Ten Consequences of Having Evolved

[KingM]

An interesting article in the Smithsonian Magazine.

 

One example:

 

 

8. Our brains squeeze our teeth

A genetic mutation in our recent ancestors caused their descendants to have roomy skulls that accommodated larger brains. This may seem like pure success—brilliance, or its antecedent anyway. But the gene that made way for a larger brain did so by diverting bone away from our jaws, which caused them to become thinner and smaller. With smaller jaws, we could not eat tough food as easily as our thicker-jawed ancestors, but we could think our way out of that problem with the use of fire and stone tools. Yet because our teeth are roughly the same size as they have long been, our shrinking jaws don’t leave enough room for them in our mouths. Our wisdom teeth need to be pulled because our brains are too big.

 

 

 

 

[Lawana]

:lol:

[Mejane]

Ah, finally an explanation of the need for everyone to have braces these days. ;)

[asta]

Ah, finally an explanation of the need for everyone to have braces these days. ;)

 

Well, not everyone.

 

 

a

[Barry Goldwater]

An interesting article in the Smithsonian Magazine.

 

One example:

 

So...the mutation that diverted bone away from the jaw was a genetic DISADVANTAGE, because we couldn't eat tougher food than thicker jawed cousins, right?

 

So...how did the thin-jawed ancestors thrive for a sufficiently long enough time to develop tools and fire, creating a selective ADVANTAGE? I didn't click the link yet...does the article explain that?

[Greta]

So...the mutation that diverted bone away from the jaw was a genetic DISADVANTAGE, because we couldn't eat tougher food than thicker jawed cousins, right?

 

So...how did the thin-jawed ancestors thrive for a sufficiently long enough time to develop tools and fire, creating a selective ADVANTAGE? I didn't click the link yet...does the article explain that?

 

I wouldn't put too much stock in this. It doesn't make a lot of sense. People in hunter-gatherer societies, who eat a traditional diet, have plenty of room for their wisdom teeth, don't need braces, and have good dental health overall. It is only the modern agricultural diet that results in a smaller jaw (I believe it has something to do with lower Vitamin A levels, but couldn't swear to it). In other words, humans who are genetically the same have widely varying jaw structures depending on lifestyle. I think they bungled the explanation on this one.

[hillfarm]

I still have my wisdom teeth, so does that mean I have a smaller brain???

 

Well that explains a lot!

[Laurie4b]

I still have my wisdom teeth, so does that mean I have a smaller brain???

 

Well that explains a lot!

 

:lol:

[MamaSheep]

If I get the rest of my teeth pulled too, will that make me smarter?

 

My dad's jaw is big enough to accommodate his wisdom teeth, and his teeth are beautifully, perfectly straight, no braces needed. My mom's jaw is too small for wisdom teeth, but that's ok because she never ever grew any. They just weren't there (does that make her more highly evolved?). But her side of the family has dreadful teeth in general. Thin enamel and all crookedy and stuff.

 

I inherited my dad's wisdom teeth, and my mom's small jaw and crooked, weak teeth. I have always thought it completely unfair. My kids both have big mouths (just ask them) but I have been glad that ds (who has to be sedated for any sort of dental work beyond a quick cleaning, which I know because he once had one small cavity, and has panic attacks when they try to x-ray his mouth) seems to have inherited his grandad's strong, straight teeth and roomy jaw and will probably not need braces (or extensive drilling). I feel sorry for dd, though. She's only 8 and has already had several abscesses and cavities that have left her with a mouth full of crowns and spacers. I hope her adult teeth are more solidly constructed.

[JeneralMom]

It is really the musculature that diminished primarily (the muscles of mastication). You can see the heavy, boney muscle attachments on the skulls of our earlier ancestors. My teeth are wonderfully straight and I had room for my wisdom teeth.

[JadeOrchidSong]

So...the mutation that diverted bone away from the jaw was a genetic DISADVANTAGE, because we couldn't eat tougher food than thicker jawed cousins, right?

 

So...how did the thin-jawed ancestors thrive for a sufficiently long enough time to develop tools and fire, creating a selective ADVANTAGE? I didn't click the link yet...does the article explain that?

Good question!:iagree:

[JadeOrchidSong]

 

How about this one:

6. We're awfully cold in winter

Fur is a warm hug on a cold day, useful and nearly ubiquitous among mammals. But we and a few other species, such as naked mole rats, lost it when we lived in tropical environments. Debate remains as to why this happened, but the most plausible explanation is that when modern humans began to live in larger groups, our hair filled with more and more ticks and lice. Individuals with less hair were perhaps less likely to get parasite-borne diseases. Being hairless in Africa was not so bad, but once we moved into Arctic lands, it had real drawbacks. Evolution has no foresight, no sense of where its work will go.

 

 

 

[Barry Goldwater]

How about this one:

 

6. We're awfully cold in winter

Fur is a warm hug on a cold day, useful and nearly ubiquitous among mammals. But we and a few other species, such as naked mole rats, lost it when we lived in tropical environments. Debate remains as to why this happened, but the most plausible explanation is that when modern humans began to live in larger groups, our hair filled with more and more ticks and lice. Individuals with less hair were perhaps less likely to get parasite-borne diseases. Being hairless in Africa was not so bad, but once we moved into Arctic lands, it had real drawbacks. Evolution has no foresight, no sense of where its work will go.

