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Author Topic:   Questions on Evolution.
Rrhain
Member
Posts: 6192
From: San Diego, CA, USA
Joined: 05-03-2003
Member Rating: 2.4


Message 16 of 43 (168295)
12-14-2004 11:00 PM
Reply to: Message 8 by CreepingTerror
12-14-2004 4:13 PM


CreepingTerror writes:

quote:
So can we give a rough estimate to the improbability of evolution?

Given that we can see evolution happen right in front of our eyes, the probability of evolution is exactly 1.

Are you trying to compute the probability that any given, specific organism coming about by evolution? Let me try to show you the difference between those two questions:

Supposed I have a standard deck of 52 cards and I draw one.

What is the probability of me drawing the Ace of Spades?
What is the probability of me drawing an Ace?
What is the probability of me drawing a Spade?
What is the probability of me drawing a black card?
What is the probability of me drawing a card?

See how each of those possibilities becomes more and more probable? i start from the worst case scenario (1 in 52) to a guaranteed result (1 in 1).

Life reproduces chemically. No chemical reaction is ever perfect. Therefore, we will necessarily have changes in the genetic structure from one generation to the next when dealing with the entire population.

Evolution simply has to happen. Unless you are willing to claim that there is perfect replication, then there is no other alternative but evolution.

But in the end, be very careful not to confuse the probability of a specific outcome with the probability of any outcome.


Rrhain
WWJD? JWRTFM!
This message is a reply to:
 Message 8 by CreepingTerror, posted 12-14-2004 4:13 PM CreepingTerror has not yet responded

  
crashfrog
Inactive Member


Message 17 of 43 (168299)
12-14-2004 11:04 PM
Reply to: Message 15 by CreepingTerror
12-14-2004 10:35 PM


What other scientifically viable theories are there that contradict Evo.

Well, there have been several. For instance, Lamarkianism, or Lysenkoism. The fact that you have never heard of them is a testament to the degree to which evolution is better than all the other competing theories. It's simply the best explanation for the history of life on Earth that we have, and, to date, nobody has come up with a better one. But maybe somebody will. Maybe you will.

But that doesn't change the fact that the chances of a mutation having a beneficial effect are extremely low.

Yes, that's true. But every organism is basically guaranteed to have somewhere between 5 and 50 mutations (that's a very rough, imprecise ballpark estimate). So, per generation, that's millions of mutations, several (say, less than 10) of which will probably be beneficial.

You're right that a beneficial mutation isn't likely. But there are so many muations per new generation that benefical mutations are a certainty.


This message is a reply to:
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jar
Member
Posts: 29622
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.1


Message 18 of 43 (168300)
12-14-2004 11:06 PM
Reply to: Message 15 by CreepingTerror
12-14-2004 10:35 PM


Re: improbablity of what
Fair enough, the good traits do get passed on. But that doesn't change the fact that the chances of a mutation having a beneficial effect are extremely low. So fine, you roll a D10**10 and set it aside everytime you get pi. That's still a lot of roles(I think I'm exagerating, but you get the point).

How about the odds if we have billions of folk rolling the dice everytime? How about if in addition, they can win with more than one combination?

Which leads me to another question. Have scientists been able to replicate this process (molecules to amino acids to life)to any extent.

Not the step to life but that will likely happen within the next decade, two at the most.

What other scientifically viable theories are there that contradict Evo.

So far the TOE is the only game in town. It would always be neat if something even better were found.


Aslan is not a Tame Lion
This message is a reply to:
 Message 15 by CreepingTerror, posted 12-14-2004 10:35 PM CreepingTerror has not yet responded

Rrhain
Member
Posts: 6192
From: San Diego, CA, USA
Joined: 05-03-2003
Member Rating: 2.4


Message 19 of 43 (168325)
12-14-2004 11:59 PM
Reply to: Message 11 by CreepingTerror
12-14-2004 4:38 PM


Re: improbablity of what
CreepingTerror writes:

quote:
Well, my point is that if the entire evo process took Approx 3.5 billion years, and the earth has been around for what 4-4.5 billion years then the universe must be rolling it's dice really well.

Yep, you're confusing the probability of getting a specific outcome with the probability of getting any outcome. You're also combining this with a variant of the logical error of the Anthropic Principle. We should not be surprised to find that a process that can create the conditions we see actually created it.

