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Evolution's Poker Hand
TechCentralStation ^ | May 31 2005 | Kenneth Silber

Posted on 05/31/2005 4:48:54 PM PDT by RightWingAtheist

As I type these words, my fingers fly across the keyboard -- albeit not as efficiently as I would like. For one thing, I have never really been a 10-finger typist. For another, I have only 10 fingers. Surely, I could get this piece written and emailed to TCS Headquarters faster if I had, say, 12 or 14 fingers. Why don't I?

Although it might sound like I'm on drugs, the question I am raising is one that is of interest in evolutionary biology. Humans and numerous other species have five (or fewer) digits per appendage. Why? And moreover, why have selection pressures not given rise to appendages with more digits? A few extra fingers, after all, would allow more detailed grasping and other operations, and thus a mutation that provided them would seem like a good bet to spread through the gene pool.

The explanation, it turns out, tells us something not only about the evolutionary past but also about humanity's future -- about the potential and limitations of genetic engineering. In one scene in the 1997 sci-fi film Gattaca, a close shot of a pianist's hands reveals that he has six fingers on each (and thus he gives a virtuoso performance of "Impromptu for Twelve Fingers"). Just what would be involved in making such a concert possible?

Some 360 million years ago, at the end of the Devonian era, an evolutionary experiment was underway. Fish, which had long been the only vertebrates on the planet, were giving rise to tetrapods, animals with four limbs. The evolutionary link consisted of fish with two pairs of fins that gave them a survival advantage in shallow water (they could push themselves off if stranded, for instance). Some tetrapods had more than five digits on their appendages. One such animal, Aconthostega (a fossil of which was found in Greenland in 1987), had eight digits on each appendage (and had lungs as well as gills).

By 340 million years ago, there were tetrapods that spent much of their time on land, such as a small, lizard-like animal called Casineria (a fossil of which was found in Scotland in 1992). Casineria had five digits on each limb. Having relatively few digits may have been an advantage in making a land animal better suited for walking rather than aquatic paddling. Casineria also had more flexible digits (the fossil bones have furrows that once held ligaments) and a stronger backbone, key adaptations to land life.

A basic pattern of having five digits thus was set early in the history of land vertebrates. It seems to have taken hold before the evolutionary break between amphibians and amniotes (a broad category that ultimately would include dinosaurs, birds, reptiles and mammals). Many land animals today have fewer than five digits, but there is a notable absence of species that have more than five. This is not entirely surprising; in evolution, losing a feature that is not needed is relatively easy, compared to gaining (or regaining) a potentially useful feature.

Still, in the sweep of evolutionary time, one would expect some species to have found a survival advantage in having extra digits -- for example, in becoming better at tree-climbing or, in the case of more recent human ancestors, tool-making. The fact that this did not happen suggests that there are genetic constraints involved. Clifford J. Tabin of Harvard Medical School has suggested that the genes that control digit formation are structured so as to produce five basic patterns (thumbs, pinkies, etc., in the case of a human hand). Thus, additional digits that arise through genetic abnormalities merely duplicate an existing digit, and thus offer little survival benefit.

An even more daunting constraint appears to arise from pleiotropy, the capacity of genes to influence multiple physical characteristics. A rare genetic disease called Hand-Foot-Genital Syndrome involves malformations of the genito-urinary system as well as limbs; the cause seems to lie in incorrect coding across the same set of genes that handle digit formation. Thus, in the course of evolution, whatever advantage arose from having more digits may have come alongside the disastrous disadvantage of having malformed reproductive organs.

Vocal proponents and critics of genetic engineering both tend to assume that the technology is on the verge of transforming humanity. But the practical difficulties of achieving the hoped-for or feared transformation are too often overlooked. Perhaps, future genetic engineers will be able to create a 12-fingered pianist without unwanted side effects. Yet the complex evolutionary and genetic history behind having five fingers on each hand suggests that such virtuosity, scientific and musical, may be a long time in coming.


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KEYWORDS: crevolist; evolution
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To: Texas Eagle

If you didn't "need" to change, you wouldn't be toilet trained now.


51 posted on 05/31/2005 6:39:27 PM PDT by furball4paws (One of the last Evil Geniuses, or the first of their return.)
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To: furball4paws

The change you are talking about is akin to replacing poopy diapers?


