Deeper Evolutionary Analyses Are Available, March 6, 2014
3.0 out of 5 stars
By 
Paul J. Watson (University of New Mexico, Biology Department, Albuquerque, New Mexico, USA)
(REAL NAME)   
Verified Purchase
This review is from: The Depths: The Evolutionary Origins of the Depression Epidemic (Hardcover)
I will be gradually adding to this review. My latest addition to the original is submitted the evening of 4/16/14... scroll down, their beginning points are easy to find. I added a paragraph to this original version 4/26/14 (paragraph 3).

Let me begin by saying that any book is to be warmly welcomed that offers an evolutionarily-informed analysis of depression as an alternative to the standard and almost criminally unimaginative medical model that posits unmitigated pathology. I can say with confidence, as an evolutionary biologist who has published on depression, that there is substance here. Yea!! So, read and consider "The Depths," but do not think that this is as good as it gets... "The Depths" largely remains in the shallows.

Several potentially important works by multiple evolutionary psychologists concerning the potential adaptive function of depression in human social life have been skirted by Rottenberg. Actually, that's an understatement.

As the author correctly states, theories don't prove anything; that may be his justification for not feeling a need to present them comprehensively. (So ironic, because the author genuinely seems to want to foster a brain-storming session around the evolved functional significance of depression.) The author seems to have a terrible under-appreciation of theory, because it is theory that guides development of actual studies that, in turn, DO provide substantive evidence for or against alternative understandings of what's going on in the world, including the world of human moods.

Let me be more specific. Most adaptations are expressed conditionally, contingently. When they are expressed, their specific triggering circumstances, is part of their functional design, which is a true hallmark of an adaptation. Without a specific theory (or, better, alternative specific theories) about the function of unipolar depression, which Rottenberg seems to wish to avoid, it will be impossible to predict specific conditions under which we expect it to be triggered, to escalate, and to go away. Rottenberg's eclectic multi-function orientation leaves us empirically handicapped. This would not be so bad, except that there ARE specific theories about the function of depression, solidly reasoned and evolutionary ones, waiting to be tested, about which he does not tell the reader.

Theories not only guide research, they also may influence how a depressed person interacts with their therapist. Here theory has an immediate effect. There is a lot at stake! Without full detailed knowledge of potentially key correct theories, which can be subtle and complex (after all, the human mind and human social life are staggeringly complex), both research and critical therapeutic interactions may not advance efficiently or effectively. Also, by ignoring obviously relevant prior works, potentially therapeutic chances simply of understanding of one's own psychological condition will not be maximized.

Note that humans are obligate social creatures that depend, cross-culturally, upon "contractual reciprocity" for survival and reproduction. Thus we all build a social network around us that helps us solve most of our fitness-related problems. This contractual matrix sustains us, but it can also trap us... this basic problem must have been very common throughout much of human and perhaps even proto-human evolutionary history.

The social navigation hypothesis (and closely related bargaining hypothesis) suggests that people who would benefit hugely from a major change in their socioeconomic niche, but who are hindered from doing so by multiple members of their social network (including friends and mates), many of whom prefer to maintain status quo relationships, may become depressed after standard strategies of negotiation fail. In such cases, the depression (1) may enhance and focus ruminations about how to gain concessions and support, (2) send costly/honest signals of need to social partners that move them to cooperate, and (3) "extort" (without conscious intent) positive fitness correlates in the social network who are non-responsive to honest signals of need by withholding the status quo goods and services called for by current contractual relationships. Escalating, and essentially para-suicidal psycho-motor perturbation (e.g., fatigue) and anhedonia (which kills motivation to accomplish basic tasks), and the resulting inability to care for self and fulfill status quo obligations to others may eventually get crucial social partners to support niche change.

Many of the features of major depression that "The Depths" portrays as probably being too costly to be evolutionarily adaptive are well explained by the above-mentioned family of theories. For more information, easily find my web page on the evolution of unipolar depression by Googling: watson evolution depression. Some of the foundational references available for download on my page are:

Watson, P.J & Andrews, P.W. 2002. Toward a revised evolutionary adaptationist analysis of depression: The social navigation hypothesis. Journal of Affective Disorders 72, 1-14.

Hagen, E.H. 2002. Depression as bargaining: the case postpartum. Evolution and Human Behavior 23, 323-336.

