Monday, March 01, 2010

The Upside of Type I Diabetes

Jonah Lehrer writes yesterday about depression's upside, the idea that depression might be an evolutionary adaptation (something that made an individual more likely to pass her or his genes on). He goes straight into the Evolutionary Psychology (EP) territory, the area where evolutionary psychology really does become a set of JustSo stories:

In the late 1990s, Thomson became interested in evolutionary psychology, which tries to explain the features of the human mind in terms of natural selection. The starting premise of the field is that the brain has a vast evolutionary history, and that this history shapes human nature. We are not a blank slate but a byproduct of imperfect adaptations, stuck with a mind that was designed to meet the needs of Pleistocene hunter-gatherers on the African savanna. While the specifics of evolutionary psychology remain controversial — it's never easy proving theories about the distant past — its underlying assumption is largely accepted by mainstream scientists. There is no longer much debate over whether evolution sculptured the fleshy machine inside our head. Instead, researchers have moved on to new questions like when and how this sculpturing happened and which of our mental traits are adaptations and which are accidents.

That bit about us being "stuck" with a mind designed to meet the needs of Pleistocene hunter-gatherers on the African savanna is the big giveaway. Remember that we don't actually know the needs of Pleistocene hunter-gatherers on the African savanna, and we don't know if they lived on the savanna. Remember that nobody knows if evolution actually has stopped since then altogether.

But let's assume, for the sake of the argument, that he is right. How then would depression have benefited a Pleistocene person? How would it have made that person more likely to leave behind children?

I'm trying to see how that could have happened. The article argues that depression makes us better focused on solving a problem because of the rumination, the insistent thinking that it's connected with. And it might have artistic benefits. So becoming depressive might lead to a solution of a problem quicker than not becoming depressive, because of that focus which makes one unable to get up from bed, eat or groom or sleep. And once the problem is solved one can go and have lots of sex (which one does NOT want to have when one is depressed).

Perhaps. But we must not forget that depression is supposed to have become an adaptation among those Pleistocene hunter-gatherers in the EP version of the story. So imagine the benefits of being depressed in a group of hunter-gatherers. You can hardly get up from whatever you slept on, then you have to go out hunting or gathering without any energy and/or mind small children at the same time, and all the while your brain circles and circles around the same horrible shit. And then the lion comes! Or if it doesn't come, your total gathering/hunting output will not feed a gnat.

I'm not arguing that depression might not have benefits, in particular the kind of depression one gets when a loved one dies or something else horrible happens. It serves as a drug which anesthesizes you for a while so that you won't die of grief. But that's not what we usually mean when we talk about depression. Clinical depression is something quite different and often the tendency toward depression is life-long.

It seems to me that we might as well talk about the upside of Type I diabetes. After all, it has been around a very long time and it has a genetic component. Is it an evolutionary adaptation, too? Something that improves fitness?

One expert interviewed in the linked article called this approach irresponsible and I can see how that could be the case if it leaks into the way depression is treated or rather NOT treated. But it seems more irresponsible to me in its focus on depression as something that benefited those Pleistocene nomads of which we know nothing rather than as something that has to do with the way we live right now.