Here's another exercise in probability:

Suppose you have 10 darts, each of which has a 1-in-10 chance of hitting the target. I throw all 10. What is the probability of me hitting the target at least once? The quick way to determine this is not to try and come up with a list of all possible results where the target was hit at least once but rather to notice that that situation is complementary to the question of finding the probability that the target never gets hit...which can only happen one way.

Thus, the result is (9/10)10: Each dart has a 9-in-10 chance of missing and there are 10 darts, each of which is independent of the others.

Note that this result is about 35%...which means that the complementary probability of hitting the target at least once is about 65%.

And the point? The universe is a huge place. Even if the probability of an event occurring is very low, we have a huge number of chances to get a hit at least once.

There also seems to be a problem of you trying to force a calculation of going from the first life immediately to the current form. Instead, we need to calculate the probability of going from the previous state to the current one. That is, if we are trying to get five 6s on a set of dice, the probability of getting that from a roll of all five dice is very low (two-thousandths of a percent)...but the probability of getting that from a roll of one die given that you've already hit four 6s on the other dice is now 1-in-6.

And that doesn't even consider the chemical specifics that might favor certain reactions over others. If I take two moles of hydrogen gas and a mole of oxygen gas, mix them at standard temperature and pressure, and then spark the mixture, I get water. Yes, there will be some unreacted gas left over and some hydrogen peroxide, but the primary reaction is water. You cannot simply make a calculation of probability based upon an assumption of independence of all variables and that all outcomes are equally likely. It may very well be that the resulting outcome is much more likely than you care to admit.

And I also get the feeling that you're also trying to sneak in abiogenesis into this request of yours. Remember, evolution does not depend upon how life came into existence. Evolution is solely about how life diversified after it came into existence. Life could have arisen chemically through abiogenesis, supernaturally through god zap-poofing it into existence, extraterrestrially through panspermia or alien seeding, interdimensionally through a rift in space-time, or any other method you care to name. So long as that life did not replicate perfectly from generation to generation, then evolution is satisfied.

quote:
and heck, who knows if the planet was favorable for the rise of Evo during that whole time.

See what I mean? The conditions of the earth before life arose are immaterial when it comes to the probability of evolution. Evolution is not abiogenesis nor is it dependent upon abiogenesis. Are you claiming god cannot create life that evolves?

quote:
I mean, evolution is still theory.

So is gravity, quantum mechanics, light, and the idea that germs cause disease. You are confusing the vernacular definition of "theory" as "an educated guess" with the scientific definition of "theory" as "analysis of a set of facts to explain the facts." You cannot have a theory without a fact to base it upon.

When I drop a ball from my hand, it falls to the ground. Since we use words to communicate, we have a word for the force that pulls the ball down and it just happens to be "gravity." That's a fact.

But what is "gravity"? How does it work? It is only through experimentation that we discover universal gravitation of F = Gm1m2/r2 and even that appears to be incomplete. The Pioneer space probes are currently leaving the solar system and their motion cannot be completely explained by our current understanding of gravity.

That's the gravitational theory. The fact that we don't understand everything about gravity (we don't even know what it is...is it a force on particles or a warpage of space-time or something else?) doesn't change the fact that when I drop a ball from my hand, it falls to the ground under the force of gravity. As the cliche goes, when Newton was working on the physics that would change our understanding of gravity, falling apples did not suspend themselves in midair waiting for the outcome.

Evolution is the same way. When we observe populations of organisms over time, they change. Since we use words to communicate, we have a word for the process that causes the change and it just happens to be "evolution." That's a fact.

But what is "evolution"? How does it work? Do characteristics acquired after an organism is born contribute to the characteristics of the next generation (Lamarck)? Or is there something fundamental about the organism that doesn't change except during the reproduction process (Darwin)? It is only through experimentation that we find things like chromosomes and genes and can see how they mutate from generation to generation, how selective pressures actively change the population (and thus determine what set of characteristics we have to work with for the next set of mutations).

That's the evolutionary theory. The fact that we don't understand everything about evolution (is this particular organism a transition between these two or these other two?) doesn't change the fact that when we observe populations of organisms over time, they change.

And notice that we have much more solid evidence for explaining evolution than we do for gravity. We have an actual mechanism for evolution (mutation and selection). We can manipulate that mechanism directly (introduction of mutagens, genetic engineering, artificial selection). We still don't really know what the mechanism of gravity is let alone have a means to manipulate it.