52 posted on 05/31/2005 6:50:30 PM PDT by Texas Eagle (If it wasn't for double-standards, Leftists would have no standards at all)
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To: Texas Eagle; Alamo-Girl

No, just don't anthropomorphize simple cells. A-G will do a very good job telling you that the answer to your question is a "will to live". She can do it much better than I.


53 posted on 05/31/2005 6:58:59 PM PDT by furball4paws (One of the last Evil Geniuses, or the first of their return.)
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To: furball4paws

Do simple cells exist to this day?


54 posted on 05/31/2005 7:00:29 PM PDT by Texas Eagle (If it wasn't for double-standards, Leftists would have no standards at all)
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To: PatrickHenry
As we evolutionists like to say, c'est la vie.
55 posted on 05/31/2005 7:42:47 PM PDT by RightWingAtheist (Creationism is not conservative!)
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To: RightWingAtheist
...A few extra fingers, after all, would allow more detailed grasping and other operations....

Not necessarily; they may just get in each others way. It's not clear that detailed grasping is needed for reproductive advantage.

Evolution is conservative; most things just hang around if not detrimental.

56 posted on 05/31/2005 8:24:14 PM PDT by Doctor Stochastic (Vegetabilisch = chaotisch is der Charakter der Modernen. - Friedrich Schlegel)
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To: PatrickHenry

Thanks for the ping!


57 posted on 05/31/2005 8:28:49 PM PDT by Alamo-Girl
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To: furball4paws; Texas Eagle
Thanks for the ping, furball4paws!

Texas Eagle, if you are interested in the discussion of the "will to live", here's a primary thread: Can the Monist view account for 'what is life?'

58 posted on 05/31/2005 8:34:16 PM PDT by Alamo-Girl
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To: RightWingAtheist; PatrickHenry
The author seems to have limited himself to five digits as opposed to more, when he should have also addressed the 5 or less argument as well..

Experiments in robotics have shown that 3 digits is minimal..
Two "fingers" and an opposable "thumb"..
One thumb and one finger will allow grasping of an object, but control or manipulation is "shaky" as the object will rotate (laterally?) between the two digits...
digit #3 allows control of that rotation..

So one could argue, that for the sake of efficiency, humans could get rid of the 4th finger (pinky) and still have sufficient digital dexterity for any imagined task...

In many animals, an extra digit remains in the form of a "dew claw", which may be a disposed of thumb..
In hooved animals, the digits have evolved into 2 digits, (cloven hooved, like cattle and deer) and 1 digit ( hooved, like horses )..

The author looked in the wrong direction.. evolution "simplifies" ...
In different orders, digits have evolved to the task at hand..

Oh.. and then there's "flippers" on seals, etc.. and the whales... Once a land mammal, now sea-borne, and still retaining vestigial digits within it's flukes..

59 posted on 06/01/2005 2:18:43 AM PDT by Drammach (Freedom; not just a job, it's an adventure..)
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To: RightWingAtheist

I once had a school buddy who was born with six fingers on each hand. He had scars from where the extra digits had been removed. I once told him he should searh the world over & find a six fingered girl to marry and he didn't think that was too funny at all.


60 posted on 06/01/2005 3:26:28 AM PDT by shuckmaster
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To: concerned about politics
Let's move down about 8" (they always leave this part out). So why does a monkey have a spinal column that attaches to the skull like that of a monkey, but a human has a spinal column that attaches to it's skull like a bear? Where's the "missing link"? Where's the "evolutionary jump"?


61 posted on 06/01/2005 3:36:11 AM PDT by bobdsmith
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To: concerned about politics
If a Chimpanzee was a man, it would have human DNA. It does not. It's still a monkey.

Chimpanzees are not monkeys, nitwit, they are apes. How the hell do you expect anyone to take you seriously when you don't even get first-grade zoology correct?

62 posted on 06/01/2005 3:57:49 AM PDT by WildHorseCrash
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To: Texas Eagle
I believe in The Big Bang Theory.

I'm partial to the 'Big Smoke' theory, right after the 'Big Bang'.

63 posted on 06/01/2005 4:38:28 AM PDT by dread78645 (Sorry Mr. Franklin, We couldn't keep it.)
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To: AshfieldK
What is it about evolution that is so difficult to comprehend,

It's not difficult to comprehend, and just about every one does comprehend it.

... and what is it about evolution that people turn aside all reason to deny it?

The belief that humans are somehow "special".

Welcome to Crevoland.

