Free Republic
Browse · Search
Bloggers & Personal
Topics · Post Article

Skip to comments.

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.


TOPICS:
KEYWORDS: crevolist; evolution
Navigation: use the links below to view more comments.
first 1-5051-83 next last

1 posted on 05/31/2005 4:48:54 PM PDT by RightWingAtheist
[ Post Reply | Private Reply | View Replies]

To: PatrickHenry

For the list?


2 posted on 05/31/2005 4:49:46 PM PDT by RightWingAtheist (Creationism is not conservative!)
[ Post Reply | Private Reply | To 1 | View Replies]

To: RightWingAtheist

What did plants evolve from?


3 posted on 05/31/2005 4:52:31 PM PDT by Texas Eagle (If it wasn't for double-standards, Leftists would have no standards at all)
[ Post Reply | Private Reply | To 1 | View Replies]

To: RightWingAtheist
Creationism is not conservative!

Oh, do tell.

4 posted on 05/31/2005 4:53:52 PM PDT by Michael Goldsberry (an enemy of islam -- Joe Boucher; Leapfrog; Dr.Zoidberg; Lazamataz; ...)
[ Post Reply | Private Reply | To 2 | View Replies]

To: RightWingAtheist
I believe in The Big Bang Theory.

I believe God spoke and BANG! it happened.

5 posted on 05/31/2005 4:54:16 PM PDT by Texas Eagle (If it wasn't for double-standards, Leftists would have no standards at all)
[ Post Reply | Private Reply | To 1 | View Replies]

To: RightWingAtheist
I believe we had a common ancestor.

Adam.

6 posted on 05/31/2005 4:54:50 PM PDT by Texas Eagle (If it wasn't for double-standards, Leftists would have no standards at all)
[ Post Reply | Private Reply | To 1 | View Replies]

To: RightWingAtheist

What was the natural enemy of the first cell to ever exist?


7 posted on 05/31/2005 4:56:22 PM PDT by Texas Eagle (If it wasn't for double-standards, Leftists would have no standards at all)
[ Post Reply | Private Reply | To 1 | View Replies]

To: RightWingAtheist
Perhaps, future genetic engineers will be able to create a 12-fingered pianist without unwanted side effects.

Genetically engineered humans crosses so many moral boundaries – I'm glad I won't live to see it.

8 posted on 05/31/2005 4:56:47 PM PDT by D-fendr
[ Post Reply | Private Reply | To 1 | View Replies]

To: RightWingAtheist
It's all HOX genes, derivative of Homeobox genes.
9 posted on 05/31/2005 4:59:15 PM PDT by SteveMcKing
[ Post Reply | Private Reply | To 1 | View Replies]

To: RightWingAtheist
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)

"Genetic constraints". "Structured". Almost sounds like it was designed that way.

10 posted on 05/31/2005 4:59:23 PM PDT by DouglasKC
[ Post Reply | Private Reply | To 1 | View Replies]

To: Texas Eagle

Its environment.


11 posted on 05/31/2005 4:59:51 PM PDT by mcg1969
[ Post Reply | Private Reply | To 7 | View Replies]

To: RightWingAtheist

I'll bet this guy was really born with 6 fingers, but born without a brain.
Evolution is a fairy tale. This guy sounds serious!


12 posted on 05/31/2005 5:00:33 PM PDT by concerned about politics (Vote Republican - Vote morally correct!)
[ Post Reply | Private Reply | To 1 | View Replies]

To: concerned about politics
Evolution is a fairy tale.

You think scientific literature reads like a fairy tale, but Genesis doesn't.

13 posted on 05/31/2005 5:03:25 PM PDT by SteveMcKing
[ Post Reply | Private Reply | To 12 | View Replies]

To: RightWingAtheist
For the list?

Sure. It's not really news, but it's a good article. Cranking up the ping machine ...

14 posted on 05/31/2005 5:04:53 PM PDT by PatrickHenry (Felix, qui potuit rerum cognoscere causas. The List-O-Links is at my homepage.)
[ Post Reply | Private Reply | To 2 | View Replies]

To: RightWingAtheist
Anne Boleyn clearly had 6 fingers (at least on one hand) and yet successfully gave birth to Elizabeh I, so I wonder about your contention of hand-foot-genital genetic problems.

Why Elizabeth didn't inherit her mother's "abnormality" is a question for history.

.

15 posted on 05/31/2005 5:05:53 PM PDT by auzerais
[ Post Reply | Private Reply | To 1 | View Replies]

To: DouglasKC

"Genetic constraints" means you die before birth (or technically anytime before you reproduce with viable offspring). That's it.


