Y.E.C. Model: Was there rapid evolution and speciation post flood?

Faith writes: Supposedly some genes are observed to have many alleles in a population,...Then I kept thinking about Adam and Eve having four alleles until it finally dawned on me that a gene has TWO,...

Restating the problem, assume that around 6500 years ago there were originally only two people, Adam and Eve.
Since each gene of a person can have at most two alleles, then Adam could have contributed at most two alleles for each gene, and the same for Eve.

This means that the most number of alleles any gene could have for both Adam and Eve (the total human population in the beginning) and all their descendants is four, so the most number of alleles of any gene in the modern human population is also four.

Since we know today through genetic analysis that some genes of the human population have more than four alleles then it must be true that there have been mutations in those genes, or that there were originally more than two people, or both that there have been mutations and there were originally more than two people.

--Percy

Faith writes: Well, if I'm getting what you are saying, I think it's really only one that each person would contribute to the next generation.

Each parent contributes only one allele to each baby, but many parents have more than one baby. For a given gene of Adam with alleles X and x, Adam could have contributed allele X to Cain and allele x to Abel.

(I got blue eyes from a combination of my parents' alleles: a b from my mother's Bb and a b from my father's bb; my sister got her brown eyes from our mother's B and of course our father's b)

Eye color is determined by multiple genes, at least six, and there are more colors than just brown and blue

Again, we all get a gene made up of two alleles from our parents, NO MATTER how many there might be in the whole human population. Is this correct?

Yes, of course.

And then seeing that only two genes for skin color with two alleles each is all it takes to produce 16 different skin colors...

Skin color is also determined by multiple genes, at least ten.

Since we know today through genetic analysis that some genes of the human population have more than four alleles true that there have been mutations in those genes, or that there were originally more than two people, or both that there have been mutations and there were originally more than two people. Yes, and I'd been assuming that all those different alleles were proof of functioning mutations, but when it occurred to me they may not actually change anything in what the gene does I figured they aren't really functioning alleles but neutral mutations.

I understand you're trying to argue that mutations cause minimal changes, but I'm making a simpler point, and it seems that you accept it. Repeating the point, any gene in the human population today that has more than four alleles (the maximum number of alleles per gene in the original human population consisting of just Adam and Eve) must have experienced mutations. Genes with many alleles must have experienced many mutations. The CFTR gene (responsible for cystic fibrosis) has over a hundred different alleles (see Alleles of CFTR; also, at the bottom of the figure is a table of mutations).

--Percy

Faith writes: Gary Parker showed it in a chart in "What is Creation Science?" -- the 16 different shades that result from only two genes with two alleles each. He also suggested there may be three genes for skin color but his calculation was based on two.

There are many genes that contribute to skin color, see Genetics of skin color variation over at Wikipedia. More genes being involved works out better for you because of permutations. If you have just one gene A with four alleles a1, a2, a3, a4, then the number of possible permutations with two copies of the gene is 16. (a1/a1, a1/a2, a1/a3, etc...)

But if you have two genes A and B, and gene A has alleles a1, a2, a3, a4 while gene B has alleles b1, b2, b3, b4, then the number of combinations is 256 (a1/a1-b1/b1, a1/a2-b1/b1, etc...).

So if skin color is determined by, say, ten genes and each gene has four alleles, that's a tremendous number of possible combinations, no mutations needed for your scenario. The Wikipedia article implies that each gene for skin color has only a couple or perhaps a few alleles.

--Percy

Edited by Percy, : Remove incorrect paragraph.

Edited by Percy, : Fix calculations.

Faith writes: ...and that the original was two alleles per gene and that is enough for a great deal of variability.

I think you meant to say "the original was *four* alleles per gene," two alleles from each of two original people.

--Percy

It is worth mentioning again that eye color is determined by at least 6 genes, and skin color by at least 10.

--Percy

Faith writes: I'm going with two alleles per gene

If by this you mean only two alleles per gene in the original human population, in your scenario this is demonstrably false. Both Adam and Eve could have contributed two unique alleles per gene for a total of four. Even though you believe you only need two alleles per gene, you actually have a potential maximum of four.

This is better for your scenario because now people have to demonstrate at least five alleles for a gene before they can claim any arose through mutation, and then they still have to show they produced new function.