64 posted on 06/01/2005 5:04:43 AM PDT by dread78645 (Sorry Mr. Franklin, We couldn't keep it.)
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To: concerned about politics
Evolution is a fairy tale.

Which version of evolution are you talking about? The one I'm familiar with is a scientific theory.

65 posted on 06/01/2005 7:02:44 AM PDT by Condorman (Changes aren't permanent, but change is.)
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To: SteveMcKing
Do you have an actual response to my statement, or can I please ignore you now?

It's just the usual chest-thumping for their side. They'll scream they're winning all the way to irrelevance and oblivion.

66 posted on 06/01/2005 7:16:46 AM PDT by Right Wing Professor
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To: ConsentofGoverned
It seems to me that intelligent design done over time has as much going for it as the above - if evolution was the only way to change species why do we still have very primitive bacteria that have Never evolved ?

This is a rehash of "if we evolved from monkeys why are there still monkeys" question. In the same way, if Americans came from Europe, why are there still Europeans?

they were exempted from the forces that have acted on other forms of life for billions of years--seems strange that any old form including sharks and crocks would not have had major evolutionary change when the Evolutionist tell us that Evolution is such a powerful force- why are these life forms not effected???

Ever hear of a local fitness maximum? Top-level predators don't have much pressure to change. But that notwithstanding, what makes you think evolution has no effect on sharks?

Perhaps you misapprehend what the theory of evolution actually says.

67 posted on 06/01/2005 7:55:24 AM PDT by Condorman (Changes aren't permanent, but change is.)
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To: Drammach

Under the external hoof, horses have 5 digits


68 posted on 06/01/2005 11:01:26 AM PDT by AntiBurr ("Ceterum censeo Islam esse delendam " with apologies to Cato)
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To: Texas Eagle

Not only do simple cells exist, the amoeba which is a one celled animal is literally a part of the first amoeba since they reproduce by division.


69 posted on 06/01/2005 11:05:32 AM PDT by AntiBurr ("Ceterum censeo Islam esse delendam " with apologies to Cato)
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To: Condorman
Evolution (the hypothesis) is changing as we learn more of genetics and biochem..I do not think evolution will ultimately be the strong force for biodiversity.

Intelligent design would not rule out evolution for variation within species, but, evolution seems to have weakness in explaining major new species which are not able to reproduce with progenitors. Are we to believe that such changes must produce offspring of both sexes at the same moment.

much like BOHEM's theory of a Holographic universe which is unfolding thru time..intellegent design may be unfolding thru time..it would explain for me at least major changes in bio diversity in very short geologic time periods.. so no I do not refute evolution I just think that it may not be the primary vehicle for major change.
70 posted on 06/01/2005 11:34:54 AM PDT by ConsentofGoverned (mark rich, s burger,flight 800, waco,cbs's national guard-just forget thats the game)
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To: ConsentofGoverned
I do not think evolution will ultimately be the strong force for biodiversity.

... evolution seems to have weakness in explaining major new species which are not able to reproduce with progenitors. Are we to believe that such changes must produce offspring of both sexes at the same moment.

...so no I do not refute evolution I just think that it may not be the primary vehicle for major change.

Again, it appears as though you labor under a number of misconceptions regarding the theory of evolution. You may be correct in that evolution may fall by the wayside, but I find it unlikely. However, should evolution ever be falsified beyond recoverability, I will cheerfully abandon it. Just remember that ID must stand or fall on its own merits.

As for your second point, try Methods of Speciation (PDF) or ring species.

71 posted on 06/01/2005 2:59:00 PM PDT by Condorman (Changes aren't permanent, but change is.)
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To: AntiBurr
Not only do simple cells exist, the amoeba which is a one celled animal is literally a part of the first amoeba since they reproduce by division.

How can they still exist if they reproduce by division? Once it evolved into something else wouldn't it divide itself into what ever form it evolved into?

Or are you saying those things live forever and the very first amoeba to ever exist still exists?

72 posted on 06/01/2005 3:14:48 PM PDT by Texas Eagle (If it wasn't for double-standards, Leftists would have no standards at all)
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To: Condorman
"By the time the salamanders reached the southernmost part of California, the separation had caused the two groups to evolve enough differences that they had become reproductively isolated. In some areas the two populations coexist, closing the "ring," but do not interbreed. They are as distinct as though they were two separate species. Yet the entire complex of populations belongs to a single taxonomic species, Ensatina escholtzii. "

as i posted variation within a species can be explained by
evolution hypothesis.. no argument there

however we are talking about basically similar salamanders here (ring) not interbreeding from what i can deduct due to not changes in morphology of physical characteristics such as sex organs but in habit of mating.

