more on epigenetics (Evolution)

by dhw, Sunday, August 12, 2012, 18:10 (4275 days ago)

In yesterday's Guardian, under the sub-heading "Epigenetics is one of the keys to explaining the mystery of life", there was a review of Identically Different: Why You Can Change Your Genes by Tim Spector, professor of genetic epidemiology at King's College London. Inevitably a lot of the focus is on disease, but I'd like to comment on the following passages:-"If you practise music for six hours a day [...] your brain will show recognizable changes both in large scale anatomy and genetically. [...] But the puzzle is that some of these changes can be passed on to offspring, and the effect ... although it eventually disappears after three to four generations ... can have profound consequences." -The profound consequence for Dolly the cloned sheep was premature death, but I'm more interested in width than in depth. Practising music six hours a day is the result of mental pressure (another example given is that of London cabbies, who have to memorize the streets of the city) and doesn't stem from physical changes in the environment, but we know that organisms also adjust to the latter ... sometimes they have to in order to survive. Now it stands to reason that a musical disposition, or the need to memorize streets, will not necessarily be transferred from one generation to the next ... but once a physical environment has changed and stabilized, why wouldn't the epigenetic changes be passed on indefinitely? I need help here. The current argument that epigenetic changes are not lasting surely depends on the nature of the organisms and the environment in which they are examined. How is it possible to gauge the limitations of heritable epigenetic change during the millions of generations of the millions of species that have inhabited the Earth, without being able to test the impact of their changing environments? In other words, is it not possible that speciation is due to the response of organisms and their cells to new environments, i.e. to permanently heritable epigenetic change?-A second passage is relevant to free will, so I'll post it accordingly.