Over 1.5 million copies sold
Books by Richard Dawkins
The Oxford Book of Modern Science Writing
by Richard Dawkins
The Selfish Gene
by Richard Dawkins
The Blind Watchmaker
by Richard Dawkins
The Ancestor's Tale
by Richard Dawkins
Unweaving the Rainbow
by Richard Dawkins
Climbing Mount Improbable
by Richard Dawkins
Print
Five Things Humans No Longer Need
by ABC News
Thanks to EJ Ashcraft III for the link.
http://abcnews.go.com/Technology/Story?id=4910778&page=1
Five Things Humans No Longer Need
By LAURA SPINNEY
Vestigial organs are parts of the body that once had a function but are now more-or-less useless. Probably the most famous example is the appendix, though it is now an open question whether the appendix is really vestigial. The idea that we are carrying around useless relics of our evolutionary past has long fascinated scientists and laypeople alike.
This week we tackle vestigial organs in a feature article that looks at how the idea has changed over the years, and how it has come under attack from creationists anxious to deny that vestigial organs (and hence evolution) exist at all. To accompany the article, here is our list of the five organs and functions most likely to be truly vestigial.
Vomeronasal organ
Rodents and other mammals secrete chemical signals called pheromones that carry information about their gender or reproductive state, and influence the behaviour of others. Pheromones are detected by a specialised sensory system, the vomeronasal organ (VNO), which consists of a pair of structures that nestle in the nasal lining or the roof of the mouth. Although most adult humans have something resembling a VNO in their nose, neuroscientist Michael Meredith of Florida State University in Tallahassee has no hesitation in dismissing it as a remnant.
"If you look at the anatomy of the structure, you don't see any cells that look like the sensory cells in other mammalian VNOs," he says. "You don't see any nerve fibres connecting the organ to the brain." He also points to genetic evidence that the human VNO is non-functional. Virtually all the genes that encode its cell-surface receptors - the molecules that bind incoming chemical signals, triggering an electrical response in the cell - are pseudogenes, and inactive.
So what about the puzzling evidence that humans respond to some pheromones? Larry Katz and a team at Duke University, North Carolina, have found that as well as the VNO, the main olfactory system in mice also responds to pheromones. If that is the case in humans too then it is possible that we may still secrete pheromones to influence the behaviour of others without using a VNO to detect them.
Goose bumps
Though goose bumps are a reflex rather than a permanent anatomical structure, they are widely considered to be vestigial in humans. The pilomotor reflex, to give them one of their technical names, occurs when the tiny muscle at the base of a hair follicle contracts, pulling the hair upright. In birds or mammals with feathers, fur or spines, this creates a layer of insulating warm air in a cold snap, or a reason for a predator to think twice before attacking. But human hair is so puny that it is incapable of either of these functions.
Goose bumps in humans may, however, have taken on a minor new role. Like flushing, another thermoregulatory mechanism, they have become linked with emotional responses - notably fear, rage or the pleasure, say, of listening to beautiful music. This could serve as a signal to others. It may also heighten emotional reactions: there is some evidence, for instance, that a music-induced frisson causes changes of activity in the brain that are associated with pleasure.
Darwin's point
Around the sixth week of gestation, six swellings of tissue called the hillocks of Hiss arise around the area that will form the ear canal. These eventually coalesce to form the outer ear. Darwin's point, or tubercle, is a minor malformation of the junction of the fourth and fifth hillocks of Hiss. It is found in a substantial minority of people and takes the form of a cartilaginous node or bump on the rim of their outer ear, which is thought to be the vestige of a joint that allowed the top part of the ancestral ear to swivel or flop down over the opening to the ear.
Technically considered a congenital defect, Darwin's point does no harm and is surgically removed for cosmetic reasons only. However, the genetics behind it tells an interesting tale, says plastic surgeon Anthony Sclafani of the New York Eye and Ear Infirmary in New York City. The trait is passed on according to an autosomal dominant pattern, meaning that a child need only inherit one copy of the gene responsible to have Darwin's point. That suggests that at one time it was useful. However, it also has variable penetration, meaning that you won't necessarily have the trait even if you inherit the gene. "The variable penetration reflects the fact that it is no longer advantageous," Sclafani says.
Tail bone
A structure that is the object of reduced evolutionary pressure can, within limits, take on different forms. As a result, one of the telltale signs of a vestige is variability. A good example is the human coccyx, a vestige of the mammalian tail, which has taken on a modified function, notably as an anchor point for the muscles that hold the anus in place.
