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Author Topic:   A Creationist's view of Natural Limitation to Evolutionary Processes (2/14/05)
Equinox
Member (Idle past 5253 days)
Posts: 329
From: Michigan
Joined: 08-18-2006


Message 144 of 218 (341066)
08-18-2006 12:44 PM


I’ve never understood why creationists try to use this “argument”.
It’s clear that mutations provide a continual new supply of variation, especially since mutation rates have been estimated based on simple copying errors. For a human genome of around 6 billion base pairs, even an extremely good copying accuracy of 99.999% would still give thousands of mutations with each birth. I’ve read estimates of the mutation rate in humans, and it is generally somewhere around 1 to 200 mutations in every birth. Wow! If most of our DNA was needed for life, this would be a terrible rate! But, most of our DNA is not essential, so many changes in it are irrelevant.
A good site for this is here: NO REDIRECT
Of course, depending on the environment, any change can be good or bad. For instance, say a mutation makes one a little taller. If you live in an environment were everyone is well fed and where women like good basketball players, this mutation could be selected for and be good. However, if you live on a small island (say, Flores . ), where food is scarce and where there are no big predators, then this will be a “bad” mutation.
So with all this variation constantly coming in, the “no variation outside of a kind” seems to make little sense. This is especially clear when we measure difference with real numbers. Using actual numerical measurements usually makes any science discussion much clearer, and biology is no exception.
So looking at the differences in the genome between animals, we can see how this all works. The genetic variation between humans of different races is less than half a percent (0.5%). I hope no one disputes the idea that mutation and selection in different environments (such as sunlight favoring dark skin) can demonstrably cause 0.5% genetic difference over time. So what about dogs? The genetic difference is around 1%. OK, could a chimp evolve into a human? Only around 3% of our DNA differs from chimps.
So if the constant introduction of mutations (which we’ve observed), coupled with environmental changes can lead to a change of 1% in 20,000 years (which I think nearly all creationists agree with), then couldn’t another 20,000 years give us another 1% change, for a total of 2% change? Using a rough number of 6 years for a dog generation (feel free to use any number between 2 and 8 if you prefer), then that’s 20,000/6 = 3,000 generations, or around (25 X 3,000=) 75,000 years for humans. At that rate, we could get from a chimp like ancestor to a human in less than 200,000 years! Of course, our evolution hasn’t been nearly as fast since our selective pressures weren’t as strong. And of course, that means that 500 million years is plenty of time for something like a roundworm to evolve into a human (roundworms and humans share only 21% of their DNA, so that’s 79% different). This is especially apparent when one takes into account the much shorter generation time as one goes back in our ancestry (for instance, roundworms certainly don’t wait 25 years to reproduce!).
When using numbers for the genetic difference like this, it seems that anyone who imagines some arbitrary “kind” boundary hasn’t tried their hand at the math. I know that there are more sophisticated ways of doing this math, but this rough back of the envelope kind of calculation shows that we have orders of magnitude of room for evolutionary change. It’s just a rough estimate.
Have a fun day-
Equinox

Replies to this message:
 Message 146 by Faith, posted 08-18-2006 1:00 PM Equinox has not replied

Equinox
Member (Idle past 5253 days)
Posts: 329
From: Michigan
Joined: 08-18-2006


Message 149 of 218 (341119)
08-18-2006 3:25 PM
Reply to: Message 145 by Faith
08-18-2006 12:51 PM


Re: Considering rapid rate of mutation
quote:
Re: Considering rapid rate of mutation
Archer O wrote:
quote:
The second fallacy is your woolly use of the word 'variability.' You use it to mean two different things: anatomical variety in a single population and as a synonym for 'ability to change,' by which you mean potential for genetic mutation across generations.
Faith replied:
Actually I don't use the term mutation in my conceptualization on this very old thread at all, and I only MEAN to use the term variability as in GENETIC variability, or genetic potential, and I doubt I've confused it with anatomical variety.
No, you are still using the same term to mean two different things. Does "variability" = genetic variability (meaning the gene pool of a population, the sum total of all the alleles), or instead do you mean that "variability" = genetic potential (by which I’m not sure what you mean, but if you mean anything having to do with future generations, then you must mean something like “the possible gene pool at some point in the future”, which, due to evolution, is very large. For instance, with that definition the future "variability" or “genetic potential” of a theropod dinosaur would include everything from a penguin to a parrot.
I'm glad we are getting our meanings straight, since that is a prerequisite to any good conversation.
-Equinox

This message is a reply to:
 Message 145 by Faith, posted 08-18-2006 12:51 PM Faith has not replied

Replies to this message:
 Message 151 by Brad McFall, posted 08-18-2006 4:11 PM Equinox has not replied

Equinox
Member (Idle past 5253 days)
Posts: 329
From: Michigan
Joined: 08-18-2006


