The Social Navigation Hypothesis of Unipolar Depression:
An Evolutionary Adaptationist Analysis of Low Mood,
with Major Practical Implications for Successful Long-Term Treatment.
What if depression, even major clinical depression, is an important evolutionary adaptation designed to serve an important function in human social life? Shouldn't that possibility be tested before we just try to turn depression off, which medical science will get better and better at doing in the next several decades via combinations of improved drugs, genetic manipulations, and talking therapies that do nothing to address the potential function of depression and thus confer none its possible benefits? We'll never know the potential costs of eradicating depression, or more proximately, why current therapies are so ineffective, until we test adaptationist hypotheses. Guess what? We've got one to test!
Here, minor and major depression are explained as a unified, contingently escalating, evolved adaptation for overcoming severe chronic constraints on socioeconomic activity imposed by the individual's social network. The purpose of this site is to promote understanding, principled criticism, and empirical testing of the social navigation model of unipolar depression, also referred to as the "niche change" or "bargaining" model.
In short, major and minor depression, the entire intensity spectrum of depression, is proposed to represent a contingently escalating unitary adaptation to help people overcome highly maladaptive constraints on their status or socioeconomic activity that are stubbornly imposed by their social network.
Dr. Paul J. Watson
Department of Biology, University of New Mexico, Albuquerque, NM, USA
Papers, manuscripts, and
interview, available online:
ALERT: Here is a link to an outstanding paper on the evolution of depression by Drs. Paul W. Andrews and Andy Thomson published in the July 2009 issue of Psychological Review entitled,
"The bright side of being blue:
Depression as an adaptation for analyzing complex problems."
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.
You can hear me in a June 2018 discussion about this theory of depression on Dr. Joe Alcock's excellent wide-ranging Evolutionary Medicine Podcast, specifically podcasts #27 and 28.
E.H, Watson, P.J, & Thomson, J.A. Love’s labour’s lost:
Depression as an evolutionary adaptation to obtain help from those with whom
one is in conflict. In prep. resubmission; rejected without review by The
Journal of the American Medical Association, The Lancet, The New England
Journal of Medicine...
Evolution of Depression - Does It Have A Role? April 3, 2004. All in the
Mind, by Natasha Mitchell, Radio National. Guests: Edward H. Hagen, Paul J. Watson, and Daniel Nettle.
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.
here for Nova Science Publishers book description and how to purchase
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.
Summary of the Social Navigation Hypothesis of
Complex Contractual Reciprocity: The Matrix Has Us - Understanding unipolar depression, I suggest depends upon understanding the pan-cultural foundations of human sociality. Humans absolutely depend on diverse social exchange contracts for their survival and reproduction. A principal feature of human sociality is that
individuals become deeply embedded in a complex matrix of socioeconomic
exchange contracts. This contractual matrix is the basis for the many
relationships that are the source of all essential goods and services a person
needs to achieve virtually any fitness-related goal. But, this same complex interactive support system entails myriad obligations and
expectations. Thus, it easily can become a kind of socioeconomic
prison. On occasion, it may keep an individual tied to a societal niche that, for them, has become obsolete and costly compared to alternative niches that
the person could come to occupy, given a properly revised regime of social support.
Our conceptual model of depression, the
“Social Navigation Hypothesis” (SNH) is based on an appreciation of
the great seriousness of the fitness dilemma outlined above and the ease with which
it can arise. A capacity/opportunity mismatch can develop as a consequence of
many major negative life events such as the loss of a valued, socioeconomically
important partner or reduced physical or mental capacity. Ironically, a mismatch can stem just as easily from certain
positive life events, such coming up with a creative and potentially lucrative idea,
or becoming pregnant, under stubbornly restrictive social conditions that block the person from actually
profiting from that event.
Development of the SNH as an explanation of how unipolar
depression may address such a personal capacity/opportunity mismatch flows from a “reverse
engineering” analysis of the widely-accepted core symptoms of depression
- anhedonia and psychomotor perturbation - as well as several of its main risk
factors. Reverse engineering of is an important technique for generating functionalist or
adaptationist hypotheses in evolutionary biology. It involves inferring the
function (adaptive significance) of a trait from an understanding of its design and the structure of
potentially relevant reproductive problems faced by the organism in its natural
environment during its evolutionary history.