The human coccyx is normally composed of four rudimentary vertebrae fused into a single bone. "But it's amazing how much variability there is at this spot," says Patrick Foye, director of the Coccyx Pain Service at New Jersey Medical School in Newark. Whereas babies born with six fingers or toes are rare, he says, the coccyx can and often does consist of anything from three to five bony segments. What's more, there are more than 100 medical reports of babies born with tails. This atavism arises if the signal that normally stops the process of vertebrate elongation during embryonic development fails to activate on time.
Wisdom teeth
Most primates have wisdom teeth (the third molars) but a few species, including marmosets and tamarins, have none. "These are probably evolutionary dwarfs," says anthropologist Peter Lucas of George Washington University, Washington DC. He suggests that when the body size of mammals reduces rapidly their jaws become too small to house all their teeth, and overcrowding eventually results in selection for fewer or smaller teeth (International Congress Series, vol 1296, p 74). This seems to be happening in Homo sapiens.
Robert Corruccini of Southern Illinois University in Carbondale, says the problem of overcrowding has been exacerbated in humans in the past four centuries as our diet has become softer and more processed. With less wear on molars, jaw space is at an even higher premium, "so the third molars, the last teeth to erupt, run out of space to erupt", he says. Not only are impacted wisdom teeth becoming more common, perhaps as many as 35% of people have no wisdom teeth at all, suggesting that we may be on an evolutionary trajectory to losing them altogether.
http://abcnews.go.com/Technology/Story?id=4910778&page=1
Five Things Humans No Longer Need
By LAURA SPINNEY
Vestigial organs are parts of the body that once had a function but are now more-or-less useless. Probably the most famous example is the appendix, though it is now an open question whether the appendix is really vestigial. The idea that we are carrying around useless relics of our evolutionary past has long fascinated scientists and laypeople alike.
This week we tackle vestigial organs in a feature article that looks at how the idea has changed over the years, and how it has come under attack from creationists anxious to deny that vestigial organs (and hence evolution) exist at all. To accompany the article, here is our list of the five organs and functions most likely to be truly vestigial.
Vomeronasal organ
Rodents and other mammals secrete chemical signals called pheromones that carry information about their gender or reproductive state, and influence the behaviour of others. Pheromones are detected by a specialised sensory system, the vomeronasal organ (VNO), which consists of a pair of structures that nestle in the nasal lining or the roof of the mouth. Although most adult humans have something resembling a VNO in their nose, neuroscientist Michael Meredith of Florida State University in Tallahassee has no hesitation in dismissing it as a remnant.
"If you look at the anatomy of the structure, you don't see any cells that look like the sensory cells in other mammalian VNOs," he says. "You don't see any nerve fibres connecting the organ to the brain." He also points to genetic evidence that the human VNO is non-functional. Virtually all the genes that encode its cell-surface receptors - the molecules that bind incoming chemical signals, triggering an electrical response in the cell - are pseudogenes, and inactive.
So what about the puzzling evidence that humans respond to some pheromones? Larry Katz and a team at Duke University, North Carolina, have found that as well as the VNO, the main olfactory system in mice also responds to pheromones. If that is the case in humans too then it is possible that we may still secrete pheromones to influence the behaviour of others without using a VNO to detect them.
Goose bumps
Though goose bumps are a reflex rather than a permanent anatomical structure, they are widely considered to be vestigial in humans. The pilomotor reflex, to give them one of their technical names, occurs when the tiny muscle at the base of a hair follicle contracts, pulling the hair upright. In birds or mammals with feathers, fur or spines, this creates a layer of insulating warm air in a cold snap, or a reason for a predator to think twice before attacking. But human hair is so puny that it is incapable of either of these functions.
Goose bumps in humans may, however, have taken on a minor new role. Like flushing, another thermoregulatory mechanism, they have become linked with emotional responses - notably fear, rage or the pleasure, say, of listening to beautiful music. This could serve as a signal to others. It may also heighten emotional reactions: there is some evidence, for instance, that a music-induced frisson causes changes of activity in the brain that are associated with pleasure.
Darwin's point
Around the sixth week of gestation, six swellings of tissue called the hillocks of Hiss arise around the area that will form the ear canal. These eventually coalesce to form the outer ear. Darwin's point, or tubercle, is a minor malformation of the junction of the fourth and fifth hillocks of Hiss. It is found in a substantial minority of people and takes the form of a cartilaginous node or bump on the rim of their outer ear, which is thought to be the vestige of a joint that allowed the top part of the ancestral ear to swivel or flop down over the opening to the ear.