16 posted on 05/31/2005 5:06:30 PM PDT by SteveMcKing
[ Post Reply | Private Reply | To 10 | View Replies]

To: VadeRetro; Junior; longshadow; RadioAstronomer; Doctor Stochastic; js1138; Shryke; RightWhale; ...
EvolutionPing
A pro-evolution science list with over 280 names.
See the list's description at my freeper homepage.
Then FReepmail to be added or dropped.

17 posted on 05/31/2005 5:06:48 PM PDT by PatrickHenry (Felix, qui potuit rerum cognoscere causas. The List-O-Links is at my homepage.)
[ Post Reply | Private Reply | To 14 | View Replies]

To: D-fendr
I'm glad I won't live to see it.

I just read that North Korea is experimenting with cloning, with the goal of cloning a human.

18 posted on 05/31/2005 5:07:19 PM PDT by Graybeard58 (Remember and pray for Spec.4 Matt Maupin - MIA/POW- Iraq since 04/09/04)
[ Post Reply | Private Reply | To 8 | View Replies]

To: concerned about politics

I've wondered the same thing about having more than two eyes. It sure would seem to give the advantage to those with eyes in the backs of their heads (like my mom!).

However, it's not just survival - it's survival in order to procreate. Not sure I would want to invite into my bed a 12-fingered-four-eyed gal!


19 posted on 05/31/2005 5:07:21 PM PDT by geopyg ("It's not that liberals don't know much, it's just that what they know just ain't so." (~ R. Reagan))
[ Post Reply | Private Reply | To 12 | View Replies]

To: SteveMcKing
You think scientific literature reads like a fairy tale, but Genesis doesn't.

Intelligent design is on it's way. Get used to it. Science is catching up - finally!

20 posted on 05/31/2005 5:07:34 PM PDT by concerned about politics (Vote Republican - Vote morally correct!)
[ Post Reply | Private Reply | To 13 | View Replies]

To: concerned about politics
Intelligent design is on it's way. Get used to it. Science is catching up - finally!

Do you have an actual response to my statement, or can I please ignore you now?

21 posted on 05/31/2005 5:09:58 PM PDT by SteveMcKing
[ Post Reply | Private Reply | To 20 | View Replies]

To: geopyg
I've wondered the same thing about having more than two eyes. It sure would seem to give the advantage to those with eyes in the backs of their heads (like my mom!).

I think my mom must have had motion sensors. I couldn't get away with anything.

22 posted on 05/31/2005 5:10:08 PM PDT by concerned about politics (Vote Republican - Vote morally correct!)
[ Post Reply | Private Reply | To 19 | View Replies]

To: concerned about politics
Intelligent design is on it's way. Get used to it. Science is catching up - finally!

Not bad for a theory that predicts nothing...

23 posted on 05/31/2005 5:10:31 PM PDT by blowfish
[ Post Reply | Private Reply | To 20 | View Replies]

To: SteveMcKing
Do you have an actual response to my statement, or can I please ignore you now?

Do what ever you want. I don't hold grudges. It's not worth it.

24 posted on 05/31/2005 5:11:26 PM PDT by concerned about politics (Vote Republican - Vote morally correct!)
[ Post Reply | Private Reply | To 21 | View Replies]

To: RightWingAtheist

Six fingers can make for an impressive swordsman; though perhaps not good enough.


25 posted on 05/31/2005 5:12:07 PM PDT by Redcloak (We'll raise up our glasses against evil forces singin' "whiskey for my men and beer for my horses!")
[ Post Reply | Private Reply | To 1 | View Replies]

To: RightWingAtheist
I think the liberals drew aces and eights.

Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)

LonePalm, le Républicain du verre cassé (The Broken Glass Republican)

26 posted on 05/31/2005 5:14:40 PM PDT by LonePalm (Commander and Chef)
[ Post Reply | Private Reply | To 1 | View Replies]

To: concerned about politics

Me neither. I relent and say good day!


27 posted on 05/31/2005 5:14:56 PM PDT by SteveMcKing
[ Post Reply | Private Reply | To 24 | View Replies]

To: DouglasKC
The basic question for those that support evolution:

was the data encoded in DNA for all life present at the beginnings and over time masked data is activated..

or the data was incomplete in DNA and new DNA was "added" with survival advantages so it was passed on..

