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THE EVOLUTIONARY CONTEXT OF POSTNATAL DEPRESSION Mira Crouch University of New South Wales "Postnatal depression" denotes the syndrome of dysphoria, debility, and anxiety that follows childbirth in about 10-20% of women (as variously es- timated). Its etiology is seen to be lodged in a variety of psychosocial as well as biological factors, among which the isolating and pressured cul- ture of contemporary society (especially for women/mothers) is com- monly singled out as a powerful precipitator. This view is extended here through the evolutionary perspective which casts maternal distress as a set of adaptive responses with the function, in ancestral environments, of so- liciting support for a mother who feels that her maternal responsiveness may be threatened. As continuous caretaking of the infant is the active ex- pression of evolved maternal responsiveness, departures from this pattern result in anxiety and distress that seek resolution. Manifestations of ma- ternal distress in contemporary society are dysfunctional, however, since the present social structure does not provide spontaneous and immediate support that can spring forth within small, closely knit social units. Fur- thermore, for present-day mothers distress is self-perpetuating since the ingrained tendency toward continuing responsiveness rarely finds practi- cal expression and is thus converted into anxious vigilance and depres- sion. This view generates the hypothesis that the emotional and cognitive contents of maternal vigilance are associated with the needs of the infant and will therefore be focused on crying and feeding. A number of quali- tative studies of women's experiences during the postpartum bear out this prediction and support the feasibility of the evolutionary hypothesis of "postnatal depression" as a set of adaptive responses, now out of place in a novel environment. Received: April 1, 1998; accepted June 30, 1998. Address all correspondence to Mira Crouch, School of Sociology, The University of New South Wales, Sydney 2052 Australia. E-mail: [email protected] Copyright 1999by Walter de Gruyter, Inc., New York Human Nature, Vol. 10, No. 2, pp. 163--182. 1045-6767199151.00+.10 163

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Page 1: Evolutionary Context of Postnatal Depression

THE EVOLUTIONARY CONTEXT OF POSTNATAL DEPRESSION

Mira Crouch University of New South Wales

"Postnatal depression" denotes the syndrome of dysphoria, debility, and anxiety that follows childbirth in about 10-20% of women (as variously es- timated). Its etiology is seen to be lodged in a variety of psychosocial as well as biological factors, among which the isolating and pressured cul- ture of contemporary society (especially for women/mothers) is com- monly singled out as a powerful precipitator. This view is extended here through the evolutionary perspective which casts maternal distress as a set of adaptive responses with the function, in ancestral environments, of so- liciting support for a mother who feels that her maternal responsiveness may be threatened. As continuous caretaking of the infant is the active ex- pression of evolved maternal responsiveness, departures from this pattern result in anxiety and distress that seek resolution. Manifestations of ma- ternal distress in contemporary society are dysfunctional, however, since the present social structure does not provide spontaneous and immediate support that can spring forth within small, closely knit social units. Fur- thermore, for present-day mothers distress is self-perpetuating since the ingrained tendency toward continuing responsiveness rarely finds practi- cal expression and is thus converted into anxious vigilance and depres- sion. This view generates the hypothesis that the emotional and cognitive contents of maternal vigilance are associated with the needs of the infant and will therefore be focused on crying and feeding. A number of quali- tative studies of women's experiences during the postpartum bear out this prediction and support the feasibility of the evolutionary hypothesis of "postnatal depression" as a set of adaptive responses, now out of place in a novel environment.

Received: April 1, 1998; accepted June 30, 1998.

Address all correspondence to Mira Crouch, School of Sociology, The University of New South Wales, Sydney 2052 Australia. E-mail: [email protected]

Copyright 1999 by Walter de Gruyter, Inc., New York Human Nature, Vol. 10, No. 2, pp. 163--182. 1045-6767199151.00+.10

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KEY WORDS: Adaption; Emotion; Evolution; Maternal responsiveness; Postnatal depression; Stress.

Affective disorder following childbirth is generally recognized in three rel- atively distinct forms. The mildest form is a transient low mood state of short duration ("baby blues"), most commonly occurring about 5 days after labor at a prevalence of 50-70% (Howard 1993:255); arguably there- fore it is, in a statistical sense at least, "normal"--however inexplicable its symptoms may be at the subjective level. Postnatal depression can surface at any time during the postpartum year; most commonly, however, it sets in during the first three months and can take a considerable period of time to resolve, especially if untreated (Cox 1986). It is an ill-defined condition characterized variously by sadness, low self-esteem, confusion, lassitude, anxiety, and somatization, the symptoms configuring differently in differ- ent individuals (Dennerstein et al. 1986; Mills and Komblith 1992). Largely because of the absence of definitive diagnostic criteria, estimates of preva- lence vary (Dermerstein et al. 1986; Kumar 1994); commonly 10-20% has been suggested (Brockington 1987; Cox 1986). At its extreme end, postna- tal depression shades over into puerperal psychosis, the most severe and least common (0.2% [Brockington 1987; Cox 1986]) emotional disorder fol- lowing childbirth.

