Psychiatry & Psychology

The Evolution of Depression

Psychiatry and Psychology CategoryMillions of people around the world suffer from depression, the most common mental disorder of all. Since depression appears to be largely genetic, several long-standing questions continue to bedevil researchers. Have the genes for clinical unipolar depression undergone selective evolution–or is depression a random product of mutation, evolutionary drift, or other non-selective forces?

The symptoms of depression are found in every culture and time period, from the ancient Greeks to modern New Yorkers, from the !Kung of southern Africa to ranchers in the American West. Why is depression so much more common than any other major mental illness? Clearly, it is a malfunction, a maladaptation — or is it?

DepressionWhat if depression sometimes turns out to be a useful adaptation, rather than a malfunction?  When people are depressed, they spend more time thinking, and less time engaged in physical activity. Paul W. Andrews, a researcher with the Virginia Institute for Psychiatric and Behavioral Genetics at Virginia Commonwealth University, believes that “depression is an evolved emotional response to complex problems, and its function is to promote changes in body systems that promote analysis of those problems.”

In a recent paper for Psychological Review — “The bright side of being blue” — Paul Andrews and Anderson Thomson propose the “analytical rumination hypothesis” to explain the widespread occurrence of depression. As an evolved response to solving complex problems, depression’s function is to “minimize disruption and sustain analysis of those problems by… reducing the desire to engage in distracting activities (anhedonia), and producing psychomotor changes that reduce exposure to distracting stimuli.”

Writing for ScientificAmerican.com, the two researchers argued that depression involves a specific, highly analytical thinking style.  Faced with a difficult math problem, “feeling depressed is often a useful response that may help you analyze and solve it,” the authors write. They claim to have found evidence that “people who get more depressed while they are working on complex problems in an intelligence test tend to score higher on the test.”

The authors point to various lab experiments indicating that depressed people may be better at solving complex social dilemmas as well, because they give more scrutiny to the costs and benefits of various options. What may look like indecision, or an inability to act decisively, may be artifacts of a particular problem-solving style; a cognitive technique that requires a minimum of outside distractions.

Viewed in this light, certain symptoms of depression — social isolation, an inability to derive pleasure from pleasurable acts (like sex), and a loss of appetite — combine to maximize the brain’s ability to focus and process information. This combination of cognitive and psychomotor effects might have the adaptive function of putting the brain in the perfect gear for certain kinds of complex problem solving.

The theory is far from watertight. Yes, depressives are capable of monumental feats of rumination and contemplation. But is obsessive brooding always a fruitful technique? As anyone who has dealt with a depressed person knows, the conclusions reached by all this high-level problem solving are often completely erroneous.  In many cases, depressives seem to be even more prone to fallacious thinking than non-depressed problem solvers.

The debate over the usefulness of depression shows no signs of early or easy resolution. But the search for the adaptive significance of mental and emotional traits always carries with it the possibility of major insights into evolutionary biology.

References

Andrews, P., Thomson Jr., J. (2009). Depression’s Evolutionary Roots. Mind Matters, August 25, scientificamerican.com.

Andrews, P., & Thomson, J. (2009). The bright side of being blue: Depression as an adaptation for analyzing complex problems. Psychological Review, 116 (3), 620-654 DOI: 10.1037/a0016242

Watson, P. (2002). Toward a revised evolutionary adaptationist analysis of depression: the social navigation hypothesis Journal of Affective Disorders, 72 (1), 1-14 DOI: 10.1016/S0165-0327(01)00459-1

Hertel, Jochen Neuhof, Thomas Theue, G. (2000). Mood effects on cooperation in small groups: Does positive mood simply lead to more cooperation? Cognition & Emotion, 14 (4), 441-472 DOI: 10.1080/026999300402754


8 Comments/Trackbacks

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Don Phillips
November 11, 2009 | Permalink

Hi Dirk,
A very thoughtful article. I wonder if it might not be useful to go back to Andrews and Thomson and ask them to comment on depression when it becomes severe mental illness (SMI) and ask them to fit that into their scheme of things.