Technically considered a congenital defect, Darwin's point does no harm and is surgically removed for cosmetic reasons only. However, the genetics behind it tells an interesting tale, says plastic surgeon Anthony Sclafani of the New York Eye and Ear Infirmary in New York City. The trait is passed on according to an autosomal dominant pattern, meaning that a child need only inherit one copy of the gene responsible to have Darwin's point. That suggests that at one time it was useful. However, it also has variable penetration, meaning that you won't necessarily have the trait even if you inherit the gene. "The variable penetration reflects the fact that it is no longer advantageous," Sclafani says.
Tail bone
A structure that is the object of reduced evolutionary pressure can, within limits, take on different forms. As a result, one of the telltale signs of a vestige is variability. A good example is the human coccyx, a vestige of the mammalian tail, which has taken on a modified function, notably as an anchor point for the muscles that hold the anus in place.
The human coccyx is normally composed of four rudimentary vertebrae fused into a single bone. "But it's amazing how much variability there is at this spot," says Patrick Foye, director of the Coccyx Pain Service at New Jersey Medical School in Newark. Whereas babies born with six fingers or toes are rare, he says, the coccyx can and often does consist of anything from three to five bony segments. What's more, there are more than 100 medical reports of babies born with tails. This atavism arises if the signal that normally stops the process of vertebrate elongation during embryonic development fails to activate on time.
Wisdom teeth
Most primates have wisdom teeth (the third molars) but a few species, including marmosets and tamarins, have none. "These are probably evolutionary dwarfs," says anthropologist Peter Lucas of George Washington University, Washington DC. He suggests that when the body size of mammals reduces rapidly their jaws become too small to house all their teeth, and overcrowding eventually results in selection for fewer or smaller teeth (International Congress Series, vol 1296, p 74). This seems to be happening in Homo sapiens.
Robert Corruccini of Southern Illinois University in Carbondale, says the problem of overcrowding has been exacerbated in humans in the past four centuries as our diet has become softer and more processed. With less wear on molars, jaw space is at an even higher premium, "so the third molars, the last teeth to erupt, run out of space to erupt", he says. Not only are impacted wisdom teeth becoming more common, perhaps as many as 35% of people have no wisdom teeth at all, suggesting that we may be on an evolutionary trajectory to losing them altogether.
Add to del.icio.us
Posted: Friday, May 23, 2008 | PermalinkComments 1 - 50 of 62 |
Reload Comments | Back to Top | Page Numbers2. Comment #183984 by MaxD on May 23, 2008 at 11:04 am
The hell with wisdom teeth. Other Comments by MaxD
3. Comment #183987 by PristinePanda on May 23, 2008 at 11:13 am
I could do without goose bumps, thank you.You can find a nice song about vestigial features of the human body sung by Dan Barker in # April 29, 2006 - Somewhere Over the Rainbow . . . Rhymes for the Irreverent: Freedom From Religion Foundation's Podcast. It cracks me up :D
Other Comments by PristinePanda
4. Comment #183996 by movingshadow on May 23, 2008 at 11:25 am
"And let's not forget the old favourite, the Appendix! "Check that first paragraph ;)
Other Comments by movingshadow
5. Comment #183999 by mordacious1 on May 23, 2008 at 11:34 am
I don't know, I still like giving my wife goosebumps, it shows I'm still doing my job.And the coccyx has a purpose. It breaks when you fall on your ass. As in: "Ben Stein's "Exposed" broke its coccyx when it fell on its ass."
"35% of people have no wisdom teeth" I didn't know that. How come I got stuck with two kids who had to have theirs removed, with an out-of-pocket cost to me of $1000 . Why couldn't they just have evolved quicker?
Other Comments by mordacious1
6. Comment #184000 by Adam Morrison on May 23, 2008 at 11:35 am
Hmmm.... Does this mean that since I have my wisdom teeth in and there's not a problem and I have the space for them.... I'm some kind of ape-man?!?
*Sob*
Damn you Darwinists! Now I'll never get a job other than as an extra for the next planet of the apes movie... (mutters into to some random and completely nonsensical anti-evolution rant :)
Seriously though, I'm pretty sure we could come up with a remarkably long list of traits that are no longer advantageous in our species.
Other Comments by Adam Morrison
7. Comment #184001 by Nefrubyr on May 23, 2008 at 11:36 am
I have Darwin's points on my ears. I've never noticed them on other people so I assumed I was just a freak.It's always good to learn that one is an officially recognised category of freak.