This paper is concerned with the implications of evolutionary theory for postnatal depression (but not including puerperal psychosis, which may be a qualitatively different state; Brockington 1987)--a condition which, because of its duration and prevalence, represents a substantial dimension of human experience overall. Indeed, it is possible to argue that postnatal depression is much more common than the (various) figures indicate, since its symptoms may often be "normalized" (in line with the general tendency for women's mental health problems to be accepted as part of life; Waiters 1993) and the condition can consequently remain unreported (Gruen 1990). This argument can also be inverted to suggest that various degrees of relatively extended dysphoria and dysfunction following child- birth are "normal" in the sense of being relatively common and that only their more extreme and protracted manifestations should be recognized as symptoms of an "illness" state. Either way, "normalization" of matemal distress postpartum is consistent with the problematic nature of postnatal depression as a diagnostic entity (e.g., Purdy and Frank 1993); this, in turn, has led some authors to redefine the syndrome more broadly as an adjust- ment disorder (e.g., Whiffen 1991) in which biological factors may also play a part, especially in serious cases (which include "postpartum panic disorder"; Mills and Kornblith 1992).

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Significantly for this discussion, the "normalization" issue also relates to the perplexing question regarding the line between predicament and dis- ease (Barnett 1994:23)----or, as Brown et al. (1985:620) put it, the point at which distress becomes (postnatal) depression. This question underlies the view of postnatal depression as mothers' "misery" (Barclay 1996) mani- fested in a continuum of emotional and biological disturbances, many of which are normal (contra "normalized") under the circumstances of the majority of mother-infant dyads in contemporary society. Barclay further holds that "postnatal depression" is often overdiagnosed, especially where objective assessment methods and clinical interview schedules are used, since these methods fail to take into account the possibility that some "symptoms" may reflect common stresses during the postpartum and that negative feelings experienced by "depressed" and "normal" women may overlap substantially (Barclay 1996:137). Cramer (1993) adds another di- mension to a broader view of postnatal depression by arguing that, in many cases, the disorder represents a mother-infant relationship disturbance brought on by the pressure of psychological tasks the baby imposes on the mother.

The varied symptomatology of postnatal depression and the lack of clarity concerning the clinical status of individuals manifesting some of its range of symptoms suggest that "postnatal depression" is an umbrella term rather than a defining one. It may therefore be ar~alytically useful to regard the broad spectrum of postnatal maternal distress manifestations as the primary category of maternal distress within which clinical "postnatal depression" may be identified (in principle, though poorly so in current practice) as a subset. In view of these considerations, the term Postnatal Stress and Depression (PNSD) is adopted here to denote the multifaceted and variable pattern of emotional and functional disturbances during the postpartum. 1 In the discussion that follows, PNSD will be used in the con- text of arguments specific to this paper, while the use of the term "postna- tal depression" will be retained where reference is made to the concept as generally employed.

From an evolutionary point of view, PNSD can be seen as an evolved adaptive response to the demands and challenges of early mothering and nursing, the psychological pain of the condition functioning just like phys- ical pain "to demand immediate attention" (Thornhill and Furlow 1998: 342). PNSD is thus a "design compromise" (Nesse and Williams 1994) within the natural selection process where the cost-benefit fitness calculus gov- erning its development becomes inappropriate under environmental pressures that have come to differ significantly from the design's long-term evolutionary de- terminants. An examination of the premises and implications of this gen- eral formulation will lead to more specific propositions regarding the na- ture and function of PNSD.

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PNSD: UNIVERSAL OR CULTURE-SPECIFIC?

The discussion so far has been couched in universal terms. Yet with any psychological disorder the question of its possible cultural specificity must be taken into account (Kleinman 1988). The relevant literature has tended to portray "postnatal depression" as a culture-bound syndrome, ascribing its manifestations in western societies to the attrition in ritual practices of reproduction that structure, socially and psychologically, the mother 's transition to parenthood in traditional societies (e.g., Harkness 1987; Homans 1982; Pilsbury 1982; Stern and Kruckman 1983). This view has been challenged by two sets of considerations arising from more recent re- search: on the one hand, it has been argued that rituals have not disap- peared, but have merely changed from magico-traditional practices to rational-medical--but still basically ritualistic--procedures (Davis-Floyd 1992) and, on the other, that in less developed and more traditionally or- ganized societies in the present, postnatal depression is not unknown and, moreover, can have the same incidence and prevalence as it has in western countries (Cox 1996; Howard 1993). The latter circumstance has been at- tributed to the dysfunctional dichotomy between modem and traditional childbearing practices that are concurrent in such societies (Steinberg 1996:1782), as well as to the various stresses associated with poverty and social factors such as the widespread oppression and low status of women (Kumar 1994).

In general, then, the cross-cultural perspective casts "postnatal depres- sion" everywhere as the result of sociocultural conditions, especially those associated with various aspects of the modernizing process. It is not clear, however, whether these conditions are seen as efficient causes or merely precipitating factors and, correspondingly, whether traditional postpar- tum practices are understood to protect women from the condition (that might otherwise occur)--or whether their presence implies that intrinsi- cally pathogenic social conditions are simply less likely to obtain.

