DrW wrote:Harold Lee wrote:
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The only option that would save those birds, is if a few lucky birds mutated another way to survive and spread it around the gene pool of the population (or benefited from a lesser known epigenetic mechanism).
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Harold,
As long as the evolutionists have the kind and undivided attention of the board's Chief Creationist in Charge, and for the benefit of others who are following the thread and may not be aware of the importance of
epigenetics in adaptation, perhaps you could provide an explanation and a relevant example or two here, since you have obviously been thinking about this.
Thanks.
I don't feel comfortable or knowledgeable enough for that, sorry. :) Haven't been diligent in putting in my CE dues, and I'm 100% sure my understanding of epigenetics isn't any near complete or accurate.
But in a general sense reproduction takes place on a cellular level- mitosis and meiosis for sex cells. Occasionally there are mutations that take place when cells "split"- transposing, transplacing, entire sections being gone, repetition of genes, etc. There's four base molecules that compose DNA (the building blocks of MODERN life). They code EVERY biological quality and trait- including basic elements of personality, skin color, eye color, baldness, etc. Given how quickly and how many millions (billions) of these molecules get zipped and unzipped in order, mutations are just going to happen. Most of the time when these mutations happen they become dormant. When they take place in somatic cells (basically not sperm or eggs) that's generally what happens. When they take place in sex cells (which require a more complicated form of cellular reproduction and thus has a much greater probability of mutation) and this is the lucky guy that fertilizes the egg and become a zygote (or it's the lucky girl that gets fertilized), that set of DNA becomes the prototype that all somatic cells for that future organism will follow. That single mutation in one cell becomes a standard quality for all cells that will grow from the zygote. Every zygote has mutations, many. Most of the times, they're also dormant. Sometimes they're in places that affect critical components of a trait and the entire program (or gene) shuts down or creates a serious problem.
But every one in a while it tweaks the program (or gene) in such a way that the program becomes different. We've already talked ad infinitum about how the principles of natural selection work so that picks up where this'll end.
Well these mutations are all A,G,T,C molecules that are scrambled inevitably (although still with 99.99% integrity) are RANDOM. Whether the trait becomes phenotypic (or expressed in any way observable) is random. How it affects the gene it's composing isn't random but is determined by random qualities.
Go back to Lamarck. His theory of evolution was the predecessor to Darwin. He theorized, in contrast to random mutations, that traits were developed. The giraffe was his trademark example. In his model the giraffe thousands, maybe millions of years ago, began stretching its neck out to reach leaves on high branches. It secreted 'pangenes' that were passed down to the next generation, that also stretched his neck out, and on and on, until millions of years later the giraffe has a long neck. This is probably how most who misunderstand evolution picture the theory happening. It's a very basic and intuitive idea for evolution, but there is in fact nothing about it that involves randomness, mutations, or even necessitates natural selection (all of which formed the foundation for our current understanding until more recently). This made more sense when, back in the day, reproduction simply seemed like two parents mixing bodily fluids, and everything taking place under the microscopes wasn't understood.
Darwin's theory involved mutations, or nature. Lamarck's theory involved choice, nurture.
Darwin's theory obviously is not complete, but is a vast improvement on Lamarck's. Well one issue with Darwin's theory is the way it's been happening is too quick. Some evolutionary biologists like the long-winded Stephen Jay Gould more recently postulated punctuated equilibrium to theorize the existence of growth spurts of change when the pressure was on. That's of course intuitive also, and helped explained a lack of gradualism in fossils. But to go from single-celled organisms to humans, even by 3.5 billion years time, just seems to be happening too quickly. Especially when you consider mammals are only a few hundred million years old. Humans from the shared ancestor of neaderthals and homo sapiens, it's happening too quickly to simply be explained via mutations in sex cells in individuals yielding significant enough changes in phenotypes to providing a significant enough advantage to overcome the fight of chance for limited resources. Something has to be guiding evolution that forces or increases the chances of mutations that are relevant or takes place or relevant genes.
This is where I think my understanding of epigenetics falls short (essentially where epigenetics starts lol). Epigenetics is about bringing the nurture, environmental factors, into the nature of genetics. Instead of genes simply being a blueprint, a one-way street, it seems that they can be affected by stresses also. Mutations are still random, always have and will be, but which genes they hit may be impacted by which traits prove invaluable to the individual or population. This can speed up the mutation process on genes that could provide a competitive advantage. Bad mutations on these genes mean the organism has little chance- it's amplified given how valuable this trait is to the organism's survival. Conversely, any mutation that provides an advantage, no matter how small, becomes extremely significant because of on which gene or trait this takes place.
It brings the element of Lamarckian evolution, "guided" evolution, that makes the short time frames much more understandable.
But as far as I know epigenetics is essentially the study of how genetics can be affected by "environmental" factors ("environmental" being relative to mean all forces outside just the cells we're considering themselves, not necessarily needing to be factor outside the organism or in the habitat), through mechanisms beyond conventionally understood genetics. I think the details of how this feedback can occur is what you wanted explained lol.
If anyone can contribute to this here with examples, corrections, or anything further information that'd be greatly appreciated.
Thanks for the information!