Good Reasons for Bad Feelings

by Randolph M. Nesse

  Harsh times require difficult high-risk decisions. My grandmother was born in February 1884 on a small island off the coast of Norway. On the day of her christening, her father sighted a swirl of fish offshore. A heaven-sent gift for extra mouths to feed in a lean winter? He and his partner rowed out despite the waves. They hoisted their nets again and again, until the boat was full. Should they persist or go home? The fish were still there, and they might not come back, so the men also filled a spare dinghy, connected to their boat by a chain. The wind rose, the dinghy flipped, the chain could not be cut, and both boats went down. My great-grandmother was helpless onshore, holding her newborn daughter as her husband drowned. Optimism and boldness are often worthwhile, but occasionally they are fatal. The perils of risk-taking in a harsh environment may help to explain why my great-grandfather’s surviving descendants have tendencies to anxiety and pessimism.

  Making decisions about foraging or fishing remains central to the lives of many people, but most of us now pursue long-term social goals in complex webs of relationships that confront us with difficult decisions about whether to continue big efforts that may be futile. Some competitions offer huge payoffs for a few winners and years of useless efforts for everyone else. Making it as a professional football player is fabulous, but 999 out of 1,000 who try will fail. The rewards for even successful novelists pale by comparison, but even more people try writing fiction. Career pursuits offer easy examples, but mood also guides more personal goals: trying to lose weight, find a job, get along with a cranky boss or spouse, or cope with everyday life despite crippling arthritis. Progress speeds and slows, and mood rises and falls, as we pursue the projects that make up our lives.

  This brings us back to the crucial question posed by the Marginal Value Theorem: When is it best to give up on a major life goal? Early in my career, I always encouraged patients to keep trying, keep trying, don’t let your depression symptoms fool you into thinking you can’t succeed. Often that was good advice. Some applicants get into medical school the fourth time they apply. Some singers land a gig with the Grand Ole Opry after their fifth year in Nashville. But more become increasingly despondent as failure follows failure. Sometimes a five-year engagement turns into marriage. Sometimes staying another year in LA trying to break into film pays off. But not often.

  Sober experience combined with my growing evolutionary perspective to encourage respecting the meaning of my patients’ moods. As often as not, their symptoms seemed to arise from a deep recognition that some major life project was never going to work. She was glad he wanted to live with her, but it looks increasingly like he will never agree to get married. The boss is nice now and then and hints at promotions, but nothing will ever come of it. Hopes for cancer cures get aroused, but all treatments so far have failed. He has stayed off booze for two weeks, but a dozen previous vows to stay on the wagon have all ended in binges. Low mood is not always an emanation from a disordered brain; it can be a normal response to pursuing an unreachable goal.

  Animal Models

  The standard way to tell if a drug will be an effective antidepressant is to see if it makes an animal persist in useless efforts. The Porsolt test measures how long a rat or mouse swims when dropped in a beaker of water.57 Rats on Prozac or another antidepressant swim longer. Because the test works to identify antidepressant drugs, it is the basis of more than four thousand scientific articles, with new ones being published at a rate of one per day. Persisting seems like a good thing, and many of those articles describe cessation of swimming as a sign of low mood or despair. But stopping swimming does not mean giving up and drowning, it just means switching to a different strategy: floating with the nose just out of the water. Rats switch to this strategy at about the right time. Those on drugs that make them swim longer are more likely to get exhausted and drown.58

  Learned helplessness is another animal model that presumes persistence is good. The psychologist Martin Seligman put dogs in a box with two compartments separated by a partition. Dogs that received a shock learned quickly to jump to the other side to escape. But dogs previously exposed to shock they could not avoid did not jump over even when they could. This “learned helplessness” is thought to be a good model of depression.59 As is the case for swimming rats, however, the dogs may only look dumb. There are no electrical shocks in the wild, but there are other dogs ready to inflict pain again if necessary to maintain their dominant position.

  Other Situations in Which Low Mood Is Useful

  I emphasized the situation of pursuing an unreachable goal in my 2000 article “Is Depression an Adaptation?”60 In retrospect, my view was too narrow. Low mood can give advantages in several other situations. Striving for social status often creates unreachable goals, but chronic low mood can also be useful for those stuck in a subordinate position. I saw scores of depressed women who had small children, no job, no relatives nearby, and an abusive husband. We tried hard to get them into a shelter, but few would go, and few returned for continuing treatment. If depression diagnoses were based on causes, “depression in someone who has no way to escape an abusive spouse” would be a common mental disorder.

  While the focus has been on social situations, physical situations also influence mood. Three are especially salient: starvation, seasonal weather changes, and infection.

  The Minnesota Starvation Experiment conducted on World War II conscientious objector volunteers provided dramatic evidence of emotional changes. All subjects were initially healthy and emotionally stable. They agreed to go on diets that reduced their body weight by 25 percent. By the time they got to that body weight, most were fatigued, depressed, and hopeless, spending most of their days thinking about food.61,62 Such caloric deprivation occurred at times for our ancestors, and it continues in many parts of the world. In such situations, it is wise to avoid vigorous competitive activities.