Assessing and Renegotiating Social
Contracts - According to the SNH, the
overall function of depression is the sober analysis and eradication of a severe socially
imposed mismatch between the depressive's
current or incipient capacities for fitness-enhancing socioeconomic activities
versus their socially sanctioned opportunities. Put more simply, the SNH
proposes that depression is a potentially adaptive response to a special social
cause of goal frustration. The SNH predicts that major
depression, in which symptoms become so intense that they cause involuntary
reduction of self-care and socioeconomic performance, should arise when the
constraints that are the cause of the mismatch have a broad multi-partner
basis in the individual's social network. In other words, the SNH posits that the main evolved trigger for depression
consists of the individual being faced with the task of simultaneously overcoming the resistance of
many social partners to helping him or her realize important practical (fitness-enhancing) goals that would
alleviate a particularly onerous capacity/opportunity mismatch.
So, the SNH argues that major depression evolved to
deal with a specific, extraordinarily difficult goal frustration context.
Fitness-reducing goal frustration is central to the social navigation
hypothesis. Under the SNH, major depression is designed for situations in which
there is a goal, importantly related to fitness, that the depressive is
chronically blocked from attaining, or maybe even adequately investigating, by
a stubborn and diffuse, non-point source of social constraint. This is a special context in which many
well-established, complexly interacting social contracts need to be revised all
at once, in a coordinated manner, to clear a new more lucrative socioeconomic niche.
The SNH contra-indicates depression as a general
response to goal frustration, even if it is severe. Instead, it predicts
depression primarily when overcoming goal frustrating situations requires that
the person change many resistant minds at once, that is, when goal frustration
is due to the mismatched individual being stuck with status quo fitness-pursuits as a result
being embedded in a contractual matrix that is, directly or indirectly,
co-enforced by many if not all of their social partners, often including
intimate friends and loving kin.
The SNH also mainly predicts depression when
the restrictive social partners are estimated to have a high degree of dependence on the goal-frustrated or mismatched individual,
such that the depressed individual's extortionary leverage is high (see below). Also, the SNH does not predict a
consistent relationship between negative life events and depression. People,
like any good organism, should be designed by selection to spring back from
most negative events, and to not only accept or accommodate most bad
situations, but be motivated to make the best of them. So, the kind of social
conflict specified above should be the key predictor of depression –
costly social conflicts that necessitate complex negotiation and honest
signaling of a need for help, and especially conflicts that call for imposing
attitude and behavior changing (motivating) costs on many social partners, so as to eventually change their original
unfavorable cost-benefit analysis of helping. Overall, the idea is to foster sober incisive social analysis (perhaps
this is the main emphasis in relatively covert forms of minor depression), issue an honest signal of need, and to
imposed escalating costs on dependent social partenrs, via self-harm,
until a tipping point is reached at which their cost-benefit analysis of helping becomes positive.
Dual Involuntary Elements: Honest Signaling
of Need and Fitness Extortion - In the special social
context outlined above, it may make adaptive sense to use the across-the-board
emotional and physical debilitation of major depression to send a strong convincing honest signal of need,
while simultaneously broadcasting an
extortionary force amongst all dependent social partners. The genuinely involuntary nature
of the entire phenomenon of major depression helps make the extortionary element non-antagonistic,
and thus minimizes social partner anger and retaliation.
Depression’s costly symptoms can serve as an
honest, involuntarily generated signal of need. Here, depression’s
disabling symptoms function to impose costs on the depressed individual, costs
that only can be recovered if long-term fitness is truly significantly enhanced
by the help consciously or unconsciously being sought. Some social partners may
be moved to help by this honest signal of need: those who are willing to invest
in the signaler, either in conventional (previously contracted) or
novel ways, as long as they have a high degree of assurance that such help
really will increase the recipient’s fitness enough to make the work,
risk, and sacrifice involved with helping worthwhile.