Hagen, E.H. 2003. The bargaining model of depression. In: Genetic and Cultural Evolution of Cooperation, Peter Hammerstein, editor. Chapter 6, pp. 95-123. The MIT Press.

Cline-Brown, K., and Watson, P.J. 2005. Investigating major depressive disorder from an evolutionary adaptationist perspective: fitness hindrances and the social navigation hypothesis. In: Focus on Depression Research, Jeremy T. Devito, editor. Nova Science Publishers, Inc.

Hagen, E.H., Watson, P.J., and Hammerstein, P. 2008. Gestures of despair and hope: A view on deliberate self-harm from economics and evolutionary biology. Biological Theory 3(2), 123-138.

HERE IS THE 4-10-2014 ADDITION:
Today's appended remarks (entered 4-10-2014) were stimulated by material beginning on book page 27, Kindle Location 414. The issue that arises here, which at first may seem very picky, technical, and inconsequential, IMO utterly thwarts and poisons the book's whole laudable project of elucidating a potential evolutionary adaptive function of unipolar depression, understanding of which would, thank goodness, allow a significantly improved approach to professional treatment and, maybe even more important, more enlightened opportunities for friends and relatives to respond to depression.

Rottenberg states that he thinks that a hallmark of evolutionary adaptations is that they have multiple utilities' and that depression is no exception. This is wrong. Moreover thinking that this is what adaptations are like leads to a hopeless analytic morass if you're trying to get a handle on the evolved function of any trait that might be an adaptation.

George C. Williams, wrote a little bombshell of a book entitled "Adaptation and Natural Selection" (1966) that was crucial in kindling the so-called "second Darwinian revolution" of the 1960's and 70's. William's book was (is) so important because it finally helped naturalists and organismal biologists / ecologists, not just quantitative geneticists, fully understand Darwin's theory and its implications. (See William's obituary in Nature 467, 790; the 14 Oct 2010 issue - everyone interested in evolution, including laypeople, should know of him. If you cannot get to it, I'll email it to you on request.)

Anyway, one of the great services William's provided in A&NS was to elucidate how to identify any organismal feature as an evolutionary adaptation. He gave three essential criteria, namely, that in relation to the reproductive problem it is hypothesized to have evolved to solve, and in the evolutionary ecological context in which the trait arose, a putative adaptation must be strikingly (1) effective, (2) efficient, and (3) SPECIFIC in its functional design. (Adaptations might also reasonably be expected to be fitness-enhancing, on average. However, while it is worth checking for specific hypothesized fitness effects that correspond to a trait's putative evolved function, positive fitness effects may be very context specific, sporadic, or small. Thus negative results may not tell you much. It's the multi-investigator, peer-reviewed, reverse engineering analysis that Williams demands that, in spite of its subjective aspects (how specific??!) that is the only way to nail whether you've really nailed an adaptation. Comparative studies can also help identify adaptations, but there is no space here for that. Comparative studies are probably not too useful in the case of human depression anyway, as if is likely to have a highly altered function in humans than it has in mice, and even in other primates. Human social systems are unique in crucial respects and human depression has evolved, I propose, to solve a uniquely human problem - especially major depression.)

So for example, the human brain is not an adaptation. To some readers this may sound weird. But the brain actually is a reasonably well integrated, still evolving (work in progress) collection of 10's of thousands of information processing adaptations, each designed to perform a specific computational task relevant to increasing an individual human's fitness (or that of his close genetic relatives and other bona fide positive fitness correlates). There is no general problem solving device in the brain, as the social sciences tragically assumed for decades. The basic reason is that (Achtung!) there are no truly general problems in the environment. All reproductive problems have a structure to them. Selection can creates adaptations in response to a specifically structured "problem template," a specific and enduring reproductive challenge. Thus we get a close "fit" of the organism and each of its many adaptations to the environment.

The eyelid example Rottenberg gives to bolster his view is very misleading. To understand the adaptive function of traits, the organism has to be "carved at its evolutionary joints." That is, you have to separate out component adaptations properly in order to understand their function, their evolutionary history. Rottenberg does not do this in his example. He lumps multiple adaptations and calls them an eyelid. When Rottenberg talks about all the advantages of eyelids, he is really talking about a collection of adaptations that, working together, provide multiple benefits. Each of these adaptations was favored by selection to solve a specific problem related to having our type of eye. Selection, of course, favors integration of different adaptations over evolutionary time so that total fitness is maximized. This is NOT the same as a properly delineated single feature of an organism having multiple functions. The eyelids are not tears, are not eyelashes, etc.