Other Comments by Nefrubyr
8. Comment #184002 by mordacious1 on May 23, 2008 at 11:40 am
I think people with lots of hair on their backs should evolve already. I'm talking to you clearmind.Other Comments by mordacious1
9. Comment #184006 by steveroot on May 23, 2008 at 11:47 am
I expected "Religion" to be on the list. I guess it's not properly considered to be a body part. So there!A structure that is the object of reduced evolutionary pressure can, within limits, take on different forms. ...
A good example is the human coccyx, a vestige of the mammalian tail, which has taken on a modified function, notably as an anchor point for the muscles that hold the anus in place.
Well, *evolutionary* pressure may be reduced... :-O
Ste5e
Other Comments by steveroot
10. Comment #184007 by Alkal on May 23, 2008 at 11:48 am
Hurray I am evolved.. no wisdom teeth here- the rest cost buckets in root canals and fillings though :(The "hillocks of Hiss" sound so cool though, don't they?
Other Comments by Alkal
11. Comment #184008 by mordacious1 on May 23, 2008 at 11:51 am
Five Things Humans No Longer NeedHow about ABC News? Go internet!
edit: Add the Postal Service to the list too.
Other Comments by mordacious1
12. Comment #184010 by steveroot on May 23, 2008 at 11:54 am
11. Comment #184008 by mordacious1 on May 23, 2008 at 11:51 am
Add the Postal Service to the list too.
One of my favorite oxymormons, like "jumbo shrimp", "military intelligence" and "rap music". ;-)
Ste5e
Other Comments by steveroot
13. Comment #184011 by Quetzalcoatl on May 23, 2008 at 11:58 am
Steveroot-
"painless dentistry" is a good oxymoron.
Other Comments by Quetzalcoatl
14. Comment #184012 by Stella on May 23, 2008 at 12:02 pm
Proof that I am highly evolved:I have no wisdom teeth.
I just found this out when visiting a new dentist a few weeks ago. She asked me, "Did you have your wisdom teeth removed?" and I said, "No - I hope I don't need to." Apparently, I have none. She even did extra X-rays to make sure. The four back molars (one in each corner) I remember coming in late, like when I was 13 or so, and only halfway. So I figured those were wisdom teeth, but as they never bothered me, or moved, or caused pain, I just assumed they didn't need to be removed. Imagine my surprise and delight!
Other Comments by Stella
15. Comment #184014 by Quetzalcoatl on May 23, 2008 at 12:09 pm
Stella-
Proof that I am highly evolved:
I have no wisdom teeth.
Show-off. :(
Other Comments by Quetzalcoatl
16. Comment #184015 by JernJane on May 23, 2008 at 12:12 pm
I like having goose bumps, especially when listening to beautiful music! I'm glad I was born before we lost the gorgeous, tickling sensation :D Other Comments by JernJane
17. Comment #184016 by Stella on May 23, 2008 at 12:14 pm
Also, the female reproductive system is SOOOO inefficient. The realization of this, when its inefficiency first intruded on my otherwise blissfully happy childhood, was the first nail in god's coffin. "Intelligent designer"? - Ha! "Merciful"? - HA! Other Comments by Stella
18. Comment #184018 by al-rawandi on May 23, 2008 at 12:17 pm
#6 Religion. Other Comments by al-rawandi
19. Comment #184019 by Fire1974 on May 23, 2008 at 12:19 pm
I lucked out of have wisdom teeth, but then I was cursed with an inflamed appendix that had to be removed 2 years ago.I guess "The Lord" intended for me to have a short, painless life. Quack!!!
It seems impossible to me that anyone could know even the basics of anatomy and physiology and still be a creationist. Does anyone know of a creationist who's gotten through Med-School?
Other Comments by Fire1974
20. Comment #184021 by Geodesic17 on May 23, 2008 at 12:38 pm
Any god that would design vestigal wisdom teeth is a total asshole.Other Comments by Geodesic17
21. Comment #184023 by mordacious1 on May 23, 2008 at 12:46 pm
My appendix played a huge role in turning me to atheism. My family was moving from NY to CA when I was 5. I was doubled up in the back seat by the time we reached IL but my parents wouldn't take me to a Dr. Finally, they did, but the Dr. told my mom that the appendix had burst a long time ago and that I probably wouldn't make it. Thanks to the medical staff I did. A few years later when I was 7 or 8 my mom told me that the only reason I survived was that she had prayed to the virgin mary. I thought about that and decided it was nonsense. She wouldn't admit it was her fault, but god had saved me. By 12 years I was turned off by all religion, and by 15 I was a full blown atheist. So in my case, the appendix did have a purpose.Other Comments by mordacious1
22. Comment #184024 by Geodesic17 on May 23, 2008 at 12:48 pm
Mordacious1:This kind of thinking is common. By the way, the worst place to be in a medical emergency is a Pentecostal Church service.