The cross-cultural issue is important here, since this paper argues that PNSD arises out of a pattern of reactions that has developed within "the (original) environment of our evolutionary adaptiveness" (Barr 1990:357) in response to stress during the postpartum period for both mother and baby. This argument implies that postnatal maternal disorder--in the form of some culturally recognizable distress and dysfunction--will be mani- fest across the species (though not necessarily to the same degree or in the same way in all societies) as an aspect of women's behavior and experi- ence during early motherhood. 2 As already implied above, some of the lit- erature on the subject offers a degree of support for this contention; fur- thermore, those studies that may counter the universalist view still leave open the possibility that "normalized," and therefore undiagnosed/un-

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recorded, protracted dysphoric states are experienced by at least some postpartum women everywhere.

THE ADAPTIVE FUNCTION OF CHILDBIRTH RITUALS

Childbearing rituals are common in many cultures; this may have impli- cations for an evolutionary account of PNSD. If we take the view that bio- logical and cultural evolution of the human species is a unified process (Alland 1967; Crouch and Potter 1979), then such rituals can be under- stood as Dawkins-type "memes" (Dawkins 1981) that have evolved and survived long-term in most societies, being functionally advantageous as stress-reducing mechanisms. It can therefore be assumed that their evolu- tion has taken place under pressure which the vulnerabilities of the mother-infant dyad exert on the social group as a whole. The structural uniformity of such rituals across cultures strongly suggests that they meet universal, biologically grounded needs. 3 Although of variable duration and diverse cultural construction, all such prescriptive practices produce the following conditions: (1) isolation and seclusion of the mother; (2) in- tense caring for, and support of, the mother (usually by female kin); (3) be- havioral proscriptions upon the mother, leading to rest and modification of diet; and (4) suspension of mother 's social roles and protection from previous demands (See11986, quoted in Kumar 1994:252). Rest, social sup- port, and recognition of new status appear to characterize the state such practices engender in the mother; in turn, this state most probably enables her to focus on the infant to a greater degree than is generally possible under the usual circumstance of her life and to do so without anxiety and loss of self-esteem that reduced social engagement may otherwise bring about.

Evolutionary theory assumes that the prototypical human mode of ex- istence is based on intimate social interaction in small, tightly knit groups. (Arguably, this is closely linked to the extreme and extended physical de- pendence of the infant, whose needs initially are met almost exclusively by the mother.) It is possible to glean an impression of the prototypical mother-infant interaction through observations of the present-day !Kung San, whose social organization and reproductive practices approximate those of our ancestral hunter-gatherer societies (Kolata 1974). In the con- text of dense social interaction characteristic of the !Kung San, the infants have practically constant caretaker contact, exhibit continuous feeding, and enjoy "virtually universal and immediate maternal responsivity to (their) signals" (Barr 1990:364). Such a pattern has adaptive significance not only because it improves fitness from the point of view of sheer sur- vival (of the infant), but also because it contributes, through lactation, to

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appropriate birth spacing. Within this pattern, infant crying is a specific adaptive response that functions as an attempt to elicit maternal respon- siveness (especially nursing); in addition, crying may also have broader adaptive significance, since it may act as a continuous reinforcer of mater- nal responsiveness understood as a "motive disposition based on emotion as a co- ordinated system of response" (Nesse 1990:264), the evolution of this "motive disposition" being a specific product of "natural selection for high invest- ment parenting among humans" (MacDonald 1997:331).

Yet this is a precarious situation. As pointed out by Trivers (1974), par- ent and offspring are locked in a conflict of interests as each strives to max- imize her/his own (inclusive) fitness; thus at particular intersections of social context and individual propensities, a situation may develop where a mother 's investment in the infant costs her more than it gains her. A case in point is infant crying, which is, in fact, "paradoxical" (Barr 1990:356) be- cause its survival value may be negated by maladaptive reactions to it. Maternal distress is one possible reaction of this kind; indeed, there is ev- idence that arousal is positively correlated with increased pitch of an in- fant's cry (Thornhill and Furlow 1998:355--356). Distress, in turn, is likely to impede the mother's capacity to care adequately for the infant; it may also contribute to her unwillingness to care for an infant whose crying pro- vides "acoustic cues of (low) reproductive value" (in which connection Thornhill and Furlow [1998:355] note the established association between high-pitched crying and a variety of ill-health indicators). In the latter case infanticide through either neglect or intent may be the ultimate result.