And yet here you are picking on evolution as if it were some unwanted stepchild of science. "Still theory"? That's the best thing there is in science. Theories are what we use to explain facts. There can be no theory without a fact. We cannot have evolutionary "theory" without there being evolutionary "fact."

quote:
We're not completely sure.

Yes, we are.

Here's an experiment you can do in the privacy of your own bio lab. It isn't very expensive and doesn't require very many materials.

Take a single E. coli bacterium of K-type. This means the bacterium is susceptible to T4 phage. Let this bacterium reproduce until it forms a lawn. Then, infect the lawn with T4 phage.

What do we expect to happen? That's right, plaques should start to form and, eventually, the entire lawn will die. After all, every single bacterium in the lawn is descended from a single ancestor, so if the ancestor is susceptible, then all the offspring should be susceptible, too.

But what we actually see is that some colonies of bacteria in the lawn are not affected by the phage.

How can this be? Again, the entire lawn is descended from a single ancestor. They should all behave identically. If one is susceptible, then they're all susceptible. If one is immune, then they're all immune. This can't be an example of "adaptation" because if one could do it, they all could do it.

But since there is a discrepancy, we are left with only one conclusion: The bacteria evolved. There must be a genetic difference between the bacteria that are surviving and those that died.

Indeed, we call the new bacteria K-4 because they are immune to T4 phage.

But we're not done. Take a single K-4 bacterium and repeat the process: Let it reproduce to form a lawn and then infect the lawn with T4 phage.

What do we expect to happen? That's right: Absolutely nothing. All of the bacteria are descended from a single ancestor that is immune to T4 phage. Therefore, they all should survive and we shouldn't see any plaques form.

But we do. Plaques do, indeed start to form. How can this be? Again, all the bacteria in the lawn are descended from a single ancestor that was immune to T4 phage, so they shold all behave identically. If one is immune, then all are immune. There must be something else going on.

Something evolved, but the question is what. What evolved? Could it be the bacteria experiencing a reversion mutation back to K-type? No, that can't be it. Suppose any given bacteria did revert back to wild. It is surrounded by K-4 type who are immune to T4 phage. As soon as the lawn is infected, those few bacteria will die and immediately be replaced by the offspring of the immune K-4 bacteria. We would never see any plaques forming because the immune bacteria keep filling in any holes that appear.

So if it isn't the bacteria that evolved, it must be the phage. And, indeed, we call the new phage T4h as it has evolved a new host specificity.

There is a similar experiment where you take bacteria that have had their lactose operons removed and they evolve to be able to digest lactose again.

You might want to look up the information regarding the development of bacteria capable of digesting nylon oligimers. It's the result of a single frame-shift mutation.

This is evolution. And please don't be disingenuous and claim that it's still a bacterium. Of course it's a bacterium. Evolution doesn't go from bacterium to ostrich in one step. If you could show that happening, you would completely overthrow our understanding of how life diversified and would probably win a Nobel Prize and could write your own ticket for the rest of your life. I am simply pointing out the proof of concept: Life changes from generation to generation.

If 1 + 1 = 2, why can't 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 = 10? We've seen speciation happen both in the lab and in the wild, but those experiments require more equipment and are much more sophisticated.

quote:
Jump me if you want, but that's how I see it.

I'm going to be blunt here: Who cares about how you see it? Reality is not a popularity contest. It does not care about your opinion.

quote:
Fine there's a lot of evidence, but we're not completely sure.

Incorrect. It is because we have a lot of evidence that we are sure. Could we be wrong? Of course...show us a replicatable experiment that takes a single bacterium and produces an ostrich in a single generation and I will be the first to admit we really screwed up. Find a fully formed rabbit fossil in Pre-Cambrian rock strata and I will eat so much crow they will become an endangered species.

But we never see that. We have looked and looked and looked and have never found anything that even hints at contradiction of the basic premise: Populations of organisms change over time. While we are cognizant of the possibility that we are wrong, it would be disingenuous in the extreme to deny all the evidence that seems to indicate that we are right simply to satisfy a personal distaste for what it might mean.

quote:
If you can convince me otherwise

Another blunt question:

Just what experience do you have in biology in general and evolutionary biology in particular that leads you to think that you have an informed opinion to begin with? When was the last time you were in a biology lab? When was the last time you took an actual biology class and spent more than a week discussing evolutionary processes? When was the last time you read a journal article regarding evolution?

