Cafe Scientifique: 2007-03-17

Cafe Scientifique Poster for 2007-03-17So I made it to Cafe Scientifique again this month. I’m two for two since I started going; here’s hoping I make it to more.

The topic this month was “Nature vs Nurture Revisited: New research is changing the age-old debate.” The expert panel was Robert Gerlai, Ph.D (Dept. of psychology, UofT) and Christopher E. Pearson, Ph.D (Dept. of genetics and genome biology, SickKids Research Institute). I expected there to be more talk about specific issues of NvN, like sexual orientation or intelligence. Instead, the talk mostly dealt (as far as I saw) with the biological mechanisms that come into play.

IANAEB, but in a nutshell there are two processes being discussed here: Darwinian evolution and Lamarckian evolution1. Darwinian evolution is of course the process by which a gene or group of genes that produces a phenotype conducive to its own propagation will tend to be better represented in the gene pool, beating out its allele rivals. Lamarckian evolution is the theory that an organism can pass on traits it has acquired during its own lifetime.

Sounds weird, right? Our DNA sequence is fixed — how could we possibly pass on genes we weren’t born with? Well, it turns out that cytosine (the “C” in GATTACA) can be methylated or de-methylated by the introduction of certain substances, and that this new form can have different phenotypic effects. This process is referred to as epigenetics. So what happens is, someone eats a diet2 containing a substance that toggles the methylation state of a certain sequence in some of their cells, including germ cells. It doesn’t affect them, or not much, because they have already developed into a human. However, the new methylation state is persistent. So when one of those germ cells becomes another person, there is a chance that the altered sequence will trigger some aberrant effect.

This has all sorts of implications, some good and some bad. On the one hand, we might find that certain diseases are caused or exacerbated by a certain methylated state on a certain gene, and that simply making sure that the population gets a certain amount of some nutrient will reduce the incidence of that disease. On the other hand, this may increase the amount of medicating that we do. Drug companies and “alternative medicine” manufacturers may jump on the band wagon, marketing products that claim to “de-methylate your cancer genes” or whatever, playing on people’s ignorance and fear to get them to eat more pills. What’s more, there may be even more pressure than there already is on women to treat their bodies like baby machines and to make sure that even before they start thinking about reproducing they maintain a diet that will produce the optimal methylation state in their bodies.

Just as with any new technology or discovery, the recent findings in epigenetics contain potential for a lot of good and a lot of evil. The talk today was very informative, and I’m grateful to the two panelists for taking the time to make it out. Today I learned about a facet of evolution that I would never have imagined existed.

1 Note that these are not competing theories, although they could be seen as competing processes. Like Darwinian evolution, Lamarckian evolution has been observed and measured, though it is more difficult to reproduce and control than Darwinian evolution for various reasons.

2 This could also be the result of other environmental influences, such as atmosphere composition, but diet seems the most effective since we actually have in-built mechanism for distributing food’s components around our bodies.

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