stress management
November 15, 2009 | Permalink

I think its the byproduct of the over-functional brain. Our irrational emotional dictates simply don’t make rational sense. It’s not some coping mechanism at all. This mechanism has the ability to wipe memory cells, and I don’t think that is advantageous in any way. It’s simply our intelligence that says that we’re not the center of the universe clashing with our survivalist emotions that says we and our ways are universally important

Andrew Nuttall
November 23, 2009 | Permalink

As I read this, I was reminded of the effects recently noted in some journals regarding how epigenetic markers affect gene expression. Experiments with mice show that the introduction of certain methyl groups into their diets can produce behavioral changes. Gene therapy experiments show their effects on the production and use of neuropeptides. And the connection between diet and depression is well-known.

So I am left wondering, could the presence of certain methyl groups in the diet lead causally to depression?

amir
January 04, 2010 | Permalink

Depression, stress and their complications:

This disease is known as burned black bile. As it was said, black bile is one of the four humors of human body which will bring complications if one of them dominates other others.
According to the age, gender, physical power and temperament of individuals, these complications differs and are demonstrated in various forms.
If the dominance of black bile continues for a long time, it will changes into concentrated black bile or termed as burned black bile. No one usually considers this dominance at the onset of the disease which causes the treatment of the disease to be extended.

Causes of Disease: The most common causes of this disease are as follows:
Consuming some of the edibles in specific mental states
If one eats very sour edibles or lentil in a disturbed mental state such as severe anger, fear, even intense happiness, the body secretes much black bile and pickles and lentil increases this secretion the result of which is the dominance of the black bile over the other ones which causes complications such as phobia, anger, hallucination, sadness, etc…
From among the other causes are hereditary black bile humor and being in inappropriate mental state for a long time.

Common Symptoms:

Initial stages: Indifference, impatience, disgust, inability to enjoy, hopelessness, feebleness, fatigue, social reclusion, anorexia, gluttony, constipation, losing sexual desire, having problem in taking decision.

Severe stages: spontaneous weeping without any specific reason, irritability, thinking of suicide, various pains without any symptom, tongue split, urticaria, and gastric acid reflex.

Considerations: Any of the abovementioned symptoms may appear individually or collectively.

Disease intensifying factors: Anger, having an obsessive, orderly and serious, idealistic or highly dependent personality, family background in depression, addicted to alcohol, failure in business, unsuccessful marriage, disputes with others, death or loss of one of the dear relatives or friends, changing occupation or moving into a new place, etc.

Medication(Treatment)

In modern medicine, there is no significant treatment for this disease because its cause has not been diagnosed yet. But in traditional medicine, its factor has been known; therefore it is easily cured.

Treatment Procedure:

1. Avoid any kind of sour edible and lentil
2. Consume little salt
3. Provide a calm and convenient situation
4. Avoid loneliness and reclusion
5. Wear light-color clothes
6. Leave home and go to nature once a week to use its healthy weather

Herbal Medicines:

1. Borage: This plant has been known as the tranquilizer since the ancient times and can help curing the abovementioned disease because of its anti-excitement property.
2. Syrup of currants extract (black bile syrup): This herbal medicine cures all the mental diseases such as depression, hallucination, irrational sadness, stress, irrational worries and insomnia.

Considering the ingredients extracted from plants, black bile syrup is a strong melting agent black bile and regulator of black bile secretion; therefore, daily consumption of this herbal medicine and completing its treatment cycle results in full and absolute treatment of depression and its resulted complications.

April
February 09, 2010 | Permalink

We all get depressed every now and then. It’s part of life. Sometimes you feel great and sometimes you feel that the whole world is falling apart. I think this creates a balance in the equilibrium of emotions and lets you appreciate life. How would one know what happiness is without experiencing sadness? How can one experience love without feeling the pain? Altogether, depression is somehow part of life. The challenge is how to overcome it and move on with life!!!! Love your blog!

Farouk
February 27, 2010 | Permalink

well that a very new angle to analyzing depression, the only problem is people remain stuck at that state and never solve their problems unless someone helps them out

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