However, other social partners may exist, who also
are key to redressing the depressive’s capacity/opportunity mismatch, who do not see it being in their interest to help even when they perceive
a highly credible signal of need. Instead, they see themselves, perhaps
unconsciously, as benefiting more by keeping the depressive in their current
social niche; these social partners may use a variety of subtle means to
attempt to enforce the mismatched individual's status, niche, and means of livelihood. The SNH posits that depression helps deal with this second, more
problematic group via its extortionary aspect.
A key inevitable consequence, and possibly the most
important adaptive function of major depression, is that the many personal
costs suffered by the depressive via psychomotor disturbance and anhedonia
automatically inflict costs on all of the depressive's close and dependent social partners,
that is, the depressive's "positive fitness correlates." Thus, when
the subconscious mental mechanisms that modulate major depression in response
to social variables and assessment of the severity and cause of the capacity/opportunity mismatch are activated, they cause the depressive to engage in
involuntary, unintentional, and potentially wholly unconscious "fitness
The extortionary element is central to major depression's adaptive
function and the principal evolutionary explanation of major depression's
potentially extreme costliness. We postulate that because the depressive's own
costs necessarily are broadcast to all social partners in direct proportion
to the positive fitness correlation between the depressive and each partner,
depression is specifically designed to deal efficiently with constraints on
fitness enhancing activity that arise from a broad, “non-point”
source in the depressive's social network. Under the SNH a major fitness-enhancing revision in the
person’s social niche is usually needed to address their mismatch. The
disabilities and costs of depression make more economic sense when many of the positive
fitness correlates who are impacted by them are all relevant to helping the
depressive overcome their fitness-reducing capacity/opportunity mismatch;
depression is an especially efficient means of overcoming a mismatch that
requires the re-writing of many social exchange contracts. This is not to say
that depression will never occur in association with problems in the subject's
life having a "point source," that is, one or a few exceptionally powerful social partners who are mainly responsible for the
problematic constraints. However, more often than not, we predict the
solution to dealing with a specific point source of constraint will be rooted
in the "non-point source," that is, a general unwillingness amongst
many of the depressive's social partners to help the depressive effectively
deal with the more blatant point source.
Extortionary pressure on
social partners, even loving ones, often may be required specifically in the
niche change context, because when inter-individual socioeconomic contracts
are in flux, which is the case whenever a person pursues a substantive niche
revision, it will be especially difficult for positive fitness correlates of
the depressive to estimate their payoffs for helping. Moreover, insofar as
there is uncertainty or pessimism regarding the expected direct and indirect
costs of helping the depressive in meaningful ways, or the long term benefits
expected from anticipated post-niche-revision contracts, most social partners will be conservatively biased toward maintaining
their status quo contracts with the depressive, and thus perpetuating the
depressive's capacity/opportunity mismatch.
One reason for a highly
conservative reluctance to help in the specified niche change context, is that
since the needed niche revision threatens to impact many relationships (many different contracts), each
person in the social network who helps has to worry about how a successful
niche change would impact not just the niche changer, but many other people
whom they share as social partners. In other words, every potential helper has to consider complicated indirect costs
to themselves that could follow from helping the depressive make big changes in their socioeconomic life that
make third parties unhappy. The SNH states that major depression's
gradually escalating fitness extortion functions to gradually lower the fitness
of social partners enough to move them across a fitness threshold, a tipping point,
quantitatively unique to each dyad, where their expected net benefits of
helping finally outweigh the costs they incur as a consequence of the depressive's inability to
By design then, major depression gradually renders
the person incapable of fulfilling their normal social and economic roles in
their community. Major depression's core symptoms reduce a person’s
ability to care for them self and others via (1) anhedonia, a generalized lack
of motivation and pleasure, and (2) psychomotor perturbation. The latter may
involve either fatigue and reduced mobility, or a level of agitation and
irritability that makes ordered productive motor activity very difficult. These
subjectively horrible symptoms have largely been the basis for labeling
depression as maladaptive and pathological. The SNH suggests that this
conclusion is very premature and needs rethinking. Like physical pain, psychological
pain is not necessarily maladaptive. Moreover, just because a trait has heavy
overt costs does not disqualify it as an evolutionary adaptation if, at least in the
ancestral evolutionary environment, on average, it conferred fitness benefits.
