hardly fair, however, because our ancestors lived shorter lives.
 

~~~

Active Member
Local time
Today, 01:55
Joined
Mar 21, 2010
Messages
359
#17
Interesting responses. The questions are not necessarily directed at those whom are quoted.

The job of wisdom teeth was to lighten the load put on our other molars and premolars by a diet composed of more coarse material (vegetation and insects).
Is there any benefit in eating more coarse material? Aren’t many humans better off eating food that takes longer to break down?

To take a different tact, did they really need to serve any purpose?
...
Would it be erroneous to say wisdom teeth might just be extra random teeth that got into the gene pool but weren't ever really necessary, but have never been weeded out since they don't really have an impact on survival? Just curious.
No, not necessarily - they could actually be vestigial. Very often though many people in society decide on the basis of what other people do. So, for instance, the Neanderthal descendants might have gone, ‘oh, we should eat whatever the Homo Sapiens eats because whatever they eat must be good’, rather than making a decision based on what is logically the best - what is good for the Homo Sapiens might not be necessarily good for the Neanderthal descendants. That is, different things might be appropriate for different people.

The other point is, assume there was something that was different - e.g. a human without a blind spot - wouldn’t this human think of ways in which that lack of a blind spot could be beneficial. Further, if there were ways in which that lack of a blind spot could be beneficial then some in the rest of society might appreciate the lack of a blind spot too. Others might go, ‘meh’. Diversity has it’s benefits.

Over time the more derived a lineage becomes and the more specialized its feeding habits, the more teeth it loses.
Excuse my ignorance - but why is this the case?

So if you have a large jaw and wisdom teeth then you don’t need them removed and the orthodontist can keep your smile straight right? If this is the case then theoretically you either want no wisdom teeth and a small jaw or wisdom teeth and a large jaw?
 

~~~

Active Member
Local time
Today, 01:55
Joined
Mar 21, 2010
Messages
359
#18
Given the right nutritional environment for the mother/foetus/human, would a human who develops wisdom teeth also ordinarily develop a jaw that could handle all the teeth without crowding (i.e. is it genetic, environmental or both)? Weston seems to suggest it is nutritional (environmental) right? Interesting given stats on the number of wisdom teeth that get pulled.
 

Agent Intellect

Absurd Anti-hero.
Local time
Yesterday, 20:55
Joined
Jul 28, 2008
Messages
4,116
Location
Michigan
#21
A good possibility is that as the human brain evolved to become larger, the jaw muscles became smaller to make way for a larger skull while still allowing the head to fit through the birth canal and not be so heavy as to strain the neck:

Notice the difference in size between the human and chimpanzee zygomatic arch (it's the origin of the masseter and the temporalis pass through it, the main chewing muscles) and the amount of room there is for the teeth:

Human shown with wisdom teeth:


Chimpanzee with normal number of teeth (for a chimp):

As the skull became smaller, the mouth became smaller, leaving less room for teeth to grow in. That's why wisdom teeth often become impacted or malposed in those who grow them.
 
Local time
Today, 02:55
Joined
Jan 15, 2010
Messages
896
Location
Oslo, Norway.
#22
Shortest answer:
We used to have more space for them,
Then we grew bigger brains, and had help processing the food, so in turn the jaws got smaller.
We breed before we weed out who gets wisdom teeth or not, so they were never subject to selective pressure.


Therefore; We don't have space for the teeth, because we have Wisdom instead.




or something like that
 
Local time
Yesterday, 20:55
Joined
Jan 7, 2012
Messages
5,026
#23
Is there any benefit in eating more coarse material? Aren’t many humans better off eating food that takes longer to break down?
The main energetic benefit from coarse food in general would be derived from our cecum, which has been greatly reduced to our modern day appendix. Otherwise the main benefit is dietary fiber which contrary to popular belief isn't important for cleaning the colon like a pipe cleaner, but produces substances that nourish epithelial cells in the colon and the stem cells within colon crypts and serves to prevent colon disease/cancer/etc.

Excuse my ignorance - but why is this the case?
WALL OF TEXT!:eek: (with pictures and a lot of extra but cool info :D)

Generally, as diets become more specialized, more specialized dentition is required. Using mammals as an example, teeth started out looking basically all the same and very similar to those of reptiles, and they all essentially functioned in the same way (i.e. inefficiently munching something into enough of a pulp to digest it).

Some synapsids (mammal predecessors) had nearly 100 teeth which could all be replaced multiple times if they fell out like those of reptiles and toothed fish. The selective pressures behind tooth loss vary, but at some point producing and replacing so many teeth became a hinderance, likely both energetically because different teeth allow an organism to process different foods more efficiently, and due to selective forces imposed by prey because well, they don't like being eaten.

Here's a loose progression and some examples:

Synapsid (some with 100+ teeth) on the top. They occupied wide niches with wide variety of predatory diets, but that's before their food sources adapted. Very low energy demand:


The tribosphenic molar, i.e. what synapsids and marsupials have in common. A single tooth with 3 peaks. They still basically function the same:


Marsupial (virginia opossum, highly generalized diet with low energy demand, 50 teeth with limited specialization):


Wolf (42 teeth). Note how things have become much more specialized to accomodate a variety of different tasks (grasping, puncturing, grooming, slicing off flesh with the 4th premolar/carnassials that line up perfectly (<-A.K.A. "precise occlusion"), more derived molars for crushing bone, etc.). More restricted diet, and energetically expensive foraging strategy, i.e. "chase and exhaust".