--Percy

Edited by Percy, : Correct misstated sentence.

bluegenes writes: ...it is Faith (although she doesn't realise it) who needs new function and positive selection for her model.

I agree, but I think more argument and clarification is needed for your position. Why is a (restating) "5% rate of occurrence or more in the sample for at least five MHC alleles" impossible in 300 generations by drift alone?

I was browsing through the Wikipedia article on Major histocompatibility complex and see some of what you've said, for instance (going from memory) that some genes of the MHC complex have nearly 1000 alleles or more. A simple question is how so many alleles could have arisen and spread through a population in only 300 generations. Which you may have asked at least once already?

--Percy

Faith writes: I know but I've come to the conclusion that it was most likely two...

Based on what?

--Percy

bluegenes writes: The easiest way to explain this might be to look at ourselves as individuals. On the YEC model, we are ~15,000 mutations away from Adam and Eve on the whole genome. That would give us ~ 180 mutational hits on the small part that is coding genes, most of them falling on different genes, so we have new alleles on ~1% of the total of ~18,000.

How are all the numbers derived?

So, if we take 120 people as above, what would we expect on a given gene in purely neutral evolution. The four original alleles dominating, and perhaps 1, 2 or 3 exceptions.

I think I follow the logic here. Given the amount of the human genome taken up by coding genes, the 15,000 mutations since Adam and Eve would be sprinkled around so that only a very small percentage of genes would be affected. Most would be unaffected, and a small percentage would have 1 maybe 2 and sometimes maybe even 3 mutations. Certainly it would be very unexpected for any gene to have experienced hundreds of mutations.

Now look at the chart, and what do we see? If the YEC model, then signals of very strong selection on lots of new alleles.

But so many alleles wouldn't be possible in the YEC Adam/Eve model, would they? Wouldn't the "signals of very strong selection" be evidence that some other model must be in play?

--Percy

Faith writes: If the human genome can't be altered hardly at all without causing deleterious effects, and if it can't have any other function than what is found in the human genome, then how can there be any other species but humans in your model?

Faith never meant to imply anything beyond the human species. Humans have their genes and alleles, other species have theirs.

--Percy

Taq writes: See the problem?

Yes, I see the problem, but I didn't interpret what Faith said in that way, and she says she didn't mean it in that way. She meant that humans have genes and alleles that work for them, while other organisms have different genes and alleles that work for them. She *is* making the claim that a species current set of genes and alleles are the only ones that will work and that any changes are deleterious.

--Percy

jar writes: Yet we know for a fact that everyone has a different set of genes which is why DNA testing can identify a specific individual.

What Faith is saying is that everyone has the same genes but with potentially a variety of different alleles, and that the current alleles are the only ones that aren't deleterious. Any mutations in existing alleles would be deleterious.

--Percy

bluegenes writes: I don't think so. Her posts here certainly seem to accept "neutral". But I'm sure she'll clarify.

Yes, you're right, I should have said that Faith accepts non-beneficial alleles, or deleterious and neutral alleles.

--Percy

Percy writes: ...but if you add more genes, such as those mentioned by Percy for eye color, and many more for skin color, the number of variations increases enormously. There is really absolutely no need for extra alleles.

No one should be arguing that extra alleles beyond two are needed for eye or skin color, since these are both determined by multiple genes. Bluegenes is arguing that the MC1R gene has 30 known alleles that occur at a frequency that indicates positive selection (i.e., they do something uniquely beneficial than other alleles). These 30 alleles had to come from mutation, and there has been insufficient time since Adam and Eve's original 4 (max) for them to arise and spread.

--Percy

Edited by Percy, : Clarify first sentence.

Faith writes: I've been arguing that the supposed frequency is an illusion...

This is just factually wrong. The frequency in the population is measured.

...based on their being assumed to be alleles that change the function of the gene,...

According to the Wikipedia article on MC1R there are a number of variants that affect hair and skin color.

...when they are most likely neutral mutations that don't change the function of the gene (or the allele whose sequence they alter).

Since the MC1R variants have an effect, such as black hair/dark skin versus red hair/fair skin versus freckles and so forth, the variants are mostly not neutral.

He needs to show actual positive change in function and I don't know how you do that with the immune system. It could be done with eye color or skin color.

This is a fair challenge. Let's see what evidence of different functions for different alleles can be mustered for you.

--Percy