We are nihilists, Lebowski! We care for nothing!

I commented a while ago on something that Dean Ornish calls genetic nihilism, a great turn of phrase that I will deftly procure for myself. This is a sort of view in which we say "well, my DNA has already programmed my health and/or behaviour, whether I will get diabetes or cancer or an aneurysm while doing backstroke in the community pool." Which, in addition to being untrue, is a pretty irresponsible way to live.

I thought of it because of a Swedish study showing that the presence of a certain variant of a gene in males is associated with increased prevalence of "marital crisis" in the last 12 months, reduced proportions in number of men married, and lower scores on a sort of "pair-bonding index." And the headlines were awesome - "Why men cheat" (Science Magazine), or "Commitment phobes can blame genes" (BBC). These are great examples of genetic nihilism. We are expected to take it at face value that men fear commitment and cheat on their wives and girlfriends, and furthermore that these are parts of being male programmed into DNA as much as a penis is, so we should be able to find a gene that makes it so.

No one is ever going to find that gene, because it doesn't exist (along with the "penis gene"). The authors of this study do some fancy calculations and say that about 28% of the variation they saw in the study were inheritable from their parents. Now, I'm going to say that heritability is not just a question of genes being passed down, and if you want to argue about that let me know. The rest is from "environmental factors," which is to say everything other than your parents.

We have roughly 25 000 protein-coding genes in our cells. Let's say 1% are involved in mating behaviour, which is probably a ridiculous underestimate given the importance of mating to continuing the species. That's 250 genes involved in mating behaviours, which are only the genetic part of their heritability measure, which in turn only accounted for about 28% of the variation in the study. While some of these genes might be more important than others, the assertion that a different version of a single gene will double your chances of being unmarried or in a turbulent relationship seems unlikely at best.

This study does have an interesting design, however, involving some 500 same-sex twins both married and unmarried. I hope they run some fishing trips (technical term: gene microarray) looking at polymorphisms on other genes that might be related.

What's "beaver" in Spanish?

Nature reports this week on how the beloved Canadian beaver has outworn its welcome in Tierra del Fuego, where 50 of the things introduced in the 1940s bred like rodents will, and now number about 100 000. As intended, it it did provide a substantial fur market for the indigenous people, but had devastating consequences for the local flora and fauna. They are now looking into ways of "eradicating" the beavers. One hopes they don't import a pile of foxes or something.

While traveling in New Zealand a couple years ago, I met a guy at the hostel who had been touring through Australia. He told a story about some guys he met in a small town up in the northeast. When asked what they did fun for fun, these guys said they "go on a catshoot," by which they meant they would drive around (perhaps in varying states of intoxication) and shoot at cats with BB guns. While this sounds cruel and appalling at first, I later learned that cats were a huge problem in the rainforests there. Escaped domestic cats bred over time have become fearsome predators and unbalanced the already wonky ecosystem (what with all the cane toads, pigs, foxes, rabbits and whatnot). Which just goes to show that country people know what's good for the country everywhere you go, even if they sometimes seem like freaky rednecks.

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Small bits of news: Nature reports that biotech giant Invitrogen (who have just finished buying Millipore, Upstate, Chemicon, and maybe several other firms) have offered about US$6.7 billion for Applied Biosystems, another giant in the industry. One is reminded of beer companies, or Microsoft. Canada will partner with California in a $100 million investment into research on cancer stem cells, which will cement our positions as world leaders in this field; strategically it looks like a smart investment, and says that cancer is back in vogue with funding agencies. Scientific American reports on another important step in killing the nature vs. nurture worldview, and what one of the study's authors very cleverly refers to as "genetic nihilism."

This kind of thinking, in which one assumes that genes dictate our lives and there's nothing we can do about, is reminiscent of destiny (or divine purpose) vs. free will debates that have raged through history (and to my admittedly primitive understanding of such things, there's still no conclusive winner). Genes don't change in their sequences over the course of life, but the ways they are structured, "read," regulated, and affect our lives is very much open to input from a surprisingly wide variety of sources. Trust me, I'm doing a whole doctoral thesis on it. Not to say that every gene can be turned up or down so easily, but very good evidence is accumulating that simple things like proper diet and regular exercise can push gene expression in certain directions, which are usually considered good for the animals involved in terms of any number of health indicators.

So what we're saying as biologists, just to make it absolutely clear: Genetics rule our lives. Genetics do not rule our lives. Any questions?