 

 

 

 

 

Wouldn't fur on all tropical animals that live in large groups have the same drawback regarding parasitic-borne illnesses? Wouldn't fur be the exception in the tropics, based on this theory?

 

I've since read the article...

[Farrar]

So...the mutation that diverted bone away from the jaw was a genetic DISADVANTAGE, because we couldn't eat tougher food than thicker jawed cousins, right?

 

So...how did the thin-jawed ancestors thrive for a sufficiently long enough time to develop tools and fire, creating a selective ADVANTAGE? I didn't click the link yet...does the article explain that?

 

No, I think I understand it. First off all, the idea is that evolution is random. The traits that lead to success are sometimes unexpected and sometimes we end up with vestiges of things we do need - or things that *seem* like evolution should have "fixed" them - but evolution doesn't work that way - looking at the body and thinking of ways to improve it.

 

I don't think you would have to necessarily live that much longer. Fire and cooking are things that are eventual results of larger brain capacity and from our need to overcome our inability to chew tough foods, but simply being able to be a quicker thinker is clearly an advantage, even if it limits your diet. If being a quicker thinker was only an advantage years down the line once it allowed us to invent cooking, then maybe we would have died off in favor of another variation. But it's an immediate advantage and I would guess could have led to the invention of rudimentary cooking with a generation or two.

 

I wouldn't put too much stock in this. It doesn't make a lot of sense. People in hunter-gatherer societies, who eat a traditional diet, have plenty of room for their wisdom teeth, don't need braces, and have good dental health overall. It is only the modern agricultural diet that results in a smaller jaw (I believe it has something to do with lower Vitamin A levels, but couldn't swear to it). In other words, humans who are genetically the same have widely varying jaw structures depending on lifestyle. I think they bungled the explanation on this one.

 

That's interesting though... My understanding had always been that we needed our wisdom teeth in part because by that time our dental health had begun to deteriorate so we got new teeth. Obviously, some of that deterioration is caused by the agricultural diet (though, another advantage/disadvantage - agricultural societies also gave rise to civilization which gave rise to dentistry) but I thought part of it was natural wear and tear for any people, even hunter/gatherers. Of course, now that I think about it, it may be i got that idea from Kurt Vonnegut. Anyone else remember that bit at the end of Galapagos?

[melissel]

I still have my wisdom teeth, so does that mean I have a smaller brain???

 

Well that explains a lot!

 

:lol::lol::lol: I immediately thought the same thing! Mine appear to have MORE than enough room in there, according to my dentist. I'm so bringing him a copy of this article when I go in next! He's absolutely hilarious, and this will give him plenty of fodder for his other clients :D

[Corraleno]

I think the "explanations" for smaller jaws and less fur are pretty weak, but the other 8 are very interesting. Regarding the loss of fur, I'd guess it has more to do with an increased need for Vitamin D, rather than parasites.

 

Jackie

[Barry Goldwater]

No, I think I understand it. First off all, the idea is that evolution is random. Actually, the mutations are random...the consequences of the mutations, whether the species is 'more' fit or 'less' fit for survival is not random at all. It depends on environmental conditions. The traits that lead to success are sometimes unexpected and sometimes we end up with vestiges of things we do need - or things that *seem* like evolution should have "fixed" them - but evolution doesn't work that way - looking at the body and thinking of ways to improve it. According to the theory, mutations that have no consequence for 'fitness' might remain for a time, because there is no pressure to eliminate or propagate them.

 

I don't think you would have to necessarily live that much longer. The theory requires that the positive mutation creates a higher propensity to pro-create, thereby potentially increasing the relative frequency of the expressed mutation, as long as the mutation is of a type that can be propagated through genetics. The individuals with the 'larger' brain and 'smaller jaw' would need to survive till reproduction is accomplish at a greater rate than their non-mutated counterparts.

 

Fire and cooking are things that are eventual results of larger brain capacity and from our need to overcome our inability to chew tough foods, but simply being able to be a quicker thinker is clearly an advantage, even if it limits your diet. If being a quicker thinker was only an advantage years down the line once it allowed us to invent cooking, then maybe we would have died off in favor of another variation. But it's an immediate advantage and I would guess could have led to the invention of rudimentary cooking with a generation or two. It would have to be...but I contend that it's a huge leap that the article makes to credit punctuated equilibrium for this, particularly if it occurred in one generation.

 

.

[mcconnellboys]

They became vegetarian....

[mcconnellboys]

Larger muscle attachments equal thickening of bone (Wolf's Law: bone is laid down where bone is needed), so smaller muscle attachments would have gradually led to a thinning of the jaw, perhaps, because the greater bone volume was no longer needed at that point....

[Peela]

I wouldn't put too much stock in this. It doesn't make a lot of sense. People in hunter-gatherer societies, who eat a traditional diet, have plenty of room for their wisdom teeth, don't need braces, and have good dental health overall. It is only the modern agricultural diet that results in a smaller jaw (I believe it has something to do with lower Vitamin A levels, but couldn't swear to it). In other words, humans who are genetically the same have widely varying jaw structures depending on lifestyle. I think they bungled the explanation on this one.

 

Thats my understandingtoo, from reading Western Price's research with traditional cultures.