  Lack of sunlight makes many people feel down, and seasonal affective disorder is common. It’s hard to say whether low mood in the gloom is an adaptation or a by-product of other mechanisms, but when activity is likely to be dangerous or unrewarding, low mood will be useful.63,64,65

  Have you ever awakened with new symptoms of a cold and felt like there was not much point in doing anything? The syndrome was named sickness behavior by the ethologist Benjamin Hart in the 1980s.66,67 He described its possible evolutionary benefits, including conserving energy to fight infection, and avoiding predators and conflicts when not in top form. Many studies document depression symptoms during infection.68 Especially dramatic are severe cases of depression precipitated by treatment with interferon, a natural chemical that gears up the body’s immune response. Nearly 30 percent of patients receiving interferon treatment for hepatitis C get serious depression symptoms, not just fatigue but also feelings of hopelessness and worthlessness.69 This demonstrates that immune responses can cause clinical depression and suggests that some aspects of low mood may be useful when fighting infection.70

  Fatigue and lack of initiative make sense during infection, but why have terrible feelings of guilt and inadequacy? These symptoms could be by-products of a crude system. A related possibility is that some systems that regulate goal pursuit evolved from preexisting systems for coping with infection. Or perhaps infections in ancestral environments caused only fatigue, and full-fledged depression occurs mainly in people with modern immune systems that are hyperactive because of excess nutrition or disrupted microbiomes.

  The bottom line is that infection is yet another situation that arouses low mood. This does not mean that all depression is a product of immune systems. However, if natural selection co-opted aspects of the immune system to create the systems that regulate mood, that would help explain the strong association of depression with inflammatory diseases such as atherosclerosis.71,72,73,74

  What Good Is High Mood?

  High mood has been neglected. It seems so obviously wonderful and useful that its adaptive significance has only rece
ntly been studied. It fits nicely as the converse of low mood, a suite of responses useful in propitious situations, especially those likely to be temporary. People whose motivation and energy rev up in response to opportunity get a selective advantage compared to those who simply carry on at the same old rate. High mood includes not just increased energy but also flares of creativity, risk taking, and eagerness to take on new initiatives. As Shakespeare put it, “There is a tide in the affairs of men, which taken at the flood, leads on to fortune.”75

  Barbara Fredrickson, a former colleague at the University of Michigan, proposed that the benefits of high mood come from tendencies to “broaden and build.” Her experiments, and those of others who followed her lead, demonstrate that high mood creates a more expansive view of the world and a greater likelihood of taking new initiatives.76 These changes are just the ticket to taking advantages of opportunities. However, framing them as functions leads to neglect of other aspects of positive mood and other subtypes that are useful in different domains. For instance, people newly in love feel spectacularly happy. They’re motivated to do anything and everything for the beloved, actions likely to pay off with a relationship and probably sex and offspring.77 Similarly, in the world of status competition, being newly appointed to a high position is exhilarating, motivating new initiatives and alliances likely to have grand payoffs. It is good to take advantage of such opportunities early, before competition from others grows.

  A Model

  Physiologists investigate what organs are for by cutting them out and watching what goes wrong. Take out the thyroid gland, and the resulting hypothyroidism reveals what thyroid hormone is good for. But there is no way to excise mood. Research on people who do not experience much emotion (alexithymia) is relevant, but it is unclear if people with alexithymia really lack emotional responses or if they suppress awareness of emotions.78

  I created a simple computer model to see if a tendency to variable mood would be a better strategy than just carrying on without mood variations. It opened my eyes to things I had not imagined. The model is a game in which three different strategies compete by making different amounts of investment on each of 100 moves. Each starts with 100 resource units.

  The “Moodless” strategy invests 10 units each time. The “Moderate” strategy invests 10 percent of its resources on each turn. The “Moody” strategy invests 15 percent of its resources if the previous move gave a payoff and 5 percent if it gave a loss. The payoff for each move is based on a combination of a random number and the payoff on the previous move, so there is some predictability. The average payoff is 1 percent, but on any move the entire investment could be lost or as much as doubled.

  It is great fun watching the game run. One click sets off 100 moves, and four lines crawl across the computer screen, one for each of the three strategies and one to indicate the payoffs at each move. Every run of the game turns out different thanks to tiny variations in the random factors.

  Four Runs of the Mood Model

  Four runs of the mood model illustrate how chance variations in payoffs result in vastly different outcomes for the three strategies: Moody (dotted), Moderate (dashed), and Moodless (solid). The thin line at the bottom indicates how payoffs vary at each different move in the game.

  What strategy wins? It depends on the environment. Usually all three strategies come out about the same. When payoffs are moderately predictable, Moody tends to win because it takes advantage of good times and avoids risk in bad times. As payoffs become less predictable, however, the Moody strategy does worse and worse because it often risks a lot and loses a lot.