As part of his justification for proposing that depression has multiple functions, he brings up the "obvious fact" that depression can be triggered by so many circumstances. It is worth noting, however, that every one of the listed triggers are circumstances UNITED by the strong possibility that they may bring about the need for major socioeconomic niche change in the affected person's life. Recognition that a need for niche change could arise in many ways in human social life, and the likelihood that such change would often be resisted by critical portions of the focal person's social network (i.e., recognition that a socially imposed capacity-opportunity mismatch vis-a'-vis fitnesss-enhancing activities would be a common occurrence in human life, thus selecting for an adaptation specifically designed to deal with that problem when standard depression-free negotiations with relevant social partners fail) - that is, in part, how the "niche change" hypothesis came about.

OK, so here is the thing. If you start by assuming that there are many depressions, that have many functions, you are never going to discover the likely SPECIFIC, or at least overwhelmingly dominant function of human unipolar depression, the key features of which Rottenberg correctly identifies (e.g., in his description of Matt, page 3 location 109). Consequently, your mission to really understand the trait better is bound to fail. This issue has kept evolutionary psychology at large from contributing significantly to the understanding of depression so far, and, for all its virtues, that failure continues in "The Depths." As far as I can tell, Rottenberg does not offer any kind of new sweeping compelling theory about the evolutionary function of depression in "The Depths," does he? Yes, he goes over some old ideas that are worth pondering, if you have not done so before, like depressive realism (easily explained by the SNH). But depression is massively over-designed to just sober one up about how life is treating you. None of these explanations are satisfying, are they? (Note some of the explanations offered in "The Depths" are on a "proximate" or "mechanistic," not an evolutionary "level of analysis" - more on this issue latter - if you want a brief paper on the confusion caused by mixing up levels of analysis I'll email you that too.)

We tried to avoid this multi-function error in developing the niche change hypothesis: THE FUNCTION of minor and major depression is hypothesized to be to confront and attain, if at all possible, and as an unconsciously chosen method of last resort, stubbornly socially opposed yet greatly needed niche change.

Even if am completely wrong about depression being a discreet psycho-physical adaptation with one crucial social navigation or bargaining function, we should still seriously TRY to determine if it has such a single core universal function, so that we can come up with a cogent useful Darwinian understanding and corresponding treatment, if one exists. Many people seem to resist making this effort.

I could go on and on. I've got to finish for today, friends. No doubt I'll edit this entry in upcoming days. (I'll also try to respond to questions about today's entry.) But, let's have at it. The time has come for me to begin to deliver on my promise of more specific critiques of this book. So here is the first. Further entries probably will be entered as comments by me under the main review, otherwise this thing will probably get too long.

Come and get me! Cheers -- PJW

END OF 4-10-14 ADDITION

MORE: 4-12,4-13, & 4-16 additions to this original PJW review have been added as comments to this thread, below.

Dr. Paul J. Watson
Department of Biology
University of New Mexico

 


PJ Watson remarks on "The Depths," added 4/12/2014

It may be best to first read my initial review.

On book page 3 or Kindle location 109, of "The Depths," Rottenberg provides a compelling case history of a young man, Matt, as a way to drive home the core symptoms of unipolar depression. It's done well. After the italicized story of Matt, you'll find a succinct paragraph that lists the symptoms that would inevitably lead to a diagnosis of major depression. Rottenberg goes on to wonder what could justify, from an evolutionary adaptationist perspective, the mind "purposely" coming up with such a seemingly pathological set of symptoms. I'm here to help out.

According to the social navigation hypothesis (SNH), a well published albeit controversial evolutionary explanation of unipolar depression inexplicably ignored in the book, these are the roles each symptom plays in potentially helping Matt attain a major revision of his social niche, which is the goal of unipolar depression according to the original version of the SNH (Watson & Andrews 2002). Here is the target paragraph, quoted from Rottenberg, with footnote numbers added to refer to SNH-based explanations of each symptom offered by me.
"From the perspective of formal diagnosis, there was no doubt about Matt's condition. He had multiple symptoms of clinical depression. For months he had lost interest or pleasure in things he used to enjoy (1), experienced crushing fatigue (2), shown an inability to concentrate (3), experienced dramatic changes in his sleeping habits (4), and even had periodic thoughts of death and suicide (5). These symptoms cast a pall over his freshman year and interfered with his ability to engage with his studies or appreciate the novelty of college life (6). Matt's symptoms and experiences clearly matched the official category of depression, a major depressive episode, as defined by the American Psychiatric Association's diagnostic manual."