Can you really say that you have what it takes to make a reasoned judgement about the fundamental concept of all biology if you haven't actually done any serious work in the subject?

By all means, question those who advocate for evolution. Make them explain themselves. If you don't understand something, don't just accept it. But realize that there is a difference between coming to a subject knowing that you don't know very much about it and coming to it thinking that you are capable of denying what literally thousands of other people have spent every working moment of their lives studying when all you have is the most nebulous of investigation of the field. You just might be able to find out where they went wrong, but you need to know what they did first before you can discover their error.


Rrhain
WWJD? JWRTFM!
This message is a reply to:
 Message 11 by CreepingTerror, posted 12-14-2004 4:38 PM CreepingTerror has responded

Replies to this message:
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crashfrog
Inactive Member


Message 20 of 43 (168331)
12-15-2004 12:08 AM
Reply to: Message 19 by Rrhain
12-14-2004 11:59 PM


What a great post. It's like "Rrhain's Greatest Hits."
This message is a reply to:
 Message 19 by Rrhain, posted 12-14-2004 11:59 PM Rrhain has not yet responded

Rrhain
Member
Posts: 6192
From: San Diego, CA, USA
Joined: 05-03-2003
Member Rating: 2.4


Message 21 of 43 (168336)
12-15-2004 12:21 AM
Reply to: Message 15 by CreepingTerror
12-14-2004 10:35 PM


Re: improbablity of what
CreepingTerror writes:

quote:
But that doesn't change the fact that the chances of a mutation having a beneficial effect are extremely low.

Irrelevant. The vast majority of mutations are neutral and we never notice them. You, specifically, are likely to have 3 to 6 of them compared to your parents. Does that make you defective?

Since the deleterious mutations are selected against, the neutral mutations are neither selected for nor against, and the beneificial mutations are selected for, what do you think is going to happen over time? You seem to be stuck on a single organism, single event mode of thinking. You need to start thinking much more broadly. Evolution doesn't happen to an individual. It happens to a population.

And note that it is difficult to determine if a mutation is beneficial or deleterious until you actually run it through the environment in which it exists. Is having a short, squat body that retains body fat a good thing or a bad thing? What about having a long, lean body that doesn't amass body fat? Wouldn't that depend upon the environment in which you live?

And if the environment changes, mutations that would be considered of one kind might suddenly shift to another. Take the sickle-cell anemia trait. If you're homozygous for it, you'll have trouble but if you're heterozygous for it, you may never know you have it if you aren't in certain types of environments. But one thing that the sickle-cell trait provides is some protection against malaria. And is it really any surprise to find that populations that are likely to have sickle-cell trait in the population are more concentrated in areas that are likely to have malaria as a probable infection? Take someone living on a high mountain with a sickle-cell allele who is having trouble with the thin air and stick him in a hot jungle. What was once a hindrance is now a benefit.

Things are much more complicated than you are making them out to be.

quote:
And as just as unlikely (I'll admit some ignorance on both of these topics) is the perfect combination of molecules to give rise to life.

As I suspected. You are confusing evolution with abiogenesis. The two have nothing to do with each other. Evolution can happen no matter how life arose. Are you seriously claiming god cannot create life that evolves?

That said, you're most likely confusing the probability of going from a completely random set of molecules directly to a living organism rather than dealing with the probability of doing it step-by-step. Getting five 6s on a single roll of five dice is very unlikely. But getting five 6s when you've already rolled four of them is much more possible.

quote:
Have scientists been able to replicate this process (molecules to amino acids to life)to any extent.

You're going to have to define what you mean by "life." We have been able to create, from non-living reagents, self-replicating, homochiral, auto catalysing molecues that evolve. Is that life? If it isn't, it's really close.

But again, that question is irrelevant with regard to evolution. Evolution is something that happens to life after it exists. It does not explain how life came to be in the first place.

quote:
What other scientifically viable theories are there that contradict Evo.

None. That's the thing. People have been trying and trying to find ways to stick it to evolution and they have all failed. That doesn't mean that current evolutionary theory is absolutely, positively correct with no possibility for error. It simply means that you're going to have to do a lot of work in order to overturn it.