Message 150 of 218 (341131)
08-18-2006 4:01 PM
Reply to: Message 147 by Faith
08-18-2006 1:17 PM


Re: mutation and immigration
quote:
What does "a change of 1% in 20,000 years" mean? You assume a positive change that can facilitate evolution, but all your examples are hypothetical and you give no statistics on the percentage of USEFUL mutations as compared to undesirable ones -- meaning those that NO environment is going to favor..
I’m talking about net change (see below) - notice that I used the dog example, there is a 1% difference between, say, a dog and a wolf (depending a bit on the breed, of course).
The labels “good” vs. “bad” mutations, as I mentioned, are misleading. The vast majority of mutations (over 90%) are neutral - they don’t do anything at all. For instance, say your instruction book contained pages of random gibberish - randomly changing a word of that doesn’t change the instructions.
OK, now, let’s think about the mutations that do change something. Most changes could be either “good” or “bad”, depending on the environment. Take a second to step back and look in a mirror. Consider changing any aspect of your body. Darker skin? Is that “harmful”? Well, it is if you are a female living in northern areas, and you need to get enough sunlight to provide vitamin D when pregnant. Or instead do you live in Africa, where it is a good mutation, since you need protection from too much sunlight, which can cause skin cancer? Larger nostrils? Do you live in a windy desert, where larger nostrils will allow more sand into your lungs (ouch)? Or instead do you live in a forest, where being able to pull in more air when running from a predator will help you escape?
We could look at examples like this all day - the point is that mutations aren’t usually inherently “good” or “bad” - that depends on the environment, which will either cause them to help the bearer have more kids, (hence, “selected for”) or not (“selected against”).
OK, now look at the 1% I mentioned for dogs. I meant the net total of the mutations that WERE SELECTED FOR over 20,000 years. The number of mutations selected against is completely irrelevant, since those mutations all disappeared with their unfortunate owners. See why the ratio is unimportant? If half of the mutations that have an effect are selected for, then the ration you want is 1:1, and you end up with only the "selected for" mutations. If there is only 1 helpful, "selected for" mutation in 5, then you ratio is 1:5, and you still have exactly the same number of mutations at the end of the day, since the ones that weren’t selected for are gone anyway. That's why the number of non-selected for mutations is irrelevant.
If you want to discuss extremely harmful mutations, such as those that cause an quick death or some such, that's fine. Again, they are completely irrelevant, since that animal dies, the mutation (new allele) is gone, and we are back to square 1.
In fact, “harmful” mutations are very often selected for by humans. Look at the pathetic bulldog. We have selected the mutations that slowly made his snout all smashed in, resulting in hampered breathing. Have you ever been near a sleeping pug? It sounds worse than Darth Vader! Whether a mutation is “good” (selected for) is a function of the environment as much as it is a function of the mutation.
So, the % is the net change in the genome due to the accumulation of mutations that were selected for. It took thousands of beneficial mutations to get to a poodle from a wolf - and that change is only “beneficial” if you keep the poodle out of the wolfpack.
You mentioned how mutations work. Here are some basic types of mutations and how they work:
Duplication of a stretch of DNA. This is like accidentally copying part of a book twice. Example - when making a copy of a book that has chapters 1, 2, 3,4,5,6,7,8,9,10,11, 12, you end up with a book that has chapters 1, 2, 3,4,5,6,7,3,4,5,6,7,8,9,10,11, 12
Deletion of a base pair. AATCTGTC becomes ATCTGTC
Addition of base pair AATCTGTC becomes ACATCTGTC
Transposition (like a mirror) AATCTGTC becomes CTGTCTAA
All of these can have no effect, an effect which is selected for, or an affect which is selected against.
To add information, first, take a functional gene, and make an extra copy using the duplication mutation. That won’t hurt the organism, since the second copy is simply redundant. Then use any of the other mutation methods so as to make the second copy do something new. The organism still has the original copy doing whatever it is supposed to do, but now has the added ability of whatever the new gene does (such as digesting nylon, as in a species of bacteria).
The process can also add entire chromosomes, that’s how, over time, the total number of chromosomes changes. For that, simply copy a whole chromosome twice (it happens), then the rest of the process is the same as above.
I don't understand what you mean by "a mistake which is only destructive". Do you mean that all mistakes have to be harmful? Why? Many inventions have been found by people making mistakes. In genetics, if a group of animals is living in a valley and the climate changes to make it colder, then wouldn't a genetic "mistake" which made their hair grow a little longer be helpful?
Oh, I'll be out until next week. Have a fun weekend-
Equinox
Edited by Equinox, : No reason given.

This message is a reply to:
 Message 147 by Faith, posted 08-18-2006 1:17 PM Faith has not replied

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