Smilodon teeth (30). The difference between these and wolf teeth reflect a different foraging strategy, a shift from "chase and exhaust" to more energetically efficient "stalk and pounce". Less teeth, but more specialized and more suited to a cat's nutritional demands, which are much less than those of a dog:


And now for something completely different:

A brief look at humans (chimp, Australopithecus, Homo sapiens),:


And then a rodent (vole, 32), with extremely specialized teeth to the point where they functionally have two mouths.


First, the grinding chamber in the back, which consists of highly modified molars that make 2 teeth function like 7:


And then the gnawing chamber, which is separated from the grinding chamber by the diastema (that huge gap between the chambers) that is closed off by the cheeks. It also functions as a storage space so they can grind food, store some for later, and gnaw through a tree stump simultaneously. The incisors not only precisely occlude when moved up and down, but the lower incisors can be moved sideways like a pair of tweezers because the two halves of the lower jaw don't fully conjoin due to the positioning of the masseter muscle:

I can't find a good picture, but you can look at this and picture the two halves of the lower jaw moving like a pair of hedge shears:
 

Jennywocky

guud languager
Local time
Yesterday, 20:55
Joined
Sep 25, 2008
Messages
10,619
Location
Charn
#24
The other point is, assume there was something that was different - e.g. a human without a blind spot - wouldn’t this human think of ways in which that lack of a blind spot could be beneficial. Further, if there were ways in which that lack of a blind spot could be beneficial then some in the rest of society might appreciate the lack of a blind spot too. Others might go, ‘meh’. Diversity has it’s benefits.
Well, I do agree with the last point.

I have some trouble imagining for hunter types in the culture how a blind spot could actually be more beneficial than having a full range of vision, but for other examples the diversity could be beneficial.
 
Local time
Yesterday, 20:55
Joined
Jan 7, 2012
Messages
5,026
#25
A good possibility is that as the human brain evolved to become larger, the jaw muscles became smaller to make way for a larger skull while still allowing the head to fit through the birth canal and not be so heavy as to strain the neck:

As the skull became smaller, the mouth became smaller, leaving less room for teeth to grow in. That's why wisdom teeth often become impacted or malposed in those who grow them.
I would argue that the process occurred in reverse, i.e. foraging pressures reduced jaw size first as opposed to the jaw/musculature being evolutionarily squeezed by the brain and birth canal (Why wouldn't selection favor women with wider birth canals instead?). I'm assuming in most cases the number, size, and position of teeth are genetically separate from jaw size (I don't have gene loci to point to but just look at the dentition of rodents, elephants, etc.) it's just that having too many or malformed teeth often results in mortality due to inability to forage.

Dogs address the same problem through completely different means, i.e. delayed bone growth.

Just look at the snout of a german shepherd puppy vs an adult:



 

Agent Intellect

Absurd Anti-hero.
Local time
Yesterday, 20:55
Joined
Jul 28, 2008
Messages
4,116
Location
Michigan
#26
I would argue that the process occurred in reverse, i.e. foraging pressures reduced jaw size first
The problem with that is it makes it seems like reduced jaw size caused larger brains. It's more likely that increasing brain size would favor offspring with smaller jaw muscles (and therefore smaller bones in the skull) than smaller jaw muscles favoring offspring with a larger brain.

Larger brains would evolve because they offer an evolutionary advantage. If jaw reduction due to foraging pressure occurred first, it doesn't seem likely that increased brain size is where the gene pool would continuously divert resources to ever increasing brain size. It seems more likely that the advantage of increased brain size would lead to the gene pool diverting resources from building larger jaws into increased brain size since that is what's offering more of an advantage.

As an analogy, you have a river that splits into two directions and due to erosion path A starts to flow more downward than path B. Path A is going to take on more water and become deeper while path B has less water and becomes more shallow. You wouldn't say that path B becoming shallow allowed path A to get deeper; because path A has a more downward flow, that offers a "gravitational advantage" to water to flow down path A, so because path A takes on more water path B becomes more shallow.

To tie it in with the brain/jaw evolution, the advantage of a larger brain making humans smarter would be like the more downward path of path A in the river and the depleting jaw size would be like path B having less water.

While there may be an advantage to a smaller jaw size on account of varying foraging pressures, it's unlikely that the smaller jaw size would lead to and/or cause the brain to become larger.

as opposed to the jaw/musculature being evolutionarily squeezed by the brain and birth canal (Why wouldn't selection favor women with wider birth canals instead?).
Sexual selection may have played a part: males preferred females with a narrower vagina and hips that aren't the size of a spare tire. Also, a more narrow vagina and a smaller uterus helps sperm make the journey from outside the cervix into the fallopian tubes more easily. The narrower vagina would also be better for maintaining pH balance, sanitation, and preventing prolapse.

Dogs address the same problem through completely different means, i.e. delayed bone growth.
Humans do too, by having only 20 deciduous teeth and up to 32 permanent teeth.
 

~~~

Active Member
Local time
Today, 01:55
Joined
Mar 21, 2010
Messages
359
#27
So we are still left with the issue of explaining Price (with the nutritional argument) and his graphic evidence of straight smiles with wisdom teeth. Some might seek to weaken the Price argument. Can the Price argument be strengthen (in order to provide a better argument one way or the other)?
 
Top Bottom