If depression has an evolutionary purpose, it’s certainly not obvious. Depression makes people consider suicide and less interested in sex, which does not encourage the species’ survival. But two evolutionary psychologists theorize that depression’s purpose is enhanced mental skills. Sadness focuses the brain’s attention on a conflict, and makes you better-equipped to make good decisions.
A fascinating New York Times magazine article entitled Depression’s Upside explains that the ventrolateral prefrontal cortex (VLPFC) is the part of our brain that controls what we pay attention to.
Several studies found an increase in brain activity (as measured indirectly by blood flow) in the VLPFC of depressed patients. Most recently, a paper to be published next month by neuroscientists in China found a spike in â€œfunctional connectivityâ€ between the lateral prefrontal cortex and other parts of the brain in depressed patients, with more severe depressions leading to more prefrontal activity. One explanation for this finding is that the hyperactive VLPFC underlies rumination, allowing people to stay focused on their problem. […] Human attention is a scarce resource â€” the neural effects of depression make sure the resource is efficiently allocated.
Therefore, when you’re depressed, your brain kicks into total-focus mode, and sets you into a cycle of rumination on the problem at hand.
The downcast mood and activation of the VLPFC are part of a â€œcoordinated systemâ€ that, Andrews and Thomson say, exists â€œfor the specific purpose of effectively analyzing the complex life problem that triggered the depression.â€ If depression didnâ€™t exist â€” if we didnâ€™t react to stress and trauma with endless ruminations â€” then we would be less likely to solve our predicaments. Wisdom isnâ€™t cheap, and we pay for it with pain.
Not everyone agrees with the positive spin on why depression exists, mostly because there are so many different types of depression–some triggered by events and problems, and others that persist for years without an obvious cause.
Ed Hagen, an anthropologist at Washington State University who is working on a book with Andrews, says that while the analytic-rumination hypothesis has persuaded him that some depressive symptoms might improve problem-solving skills, he remains unconvinced that it is a sufficient explanation for depression. â€œIndividuals with major depression often donâ€™t groom, bathe and sometimes donâ€™t even use the toilet,â€ Hagen says. They also significantly â€œreduce investment in child care,â€ which could have detrimental effects on the survival of offspring. The steep fitness costs of these behaviors, Hagen says, would not be offset by â€œmore uninterrupted time to think.â€
Still, those who suffer from depression do get the benefits of enhanced mental skills.
Joe Forgas, a social psychologist at the University of New South Wales in Australia, has repeatedly demonstrated in experiments that negative moods lead to better decisions in complex situations. The reason, Forgas suggests, is rooted in the intertwined nature of mood and cognition: sadness promotes â€œinformation-processing strategies best suited to dealing with more-demanding situations.â€ This helps explain why test subjects who are melancholy â€” Forgas induces the mood with a short film about death and cancer â€” are better at judging the accuracy of rumors and recalling past events; theyâ€™re also much less likely to stereotype strangers.
These mental boosts are often responsible for quality creative output.
In a survey led by the neuroscientist Nancy Andreasen, 30 writers from the Iowa Writersâ€™ Workshop were interviewed about their mental history. Eighty percent of the writers met the formal diagnostic criteria for some form of depression. A similar theme emerged from biographical studies of British writers and artists by Kay Redfield Jamison, a professor of psychiatry at Johns Hopkins, who found that successful individuals were eight times as likely as people in the general population to suffer from major depressive illness.
Even though I quoted it at length, this whole article is worth the read, especially for folks who tend toward depression. Knowing about the ways sadness can benefit you just might make you feel a little better.
Depressionâ€™s Upside [NYT via]
Very interesting… I admit I hadn’t thought of the “positive” side like that. I believe I’ve either experienced or witnessed those two sides of the issue. The negative is very hard to just write off, especially for those with severe difficulty, but as pointed out there are lots of varying types and reasons for depression.
Not that I’m a depressed basket-case, but I can find a place in my past for this as a contributing explanation for my creative drives.
Thanks for sharing that. I was unsure what it was doing on what I normally see as a tech blog 🙂 But that was excellent.
I’m really glad you brought this to my attention. However, please don’t refer to depression as “sadness”. It’s demeaning and upsetting.
Right, depression != sadness. I didn’t use the two terms interchangeably; when I referred to sadness I was doing so as the primary symptom of depression.
As someone who has struggled with depression and anxiety nearly all my life, thanks Gina — the info is much appreciated.
Paul the Counsellor
I am a counsellor and psychotherapist in private practice who often sees people suffering from depression. There are lots of ways to conceptualise depression and it’s quite possible that we are lumping together several different mood states under the same term. This particular study demonstrates a potential selective advantage to having certain symptoms of depression. I would tend to agree that depressive states are combined with rumination, which sometimes sews the seeds of new ideas that help to change life circumstances. However, severe clinical depression impairs function to such a level that it would be hard to imagine a selective advantage. It may be that the people who get severe depression have essentially got a double dose of the gene that provides a selective advantage through rumination.
Thanks Gina. This is a great link. Both my partner and I have mood disorders (he suffers from Seasonal Affective Disorder, and I have recurrent Major Depression), so I found this article especially interesting.
I believe in your good intentions, but writing something like “for folks who tend toward depression” just doesn’t feel right to me. Replace the word “depression” with “cancer” or “AIDS” or some other disease, and I think you’ll see what I mean. Still, I believe you mean well, and thank you for the link.
“If depression has an evolutionary purpose, it’s certainly not obvious.”
Perhaps it serves to decrease the production of children of miserable, unsuccessful, depressed persons by lowering their sex drives and making them less attractive to mates, thus increasing the percentage in the species Homo sapiens of happy, potentially successful children born to happy, successful people?
It occurred to me long ago that people are both social creatures and individuals, and much self-destructive behavior that seems inexplicable might be socially beneficial by weeding out people who don’t add to the hive.
Interesting post Gina – but from someone who has been living with depression their whole life and the terrible side effects that go with it -it doesn’t really help to know that there is a “positive benefit” of having it.
Thats just my take.
Thanks for your comments on the NY Times article highlighting the potential benefits that may be overlooked by those in depressive states.
Those of us who are given over to extended fits of “rumination” appreciate the post.
Thanks for the pointer to the article.
Actually, depression MAY have an evolutionary purpose, as written about in The Atlantic magazine a short time ago in an article titled “The Science of Success”, http://www.theatlantic.com/magazine/archive/2010/03/the-science-of-success/7761/
This is interesting, and I would certainly agree that happiness is not required for survival and evolutionary success. The bar, really, is quite low. Live to about 15 and breed.
I wouldn’t go looking for a purpose to every phenomenon evident in humans, especially the diseases and dysfunctions that beset us from the age of reproductive fertility onward. By definition, evolutionary selection has not had as much opportunity to operate upon afflictions that arrive after the age of reproductive fertility. Back to the low bar: if you live to 15 and breed, the disease and misery you suffer for the rest of your life has little further consequence. You’ve already passed the selection bar and passed on your genome, as-is, just as successfully as the person next to you who doesn’t experience adult depression (or prostate cancer, or heart disease, or whatever the case may be).
Depressed monkeys stay up late and warn others of approaching predators
While it might seem like there’s a lot of stuff going on in the depressed brain (and specific parts of it) when looking at it from the observer’s point of view, taking the depressed person’s POV might shed some dark light on the matter.
As many depressed people have said, being in a depressed state of mind is like being stuck in a whirlwind revloving around a black hole into which all existance is pulled.
So, all the fuss and busy looking is actually a sham. Now a clincally approved sham, but still – not much positivity.