[exDemMom]

Yes, but in that case the mutation goes nowhere and does nothing. Pointing it out isn't making a point. Everyone knows DNA can be damaged and repaired, and the repair job is not always perfect. You really should stop assuming people are stupid or ignorant because they disagree with you.

The problem is not that you're "disagreeing" with me. The problem is that you're loudly denying the nature of reality. I have not expressed a single debatable opinion about the nature of DNA, how it works, how evolution proceeds, etc. Everything I have said is based on solid evidence painstakingly assembled by thousands of scientists for well over 100 years.

Populations only gain and lose traits because of DNA mutations. Genetic drift--the major component of evolution--happens because of the cumulative effect of gain and loss of traits over time.

Traits can be lost or suppressed if the population faces a pressure that deselects it. It isn't a mutation that makes it go away, it is the environment.

Similarly, a trait that is suppressed in the general population can become dominant if a portion of the population is cutoff and the pressure against a trait is removed. There is no need to even cite mutations unless they are positively identified by showing the trait did not exist in the population previously.

I repeated the statement about mutations, because it is an important point that you still don't seem to grasp.

Let's go to very basic Introductory Genetics.

Traits are encoded in genes in the DNA.

• The expression of traits has nothing to do with selection. It has everything to do with whether the individual has the genes for those traits or not.
• A trait that is not encoded in the DNA will never be expressed, because it is not there. No amount of selection will cause it to be there.
• If a new trait appears, it is because the DNA was altered somehow to make it appear. The most common alteration is a point mutation, but other, more drastic alterations can and do happen.
• DNA undergoes constant mutation. In evolution, that matters when the mutation(s) occur in germ cells--the sperms and eggs. According to the biochemistry professor who wrote this blog, a human zygote has ~130 mutations. Most mutations, of course, are DNA errors that missed being repaired.
• Selection only becomes a factor when survival is concerned. About half of all human zygotes die before they can ever implant in the uterine wall, because one or more of their ~130 mutations was incompatible with survival. Of the ones who implant, about another third will die within a few weeks. Out of the remaining 1/3 who survive (if their mothers don't kill them), not all will end up reproducing. The minority of zygotes who live long enough and reproduce will pass ~half of their mutations to their offspring--along with the ~130 new germ cell mutations they pass along.
• It is the accumulation of mutations from generation to generation that causes genetic drift. Humans now are not the same genetically as humans 10,000 years ago. Humans 10,000 years from now won't be genetically the same as us.
• Speciation occurs when a population is split into two separate groups for a sufficient period of time. Each population continues the genetic drift, but in a different direction (because mutations are random). Eventually, the number of accumulated mutations causes the populations to no longer be able to reproduce with each other, at which point they are considered different species.

I have not expressed a single opinion here. Everything I have said is supported by mountains of evidence, painstakingly gathered and documented for well over 100 years. One cannot "agree" or "disagree"; the only possibility here is to accept or reject the evidence. Rejecting it, of course, does not make it disappear.

Anyway, I can't specifically address the rest of your post, I have to go to work. Where, no doubt, I'll be reading about the challenges presented by the ongoing evolution of pathogenic microbes.

[hopespringseternal]

The problem is not that you're "disagreeing" with me. ... I have not expressed a single debatable opinion about the nature of DNA, how it works, how evolution proceeds, etc.

When you claim something is beyond debate then disagreeing with you is precisely what you are defining to be the problem.

The expression of traits has nothing to do with selection. It has everything to do with whether the individual has the genes for those traits or not.

Speaking of sexual reproduction, genes can exist in a population but not be expressed because 1) the proper combination happens too rarely to be noticed or 2) in the natural environment the combination results in the death of the individual organism. Change the environment or select for the specific gene and it will be expressed. No mutation needs to have occurred.

A trait that is not encoded in the DNA will never be expressed, because it is not there. No amount of selection will cause it to be there.

Unless you can conclusively prove that it is not encoded in the DNA of any individual in a population you haven't proved that it is not there.

If a new trait appears, it is because the DNA was altered somehow to make it appear. The most common alteration is a point mutation, but other, more drastic alterations can and do happen.

Not if you are talking about a combination of genes to produce the trait.

DNA undergoes constant mutation. In evolution, that matters when the mutation(s) occur in germ cells--the sperms and eggs. According to the biochemistry professor who wrote this blog, a human zygote has ~130 mutations. Most mutations, of course, are DNA errors that missed being repaired.

Some things are just absurd and should be considered more carefully. If those mutations are truly random they would be predominately negative and quickly result in the non-viability of humanity.

The minority of zygotes who live long enough and reproduce will pass ~half of their mutations to their offspring--along with the ~130 new germ cell mutations they pass along.

Might out to check that ratio of positive mutations to negative mutations again. And assuming the the negative mutations are adding up to positive mutations because we are still alive is another one of those show your homework moments.

One cannot "agree" or "disagree"; the only possibility here is to accept or reject the evidence.

What evidence? I see clearly delineated species that occurred relatively suddenly followed by changes that are best characterized by species dying off. I see a mountain of assumptions that dwarfs the data and understanding we do have. I see you sparing no effort to defend your beliefs and expending none to test your theories. Anyone who fails to mindlessly parrot the official line is branded a charlatan and shunned.

Settled science is dead science. Even the most basic core of science is subject to reconsideration: Newton gives way to Einstein. Not so with evolution. You don't discard the old theory, you redefine the new observations to fit it. For you the earth will always be the center of the universe because it is "beyond debate."