(1) Anhedonia: As it escalates, increasingly thwarts any attempts the person might consciously strive to make to perform as expected under existing social exchange contracts. Besides helping the mind to concentrate on the "bad" fitness-limiting aspects of the individual's social life, involuntarily worsening performance in relation to status quo commitments and self-care resulting from anhedonia (a) sends a costly, honest signal of need (bee next paragraph) in an effort to persuade social partners that the need for help is serious; (b) changes the calculations of social partners initially determined to oppose niche change, despite receiving honest signals of need, by demonstrating that attempts to keep the depressed in their current social niche not only are futile but, as symptoms escalate, risk leading to loss of the depressed social partner altogether (see discussion of parasuicidality of depression below, in footnote 4).

Costly behaviors that entail various requests for investment can usually be understood as costly (or hard or impossible to fake) signals of need - a signal of need costly enough that it would be uneconomical to produce (i.e., consistently subject to negative selection pressures) at a level that exaggerates actual need. Investing individuals (signal receivers) evolve to only pay attention to signals of need that meet this criteria. An example of a costly signal that is easy to understand entails baby birds begging for food in the nest. Why should they have to beg? Because, the parents are NOT programmed to assure each individual offspring's survival or maximize its individual fitness. No, the parents are designed to maximize their own lifetime reproductive success. Therefore they unconsciously operate in such a way as to get the most lifetime reproductive benefit out of each morsel of food they provide to their brood. If their chicks are signalling honestly, the parents can distribute food and other investment in a way that meets THEIR fitness goals.

BTW, this topic is hugely fascinating, partly because we do not really expect perfect honesty to evolve in most cases, leaving room for deception and even self-deception. Honest signaling systems evolve in the context of evolutionary arms races between signalers and receivers (every human plays each role many times per day) that always have some degree of conflict-of-interest (i.e., fitness interests) between them. Signaler psychology evolves in such a way as to make receivers respond more in line with the signaler's interests, while receiver psychology evolves to defend against manipulation and even to persuade the signaler to be more perfectly truthful. There can be little doubt that even if depression partly functions as a powerful and nearly perfect honest signal of need, that interactions between depressives and their social partners will involve complex "mind-games," although neither party may be aware of this whatsoever.

How could an expert like Rottenberg write a book about the potential evolutionary function of depression without even trying to introduce his readers to honest signaling theory, which offers Darwinians profound understanding of so many costly behaviors? This is another reason for my 3-star rating. Honest signaling theory, applied both to signals of need and commitment, is a cornerstone concept in theories about sexual and social partner selection processes, as well as Darwinian sub-theories elucidating parent-offspring and in-group / out-group relations.

(2) Psychomotor perturbation: Serves a purpose complimentary to anhedonia (see above).

(3) Disruption of sleep: Like anhedonia and psychomotor change, inadequate or disturbed sleep, again, makes one unable to perform well, if at all, in relation to obligations to others contained in the matrix of one's status quo social exchange contracts.

(4) Inability to concentrate: "Lack of concentration ability" may be the result of unconscious mental mechanisms forcing the mind's limited processing power to analyze a fitness-limiting social problem, like how to attain niche change. Focused invasive ruminations on a social problem, one probably impeding major niche change, or threatening the sustainability of an existing adequate niche, would be in line with the SNH - perhaps a feeling that he does not have sufficient support in school (a good new niche?) or that he will not have good job prospects or be able to do what he really wants with his education after it is over. A process of discovery guided by socially related niche problems and fitness considerations is called for at the beginning of every intervention on behalf of a depressed person. You do not just assume they are sick. Note that fitness is a relative thing, so just because a person seems to be in a good situation KEEP IN MIND THERE IS NO SUCH THING AS GOOD ENOUGH WHEN IT COMES TO ONE'S ABILITY TO GENERATE MAXIMAL EXPECTED LIFETIME INCLUSIVE FITNESS. Yo as therapist or friend have to help the depressive identify a present or anticipated major capacity-opportunity mismatch and develop a social strategy that will solve that problem in a sustainable way.