A horse can produce a mule is that evolution?

i can understand those who would propose this ring data shows evolution - it well may- but you do not have a
mule at the far end of the ring you still have a salamander with unique breeding habits.

what am i missing??
73 posted on 06/01/2005 3:15:08 PM PDT by ConsentofGoverned (mark rich, s burger,flight 800, waco,cbs's national guard-just forget thats the game)
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To: AntiBurr
Under the external hoof, horses have 5 digits

No, They don't..

74 posted on 06/02/2005 5:59:35 AM PDT by Drammach (Freedom; not just a job, it's an adventure..)
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To: AntiBurr
Let's do that again, just so it's clear...

"The horse’s foot contacts the ground only with the hoof of the third digit [like our middle toe] in an almost vertical position [like a ballet dancer, en pointe]," says Gheorghe M. Constantinescu, professor of veterinary anatomy, University of Missouri-Columbia and author of the book Clinical Dissection Guide for Large Animals.

Only splint bones alongside the cannon bone remain of its second and fourth toes. [P.D. Garrett, DVD, MS]
Moreover, the so-called cannon bone is much longer proportionately than ours.
What do I mean by "cannon bone"? Look at your foot.
The five bones going from your ankle to your toes correspond to the one bone in the horse’s foot: the cannon bone.
But, it’s huge — running half way up the horse’s leg to what looks like its knee but is actually its ankle (called the hock).
Almost all trace of its other toes has vanished. Only splint bones alongside the cannon bone remain of its second and fourth toes. Short, strong ligaments tie the splint bones to the cannon bone.

75 posted on 06/02/2005 6:10:27 AM PDT by Drammach (Freedom; not just a job, it's an adventure..)
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To: ConsentofGoverned
A horse can produce a mule is that evolution?

That should read:
"A horse can still produce a mule..."

I'm not sure if this is scientifically correct, but the principle involved is the "differentiation" of the species of horse and donkey..

At some point, horses and donkeys split into two different breeds or species..
For a very long time, there was plenty of interbreeding, but over eons, the two species became less and less alike..
Such matings became "accidental" until man came along and started interbreeding on purpose..
Without human interference, ( and maybe in spite of it, ) horse and donkey will eventually be unable to interbreed at all..
Result,.. No more Mules..
While still closely "related" enough to produce offspring, they are generally infertile.
Occassionally a horse/jenny or donkey/mare offspring will be fertile and able to produce offspring..

What am I missing?

I think what is missing is Time.

The Salamanders have not remained distinct for a long enough period to completely become two different "species", if that's the right word..

Something similar was reported recently concerning birds that split their migration around the Himalayan mountain range.. ( National Geographic? )
Those that went North and East can interbreed...
Those that went North and West can interbreed..
Those IN the Northeast and Northwest cannot..
The two branches even have developed different coloration, as well as mating calls and habits..

Given time, the salamanders will become distinct branches of their species, with more than mating habits to differentiate them.. physical characteristics will eventually develop as well, to make identification of qualified mating material easier to identify..

76 posted on 06/02/2005 6:35:50 AM PDT by Drammach (Freedom; not just a job, it's an adventure..)
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To: Drammach
given enough time - paper and word processors, a million monkeys will produce "war and peace". LOL

Time has not cause blue green algae to evolve - billions of yrs

What is so hard to comprehend - intelligent design can explain much of what is attributed to evolution - those species suitable for an environment are not changed by the designer -

Species that are needed to evolve into conscious beings
are changed to allow that outcome. species that need to change to survive and support a niche in the eco-sphere - are changed, by design.

A small weak humanoid had very few characteristics to survive and thus evolve ..if we take only evolution as the prime mover for change..we are not here now. LOL

the evolution of modern man is recent 100,000 yrs give or take..so "time" in geologic sense is not able to explain the changes to modern man fully.
77 posted on 06/02/2005 7:40:21 AM PDT by ConsentofGoverned (mark rich, s burger,flight 800, waco,cbs's national guard-just forget thats the game)
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To: ConsentofGoverned
given enough time - paper and word processors, a million monkeys will produce "war and peace". LOL

The old "It's all random" argument..
Evolution isn't random..