  Other outcomes were unexpected, just what you hope for from a computer model. The illustration shows the results of running the game four times with identical formulas and starting values. Like the famous hypothetical example of a butterfly flapping its wings in Brazil setting off a hurricane in Florida,79 slight variations in the random numbers result in wildly different outcomes. Usually all three strategies give similar results. Sometimes no strategy does very well. When there is a big winner or loser, however, it is usually Moody.

  The results from this simple model may help to explain why mood regulation mechanisms vary so much from individual to individual. Minor environmental perturbations can result in drastically different payoffs for different mood regulation mechanisms, even when everything else stays the same. No one system reliably wins; much depends on chance.

  When he was a graduate student in my laboratory, Eric Jackson took this much further. He programmed a computer to do 10,000 runs of the game to find out how much mood variability is best. His main conclusion is simple: when rewards vary widely and are somewhat predictable, the optimal strategy is to vary your investments substantially depending on recent payoffs—that is, use the Moody strategy. When rewards are unpredictable, however, more stable strategies win and the Moody strategy goes extinct quickly.

  Psychologists Knew It All Along

  The idea that mood tracks propitiousness was inspired by my studies of animal foraging, but it is not new. Psychologist friends pointed me to many articles that described the phenomenon in detail. Eric Klinger, a University of Minnesota psychologist, laid out the central ideas especially clearly in 1975.80 When people are making progress toward their main life goals, they feel fine. Obstacles provoke frustration, often observed as anger and aggression. Inability to make progress toward a goal causes demoralization and temporary withdrawal. Prolonged failure of a strategy leads to more severe demoralization and attempts to find alternatives. When extended efforts fail to find a new route to the goal, intense low mood disengages motivation from the goal. When the unreachable goal is truly given up, low mood is replaced by temporary sadness aroused by the loss, and the person moves on to pursue other more reachable goals. Sometimes, however, the goal is something the person cannot give up, such as finding a job or a partner or a cure for a fatal condition. In such a situation, people can get trapped pursuing an unreachable goal, and ordinary low mood escalates into severe depression. Every clinician should read Klinger’s work.

  Others have extended these ideas and studied related phenomena. The German psychologist Jutta Heckhausen, now in California, studied a group of childless middle-aged women who were still hoping to have a baby. As they approached menopause, their emotional distress became more and more intense. But after menopause those who gave up their hope for pregnancy lost their depression symptoms.81 The irony is deep: hope is often at the root of depression.

  The Canadian psychologist Carsten Wrosch followed up with related studies on parents trying to get help for their children with cancer. The parents who were most set on their goals were more prone to depression.82 Those with a greater ability to shift or give up their goals tended to experience less depression.83

  American psychologists Charles Carver and Michael Scheier conducted a series of studies about how the exigencies of goal pursuit influence mood.84 They found that mood is influenced most not by success or failure but by rate of progress toward a goal.85 Faster-than-expected progress bumps mood up, slower-than-expected progress pushes mood down. This is not as obvious as it might seem. Many people think that mood reflects what a person has. This is an illusion, as illustrated by the many rich, healthy, admired people who are nonetheless despondent. People strive to get things, expecting happiness, but it doesn’t work for long. Mood is only modestly influenced by what a person has and only briefly influenced by success or failure. Baseline mood is remarkably stable for most people, and variations reflect mainly the rate of progress toward a goal.86,87

  Bad Situations, Low Motivation, and Feeling Bad

  When progress toward a major life goal is slowing or stopped, low mood symptoms disengage motivation and induce waiting and considering alternative strategies; then, if no alternative seems viable, giving up on a goal. But is low motivation really the best response in such situations? It avoids wasting energy on fruitless efforts, but if
a life strategy is failing, why mope alone in your room? Risk taking and enthusiasm would seem more likely to lead to a successful new strategy. Why don’t life’s reverses shift cognition to an optimistic view of self, the world, and the future to energize a shift to a more useful project?

  Sometimes they do. Some people come home after losing a job and quickly realize they have been freed from what would have been decades of drudgery. After a divorce, initial despair is often followed by realizing that better relationships are possible. Even giving up on a failing scientific research project can be exhilarating if it opens new opportunities to conduct more interesting studies. Lines from Tony Hoagland’s poem “Disappointment” capture the moment when “he didn’t get the job,— / or her father died before she told him / that one, most important thing— / and everything got still. . . . You don’t have to pursue anything ever again / It’s over / You’re free.”88

  Many benefits of an optimistic view of life are obvious, such as avoiding depression and its associated health risks.89 Compared to pessimists, optimists are half as likely to die of a heart attack.90 Their rose-colored glasses make optimists persist happily without the hesitations that plague others. This can, however, lead to the “Concorde Effect,” the mistake of continuing to sink effort into a hopeless cause. If you walked for hours to get to a hunting place and no game animals show up in the first hour, it is probably worth staying longer but not for days. Making good decisions about when to move on is crucial. Persistence and optimism pay off for most life projects. The costs of finding a new job or partner are huge. Usually it is better just to carry on despite problems, oblivious to possible alternatives, with hopes that things will eventually get better. They usually do.