Mutations

I thought I might say a word or two about mutations since neo-Darwinists often cite natural selection acting on "beneficial" mutations that occurred by random chance to bring about macroevolutionary changes:

1. A mutation is a permanent change in the structure of an organism's DNA (or RNA, such as in retroviruses like HIV).

2. Judging by the numbers, most mutations are neutral, many are harmful, and few are beneficial.

3. However, what's beneficial or harmful or neutral is often relative.

   a. Is the mutation for lactose intolerance beneficial, harmful, or neutral? Well, it depends.

   When we're born, we produce something called lactase. Lactase helps us absorb and digest diary products like milk and ice cream. Without lactase, we couldn't, say, drink milk or eat ice cream without experiencing difficulties taking the milk or ice cream into our bodies and digesting the milk or ice cream. After we're weaned as babies, our bodies normally turn off lactase. So we can't tolerate drinking milk or eating ice cream anymore.

   But there are people who have a genetic mutation that keeps the gene that regulates lactase turned on. So they can still drink milk and eat ice cream just fine. In fact, most people with northern European ancestry have this genetic mutation. I think about 50% of southern Europeans like the French and Spanish have this mutation while the other 50% doesn't. A minority of Africans have this mutation too, but the majority of Africans don't have this mutation. And almost all Asians don't have this mutation.

   So this mutation is probably beneficial in an environment or community where there's a lot of dairy based foods. But neutral elsewhere.

   Or maybe this mutation would be beneficial in the future if in the future dairy consumption is widespread around the world.

   b. Similarly mutations for Asian flush syndrome. Asian flush is caused by a mutation so that people with Asian flush (mainly East Asians) can't completely breakdown alcohol in their bodies, so half broken down alcohol accumulates in the bloodstream, and causes the Asian flush. If someone is prone to alcoholism, then it might be beneficial to have this particular mutation.

   c. Likewise there are mutations which can cause resistance to certain diseases, which would be beneficial, but at the same time susceptibility to other diseases, which would be deleterious. Take a mutation of the CCR5-Δ32 allele which appears to help resist smallpox and HIV, but the tradeoff is increased risk to West Nile virus.

4. There are many other variables to consider in order to better determining whether a mutation is beneficial, harmful, and/or neutral. For example:

   a. There are different types of mutations in DNA. Take point mutations (e.g. silent; missense; nonsense; frameshift mutations - which in turn can be insertions or deletions). Or mutations that affect the entire chromosome (e.g. inversions, translocations, duplications). There are many other examples.

   b. There are different inheritance patterns such as autosomal dominant, autosomal recessive, X-linked, mitochondrial, etc. For instance, although I'll simplify, if someone has inherited a sickle gene from only one parent, then they would be asymptomatic and it would actually be beneficial in fighting against malaria. However, if someone has inherited sickle genes from both parents who are carriers, then they will have sickle cell anemia, which would be detrimental.

   BTW, how can evolution occur unless the normal (unmutated) gene is replaced by the (mutated) sickle gene in the gene pool? Yet if the normal gene is gone, then won't there be a significantly increased risk of sickle cell anemia running rampant through the population?

   c. Related to (b), it's common for people with the exact same mutation to have different patterns of disease. This is due to what's caused penetrance and/or expressivity. Two people can have the same mutation, but the mutation may penetrate and a disease may express in severity very differently. Perhaps, despite carrying the same mutation, it's partially penetrant in John, but fully penetrant in Dave.

   Why does the same mutation often have different penetrance or expressivity in different individuals even individuals in the same family? It's possible other genes are acting to modify the mutated gene's function. Or perhaps there are environmental factors involved.

   d. There are various consequences of genetic variation such as neutral variants with no detectable, loss of function variants, and gain of function variants. Gain of function may seem beneficial, but this is not necessarily the case. For instance, mutations in the FBN1 gene can result in the production of an "abnormal" protein as in Marfan syndrome.

   e. There are DNA repair mechanisms (e.g. mismatch repair), cell cycle checkpoints, and of course the cell itself can senesce or undergo apoptosis which is basically like hitting the self-destruct button if it all goes south. But what happens if the repair mechanisms and the like themselves become damaged? Apoptosis fails in cancer cells, for instance.

   f. If a mutation occurs in an early embryo (in utero), it'll most likely be lethal. Timing matters.

5. Mutations can be caused by a number of things like radiation, chemicals, microorganisms, etc. Sometimes mutations can be caused by random chance events. Is there a way to test the likelihood of random mutations across various organisms? Has it already been done?

6. It seems neo-Darwinists sometimes retrofit the idea of "beneficial" mutations after the fact in the sense that, so long as a neutral mutation happens to exist and persist in an organism and population, then the implication is there must be a benefit whether or not we are aware of a specific benefit. It's something further research will need to uncover - or so is said!

7. As we can see with what I've said above (especially points in #4), there's an entire pre-existing architecture or network or system in which mutations take place. Mutations are part and parcel of an orchestrated whole. Maybe sort of like saying it's not possible to misstype a word if there's no typewriter (or keyboard connected to a computer with a monitor and plugged in to a power outlet and so forth).

8. As an ID theorist might ask, is it possible for a mutation to generate new information in such a way as to bring about macroevolution in a population? Don't so-called "beneficial" mutations almost always if not always result in damage or loss of genetic information? Where's the creative power in beneficial mutations?

9. Ultimately, mutations can only act on already pre-existing DNA.