Other Comments by Geodesic17
23. Comment #184031 by Frankus1122 on May 23, 2008 at 1:00 pm
He suggests that when the body size of mammals reduces rapidly their jaws become too small to house all their teeth, and overcrowding eventually results in selection for fewer or smaller teeth (International Congress Series, vol 1296, p 74). This seems to be happening in Homo sapiens.
I don't understand how this is happening.
Am I less likely to reproduce because I have wisdom teeth? Are homo sapiens with wisdom teeth generally less likely to reproduce because they have wisdom teeth?
If that is not the case (and I don't see how wisdom teeth or lack thereof would influence reproductive success) then what is the mechanism that is causing homo sapiens to evolve in this direction?
Other Comments by Frankus1122
24. Comment #184032 by aquilacane on May 23, 2008 at 1:03 pm
My wise-ass teeth came in at 17 and didn't cause a problem. They took them out anyway (cash grab) under a local. As for Darwin's Point, I've seen it on many friends and thought nothing of it. I have noticed that for many people the brain is becoming a vestigial organ. Not much thinking going on with the majority of the human race, I think we'll discover we're better off being stupid in numbers than smart and alone.
Other Comments by aquilacane
25. Comment #184037 by Teratornis on May 23, 2008 at 1:19 pm
Goose bumps could make a comeback, if humans who live outside the tropics decide to genetically engineer themselves to grow seasonal fur again. That would allow for enormous energy savings, as it would no longer be necessary to heat buildings to subtropical temperatures year-round. It would only be necessary to keep the water pipes above freezing.Animals like the arctic fox have such efficient fur that they don't even need buildings.
Allowing buildings to cool in winter would also help eliminate many pest organisms which crave warmth as much as humans currently do: bedbugs, dust mites, roaches, etc.
Our heat craving leads to many unnecessary deaths each year. Building fires and carbon monoxide poisoning can result from malfunctioning furnaces.
I wonder if infectious diseases like colds and influenza spread faster inside heated buildings. Over the years, as I have trained myself to live with progressively less heat each winter, I've also noticed that I get sick less often. But I read somewhere that as people reach middle age, they tend to build up immunity to more cold and flu viruses, having had more years of exposure to the various strains in circulation. Thus my anecdotal observation may not isolate the effect of living in a colder house for about five months out of the year. But at least a cold house does not make me sicker.
Other Comments by Teratornis
26. Comment #184038 by steveroot on May 23, 2008 at 1:21 pm
24. Comment #184031 by Frankus1122 on May 23, 2008 at 1:00 pm
Are homo sapiens with wisdom teeth generally less likely to reproduce because they have wisdom teeth?
Don't we hear that the less-wise have more children? ;-)
19. Comment #184018 by al-rawandi on May 23, 2008 at 12:17 pm
#6 Religion.
Ahem... 9. Comment #184006 by steveroot
14. Comment #184011 by Quetzalcoatl on May 23, 2008 at 11:58 am
Steveroot-
"painless dentistry" is a good oxymoron.
Generally yes, and it makes a good dental joke. However, and excuse the OT, about 1/3 of the root canal treatments I do are without anesthesia and, yes, they *are* painless!
Ste5e
Other Comments by steveroot
27. Comment #184042 by Teratornis on May 23, 2008 at 1:27 pm
Comment #184032 by aquilacane:
I have noticed that for many people the brain is becoming a vestigial organ. Not much thinking going on with the majority of the human race, I think we'll discover we're better off being stupid in numbers than smart and alone.
You'll probably be as surprised I was, then, to discover there is objective evidence that people could actually be getting smarter, or at least getting better at taking tests which try to measure how smart they are:
http://en.wikipedia.org/wiki/Flynn_effect
The Flynn Effect is the opposite of what one would expect from the inverse correlation between IQ and fertility in modern societies, let alone what one would expect simply from going outside and talking to people. Nevertheless the Flynn Effect is consistently measurable.
Science still has a few things left to figure out about humans.
Other Comments by Teratornis
28. Comment #184043 by mordacious1 on May 23, 2008 at 1:28 pm
My root canal was the most relaxing thing I've had done in a long time, the Dr. was great. Totally painless.Other Comments by mordacious1
29. Comment #184053 by moderndaythomas on May 23, 2008 at 1:51 pm
mordacious1
Add the Postal Service to the list too.