If you look at old life (blue/green) bacteria the full genetic code for mammals is missing so #1 seem less likely

So more likely data in form of DNA was added to genetic code ..was this data the result of virus infections or prions..chemical or energy (UV light) impacts..

The problem with #2..why would one assume that random additions of data or mutation of data is viable it would be an article of faith in theory of evolution -

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 ? 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???
grist for the mill
28 posted on 05/31/2005 5:16:02 PM PDT by ConsentofGoverned (mark rich, s burger,flight 800, waco,cbs's national guard-just forget thats the game)
[ Post Reply | Private Reply | To 10 | View Replies]

To: RightWingAtheist
This guy must not know that six-fingered hands (hexyldactyly)are rather common:

http://www.medterms.com/script/main/art.asp?articlekey=7756

In fact, I've known two people who exhibit this "defect," although one had the finger cut off at birth. Both were born in the Dominican Republican, where cousin marriage isn't uncommon.

29 posted on 05/31/2005 5:18:11 PM PDT by two134711 (If you're too open minded, your brains will fall out.)
[ Post Reply | Private Reply | To 1 | View Replies]

To: concerned about politics
I don't know why in the world I'm bothering to jump into this, but I have to know...

What is it about evolution that is so difficult to comprehend, and what is it about evolution that people turn aside all reason to deny it?

30 posted on 05/31/2005 5:20:59 PM PDT by AshfieldK
[ Post Reply | Private Reply | To 12 | View Replies]

To: SteveMcKing
And without faith, it is impossible to accept creation. And in the same way, without faith, it is impossible to accept evolution. It is your choice what you want to believe.

There are things in this world that point to a Creator. Those who don't believe in The Creator have not seen enough.

31 posted on 05/31/2005 5:25:22 PM PDT by blueberry12
[ Post Reply | Private Reply | To 13 | View Replies]

To: Texas Eagle

It's thought that plants and the green algae charophyceans share a common ancestor.


32 posted on 05/31/2005 5:26:28 PM PDT by staterightsfirst
[ Post Reply | Private Reply | To 3 | View Replies]

To: RightWingAtheist

The only poker hand evolution holds is a "busted flush".


33 posted on 05/31/2005 5:27:58 PM PDT by Gritty ("Statism is what fascism, Nazism, communism and now the European Union all have in common-Mark Steyn)
[ Post Reply | Private Reply | To 1 | View Replies]

To: RightWingAtheist
I donno what happened, but your thread's been tossed into the blogger forum.
34 posted on 05/31/2005 5:30:16 PM PDT by PatrickHenry (Felix, qui potuit rerum cognoscere causas. The List-O-Links is at my homepage.)
[ Post Reply | Private Reply | To 2 | View Replies]

To: mcg1969

How could its environment be its natural enemy when it was its environment that laid the groundwork for its life?


35 posted on 05/31/2005 5:33:42 PM PDT by Texas Eagle (If it wasn't for double-standards, Leftists would have no standards at all)
[ Post Reply | Private Reply | To 11 | View Replies]

To: staterightsfirst
It's thought that plants and the green algae charophyceans share a common ancestor.

Heh, heh. Let me guess -- the ape.

36 posted on 05/31/2005 5:34:33 PM PDT by Texas Eagle (If it wasn't for double-standards, Leftists would have no standards at all)
[ Post Reply | Private Reply | To 32 | View Replies]

To: AshfieldK
What is it about evolution that is so difficult to comprehend, and what is it about evolution that people turn aside all reason to deny it?

Because we have ape-type animal remains (no human DNA), and then "Poof!", we have man. There is no link between the two. It's just the way the Bible describes it. Man was created.
I'm no saint, but the Bible's description of man is more logical.
There must have been some type of serious tinkering going on around here!!! The complexity of it all is no accident. Everything is preprogrammed and deliberate. That's why intelligent design is becoming more and more logical as scientific technology "evolves".

37 posted on 05/31/2005 5:35:28 PM PDT by concerned about politics (Vote Republican - Vote morally correct!)
[ Post Reply | Private Reply | To 30 | View Replies]

To: concerned about politics
There must have been some type of serious tinkering going on around here!!!

I can buy that (and do, actually), but intelligent design, or divine purpose, doesn't preclude the process being a reality.

38 posted on 05/31/2005 5:43:18 PM PDT by AshfieldK
[ Post Reply | Private Reply | To 37 | View Replies]

To: Texas Eagle

Oh, okay, so you're not really interested.

Enjoy your 'willful ignorance.'