And if you are successful, you will be considered a hero. There is no conspiracy against such work. If you could overturn the dominant paradigm of any field, you would become the most celebrated person in that field. There's a reason we remember people like Newton and Einstein and Godel. They completely changed the way we thought about everything.


Rrhain
WWJD? JWRTFM!
This message is a reply to:
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CreepingTerror
Inactive Member


Message 22 of 43 (168340)
12-15-2004 12:29 AM
Reply to: Message 19 by Rrhain
12-14-2004 11:59 PM


Re: improbablity of what
Well, that was a long read. Good post, except for the part where you told me to shut up because I'm not as smart as you. It's a good thing that everyone doesn't apply to your thinking, or no one would learn anything. Just so I'm not open to the interpretation that I am trying to tell everyone that they are wrong, and that I am not trying to learn: What are some examples of speciation in a laboratory, not saying it can't happen mind you, just I'd like to know what they are.

And I wasn't trying to tell everyone that they're wrong, nor was I saying that my opinion is the best, I'm just trying to learn here.


This message is a reply to:
 Message 19 by Rrhain, posted 12-14-2004 11:59 PM Rrhain has responded

Replies to this message:
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Lammy
Member
Posts: 3577
From: Florida
Joined: 03-29-2004


Message 23 of 43 (168341)
12-15-2004 12:31 AM
Reply to: Message 15 by CreepingTerror
12-14-2004 10:35 PM


Re: improbablity of what
CT writes:

But that doesn't change the fact that the chances of a mutation having a beneficial effect are extremely low.


Low by whose standard?

There have been experiments where a single non-penincillin resistant E. coli bacterium is placed in a dish and allowed to divide. Just in case you don't know, bacteria reproduce through mitosis where the daughter cells are completely identical to the mother cells. After the culture is sufficiently large enough, a dose of penicillin is administered into the colony and voila! Most of the bacteria died but a few survived and began to grow into a new colony.

What I have just described, which have been observed many times in laboratories, is a beneficial mutation happening right in front of our eyes. Even though bacterial daughter cells are supposed to be identical to the mother cells, somehow along the line there must have been a mutation that gave some bacteria an advantage over the others.

The chances of such a mutation, specifically one that would give the bacteria resistance to a specific anti-biotic is, you could say, infinitesimally small. Yet, it happens all the time.

You are still thinking in small terms. It is unlikely if there are, say, a hundred breeding individuals. However, multiply that number by a a few billion and the chances of getting beneficial mutations are a lot higher.

Have scientists been able to replicate this process (molecules to amino acids to life)to any extent. I vaguely remember hearing that they had, but I'm not sure.

They have successfully produced pre-cells, which have most of the charateristics of a cell, through natural processes. However, as far as I know noone has produced a living cell from non-organic matter.
This message is a reply to:
 Message 15 by CreepingTerror, posted 12-14-2004 10:35 PM CreepingTerror has responded

Replies to this message:
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CreepingTerror
Inactive Member


Message 24 of 43 (168343)
12-15-2004 12:35 AM
Reply to: Message 23 by Lammy
12-15-2004 12:31 AM


Re: improbablity of what
I'm sure I'm probably beating a dead horse, but is there a difference between micro and macro evolution. Is it harder to change "species" or does it just require more time?

Edit: I suppose that's not the clearest thing to say. What I mean is, is it harder to go from reptile to bird, than it is for bacteria to develope immunity, or does it just require more time.

This message has been edited by CreepingTerror, 12-15-2004 12:38 AM


This message is a reply to:
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Lammy
Member
Posts: 3577
From: Florida
Joined: 03-29-2004


Message 25 of 43 (168350)
12-15-2004 12:49 AM
Reply to: Message 24 by CreepingTerror
12-15-2004 12:35 AM


Re: improbablity of what
CT writes:

...but is there a difference between micro and macro evolution. Is it harder to change "species" or does it just require more time?

There is no difference between micro and macro evolution except the fact that one occur frequently over a relatively short amount of time and the other is a combination of the first one.

Micro-evolution describes a mutation such as a change in color of a species or a production of an enzyme to allow the organism to become immune to a certain chemical. But suppose you have micro-evolution happening over a very long period of time. After this long period of time combining with some kind of barrier such as a body of water seperating a population into two, a new species emerges.