What's a postal service?
Fire1974
Does anyone know of a creationist who's gotten through Med-School?
I know a psychiatrist?
I don't have my top wisdom teeth. Half way there is better then not at all.
Actually I wonder if this kind of thing could be considered as an indicator of a gene becoming a fossil?
Our health no longer depends on the presence of large cheek teeth, so when the mutations occur and the teeth don't come, it otherwise goes unnoticed. And nature doesn't purge us from the population. In fact, the less teeth that we have in our skull translates to fewer cavities and abscesses.
Other Comments by moderndaythomas
30. Comment #184056 by Geodesic17 on May 23, 2008 at 1:55 pm
There is a documentary called The Ghost in Your Genes that suggests that environmental events can switch off certain genes. I do not know enough about the subject, but I do not care for their choice of metaphor.http://www.pbs.org/wgbh/nova/genes/
Other Comments by Geodesic17
31. Comment #184063 by steveroot on May 23, 2008 at 2:03 pm
30. Comment #184053 by moderndaythomas on May 23, 2008 at 1:51 pm
Fire1974: "Does anyone know of a creationist who's gotten through Med-School?"
I know a psychiatrist?
Dr. Benway is *not* a creationist!
;-)
Ste5e
Other Comments by steveroot
32. Comment #184067 by Frankus1122 on May 23, 2008 at 2:09 pm
Comment #184053 by moderndaythomas
Our health no longer depends on the presence of large cheek teeth, so when the mutations occur and the teeth don't come, it otherwise goes unnoticed. And nature doesn't purge use from the population. In fact, the less teeth that we have in our skull translates to fewer cavities and abscesses
Is it one gene that is responsible for the formation of wisdom teeth? Do other mutations occur that cause other teeth (canine, for example)to not form?
Is there anyone who can seriously answer my question? (Thanks steveroot:)
Is it still the case that more absesses and cavities would lead to less reproductive success?
Are there now different selection mechanisms going on in societies that have dental care?
I don't think I am wrong to believe that reproductive success is the mechanism by which evolution works.
I can't see how a genetic mutation that causes a lack of wisdom teeth can be a factor in reproductive success.
If I have wisdom teeth am I less likely to reproduce? It could be the case, I suppose, but has there ever been any studies to determine whether or not this is true?
Evolution is blind (not intelligent). It does not 'know' that we no longer need wisdom teeth. According to the Theory of Evolution it is only through mutations that lead to offspring producing more offspring that those mutations survive and slowly change the structure of the organism.
Can someone explain this to me or was Ben Stein right?
Other Comments by Frankus1122
33. Comment #184092 by Chuk15 on May 23, 2008 at 2:57 pm
http://en.wikipedia.org/wiki/EpigeneticsOther Comments by Chuk15
34. Comment #184095 by steveroot on May 23, 2008 at 3:23 pm
33. Comment #184067 by Frankus1122 on May 23, 2008 at 2:09 pm
Is it one gene that is responsible for the formation of wisdom teeth? Do other mutations occur that cause other teeth (canine, for example)to not form?
Is there anyone who can seriously answer my question? (Thanks steveroot:)
I'm working on it. There are people here who know a hell of a lot more than I do about the genetic control of tooth development. I can say that there is genetic control and also there are developmental issues involved. Also, since you mention "canine" teeth, these are commonly impacted which prevents their eruption. The teeth are fully-formed, but blocked by other teeth or other pathological entities. They would appear to be missing, but would be seen on radiographs.
Children who suffer dental caries are at increased risk for abscess formation. Sometimes these get out of hand and the child will die. I'm not sure how much actual "selection" is going on in cases like these.
Anyway... off to the homeland. I'll have more info on this next week.
Ste5e
Other Comments by steveroot
35. Comment #184108 by Veon on May 23, 2008 at 4:07 pm
I don't know how the postal service is where you are from; but here in Norway it's great.What we really don't need is these silly delivery companies that can't even deliver a single package. I'm looking at you DHL.
EDIT: Oh and my wisdom teeth fit just fine. I guess wisdom just comes natural for some of us. Or not, as I'm gonna have to have them removed due to bad diet and maintenance.