Maternal distress can certainly arise for reasons other than an infant's crying. In the social and environmental context of hunter-gatherer soci- eties, general exigencies of life are perhaps more likely to represent stres- sors for the mother than infant crying, which, as Barr (1990) has pointed out, is less intense in societies where continuous caretaking of infants is the norm. In any case, regardless of the nature of its precipitating factors, ma- ternal psychological pain can at times be associated with variations in maternal solicitude that are, in all probability, outputs of motivational sys- tems honed through selection "to modulate parental effort" (Daly and Wil- son 1995:1281 ) under circumstances where parental investment in one par- ticular infant may be detrimental to inclusive fitness. At the same time, the manifest expressions of maternal distress can also have adaptive signifi- cance as they signal the mother's inability to manage adequately and thus can, especially in a "dense" social context, attract support and help for her- self and, by extension, for the infant as well. It is postulated here that man- ifest maternal distress has evolved as an adaptive response to the mother's dimin- ished capacity (for whatever reason) to care adequately for the infant. As such, it is an integral part of the coordinated system of emotions and actions that form the evolved motive disposition of maternal responsiveness.

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Cultural practices in relation to the postpartum may have their origins in this pattern. It is reasonable to suggest that such practices have devel- oped as adaptations to change in the ancestral social structure towards dif- ferentiation and complexity--relative to some hypothesized earlier, cul- turally less elaborated social organization (i.e., under the environmental circumstance of the Pleistocene savanna, hypothesized to be the milieu in which human selection has largely taken place; Lewin 1998:44; Williams and Nesse 1991:13). Yet, given the inevitable variability associated with the human genetic make-up---and within which adaptation/selection unfold in response to environmental pressures (Nesse 1990:261)--adaptive social practices in relation to childbearing cannot cancel, in every individual case, reproduction's potential for noxious effects on the psychological and physical equilibrium of the mother. 4 It can therefore be expected that post- natal maternal distress will surface though variably in both form and de- gree whatever the cultural practices of the postpartum.

THE SIGNIFICANCE OF MATERNAL DISTRESS POSTPARTUM

Maternal distress, then, is likely to emerge in the context of the mother 's in- ability to respond appropriately and consistently to her infant. Insofar as the infant's crying is perceived as a danger signal, it may constitute a pow- erful precipitating factor in the mother 's reactions of arousal, negative af- fect, and /o r withdrawal. Such reactions may serve to solicit social support in the form of greater level of care for both the mother and offspring; hy- pothetically, this is likely to be prompt, personal, and direct in dense social contexts of simple, pre-industrial societies--as well as in ancestral social environments. By contrast, delay, deliberation, and delegation to experts are the more probable strategies in western societies. Conditions for pro- longation of stress and escalation of negative affect are built into the latter pattern: in the enclosed private lives of contemporary, self-consciously and deliberately autonomous individuals, the lack of immediate and in- tensively supportive social response to the mother 's distress signals is likely to inhibit the development of useful coping strategies in the "re- appraisal phase" (in terms of the Lazarus and Folkman [1984] model) of her stress response. Anxiety-induced avoidance, then, becomes her best strat- egy, and depression, in the tangible sense of disablement, its final path.

In the light of such considerations, the condition of PNSD is not neces- sarily an abnormality, but rather an evolved defensive pattern of re- sponses to the loss of capacity for effective maternal solicitude. The inten- sity of that response can be accounted for in evolutionary terms: since the cost of not expressing a defensive response in the presence of a threat may be enormous, regulatory systems for such responses have been shaped

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through natural selection to be, in general, overactive, producing reactions that may be too quick, too intense, and too prolonged, much of the time more so than is essential (Nesse 1990:283). Such acuity and strength can lose usefulness when the environment in which the adaptive responses occur is substantially different from that in whichmand for which, adap- tively speaking--they have evolved. PNSD as a pattern of such responses may be a case in point: in a sociocultural environment that is largely eman- cipated from established traditions and within which "rational" judg- ments and action are (at least ostensibly) favored, postnatal distress re- sponses can appear to be inappropriate and disproportionate and are therefore seen to represent symptoms of an illness.

To sum up the discussion so far: PNSD is an adaptive aspect of maternal re- sponsiveness that has evolved through natural selection in a context where some environmental (including social)factors can challenge the mother's capacity to provide continuing care for the infant. In most societies, evolved cultural practices support the vulnerable mother through the provision of condi- tions for rest, help, and psychological security. Given the variability that can be assumed in respect to stress tolerance and levels of arousal (as well as in personal histories), this support may not be sufficient for some indi- viduals, who will still experience and express distress. In a closely knit and dense social context a strong emotional reaction may be an useful strategy, but in a complex social setting far removed from the conditions under which the response pattern evolved, the painful emotional state and its overt manifestations are counterproductive and compound the difficulties that have precipitated them.

MATERNAL RESPONSIVENESS: AN EVOLUTIONARY HYPOTHESIS FOR PNSD

The assumption that the mother's responsiveness to the infant is a dispo- sitional fitness-enhancing tendency lies at the root of the evolutionary un- derstanding of postnatal maternal distress as put forward in this paper. When this tendency is thwarted and the mother feels--rightly or wrongly, and for whatever reason--that the level of her care for the infant is thrown into question, psychological pain results as an adaptation to this situation, since the overt expressions of the pain have the potential to recruit social support that may help restore effective maternal responsiveness. This for- mulation constitutes an evolutionary hypothesis that attempts to account for PNSD. Since evolutionary hypotheses necessarily rest on premises con- cerning distant events, their usefulness must be evaluated in terms of pre- dictions regarding proximate mechanisms of the entities in question (Nesse and Williams 1994:7). What, then, are the proximate mechanisms that are

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relevant to PNSD---and how is their "normal" function disrupted? The distant events on which the PNSD evolutionary hypothesis is based focus on circumstances that affect the dispositional tendency of maternal re- sponsiveness; therefore the proximate mechanisms must operate in the same dispositional realm. It follows that these mechanisms are to be lo- cated in what is generally understood to be the symptomatology of "post- natal depression"--in other words, in the way in which postnatally dis- tressed and depressed women act, think, and feel.