(5) Suicidality: Any level of depression that decreases performance in the various domains of self-care make the condition essentially "parasuicidal." These costs are key to generating honest signals of need and the extortionary forces that depression, under the niche change hypothesis, uses to persuade social partners to allow and facilitate niche change. Progression to explicitly suicidal thoughts and action, mostly still parasuicidal as far as their end results are concerned (especially in our ancient evolutionary environment, where human depression was designed by natural selection, and where arguably, there were fewer easy ways to kill yourself), is a logical extension of the strategy. Explicit suicidality is meant to affect the calculations of social partners resisting your niche change who are too dull-witted or so strongly in favor of maintaining the status quo to respond favorably (helpfully) to more abstract fitness- or survival-probability reducing behaviors. Note here that a key to understanding the niche change hypothesis, particularly as applied to the extortionary aspect of major depression, is that as the probability diminishes that status quo social contracts are sustainable due to the inability of the depressed person to deliver their usual goods and services and because they might be permanently lost through death, the less economic sense it makes to try to maintain that status quo. Success of major depression in situations where key social partners do not find it in their interests to respond to costly honest signals of need depends on such holdouts concluding that having their social partner change niche and recover will be more beneficial than losing that social completely.

Back when the human capacity for depression evolved, we did not have as many easy ways to kill ourselves. Strong instincts had a chance to evolve that often kept us from using ancient ways of doing ourselves in (e.g., jumping off cliffs, walking into a pride of lion, cutting ourselves with sharp rocks). Today's high rates of successful depression-associated suicide are probably an artifact of our having such novel and easy ways to end our lives. Thus the high rates of suicide associated with depression today should not lead one to regard consideration of major depression as an adaptation unthinkable.

(6) Disengagement: When the conscious or subconscious mind at least tentatively concludes that niche change is needed, it should begin to cause the person to "detach" from their current niche. This will, in addition to the "effects of last resort" conducive to niche change listed above, prepare the person to make a move into a new and better niche should that opportunity finally arise. Under the SNH, a first priority of the therapist should be to discover what the patient's conscious and subconscious thinks of their current niche in terms relevant to long term fitness, and should not have their own outsider, intuitive, common sense judgments of its quality strongly influence the course of therapy. Circumstances that look superficially auspicious from the outside may constitute a semiconscious intrapsychic hell for the patient, one that may be well justified from a sober fitness perspective. END of 4/12/14 entry. -- Paul Watson


P.J. Watson additional comment added 4-13-2014

You might wish to read my original review and 4-12-14 comment before this one...

With welcome urgency, Rottenberg points out the "deteriorating situation" with regard to the growing prevalence of depression, despite (non-evolutionary) medical advances in treatment (book page 2, Kindle location 90). He points out that we have a "growing arsenal of psychological and drug treatments for depression." Moreover, he points out that, "Social awareness about the symptoms of depression is increasing, and more people are recognizing that it is a bona fide health condition, not a personal weakness or character flaw. Scientific research on depression, from neuroscience to cross-cultural studies, has absolutely exploded."

All true. The problem is, as Rottenberg clearly suspects, we don't have a clue what depression is really all about, a condition that full-bodied Darwinian analyses could reverse. Operating from ignorance as to the possible functional significance of depression, mental health professionals as well as the social partners of depressed people are, with varying and often transient effects, just repressing depression's symptoms, both chemically and via social interaction. The brain is designed to stubbornly address life circumstances that negatively affect fitness, so depression often returns, often perhaps more resistant to the manipulations that may have caused it to subside for a while.

The SNH or, more specifically, the niche change hypothesis of depression, offers a cogent explanation for this tragic state of affairs. It is NOT just that we have inadequate treatments for depression compared, perhaps, even to more "primitive" or traditional societies. Mainly it is due to increased instability and dynamism of socioeconomic niches in modern societies. Even if you have a great niche these days, there are a number of ways it can get pulled out from under you, thus forcing you to contemplate niche change, indeed, in many circumstances, in the face of losing everything. Or, for a younger person trying to home in on a niche, it can be like looking into an ever changing kaleidoscope. The skills and credentials one needs to thrive in society, and thus maximize expected lifetime inclusive fitness, are changing all the time at increasing rates of speed. Unlike the much more stabile and predictable socioeconomic conditions faced by young people in traditional societies, under modern conditions one's parents, adult relatives, teachers, and holy men "made it" in a world that is in many respects gone. They cannot help you as much getting the training and making the political connections needed to make it in your new world. Even the most intelligent and hip young person has more to worry about plans going wrong than thier ancestors did. Since we propose that depression is about securing a niche that matches one's capacities and opportunities for fitness-enhancing activity and gaining effective social help necessary to do so, this modern situation is naturally expected to trigger depression with increasing frequency.