Other Comments by Veon
36. Comment #184111 by HourglassMemory on May 23, 2008 at 4:18 pm
I'm going to be honest and say that the first thing that I thought of when I read the title was "Religion".Other Comments by HourglassMemory
37. Comment #184114 by kram50 on May 23, 2008 at 4:38 pm
Years ago I had an accident while building a roof. Now I carry around a nail in the middle of my forehead. The skin has grown over and there is a noticable bump. Sometimes I will joke around with kids and tell them that my relatives were related to a family of unicorns, and this is the last evidence of it you will see. Of course you can imagine the look on their faces.I come clean with them real soon...no harm done...I hope.
You may ask if I have had any ill effects from the nail....absolutely not!
Oh wait,...my eye is twitching,...my leg is sore,...and my balls hurt,....now I can't see!!!!
Must be Joe Pesche!!!!
(I have no idea how to spell Pesche)
Other Comments by kram50
38. Comment #184116 by Dale_Husband on May 23, 2008 at 4:51 pm
"Probably the most famous example is the appendix, though it is now an open question whether the appendix is really vestigial."No, it is not! That the appendix contains some lymphatic tissue does not make it an organ of the immune system, as Creationists falsely claim. Since the human appendix is so subject to infection, it is only natural that the process of evolution would place lymphatic tissue there to prevent the infection. Other animals have a large appendix that has a clearly defined digestive function. That is not the case with the human appendix.
Other Comments by Dale_Husband
39. Comment #184132 by jo5ef on May 23, 2008 at 6:32 pm
OK Frankus1122, I'll have a go. While people living in modern western cities may not be at risk of being selected against, the eruption of wisdom teeth can cause serious infection in teenagers (it happened to me, ouch). If untreated this could certainly impact on their reproductive success, especially in conjunction with other health issues. If you look at the proportion of the worlds population that still don't have access to adequate medical care then I think its possible that selection is still occurring. If (for instance) a teenage boy in sub-Saharan Africa, already struggling with various parasitic conditions, gets a serious and debilitating abscess due to an impacted wisdom tooth, and his only treatment option is the local witch doctor, this could result in permanent disfiguration (which may harm his chances of finding a wife) or even death.Other Comments by jo5ef
40. Comment #184146 by Frankus1122 on May 23, 2008 at 7:25 pm
Thanks jo5ef.I did a bit of poking around and it seems you are perhaps partially correct. There seems to be a lot more involved if I understand this article correctly:
http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1458632
Which I am not sure I do entirely. I ain't no scientist but I think I got the gist of the paper.
Here is a relevant excerpt:
A reduced number of molars may be advantageous from a human evolutionary perspective. Because of the dramatic lifestyle and diet shift experienced since the discovery of fire and the development of cooking utensils, third molars, which could have been essential for the survival of earlier hominids, became not only functionless but also an important cause of morbidity for modern humans (54). Dental arches have been reduced over hominid evolution (2â€"4, 56). As a result, third molars became frequently impacted or malpositioned, preventing the teeth from attaining a functional position. Furthermore, because of the difficulty of cleaning them and keeping them free of disease, impacted or malpositioned third molars lead to a higher susceptibility to periodontal disease, such as infections, carious lesions, cysts, tumors, and destruction of adjacent teeth and bone
Other Comments by Frankus1122
41. Comment #184153 by mordacious1 on May 23, 2008 at 7:51 pm
This is an interesting topic when discussing H. Sapien's ability to mess with natural selection. We have the ability to keep certain attributes going that may have disappeared long ago. Denistry is one way to interfer. I wonder if there were no dentists, then would there be more than 35% more of the population without wisdom teeth, probably. And what about parts of the world where there isn't access to dentists, are wisdom-toothless people higher than 35% because those with them died off or are not as attractive?Other Comments by mordacious1
42. Comment #184164 by Frankus1122 on May 23, 2008 at 8:07 pm
Comment #184153 by mordacious1And what about parts of the world where there isn't access to dentists, are wisdom-toothless people higher than 35% because those with them died off or are not as attractive?
Actually the article I referred to said that about 99.8 percent of Bantu speaking people have wisdom teeth while no Mexican Indians do. I don't think dentistry has had any effect yet.
But I have wondered the same thing about eye-glasses. Certainly there would be selection pressure on people who couldn't see clearly.
However, from what I read (and learned from posters on this site) it seems as though genes are not as specific as we sometimes think. They can express themselves in various way depending on other genes and environmental factors. They also have many purposes. Poor eyesight or fewer teeth may be the result of some other selection factor.
It is a complicated process.