39 posted on 05/31/2005 5:43:51 PM PDT by staterightsfirst
[ Post Reply | Private Reply | To 36 | View Replies]

To: staterightsfirst

You were serious?


40 posted on 05/31/2005 5:47:58 PM PDT by Texas Eagle (If it wasn't for double-standards, Leftists would have no standards at all)
[ Post Reply | Private Reply | To 39 | View Replies]

To: AshfieldK
I can buy that (and do, actually), but intelligent design, or divine purpose, doesn't preclude the process being a reality.

Sure it does. Man DNA appeared out of no where. "Poof!"

41 posted on 05/31/2005 5:48:14 PM PDT by concerned about politics (Vote Republican - Vote morally correct!)
[ Post Reply | Private Reply | To 38 | View Replies]

To: concerned about politics
Man DNA appeared out of no where. "Poof!"

Human Ancestors.
The Evidence for Human Evolution.
Comparison of all Hominid skulls.

Don't miss this one: Chimpanzees and humans share a common ancestor, and even today 99 percent of the two species' DNA is identical.

42 posted on 05/31/2005 5:59:52 PM PDT by PatrickHenry (Felix, qui potuit rerum cognoscere causas. The List-O-Links is at my homepage.)
[ Post Reply | Private Reply | To 41 | View Replies]

To: PatrickHenry
Chimpanzees and humans share a common ancestor, and even today 99 percent of the two species' DNA is identical.

If a Chimpanzee was a man, it would have human DNA. It does not. It's still a monkey.

43 posted on 05/31/2005 6:04:26 PM PDT by concerned about politics (Vote Republican - Vote morally correct!)
[ Post Reply | Private Reply | To 42 | View Replies]

To: concerned about politics
DNA did come from nowhere. All matter came from nowhere. First there was nothing, then there was everything - creation. The subsequent ordering of that random new stuff is also creation. The evolution of life is creation. Creation wasn't just a single moment. Creation is the entirety of history and the entirety of the future. The source of creation is the creator, God. There isn't any contradiction between evoultion and creation, because, like I said, evolution is part of the total creation.
44 posted on 05/31/2005 6:07:52 PM PDT by AshfieldK
[ Post Reply | Private Reply | To 41 | View Replies]

To: PatrickHenry
The Evidence for Human Evolution. Comparison of all Hominid skulls.

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"?

Ok. I have to go out and feed our critters (Animal chores. Ack!)
My 16 year old will steal the computer. She always does. She's already begging for it.
I hope to engage in further debate sometime. The Evolution theory is easy to crack.

45 posted on 05/31/2005 6:14:04 PM PDT by concerned about politics (Vote Republican - Vote morally correct!)
[ Post Reply | Private Reply | To 42 | View Replies]

To: SteveMcKing
"Genetic constraints" means you die before birth (or technically anytime before you reproduce with viable offspring). That's it.

Who put the constraint there? In your example, why doesn't evolution favor humans who live 150 years and are able to reproduce for 135 of those years? You would think that after millions of years that evolution would have figured this out.

46 posted on 05/31/2005 6:15:55 PM PDT by DouglasKC
[ Post Reply | Private Reply | To 16 | View Replies]

To: Texas Eagle

entropy


47 posted on 05/31/2005 6:32:08 PM PDT by furball4paws (One of the last Evil Geniuses, or the first of their return.)
[ Post Reply | Private Reply | To 7 | View Replies]

To: Texas Eagle

pond scum


48 posted on 05/31/2005 6:32:28 PM PDT by furball4paws (One of the last Evil Geniuses, or the first of their return.)
[ Post Reply | Private Reply | To 3 | View Replies]

To: furball4paws

Why did it need to change?


49 posted on 05/31/2005 6:36:06 PM PDT by Texas Eagle (If it wasn't for double-standards, Leftists would have no standards at all)
[ Post Reply | Private Reply | To 47 | View Replies]

To: blueberry12
And without faith, it is impossible to accept creation. And in the same way, without faith, it is impossible to accept evolution.

The old "everybody else does it. Why shouldn't I?" excuse

50 posted on 05/31/2005 6:36:13 PM PDT by Oztrich Boy (here to help)
[ Post Reply | Private Reply | To 31 | View Replies]


Navigation: use the links below to view more comments.
first 1-5051-83 next last

Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.

Free Republic
Browse · Search
Bloggers & Personal
Topics · Post Article

FreeRepublic, LLC, PO BOX 9771, FRESNO, CA 93794
FreeRepublic.com is powered by software copyright 2000-2008 John Robinson