Try to think of it this way. Micro-evolution is like taking a walk to your next door neighbor. Macro-evolution is like taking a walk to the nearest convienient store but stopping at every house along the way.

I suppose that's not the clearest thing to say. What I mean is, is it harder to go from reptile to bird, than it is for bacteria to develope immunity, or does it just require more time.

Depends on what you mean by "harder" I suppose. It would certainly seem like a big jump.

Let's refer back to my walking example. Say that my house is number 1 and the convienient store is number 100. When I'm at house 7, someone use a camera and takes a snapshot of me being there. When I'm at house 36, someone else takes a snapshot of me at that house. When I'm at house 74, again someone takes a snapshot of me being there. Finally, I'm at the convienient store.

The question is did I walk from my house to the store or there are at least 4 versions of me walking around?

The fossil record is a snapshot of evolution happening through a very long period of time. Just in case you didn't know, fossilization is a very rare process, especially one that would preserve enough data for us to look at.


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NosyNed
Member
Posts: 8800
From: Canada
Joined: 04-04-2003
Member Rating: 9.9


Message 26 of 43 (168351)
12-15-2004 12:49 AM
Reply to: Message 22 by CreepingTerror
12-15-2004 12:29 AM


Re: improbablity of what
Creeping Terror CT writes:

To me, it seems to come down to a matter of faith. I mean, evolution is still theory. We're not completely sure. Jump me if you want, but that's how I see it. Fine there's a lot of evidence, but we're not completely sure.

CT writes:

Good post, except for the part where you told me to shut up because I'm not as smart as you. It's a good thing that everyone doesn't apply to your thinking, or no one would learn anything. Just so I'm not open to the interpretation that I am trying to tell everyone that they are wrong, and that I am not trying to learn:

You were not told to "shut up". It was suggested that you not make what sound like firm, solid statments when you don't know very much about the subject. It is, by the way, apparent from what you have posted so far that you know very, very little indeed.

The "that's how I see it" is a hint of the problem. A more appropriate position is that you understand that "we" are very sure indeed but that you would like to understand the why behind that. It is always fair and a good idea to understand why someone accepts something (or doesn't) before you come to some tentative conclusion of your own.

You might also note the context that you are discussing this in. We get a steady stream of fundamentalist, literalists through here who think that after spending an hour reading a few creationist sites (that, incidentally have lied about the subject) that they know it all and can overturn a couple of centuries of work by many very smart, dedicated and honest individuals (of whom a large fraction are believers)..

Some people here are a bit sensitive after wasting time on such very closed minded, uh, mmm hard to be polite, jackasses. If you think Rrhain was being rough on you then you'd better thicken your skin a bit. He (and others) have been far worse.

Just remember, it is almost always the ideas that are being shredded and not the individual. At least, not if the individual does show some willingness to read, think and learn.

This message has been edited by NosyNed, 12-15-2004 01:02 AM


This message is a reply to:
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Replies to this message:
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Lammy
Member
Posts: 3577
From: Florida
Joined: 03-29-2004


Message 27 of 43 (168358)
12-15-2004 12:57 AM
Reply to: Message 24 by CreepingTerror
12-15-2004 12:35 AM


Re: improbablity of what
If examples in bacteria isn't enough, I suppose I can name a few others.

Does the tetraploid rat in Argintina count?

http://www.intl-pag.org/pag/8/abstracts/pag8374.html

http://www.cricyt.edu.ar/institutos/iadiza/ojeda/grecia%202000.htm

First Tetraploid Mammal Reported

quote:
"It's a highly specialized animal that has adapted well to living with little water," Honeycutt said. "It has to have certain conditions to live. It has brushes in its mouth, for example, to strip sage for eating."


We have also observed a mutation in a lab condition where a group of snails gained a mutation that caused the shape of their shells to change preventing them from physically mate with snails of the original population.

Pinky writes:

The researchers witnessed a speciation event in a closed population they were studying, a single gene mutation changed the shell pattern of a snail, and the constraints of the new shell shape prevent the snails with the two types of shells from aligning their genitals to mate. But, the old-shelled snails could mate with the old-shelled, and the new-shelled could mate with other new-shelled snails. Thus snails with the shell-changing mutation are incapable of "interbreeding" with the ones without the mutation - even if they are sitting next to each other in the same pond - thus reproductive isolation.

www.evcforum.net/cgi-bin/dm.cgi?action=msg&f=5&t=509&m=47#47 -->www.evcforum.net/cgi-bin/dm.cgi?action=msg&f=5&t=509&m=47#47">http://www.evcforum.net/cgi-bin/dm.cgi?action=msg&f=5&t=509&m=47#47

Want more examples?


