Epigenetics, revisited (Introduction)

by dhw, Saturday, August 27, 2011, 14:00 (4816 days ago) @ David Turell

DAVID (under "Early Embryology"): I'd love some Darwinist explain this phenomenon to me. How did evolution add this protective mechanism to embryoes that are in the 3 to 5 day range of development? How does natural selection operate in this situation? -http://www.sciencedaily.com/releases/2011/07/110705071546.htm-In the good old days when George used to fire his atheist arrows at me, he often objected to my using the word "mechanism", but it's very difficult to avoid, as we can see from this latest article. Atheists don't like it because it automatically smacks of design, but the more complex the operations, the more difficult it is to avoid thinking and talking in such terms.-A new book called The Epigenetic Revolution by Nessa Carey (a lecturer in genetics at Imperial College) was reviewed last week in The Guardian. The review is too long for me to quote, but here are some interesting snippets:-"The cell tells the DNA what to do just as much as the DNA instructs the cell: you can't have one without the other."-"Epigenetics is what happens when genes are actually in action: in the growth of the foetus, in responding to hormones and environmental stress, to learning, to maturation at puberty. In all of these processes genes are modified slightly and act differently from that point on. In short, epigenetics is where nature meets nurture."-"It is almost certain that memory ... a classic nurture problem: we learn something and it becomes biologically encoded ... involves epigenetics. Once made, epigenetic changes can be very long lasting, which is how our long-term memory is possible."-" [...] it claims that some epigenetic changes are so long-lasting they cover several generations. This flouts one of biology's most cherished dogmas ... taught to all students ... namely that changes acquired during life cannot be passed on ... the heresy of Lamarckism."-"She hasn't, though, solved the problem of how to make the mind-numbing complexity of some genomic interactions and the confusing nomenclatures of genes palatable to the general reader. On one page alone, we encounter H3K4, H3K27, DNMT3L, EZH2, LSD1 and DNMT3A&B."-It is indeed mind-numbing. And all this, bear in mind, is part of a mechanism that actually works. It's "the book of life; a huge encyclopaedia; a sacred chain of code 3 bn characters long". You really have to admire the faith of those who reject even the possibility of design.