The literature on postnatal depression does not provide many leads in this direction. The volume of publications in this field is by now enor- mous, and no attempt has been made here to survey it. For the purpose of the present discussion, issues relating to diagnosis and etiology are more important than discussions of management/treatment. In the former cat- egory, biological (especially hormonal), sociocultural, as well as predispo- sitional (constitutional and /o r biographical) factors have been identified, variously emphasized and, more often than not, understood to operate in interaction with one another. Precipitating circumstances, such as difficult delivery and illness/deformity (or prematurity) of the infant, have also been identified. (For a concise but comprehensive review of recent litera- ture on postnatal depression, see Thornhill and Furlow 1998.)

In much of this literature the functional disturbances (e.g., excessive fa- tigue, inability to feed or bathe the infant) and the mental states (sadness, anxiety, guilt, pessimistic and destructive ruminations about self and baby) are treated as symptoms of the d isorder /syndrome in other words, as indicators of an underlying, more general, disturbance. For in- stance, the negative emotional tone is often discussed in terms of, inter alia, role-conflict over motherhood for contemporary women, lack of cultural esteem for mothering functions, and social isolation. These circumstances are recognized to be "stressful" and, in combination with individual ma- ternal characteristics (e.g., age, biographical factors--such as relationship with own mother, pregnancy terminations, and other bereavements--and previous psychiatric history), are often structured into a set of "risk fac- tors." In the process of such conceptualizations, the actual experiences of "depressed" women are explained away.

Yet these very experiences constitute the "proximate mechanisms" of the adaptive response pattern that is now labeled "postnatal depression." In somewhat more detail: if the adaptive responses that constitute PNSD are predominantly dispositional, their proximate mechanisms will be pre- cisely those of feeling, emotion, perception, and motivation, and the actual ideational content of these "reactions" can therefore be expected to be de- termined by the mother 's tendency towards responsiveness to the infant, s During the early weeks and months postpartum, this responsiveness re- solves into attention to the infant's relatively simple needs for food and

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succor. The fundamental nature of these needs is the selective force that has shaped the mother 's adaptive response to it; insofar as this response is dispositional/emotional, the details of the ensuing state will correspond to their operative selective force. To put it more simply: what the mother feels and thinks should bear out the predominant role of the needs of the infant in the development of PNS D.

"CONSTANT CARETAKING" AND ITS MODERN EQUIVALENTS

Before support for this proposition can be usefully examined, it is neces- sary to consider the manner in which the distant mechanisms of maternal responsiveness are echoed in their putative proximal correlates.

Barr (1990) shows that constant caretaking and continuous feeding con- stitute the behavioral facets of maternal responsiveness to the infant and, more specifically, the infant's crying. Crying, as already pointed out, has demand features. Barr has observed that among the !Kung Sun, where constant caretaker contact with the infant ensures a continuous feeding pattern, "immediate maternal responsivity to infant signals" is invariably forthcoming (1990:364). Under such conditions crying does not occur less frequently, but its bouts are much shorter than those of infants in western societies where "constant caretaking" is not practiced. Barr therefore holds that what is thought to be "excessive crying" in western societies is, in fact, prolonged crying resulting from the physical separation of infant and care- taker (i.e., mother) and the unwillingness of western parents to be "indul- gent" with their infants' demands (Barr 1990). (Even "demand feeding" is not truly "indulgent," since it is almost always shaped by some notion of appropriate manner and timing of feeds, and even in the context of "con- stant caretaker contact" it is guided by "hunger cries," which the mother needs to learn to identify [Crouch and Manderson 1993:138].)

Of course the nurturing practices in western countries are enmeshed with the complexities of their social structure generally, just as constant caretaking among the !Kung Sun is embedded in its own dense social con- text. If it is the case that a biosocial complex of close interaction represents the environment within which the human mother-infant dyad 's behavior pattern has evolved, the affective correlates of responsiveness (oriented towards constant caretaking) have constituted an integral part of this situ- ation, the emotion contributing to the mother 's necessary vigilance and motivating her conscious activity in relation to the infant while simulta- neously signifying its importance to the community (as well as having the capacity to elicit help if necessary). In the radically altered circumstances of contemporary society, the mother 's evolved dispositional tendency to- wards responsiveness will still come into play, and her emotional re-

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sponses will still be provoked by the infant's signals--but in a social con- text where constant caretaking is, generally speaking, neither possible nor culturally valued in the absolute sense of being taken for granted. Ar- guably, then, maternal disposition (with its emotional underpinnings) is at variance with the social environment.