Other Comments by Frankus1122
43. Comment #184172 by mordacious1 on May 23, 2008 at 8:26 pm
Poor eyesight has always interested me. Could I have survived thousands of years ago? I am legally blind without my glasses. On the other hand, when I'm not wearing them I can see detail better than most, close up. So as long as I specialized in, say tool making, I could become a needed asset to the tribe and they would protect me and feed me. I like to think so anyway.Other Comments by mordacious1
44. Comment #184174 by King of NH on May 23, 2008 at 8:32 pm
On the appendix:
It seems that there is still study to do, but it may be that the appendix serves modern humans in less developed nations by hosting bacteria that helps to digest food and prevent infections in the intestines. My source: wikipedia
Other Comments by King of NH
45. Comment #184177 by mordacious1 on May 23, 2008 at 8:37 pm
King of NHYes, I've read that somewhere too, quite interesting.
Other Comments by mordacious1
46. Comment #184178 by Frankus1122 on May 23, 2008 at 8:40 pm
Dr. William Parker, a professor of Surgery at Duke University, and his colleagues, think they've discovered why we have an appendix. In their studies of benign gut bacteria, they've found curious biofilms and concentrations of "good" bacteria in and around the appendix. These bacteria aid in digestion throughout the gut. Dr. Parker suspects that the appendix is a kind of "safe house" for these bacteria, where they can hide during episodes of diarrhea that flush the gut clean, and then move out to re-colonize the gut when the coast is clear. Ironically, he thinks that due to modern medicine, which makes diseases like cholera and dysentery uncommon, the appendix is under-stimulated and occasionally overreacts, causing appendicitis.
I heard this on Quirks and Quarks
Other Comments by Frankus1122
47. Comment #184181 by Steven Mading on May 23, 2008 at 8:44 pm
I have the opposite scenario. I'm a throwback. I have extra molars - too many. So did my father.A few years ago I had very bad pain way in the back of my mouth, way back where the upper and lower gums join. I also had bad ear canal drainage that gave me "airplane ear" pain. Turns out that the two were related. X-rays showed that I had extra molars. Behind the wisdom teeth I had even MORE teeth, but they were hard to see because they were too far back. I had to have them removed (think like getting your wisdom teeth out, but the recovery takes longer because they have to slice open the gums to get to the teeth.) It turns out that there was just enough of the teeth poking through where I couldn't reach with the toothbrush, and so these back teeth were getting exposed and getting bad cavities. These teeth also were causing my ear canal to be pinched off, causing the other problems.
So I guess it can go the other way too.
Other Comments by Steven Mading
48. Comment #184183 by King of NH on May 23, 2008 at 8:49 pm
'I could become a needed asset to the tribe and they would protect me and feed me'
The tribe has spoken. Give me your torch. =P
I think with eyes, most people that need glasses need them to drive and read and such. These are modern uses for the ancient eye. So in [easier?] times, a slightly misfunctioning eye would still work. I wear glasses to read signs while driving or working, but can 'see' just fine without them. I was 30 before I even knew I had a problem with vision, I thought I saw perfectly. In prehistoric times, I would have just been a lousy spear thrower. Eyes that are worse off would, I think, fall under most other problems that people are born with every day. The conception of life is a complicated process, and the engineer has no brain.
Other Comments by King of NH
49. Comment #184191 by Quine on May 23, 2008 at 9:40 pm
King of NH, in prehistoric times you would not have lived much past 30, and so would have had perfectly adequate vision to pass on your genes long before. Other Comments by Quine
50. Comment #184193 by moderndaythomas on May 23, 2008 at 10:06 pm
Frankus1122
Is it still the case that more absesses and cavities would lead to less reproductive success?
The Turkana boy, Homo habilis, is thought to have died from an abscessed tooth. He didn't have all of his molars in yet indicating that he was in his last growth spurt. About 13 or so.
What book I had read this in I couldn't tell you, but he didn't get a chance to leave any offspring.
Don't mind the improper spelling, I have no source in front of me.
Other Comments by moderndaythomas
Upcoming Events:
Mailing List
Enter your email:
DVDs
'The Enemies of Reason: The Uncut Interviews' DVD
'Voices of Reason' DVD
'Richard Dawkins: Appearances & Events 2007-2008' DVD
'Enemies of Reason' DVD
'Root of All Evil?' DVD
'Root of All Evil? The Uncut Interviews' DVD
'Growing Up in the Universe' DVD
'Voices of Science' DVD
'The Four Horsemen' DVD
'Break the Science Barrier' DVD
1. Comment #183983 by DamnDirtyApe on May 23, 2008 at 11:02 am
Otherwise, I agree. Especially on the overcrowded party that is ruined by my wisdom teeth.
And let's not forget the old favourite, the Appendix!
Other Comments by DamnDirtyApe