Thursday, March 10, 2011

epigenetics and society

The Scientist | The potent wish in the productive hour
Calls to its aid Imagination’s power,
O’er embryon throngs with mystic charm presides,
And sex from sex the nascent world divides…
—Erasmus Darwin,

“The Temple of Nature,” Canto II

I was first introduced to Charles Darwin’s flamboyant grandfather when I was an undergraduate searching through Michigan State’s wonderful Special Collections. In between bothering the curators for archived copies of Howard the Duck, I read Erasmus’s prose and poetry, and was treated to a great mind grappling with ideas that presaged one of the truly great ideas of modern times, the theory of evolution. As the passage above hints, Erasmus believed that environmental influences, in particular the “Imagination” of the parents, greatly influenced the phenotype of the child.

How very pre-Victorian (and post-). Erasmus anticipated Charles in many ways, but surprising results in the field of epigenetics—heritable (and reversible) changes in gene expression—suggest that he may have been very far ahead of his time indeed. In the current issue, David Berreby cites the increasing body of work that correlates childhood trauma with DNA methylation with suicide. One’s personal epigenome is modified by environmental perturbations, and that influences behavior. Certainly the Victorians could have related to the notion of an Original Sin that made its heritable mark on the genomes of parents created innocent, passing the curse down to their descendants. That said, the Victorians did have their biases, and it was of course the father who had the predominant influence over the child. But recently published studies of genetic imprinting show that the two parents’ influence on their offspring is more akin to a tug of war.

The Lamarckian idea that giraffes’ reaching for leaves resulted in longer-necked progeny seems silly to us today, primarily because we know so very much about the underlying mechanisms of genetics. And yet Lamarck may have a last laugh—think inheritance patterns in ciliates, or the effect of diet on the coat color of agouti mouse offspring. We are in the midst of a paradigm shift in our understanding of how evolution can act…on evolution, yielding mechanisms that allow both adaptation and heritability within the course of a lifetime. And such paradigm shifts almost always have societal consequences. Manel Esteller shows that epigenetics also impacts the “dark genome” in a way that may improve cancer diagnostics. An even more far-reaching consequence is that it may prove possible to engineer epigenetics, as Bob Kingston’s Thought Experiment tacitly suggests. If so, will epigenetic engineering be subject to the same restrictions as genetic engineering? Or will this be a way that we can not merely treat disease, but possibly engineer human health into future generations?
Andrzej Krauze

Such possibilities will be the rational outcome of a great deal of research and debate that is yet to come. However, there are at least two outcomes of the revolution in progress that would seem to have more near-term consequences. First, the overturning of a purely Darwinian paradigm will undoubtedly be viewed as the overturning of Darwin and his Theory itself. It matters not a whit that science will have been shown, once again, to be self-correcting, and to provide a means of advancing knowledge through the application of the experimental method and mechanistic naturalism. We can expect that epigenetics will be held up as the forerunner of that bastard child of Creationism, Intelligent Design. Dribs and drabs of this are already appearing on the Interwebs, but it may soon come to a school board near you. Second, the notion that environmental tags are embedded in our genome within a human time frame has got to be one of the best things to happen to tort law in a long time. DNA typing has led to the conviction of the guilty and the freeing of the innocent. Epigenetic typing may now lead to expert testimony regarding the presymptomatic impact of environmental disasters on susceptible populations. This may seem fanciful, but where there are moneyed interests (on either side), the science will inevitably follow.


nanakwame said...

Developmental Biologist; Author, The Sense of Being Stared At

In the nineteenth century, many scientists were convinced that the course of nature was totally determinate and in principle predictable in every detail, as in Laplace's famous fantasy of scientific omniscience: "Consider an intelligence which, at any instant, could have a knowledge of all the forces controlling nature together with the momentary conditions of all the entities of which nature consists. If this intelligence were powerful enough to submit all these data to analysis it would be able to embrace in a single formula the movements of the largest bodies in the universe and those of the lightest atoms; for it nothing would be uncertain; the past and future would be equally present for its eyes."
T.H. Huxley even imagined that the course of evolution was predictable: "If the fundamental proposition of evolution is true, that the entire world living and not living, is the result of the mutual interaction, according to definite laws, of the forces possessed by the molecules of which the primitive nebulosity of the universe was composed, it is no less certain the existing world lay, potentially, in the cosmic vapour, and that a sufficient intellect could, from a knowledge of the properties of the molecules of that vapour, have predicted, say, the state of the fauna of Great Britain in 1869."
With the advent of quantum theory, indeterminacy rendered the belief in determinism untenable, and in the neo-Darwinian theory of evolution (which T.H. Huxley's grandson, Julian, did so much to promote) randomness plays a central role through the chance mutations of genes.

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