To expand on the above: if constant caretaking and continuous feeding represent the pattern of action/disposition for the mother-infant dyad that has become entrenched through the evolutionary process, an enforced change in this pattern will unsettle not only the infant (i.e., producing longer crying bouts) but also the mother. She may become disturbed not merely because the infant "cries too much" but a lso--and more impor- t an t ly -because her "continuous responsiveness" tendency is thwarted by the environmental and cultural conditions contemporary social life im- poses on her (more often than not in a complicated manner through both external forces and their internalized representation). On this view, regard- less of the "'objective" amount of crying and nourishment intake by the infant, the mother's emotional state and its cognitive correlates will be focused on the infant's crying and feeding; this, in turn, can result in obsessive worry, depression, anxiety, debility, sleep disturbances and the like all of which signal that "there is something wrong" and thus cry out for immediate help and sup- port, whether they are obtainable or not. 6 It follows that the major stressors during the postpartum are associated with infant crying and feeding, since these factors inevitably signal ruptures in the continuous caretaking pat- tern which selection has entrenched in the maternal responsiveness dis- position overall.

The above considerations lead to an addendum to the hypothesis that "what the mother feels and thinks should bear out the predominant role of the needs of the infant in the development of PNSD" (see above). It can now be argued, more specifically, that tf PNSD is an adaptive aspect of evolved maternal responsiveness disposition, the actual content of women's ideations and emotions postpartum can be expected to reflect specific concerns with infant crying and feeding.

SU PPORT FOR TIlE H Y P O T H E S I S

It does indeed seem to be the case that women's thoughts and feelings dur- ing the postpartum are overwhelmingly focused on the infant's crying and her/his feeding pattern (or lack thereof). The literature (often from psy- chology and nursing) on early parenting (and, sometimes, postnatal de- pression) demonstrates that infant crying and infant feeding---both sepa- rately and as an interrelated complex of variables---dominate as stressors in studies on "coping" with babies (reviewed in Terry et al. 1996). 7 The popular literature on postpartum depression also very clearly emphasizes

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the ubiquity of worries over crying and feeding (for example, Dix 1987; Welburn 1980)�9 As Barr (1990:363) has observed, crying is the most com- mon problem dealt with in the popular "baby" literature, and parents measure their parenting effectiveness by their ability to control crying. Disrupted sleep, fatigue, loss of control (relative to the generally planned and managed character of contemporary activities, even at a personal level), confusion, anxiety, and negative feelings concerning one's per- formance as a parent--all these reactions are positively correlated with parental perceptions of "excessive crying" and "feeding problems" that dominate "adjustment difficulties" during the transition to parenthood.

Most investigations of early parenting from the "coping" perspective (as well the majority of studies of postnatal depression) are generally inven- tory-based and analyzed in terms of predetermined variables and their in- teractions. Such research tends not to be concerned with emotions and the intrinsic meaning of the thoughts associated with them. There have been few qualitative studies of women's subjective experience during the post- partum, yet arguably it is only through this type of research that the men- tal and affective state of what has been called "postnatal depression" can be apprehended. Here Ann Oakley's work (1979, 1980, 1981) stands out as a methodological exemplar where the analysis of interview data is guided by a feminist sensitivity to issues of women's vulnerabilities at this time. But even Oakley has tended to accept "postnatal depression" as a given di- agnostic entity, thus permitting her analysis to slide over those manifesta- tions that can be construed as "symptoms" and to concentrate, instead, on attitudes suggesting that "postnatal depression" is a reaction to the loss of a more autonomous pre-motherhood self and way of life (Oakley 1980)�9

Following Oakley's general approach but cast in a more eclectic theoret- ical framework, a study of 92 first-time mothers (Crouch and Manderson 1993) has identified two primary themes in the experience of women who reported some anxiety and negative affect postpartum. These themes are (1) "overcome by responsibility" (1993:149-153) and (2) "feeding-and-cry- ing" (1993:153-158). The first theme is related to lack of social support in the face of anxiety regarding one's own mothering practices and capacity. The second theme meshes constant worry about crying with obsessive con- cern over feeding, particularly in relation to the amount of baby's intake. Considerable anxiety is associated with the uncertainty which is inevitable in this respect, and the apprehension becomes focused around unease about the baby's feeding pattern and the mother 's own response to it. Each feed becomes a control task judged by its outcome, and every cry a sign that the outcome is negative (Crouch and Manderson 1993:154). Naturally the sociocultural context of contemporary society contains factors which pre- cipitate this unease and exert decisive influence on the imagery through which it is expressed; as Harkness (1987:208) put it, the "inner experience � 9 of the post-partum period reflects biological functioning as well as in-

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dividual history and life-circumstances, all within the context of cultural practice and meaning shared by mothers giving birth and those that attend them." Thus, for example, in a world where eating is an infinitely calcula- ble activity along sundry dimensions of price, amount, caloric value, nu- tritional make-up, timing of meals, and number of courses (as well as baby's weekly weight gain), the necessarily uncertain business of baby feeds is disorienting in the absence of boundaries. So a woman who breast- feeds is concerned about not being able to "actually see how much he has had" (Crouch and Manderson 1993:155), and women who do not breast- feed are worried when they see how much milk (or formula) their bottle- fed infants did not have. Dangers lurk in such uncertainties, and anxiety grows with the proliferation of sources of "expert" advice on mothering and baby-care as their sundry and often confusing advice compounds, rather than assuages, the insecurity and dependency needs of women who are ill at ease in their early mothering situations.