Under the SNH, the two above-mentioned synergistically disabling and costly
symptoms of depression are exactly what give it social problem-solving power.
Suicidality - Depressed individuals are at increased risk of actual and attmpted suicide.
How could such behavior ever be evolutionarily adaptive, as the SNH implies? The SNH sees explicit
suicidality and parasuicidality (i.e. suicide attempts really not intended to cause death) as just a
different, possibly more attention-arresting version of the generally reduced levels
of self-care imposed by major depression. In other words, the SNH proposes that it was parasuicidal
any time a person living in the stone-age environment in which human depression evolved neglected a good
chance to take care of his socioeconomic contracts with others, or to directly take care of himself by
tending to shelter, food stores, hygiene, etc. Thus, like all these other costly lapses, explicit
suicidality potentially serves as an honest signal of need and a means to compel social partners to
consider how they might help the depressed individual improve their life circumstances. (See also Posting #2, from 7-19-2008, below.)
Minor Depression - The SNH proposes logically related functional roles for
minor and major depression. We operationally define minor depression as a level of depression in which the symptoms can be
intentionally hidden from social partners. However, the pain and discomfort of
minor depression, as well as its ability to reduce the afflicted
individual’s ability to escape thoughts concerning fitness-reducing
problems by doing normally pleasant activities (parties, sports, reading,
movies, etc.) helps make depression a state in which cognitive and emotional
resources are strongly dedicated to problem-solving analysis and negotiation.
Under the SNH, minor depression optimizes emotionality and cognition for (1)
identifying and analyzing possible mismatch-causing factors within the
individual's socioeconomic network and (2) planning active negotiating tactics
to ameliorate fitness-hindering constraints. Under our hypothesis, major
depression only ensues facultatively if active tactics of negotiation or coercion
fail to yield the kinds of investments and concessions from partners required
for niche change, that is, for substantive revision of the person’s socioeconomic
or political position. Follow Dr. Paul W. Andrews' continuing work on depressive rumination for more on the
possible social problem analysis function of depression.
Some work on people in a depressed state indicates that their analytical abilities
are reduced, not enhanced. This seems to contradict the SNH. Here, however, is a good example
of how the SNH suggests new research paradigms in the study of depression. The SNH proposes that
depression forces the indivdiual to focus analytical resources on the fitness-reducing social problem
that is causing a major capacity/opportunity mismatch in their lives. It functions to reduce their
freedom of attention and their ability to escape from ruminating on this pivotal issue. It makes the
usual pleasures of the current social niche, which may serve to keep them maladaptively stuck there,
inaccessible. And it makes novel pleasures unattractive as well, again, to make avoidance
of the fitness-reducing problem difficult. The SNH predicts that, by design, people in the midst
of depression will indeed be less able to solve the kind of standardized arbitrary problems and
puzzles typically presented to subjects in traditional psychiatric lab studies.
Therefore, an investigator who wishes to look at
the analytical abilities of depressives needs to challenge them with tasks that clearly
represent some aspect of the specific social problem(s) or capacity/opportunity mismatch that caused their depression in the first place.
The SNH and Anti-Depressant Medications – Whether or not depression is an evolutionary adaptation does matter - its has
major implications for how it can, and perhaps how it should be treated. The SNH suggests that conceptualizing
unipolar depression strictly in traditional medical terms, that is by simply
pathologizing it, typically fails to serve its victims well. A pharmaceutically
centered approach often may be severely misguided. Talking therapies that
skillfully attempt to convince the depressive that his or her thoughts and
emotional states are irrational or unwarranted may also be lacking. The SNH perspective on
depression may help explain why it is increasingly epidemic in modern western
populations in spite of the fact that these populations are virtually awash in modern
anti-depressive medication (such as the many SSRI’s) and
cognitive-behavioral oriented psychotherapies. The SNH also helps us see that
part of the depression epidemic may be attributable to the extreme dynamism,
myriad opportunities, and onerous socioeconomic insecurities of modern social
life, which generate high rates of capacity/opportunity mismatching.
