Thursday, September 9, 2010

Epigenetics and PTSD

This news release from Science Daily highlights yet another epigenetic study that raises difficult questions about our understanding of natural selection. There is a long, fascinating, and in some ways sad history about epigenetics. It all began with the Australian immunologist Ted Steele.

Does the Impact of Psychological Trauma Cross Generations?

It has been assumed that these trans-generational effects reflected the impact of PTSD upon the parent-child relationship rather than a trait passed biologically from parent to child. 
However, Dr. Isabelle Mansuy and colleagues provide new evidence in the current issue of Biological Psychiatry that some aspects of the impact of trauma cross generations and are associated with epigenetic changes, i.e., the regulation of the pattern of gene expression, without changing the DNA sequence

The Australian immunologist Ted Steele, in the 1970's, was the first to strongly argue for a Lamarckian style of inheritance. I read his book long ago, Lamarck's Signature, and put a question mark over it, waiting for studies. Ted Steele was treated like a pariah by the scientific community. Not surprising, science does have its stories of the intellectually adventurous being burnt alive. A friend of mine once noted that Aussies tend towards the iconoclastic type. (Can we find an epigenetic trait for that Frank!?). Ted Steele, and that wonderfully cynical and insightful Aus philosopher, Dave Stove, are excellent examples of that iconoclastic motif. Dave Stove is one of those few precious philosophers who can call out bullshit with remarkable clarity. For example, in regard to the Selfish Gene hypothesis, one of the dumbest ways you can ever perceive genetics, Stove writes: if genes were that selfish incest would be all the rage. So FU Dawkins, I always knew you were wrong and now everyone does. But I digress ...

Epigenetics Nutshell: The concept refers to changes in gene transcription mediated by the the attachment of methyl and\or acetyl groups to the proteins which surrounds genes (chromatin, heterochromatin) and impact on the rate of gene transcription.

Ted Steele's fight cost him his career, he was even subject to disciplinary proceedings which were later thrown out on appeal. In science rocking the boat can have you tossed overboard. He crossed a sacred barrier, the Weismann Barrier. This refers to the long held view that irrespective of what happens to the body(soma), the germ line cells remain unaffected. We can now regard that as unmitigated bollocks.

There are deep and difficult questions surrounding epigenetics. This study highlights one such problem. For it is unimaginable how epigenetic changes could have the precision suggested in this article. The same problem is suggested in relation to epigenetic findings on diabetes, that if your grandparents went through a noticeable famine your diabetes risk was raised. This is quite fascinating, especially when you consider that India is the diabetes capital of the world and aborigines also have extraordinarily high rates of diabetes. How's that for an unintended consequence of being well fed! So even if we looked for gene changes the answer may be masked, what we need to also look for is epigenetic changes. These findings and many like findings have profound implications for our understanding of evolution. It is going to be another revolution and calls into question all those models of gene variation and natural selection dynamics.

BTW, a study released a few months ago suggested that congenital mental retardation can occur not through changes in the genes but in epigenetic changes.

1 comment:

Anonymous said...

As if relevant kinds of conditioning and its repercussions were not enough!