78 posted on 06/02/2005 8:03:23 AM PDT by Drammach (Freedom; not just a job, it's an adventure..)
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To: Drammach
"The old "It's all random" argument..
Evolution isn't random.."

random is random until a pattern is seen such as computer review of recent lotto winning numbers to make a selection for the next winning numbers..LOL

Me thinks it's in the stars and none of us will understand the grand design for it's all unknowable but fun to think we know..sure looks very cold, dark and empty out there in the vast universe us monkeys can now see..

the old razor of the simple answer might be a clue.
79 posted on 06/02/2005 8:10:05 AM PDT by ConsentofGoverned (mark rich, s burger,flight 800, waco,cbs's national guard-just forget thats the game)
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To: ConsentofGoverned
First let's establish a point here..

I beleive in God, and God's creation of the Universe..

Second, I believe God created evolution..
I have no I repeat, no problem with the existance of God and Evolution in the same universe..

I don't see evolution as an attempt to discount the existence of God, I see it as an attempt to understand how God created the universe and everything in it..

That said, let's get back to randomicity..

All life has certain priorities, the foremost are survival and reproduction..
This fact (FACT) alone precludes the idea that evolution is a "random" process..

That which survives has the (an) opportunity to determine the characteristics of the following generation(s)..by passing on it's genes...
That which has the best chances for procreation, (health, choice of mate, health of said mate) are most likely to do so, and to produce healthy offspring, with the best survival characteristics..

Often, the environment in which that life exists can have a determining effect on which characteristics are emminently "survival" and "health" characteristics, and when (not if, when) that suited life "exhibits" certain feaures which identify it as more suited to survive, said life will increase it's chances at mating, and therefore, passing on it's survivability, health, preferable mating features, etc..

This is, in essence, evolution.. in it's simplist form..
As you can plainly see, it is not random..
I have pointed out the "external factors" that influence that life, and will, in Time, differentiate it from other life forms...

It has nothing to do with monkeys on typewriters...
It is not random..
It is evolution..

And like I said at the beginning, it does Not Exclude God in any way..
A God or Being, whatever or however you wish to describe It/Him/Her that can create a Universe, create the Physical Laws that govern Mass, Energy, Gravity, the orbits of Galaxies, Stars and planets, That created Elements in solid liquid and gas, and that created Life itself, is surely intelligent enough to create an orderly way in which to do all that and more...

Look to your Bible..
Man cannot comprehend God..

I suppose, if God had "wanted" to create Man out of the blue, God could very well have done so..
But, that would be like an "afterthought" wouldn't it??
If God were to create a Universe, and a place for man to live, called Earth, and all the Cosmos, wouldn't God just "do it" ???
Wouldn't God Just Do It, All At Once, and simply let the process happen?

80 posted on 06/02/2005 8:40:06 AM PDT by Drammach (Freedom; not just a job, it's an adventure..)
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To: Drammach

well said , I will have plenty of time to see if evolution holds up as main engine of diversity of life - but those monkeys typing away over millions of years surely they have a shot at something great. Thanks for your discussion on a very polarizing subject..Peace thru strength.


81 posted on 06/02/2005 12:13:16 PM PDT by ConsentofGoverned (mark rich, s burger,flight 800, waco,cbs's national guard-just forget thats the game)
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To: Drammach

I stand corrected.


82 posted on 06/02/2005 5:28:11 PM PDT by AntiBurr ("Ceterum censeo Islam esse delendam " with apologies to Cato)
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To: ConsentofGoverned
we are talking about basically similar salamanders here (ring) not interbreeding from what i can deduct due to not changes in morphology of physical characteristics such as sex organs but in habit of mating.

i can understand those who would propose this ring data shows evolution - it well may- but you do not have a mule at the far end of the ring you still have a salamander with unique breeding habits.

what am i missing??

The fact that these two populations are reproductively isolated.

  C - D
 /     \
B       E
 \     /
  A | F

A breeds with B, B breeds with C, C breeds with D, D breeds with E, E breeds with F, but A and F do not breed.

They are still technically classified as a single species, but incremental changes along the continuum have accumulated to the point that the ends of the ring function as separate species. Each end is free to drift (genetically speaking) independently of the other. What difference does it make if they don't breed because of coloration or sex organs or a funky mating dance? They are now separate and will in all likelihood continue to diverge.

83 posted on 06/03/2005 7:49:39 AM PDT by Condorman (Changes aren't permanent, but change is.)
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