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NosyNed
Member
Posts: 8800
From: Canada
Joined: 04-04-2003
Member Rating: 9.9


Message 28 of 43 (168363)
12-15-2004 1:01 AM
Reply to: Message 24 by CreepingTerror
12-15-2004 12:35 AM


Macro Harder?
Is it harder to change "species" or does it just require more time?

That is actually a very good question. For one reason, if the species line is crossed then the much larger changes between higher taxa isn't so hard given enough time.

However, if speciation hasn't happened then (and there is a mountain or research on this) there are evolutionary forces that would tend to homogenize the population involved.

In other words to get a speciation event (it is argued) requires something to separate a population. The typical example is geography; they have to be kept separate.

However, lots of things can cause this separation. If birds sing a different song they may not mate. Even though they would produce perfectly viable offspring if they did.

I don't remember details but there is some parasite of some mmm fly? I think. That changes the reproduction in some way (good isn't this, fuzzy as hell) that means that an indivdual infected with the parasite can only successfully breed with an other infected individual.

This can separate the population into two and allow full speciation to take place.

There are cases of "instant" speciation where a plants get a chromasomal mutation that means they can not longer reproduce with the other "kind". This can happen in one step.

And so on and so forth.

So let's back up.

"Micro" happens all the time, every individual is different from others. They have some mutations. However, if there is no speciation event or some kind of separation the mutations will spread through the population and it will stay somewhat uniform.

That, by the way, doesn't mean that these changes can't gradually pile up so that an individual of the population that is around 10,000 generations from now would still be the same species as the starting population.

If however, there is something to separate the population into two different ones for awhile then speciation, it seems, can happen pretty quickly.

Once you have separate species the changes can not longer be smoothed out between them and over a long enough time very, very large changes happen. Obviously something as large as reptile to mammal doesn't happen in only 1,000's of generations.


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CreepingTerror
Inactive Member


Message 29 of 43 (168366)
12-15-2004 1:08 AM
Reply to: Message 26 by NosyNed
12-15-2004 12:49 AM


Re: improbablity of what
Apologies, I read to much into that. I think my mind is trying desperately to hold on to the beliefs that I've had my whole life. Ugh, the funny thing is that I thought that I was open minded about this whole thing. The problem that we as fundamentalists have with the whole Evolution side of things is that almost all of us see it as a direct attack on our faith, that God didn't create the universe, an idea reinforced by the fact that evolution has been a secular institution for a very long time, and most of the proponents of it are athiests or agnostics, or whatever people say when they don't believe in God.

Anyways. I apologize for being short. And by the way Lam, I never said it wasn't enough, I was just interested in the examples.


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 Message 33 by NosyNed, posted 12-15-2004 1:25 AM CreepingTerror has responded

Lammy
Member
Posts: 3577
From: Florida
Joined: 03-29-2004


Message 30 of 43 (168370)
12-15-2004 1:13 AM
Reply to: Message 28 by NosyNed
12-15-2004 1:01 AM


Re: Macro Harder?
Ned writes:

Obviously something as large as reptile to mammal doesn't happen in only 1,000's of generations.


Let's count the zeros.

So, we believe that the first life on Earth came about say 3.8 billion years ago.

That's 3,800,000,000. It is also important to note that the humans have the longest lifespans among the mammals. So, say that each generation is 50 years.

3,800,000,000 / 50 = 76,000,000

That's 76 million generations, and I'm being conservative, too. Up until 200 years ago, a human generation is only about 30 years. That would make 3.8 billion years to equal 126,666,666. That's about 130 million generations.

But we know for a fact that the vast majority of organisms both in the past and present have much shorter lifespans, thus much more generations per unit time.

Certain insects only have about 10 days per generation. So, for them 3.8 billion years mean 138,700,000,000 generations. That's 138.7 billion generations.

The question is how often do you see this kind of number show up in your everday life? Another reason why you don't want to use common sense for something like this.


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