An analytic eye jaded by evolutionary thinking will interpret the perva- sive unease of these women as a vigilance which is, in fact, the psychologi- cal equivalent of constant caretaking. (This is, in all probability, just one ex- ample of dispositional tendencies evolved through selection pressures but dysfunctional in their present environments, the expressions of which are converted from adaptive actions into internalized and painful reactions that reflect, but cannot any more effect, an appropriate program of re- sponses to stress.) s The vigilance is focused, in consciousness, on the de- mand characteristics of the infant's behavior--which is precisely the pre- diction that has been deduced from the evolutionary hypothesis of PNSD as presented here.

The finding by Crouch and Manderson (1993) that infant feeding and crying are the nub of mothers' postnatal distress is in line with at least some clinical studies of postnatal depression. For example, Chalmers and Chalmers (1986) have also observed that "babycare" is a major concern of women with postpartum depression, and Sussman and Katz (1988) re- port weaning to be a major etiological factor for this condition (leading, as it must, to increased attention, at least initially, to the process of infant feeding and, by extension, to uncertainties and anxieties inevitably at- tached to it).

In general, then, qualitative research of the kind described above is both appropriate and necessary for the testing of evolutionary hypotheses re- garding dispositional tendencies. Although the studies briefly discussed here have not been carried out with this aim in mind, it is possible to use some of their results to give credence to the hypothesis advanced here. Other research can be cited for the same purpose. For example, the previ- ously discussed work by Barr (1990) demonstrates that increased caretak- ing decreases infant crying; in line with this finding are therapeutic ap- proaches for postnatal depression which include enhancement of the

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mother-infant relationship (e.g., Searle 1987; Steiner 1990). (These three studies support the hypothesis because mother-infant interaction can be taken to be the active expression of maternal responsiveness; an increase in interaction would therefore move maternal behavior closer to the con- tinuous caretaking pattern of responsiveness, and this, in turn, shoutd de- crease the level of its psychological equivalent of vigilance, anxiety, and depression.) Also relevant in this connection is the body of research that demonstrates the importance of close and intimate social support as a pos- itive factor in maternal emotional health and in the quality of mother- infant interaction (as reviewed variously by Oakley 1993; Kumar 1994; Terry et al. 1996).

This paper makes no claim that the research cited supports the hypoth- esis in any substantial way. The approach has been explicitly speculative throughout, and the links between the theoretical position advanced and selected empirical research have been made to demonstrate the feasibility of the hypothesis put forward, rather than to uphold or verify it. A more productive approach towards the strengthening of the hypothesis would be through the logic of falsification, but such a process is beyond the scope of the present discussion. Instead, I briefly compare the view of PNSD as advanced here with evolutionary hypotheses of "postnatal depression" that emphasize different operative factors.

ALTERNATIVE HYPOTHESES

Hagen (1998) defines postpartum depression (PPD) as "threat to defect" that represents a negotiating tactic for securing greater investment (in the infant) by father and kin in situations where the cost of child-rearing out- weighs its benefits for the mother--or, less frequently, as a mechanism of gaining social acceptance for defection from investing in the infant. Like Hagen, Thornhill and Furlow (1998) also focus on parental investment costs in their evolutionary explanation of PPD. While not using the term "defection" (which heeds the possibility of social repercussion for lapses in maternal solicitude), Thornhill and Furlow nonetheless come close to Hagen's position by offering a definition of PPD which emphasizes escape from mothering: "PPD is a form of evolved psychological pain, designed to encourage maternal withdrawal of investment from offspring when doing so would have increased long-term maternal fitness in ancestral en- vironments" (Thornhill and Furlow 1998:347). Notably, however, Thorn- hill and Furlow also state that "another purpose of PPD may be the demonstration of need to people likely to respond by changing the envi- ronmental conditions that are extrinsic to the offspring but nevertheless lower its reproductive value" (1998:149).

