None of the regular posters, creationist or otherwise, appear to have a comprehensive, in depth understanding of evolutionary biology. We all know bits and pieces.
I think what happens is that evolutionists become frustrated when creationists won't accept a basic concept of evolution, if only for the sake of discussion. There are lots of examples, but here's just one:
Evolution is random.
We can agrue at length whether this is true or not (and we have), but the long and short of it is that the ToE says it is not random, like it or not. It would be great if someone would say, 'okay, I don't necessarily agree, but let's go with it for argument's sake'. Instead, we get stuck here and the discussion goes nowhere.
I haven't heard any educated YEC's say evolution is random, because of natural selection. The theory makes sense as a part of adaptation for me. But many, even some atheists and agnostics see an ineffective mechanism in mutation.
As you know Mutations are changes in our DNA that are deviations from an original sequence causing the "machine to run differently." I was just reading a paper this morning on pleiotropy
. I don't have time to go into detail, but the jist is that genes work together. A mutation in one, though it may be beneficial, causes problems in other areas. They have actually classified different types of pleiotropy. I'll put it at the bottom of this post.
The idea for me and other creationists-- that it is way too difficult to come up with transitions so many times that they would not die off completely. Simply because of genetic malfunction and secondary problems. This itself would stop transition from going to a completely different phenotype.
1. Artefactual pleiotropy, in which adjacent but functionally unrelated genes are affected by a single mutation, such as when two genes are located next to each other on a chromosome and a mutation in one affects the other. Hodgkin claimed that organisms with Ã¢â‚¬Å“compact, gene-dense genomes will be especially susceptible to artefactual pleiotropiesÃ¢â‚¬Â (1998, p. 502). This observation indicates that pleiotropy may be more of an impediment in simpler and more primitive organisms. An example is the Drosophila claret-nondisjunction mutation that causes both eye color abnormalities and meiosis nondisjunction.
2. Secondary pleiotropy, or Ã¢â‚¬Å“relational pleiotropy,Ã¢â‚¬Â involves a single mutation causing biochemical alterations that produce changes affecting many structural changes. An example is a mutation causing phenylketonurea, a defect in a liver enzyme (phenylalanine hydroxylase) that causes a deficiency in axon myelination. It leads to numerous health defects, including mental retardation (Hodgkin, 1998, p. 502). Secondary pleiotropy is especially common in complex, long-lived organisms, and consequently presents a major problem for the evolution of Ã¢â‚¬Å“higherÃ¢â‚¬Â creatures.
3. Adoptive, or exaptational pleiotropy, is the situation whereby one gene product is used for very different biochemical reactions in different tissues. An example Hodgkin gave is crystalline protein that is not only the most abundant protein in the eye lens but also is used for structural roles in other tissues such as smooth muscle.
4. Parsimonious pleiotropy is the case in which one enzyme is used to catalyze the same chemical reaction in many different tissues and organ systems or is used in different biochemical pathways. An example is that the same enzymes are used in very different branches of a biochemical pathway that synthesizes isoleucine and valine.
5. Opportunistic pleiotropy is an event whereby one regulatory protein serves an important role with other cell or tissue types in addition to its main functions. The example Hodgkin used is the control elements sisB and runt on the x chromosome that cause problems early in development and which genes are also used in later stages of growth, such as during secondary S@xual development.
6. Combinatorial pleiotropy is a case of one gene product interacting with different proteins in different cell types and being used in several different ways that result in distinct variations. A large number of examples exist, including most transcription factors, which cause a very different biochemical activity, depending on where they interact with the genome. As a result, mutations affecting this protein Ã¢â‚¬Å“have multiple and often very diverse effects on a wide variety of tissuesÃ¢â‚¬Â (Hodgkin, 1998, p. 503).
7. Unifying pleiotropy is a phenomenon whereby one gene or cluster of adjacent genes encodes multiple proteins that have common or related biological functions. Examples include various structural components, binding domains and enzymes. As a result, mutations in genes in this category Ã¢â‚¬Å“have complex physiological consequences, which may be hard to explain if the underlying biology is not understoodÃ¢â‚¬Â ( Hodgkin, J. 1998. Seven types of pleiotropy. International Journal of Developmental Biology.Ã‚Â p. 503). Cited by Jerry Bergman in this article.