The Evolution of Depression

Millions 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?

What 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, 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.


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

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

  • Don Phillips

    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.

  • 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

  • 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?

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  • 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.


    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.

  • 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!

    • Rik

      As somebody who is very close to depression I can assure you that it bares no resemblance to the normal ups and downs of life. Depression is debilitating it steals ones life away. Simple tasks such as making a cup of coffee for oneself can feel like climbing mount Everest.

    • Maeve

      I believe the misunderstanding between the concepts of “feeling depressed” and “clinical depression” rests in the term “depression” – it is a misnomer. The clinical diagnosis name should be changed to reflect an independent condition, separate from depression, which accurately reflects the devastating symptoms of this body, mind, spirit illness. Yes, feeling ‘down’ might be a way of simplistically giving a name to part of the condition but it in no way reflects the paralyzing, numbing, excruciating pain of living a non-life. Other symptoms include tremors, physical pain, inability to use cognitive skills, perceiving the world in black, white and gray colors only, distorted thinking and feeling states, suicide ideation, panic, etc.

      One loses control of one’s internal and external lives and this even impacts the concept of free will. How can we have free will if we are unable to accurately evaluate data in our world? The impact of this condition robs the person of even having the energy to continue seeking help. Dick Cavett is quoted as saying “if you told me there was a pill on the table across the room which would cure me of this, it would be too much work for me to go over there and get it”.

      That’s not ‘the blues’ – that’s a potentially terminal illness. Please, let us re-name it so we can avoid people telling us to ‘snap out of it’. If others understood then they would no more tell a patient with clinical depression that than they would tell a cancer patient to stop the devastation going on within their body.

  • 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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  • Z

    That’s actually very interesting – also encouraging. I’ve been depressed before and been assigned antidepressants; never liked them because although they will dull pain, they also dull thought, which makes it harder to make any progress.

  • john

    a notice about the new aspect odf depresion

  • Chandler

    There is certainly something to be said about the adrenaline and natural endorphins that are created in physical activity. If you just make yourself get out and get moving, you would be surprised how much better you actually feel afterwards.

  • Rik

    Has there ever been any research into the mechanisms which drive boredom and how it may relate to depression. This is a simplistic thought but there are reasons for asking it.

    In general i feel that there are many reasons why people are driven by depression. Such as environment (Personal that is), genetic, conditioning, medical and many others one or more could be in affect at any one time.

    A side thought on the problem mind and why it does not fit into today’s society so well.

    Why problem solving minds foster depression in today’s society

    A problem solving mind is geared to ponder/ruminate on the problem and information which defines the problem. It will assimilate all the information then work on it to find a solution. This pondering of all the possible scenarios (the ifs and buts etc) either consciously or in the subconscious or thinking on it when away from the problem, is what drives the problem solving mind. It’s reward is finding the solution. (reward is important)

    Faced with a society full of procedures and ever growing forms (both in amount and in size) the problem solving mind is an enemy within. Why? Well it already knows the answer. It just has to sit and fill in the forms. Very little reward for it here. The worst part is when away from the task the problem solving mind will still ruminate on all the information and possible scenarios (outcomes) unfortunately not just the positive one but all the possible reasons for failure too! And all the things that could go wrong whilst filling in the form. Every question is a mine field of possible ambiguities to the problem solving mind. It quickly deduces all the possible meanings of a question, meant or inferred!

    Why is this a problem. Well for depressives to get help they are often faced with a barrage of forms!

    A personal nemesis of mind which has often steered my life choices and caused me a great deal of anxiety and often pushed me into a deep depressive state.

    Anyway enough rambling on by me.

  • _beltie

    How about depression being the paralysis if the unconscious mind challenging the conscious? That’s why it’s exhausting!

    Also Neuro studies have shown rumination reinforces negative neural pathways, whereas reaching out with support to fresh ways if thinking grows new ones.

Dirk Hanson, MA

Dirk Hanson, MA, is a freelance science writer and the author of “The Chemical Carousel: What Science Tells Us About Beating Addiction.” He is also the author of ”The New Alchemists: Silicon Valley and the Microelectronics Revolution.” He has worked as a business and science reporter for numerous magazines and trade publications. He currently edits the Addiction Inbox blog, and is senior contributing editor for the addiction and recovery website, The Fix.

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