The diminished and less durable positive fitness
correlations common to many modern societies may have led to more frequent
extreme escalations of major depression than in the ancient evolutionary
environments, as well as reduced overall effectiveness of depression as an
adaptation. If therapists are aware of this, the SNH predicts that they may
alleviate depression, when warranted, by helping the person see more clearly
that they lack the leverage needed to elicit help from social partners via a
depressive strategy. In such a case the therapist may be especially well
situated to help start or re-start a more conventional active negotiating
strategy to ameliorate fitness-reducing social constraints.
Nevertheless, these mismatches and their causes
beg to be addressed with specificity in therapy. The SNH does not altogether
condemn the use of medications, but it does predict that depression will be far
more responsive in the long run to in-depth, thoughtful,
evolutionarily-informed, individually-tailored social problem solving therapy.
More specifically, the SNH would indicate
talking therapies specifically aimed at identifying personal mismatches in
capacities versus opportunities for fitness-enhancing socioeconomic activities,
plausibly caused by constraints imposed by the depressed person’s social
network. Once specific hypotheses are generated concerning mismatches and their
social cause (a process that may already be of therapeutic value), the talking
intervention should move quickly to developing and implementing practical and
efficient strategies for overcoming the constraints. Medications should be used
in a way that makes this process feasible and reasonably safe, but not unnecessary.
Additional Reading - Besides the Watson & Andrews JAD
72: 1-14 article on the social navigation hypothesis of depression, there
are important related contributions to the evolutionary analysis of unipolar depression
developed independently by my brilliant colleague, Dr. Edward H. Hagen: (1) The
functions of postpartum depression , (2) The
bargaining model of depression.
Dr. Paul W. Andrews continues to perform research on depression
as an adaptation to enhance complex problem-solving ability and garner enhanced investment from
social partners. One recent paper of his, published in the journal Human Nature (Summer 2006),
examines the possible role of adolescent suicidality in leveraging increased investment from parents.
Parent-offspring conflict and cost-benefit analysis in adolescent suicidal behavior.
Dr. Daniel Nettle published a critique of the Social
Navigation Hypothesis in the Journal of Affective Disorders (August 2004), entitled, Evolutionary
origins of depression: a review and reformulation.
have written two responses to Nettle’s article:
E.H. and Thomson, J.A. Social navigation hypothesis of depression revisited. Journal of Affective Disorders 83,
P.J. Submitted, rejected without review,
Journal of Affective Disorders.
LINKS TO NEW POSTINGS:
I welcome comments and discussion concerning the Social Navigation and Bargaining Hypotheses of Depression,
and related or competing theories. I have begun posting comments sparked by correspondence, as well as items in the news. See links to my new postings, below.
Posting #2 (07/19/2008): Remarks on Suicide Prevention based on the SNH and Scott Anderson's 6 July 2008 NYT Magazine article, The Urge to End It All.
I am a member of the
University of New Mexico Biology Department’s “Research
Faculty.” My salary and research funds depend on
grants and private donations. The former are hard to come by. Evolutionary
psychology in general is very poorly represented on National Institutes of
Health grant review panels. Chances for funding are even worse when one's core ideas challenge the medical and corporate pharmaceutical mainstream, as does the SNH. By the way, this is one reason why evolutionary psychological hypotheses to do with mental health, regardless
of how compelling they may be on theoretical grounds, so often lack empirical support, as is often pointed out by critics of hypotheses like the SNH.
If you find these ideas
of value, consider making a donation to my researh progrm via Paypal, using the magic
button above. No amount is too small, really, so if you want to sample the inner glow of being a micro-philanthropist, by all means go for it!
Thank you for helping to make my social niche viable.
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This page was last revised on 5 December 2018.