Archive for May, 2011

In Which The Complaint Is Longer Than The Original Piece

Thursday, May 19th, 2011

Something that caught my eye in the news the other day: an article about scientists discovering a potential genetic link to depression. Whilst the subject itself is interesting, and we will get to that in a moment, this article also provides us an illustrative example of the problem with overly-simplistic science reporting. In this case, it is playing up to a popular misconception about the nature of genetics, by stating that the genes in question actively cause depression. This is almost certainly wrong, for reasons which experts would have a much easier time explaining, but I will give it a shot.

All human behaviour, to varying extents, is the product of a complex interaction between genes and environment (additionally, you could also say that genes construct phenotypes – some of which, such as the psychological makeup of the human brain, become a kind of third player in this interaction, transcending their genetic origins but also acting independently of any environmental influences). The idea of genes playing a predominant role in this process is kind of like suggesting that all you need is the recipe to know how a meal is going to taste. If you don’t go to the trouble of gathering the necessary ingredients, cooking them, and actually eating the final product, you’re going to miss out on a lot of important information. And even then, you can’t speak authoritatively about the recipe, because variations in ingredients and the cooking process will produce subtlely – or even substantially – different results each time.

Depression is no different in this regard, and its status as a problem that has both genetic and environmental roots is fairly well accepted by most experts. And yet the idea of a neat genetic cause remains appealing, both here and with many other problems, for a couple of reasons. First is just the basic simplicity of it – but whilst simplicity is of course highly valued in science, this simplicity should never come at the expense of fact. Elegant simplicity, encompassing all the known facts, is the real ideal to strive for. And secondly, there is a strange comfort that people seem to derive from the idea of genetic predeterminism, even when it causes significant problems, because it negates responsibility for any actions that may have otherwise caused said problems. In other words, no one has to modify their behaviour to prevent depression in this scenario, because it’s just genes and there’s not much you can do about it. Naturally, this is especially appealing to people who don’t actually suffer from depression, but whose actions or beliefs may have contributed to other people’s problems with the disease.

In reality, most people with depression can trace it back to an environmental cause, though the actual nature of those causes can vary greatly, from interpersonal problems to physical injuries to any number of odd and unexpected things. But of course, if the causes are so varied and widespread, why do some people suffer from it and not others? This is where the genetic component comes in: theoretically, genes may provide a predisposition towards depression in some people, explaining why they react differently to others when presented with the same stimulus. As a general rule of thumb, this is usually how genes work: they can only create a predisposition towards certain behaviours, which is then fulfilled or altered by environmental conditions. Some predispositions are easily changed, whilst others require a more complex confluence of factors before they will start to shift, but generally speaking, humans have evolved to be highly malleable and to adapt to a wide range of environments – including entirely artificial environments of their own creation. Indeed, one of the largely unique functions of the human brain is its ability to override its own predisposed behavioural patterns, which is why we can adapt so readily to new environments, and is also why we possess some semblance of biologically-constrained free will. Additionally, contrary to what you may at first assume, knowledge of our genetic predispositions doesn’t excuse behaviour (ie. you won’t be able to say, “this person has the dickhead gene, therefore they can’t help being a dickhead”) – in fact, this knowledge is actually more likely to make it easier to change these predisposed tendencies. In much the same way that it’s easier to control your hands when you can see what they’re doing, as opposed to groping about in the dark, self-knowledge often empowers the brain to overcome its own limitations. So, you know, it’s not something we should be particularly afraid of, even though many people seem to be, in my own experience at least.

The real trick here, if you want to understand how human behaviour works, is trying to unravel a tremendously convoluted chain of cause and effect – which is why simplistic explanations like “genes cause depression” usually fall apart fairly quickly. I expect the actual answers will be somewhat harder to pry out.

While we’re on the subject, one interesting point to come out of this discovery is that a genetic predisposition to depression may help strengthen the theory that depression has some adaptive value, under the right circumstances. This will largely depend on whether these genes have been actively selected for, as opposed to just being a harmful mutation or an unfortunate by-product of some other beneficial process. Whilst depression is generally a debilitating problem, especially once it spirals out of control, it is also unusual in the sense that it actively reshapes the brain’s thought processes to make it better at solving problems. Most of the harmful symptoms of depression only occur because the brain is devoting too much of its finite resources to this effort, thereby neglecting other important functions. Which means that if depression occurs in response to a genuine problem, the person may well be in the optimum position to solve this problem, assuming their depression doesn’t go too far and drag them under entirely. If it does give people an edge when it comes to problem-solving, then this benefit may be enough for natural selection to favour it, despite the unpleasant side effects (especially if the side effects of failing to solve problems are significantly worse, which is not hard to imagine). But this idea is still fairly speculative, and the debate is far from over.

To return to the original article, we should probably ask the question: did the reporter actively misunderstand the concept, or were they simply trying to create a quick summary and didn’t realise the implications of their imprecise language? (This is a common problem in science – as I have often discovered in the past, even if you have a basic understanding of a concept, there’s still like a thousand ways you can get the terminology wrong.) Or alternatively: is it perhaps an accurate record of an overzealous announcement by one of the research teams in question? Well, here is one of the papers referenced in the article, so check it out for yourself. You’ll notice they are rather more conservative in their wording, revealing the actual nature of their discovery: they are merely documenting an interesting and potentially significant correlation, not the be-all and end-all causal link suggested by the subsequent article reporting their findings. Unfortunately, as usual, the real science is rather more boring and messy than most people would like.

Ultimately, this is just another reminder to remain skeptical about information that has filtered through the science news cycle.