Quite by accident, I watched Nova last week. The show was about epigenetics, the biological mechanisms that control gene expression. The rest of this post is based on my TV show’s worth of education, so please just take it as just my impression. Look in Wikipedia or other sources for more accurate descriptions.
These mechanisms cause cell differentiation within a complex organism. The way they work can also be affected by the environment. In a sense, they carry a memory from the environment and even in some cases from the environments of previous generations. They help explain why identical twins become less and less physically alike as they get older. The show used the analogy of the genome being the computer hardware, while the epigenome is the software. I think a better analogy might be that the genome is a piano and the epigenome is the pianist. A lot of the quality of the sound is built into the piano, but the specific music comes from which keys are struck when.
Aside: I’ve read a number of books on the human genetics, my favorite being James Watson’s book, DNA: The secret of life. It was so clear and well explained that I stopped resenting his arrogance in The Double Helix. I loved learning about searches for the genes associated with specific diseases, about isolating specific genes, about so-called junk DNA, about overlapping genes. The secret of life … well, maybe just the first touch of the secret of life. Other studies such as proteonomics and epigenetics make genetics seem simple by comparison. This all reminds me of Mark Twain’s Life on the Mississippi. Every time he thought he’d learned enough to be a river pilot, the master pilot would give him another mammoth task. When he learned to remember shapes seen all along the shore and how they related to river depth, then he had to learn them at night. Then he had to learn to remember river soundings called out by leadsmen from earlier trips — so he could remember enough to avoid the 500 shoals between St. Louis and New Orleans. Then …
During the Nova program, I was entranced to learn about a cancer treatment drug that manipulates epigenes associated with cell division. Instead of killing cancer cells outright, this drug works by turning off the oncogenes that make the cancer cells keep replicating past their normal rate. The scientist explained it fancifully as reminding the cell that it is part of a human and needs to play by the rules. Cancer normally plays a win-lose game that turns into a lose-lose game with the body. After all, cancer cells die with the body they kill. So in a way, they win when the body wins. The drug was in clinical trial so I have no idea how effective it will really turn out to be. TV shows tend to select people who are improving dramatically. But it’s a very interesting concept to watch.
I remember reading about cancer patients using visualization as part of the therapy. Right now, visualization often involves picturing oneself killing the cancer cells. What an advance, if people can start visualizing their cancer cells humbly dropping back into their appointed roles.