Paul J. Watson

P.J. Watson, additional comment, 4-16-2014

As I go over the many notes I've made on my Kindle while reading Rottenberg, it just blows me away how many of his observations about depression, and so many of the things he puzzles over in the book, are readily explained from the perspective of the niche change / social navigation / bargaining hypothesis. Let me pick up on one matter Rottenberg brings up in "The Depths" that would lead many to conclude, naively, that depression cannot be a cognitive-emotional adaptation, that is, a mood-state designed by natural selection, for contingent expression, to solve a specific and probably very important (given its high costs) fitness-related problem in humans life.

On page 151 (Kindle location, 1966) Rottenberg expresses some surprise that positive life events do not have a stronger effect on reducing or curing depression. If you have been reading my previous entries, papers, or web site, you will probably already know why this pattern exists. Most of the positive life events that happen in a depressed person's life have nothing to do with the socioeconomic niche change that they need. Under the niche change hypothesis, depression is designed to ruthlessly keep the person's eye on the ball, overcoming the fitness-limiting socially enforced mismatch between their intrinsic capacities and socially-granted opportunities for fitness-enhancing activities. Random positive life events, under the niche change hypothesis are specifically expected to have little or no effect on depression - not unless they entail or represent a major sustainable step toward the needed patient-specific niche change.

Committing to a hypothesis about the function niche change that makes specific predictions about things like this, something Rottenberg resists (see my earlier comments) would allow some actual hypothesis testing, which is what will advance our knowledge about depression. Purely by accident, however, and therefore perhaps more sloppily than we would like, there is a paper in the positive event literature cited by Rottenberg (see page 150, loc. 1962), namely, the Brown and Harris study, that does test a prediction of the niche change hypothesis. "Fresh start events," low and behold, may represent a category of positive life events that are especially potent in mitigating depression, (Although Rottenberg does not state outright that this is so, he does single out the study. Wouldn't in be interesting to know if they are a relatively "curative" kind of positive live event?) Guess what?! A lot of these fresh start events are going to look like niche change, much more often than random positive life events. I take this observation, tentatively, as lending support to the niche change hypothesis ignored by "The Depths."

I'll end today with this, one thing that should be clear to all readers. If there really are a lot of depressions occurring out there that are non-responsive to the kinds of life changes that specific evolutionary adaptationist hypotheses of depression claim depression was designed by selection to bring about, then we can discard that adaptationist hypothesis. In other words, once we demonstrate that depression is not contingently expressed vis-`a-vis solution of the specific hypothesized reproductive problems that evolutionary analyses of the sort that lead to the niche change hypothesis predict, then we are in a position, by default, to accept the null hypothesis that depression is a pathology - but not until then. But, this will never happen until we begin testing specific hypotheses that make specific suites of predictions.

-- PJW


Non-PJW Comment

 

I am not in a position to offer a substantive critique of the evolutionary biology of depression, as I presume Dr. Watson can. Jonathan Rottenberg has accurately described the arc into deep depression with brilliance. He also offers a compelling critique of our DSM and medication saturated culture. In its place, Rottenberg offers a complex multifactorial model of depression. Most importantly, he points to a way out. His description of the slow path out of severe depression comports with the data and with my many years experience treating depression. At this point in the trail of data, from randomized trials of drugs and of evidence-based psychotherapies, we remain unable to stem the suffering of millions of people suffering from depression. The approach Rottenberg outlines integrates biological and psychological models of treatment, including newer forms of CBT and positive psychology. Last, he offers suggestions about culture change that bears reflection by all.

Dear X,

If there is only, or mostly just, a slow path out of serious depression, then that could be because we have not yet understood its function and how to treat it accordingly (see also my new paragraph 3 in original review). Depression is such an expensive condition that, if it is an adaptation, it should respond rather quickly to solution of the reproductive problem (e.g., socioeconomic niche change) that selection designed it to solve. If we cannot find crisp contingency in the expression of most genuine depressions, then it probably is just pathological. But to develop a reliable faster path out of depression, we have to pin down what it is for. That calls for a theory that offers to elegantly cut through the multifactorial swamp. Thank you for furthering the discussion with your post.

Paul Watson