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The understanding of psychological pain as an adaptive response evolved to secure attention and help from others is common to both of these hypotheses, and it also underlies the view of PNSD as put forward in this paper. Therefore there is some overlap among all three positions; as well, the three hypotheses are not necessarily competing ones, since there are no obvious contradictions among the predictions that can be drawn from them. Logically speaking, these hypotheses can therefore be re- garded as potentially complementary-- though it is equally possible that further elaborations of the positions involved may reveal rival conceptu- alizations. One possible area of disagreement may develop with respect to psychological pain, which in the present paper receives greater emphasis because of its postulated primary function as an aid to maternal respon- siveness whereas both Hagen (1998) and Thornhill and Furlow (1998) see it as an inducement for the withdrawal of investment. Underlying this dif- ference is the explicated evolutionary view of maternal responsiveness in this paper which clearly implies its antecedent status in relation to PNSD; this contrasts with the understanding of responsiveness as operational "investment" as put forward by both Hagen (1998) and Thornhill and Fur- low (1998) with the strong implication that this investment is a consequent (upon "assessment" of offspring's fitness potential) condition. The unrav- eling of these conceptual differences may well be an appropriate project for future theoretical endeavors.

THE WAY FORWARD?

With respect to empirical research, perhaps more studies of PNSD might be explicitly guided by evolutionary thinking if it were realized that such an outlook would not necessarily compete with theoretical standpoints that emphasize social and cultural factors. For example, from a sociologi- cal viewpoint, "post-natal ill health can be seen as the response to emo- tional and sociocultural stress on the individual w o m a n . . , as well as the stress that may be inherent in the structure of society and constantly im- pinging upon women's lives" (Thurtle 1995:419). Nothing in this state- ment is contradicted by the evolutionary view of PNSD. The discussion in this paper is testimony to the fact that an evolutionary hypothesis about human behavior and action must necessarily include considerations re- garding the cultural and social dimensions of human action and experi- ence. However, this statement could be both simplistic and trite without explicit recognition that the evolutionary line of thought would, again necessarily, gloss over many relevant intricacies and complexities of the psycho-social and cultural spheres that might be illuminated through a different analytic prism. The converse, of course, is also the case; one of the

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a ims of this p a p e r has been to sugge s t tha t an e v o l u t i o n a r y v i e w of P N S D brh~gs to a t t en t ion intricacies a n d complex i t i es of h u m a n in te rac t ion tha t are no t a l w a y s seen or even e n v i s a g e d f r o m s t a n d p o i n t s w h i c h e s c h e w e v o l u t i o n a r y premises . T h u s the pos i t ion t aken here is far f rom be ing re- duc t ion i s t since it rests on the poss ib i l i ty of c o n s i d e r i n g di f ferent levels of o rgan iza t ion of h u m a n act ion in re la t ion to one ano the r ; in a m o s t genera l sense this invo lves c o n t e m p l a t i o n of the exigencies of h u m a n exis tence as the basis for inves t iga t ions of select character is t ics o f the species.

I would like to thank the three reviewers of the first version of this paper. Their de- tailed, careful, and sympathetic comments have helped me develop and clarify the ideas presented here.

Mira Crouch (B.A.) is Senior Lecturer in the School of Sociology at the University of New South Wales (Sydney, Australia). Her main interests are in the interface of "culture" and "nature" in human experience. Her current research project con- ceres the implications of menarche for the subjective sense of the end of childhood.

N O T E S

l. The term "postnatal stress and depression" has been adopted by an infor- mal interest group of practitioners and academics formed in NSW in 1994 to pro- mote research, education, and support services in relation to "postnatal depres- sion." This broader view of postnatal depression has come out of a workshop on the syndrome held at the University of Melbourne under the auspices of the Re- search Advisory Committee (Australia: Department of Human Services and Health).

2. The question of cultural variation in mental illness symptomatology is a vexing one, both empirically and logically. If it is accepted that macro-social and bio-psychological variables are different contexts in which various patterns of forces operate on one another (Marsella et al. 1985:315), culturally variable disor- dered states--variable in both their manifestations (e.g., somatization vs. affective disturbance in depression [Kleinman and Kleinman 1985]) and the way in which these are socially unders tood--may in fact have at least some bio-psychological factors in common.

3. "Biological" here subsumes "social" insofar as the inherent sociality of hu- mans has been a constant feature of the evolution of the species.

4. Much could be said on this point; in the context of the present discussion, relevant considerations must be restricted to a global comment to the effect that, beginning dramatically with childbirth, the mother enters a period of considerable vulnerability which is the direct result of her increasing physical and emotional en- tanglement with the infant. The "bonding" that is so valued as an emotional com- modity in western societies (Crouch and Manderson 1995) is, in all probability, a culturally imagined entity which springs from this vulnerability that is simultane- ously embedded in, and denied by, current social circumstances.

5. It is possible that such reactions are a specialized, domain-specific, content- imparting mechanism, as Cosmides and Tooby (1997:288) might argue, l-Iowever,

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for the present discussion it is not necessary to assume that the disposition in ques- tion is totally "hard-wired," since "natural selection should modify when and how learning occurs just as powerfully as it shapes other aspects of phenotypes" (Sher- man and Reeve 1997:157).

6. The range and intensity of manifestations of PNSD vary enormously, as the literature on "postnatal depression" bears out. Also, at least some studies of early motherhood have found that subjectively adjudged undue negative affect is expe- rienced by almost all women during the first six months or so after giving birth (Barclay 1996; Crouch and Manderson 1993).

7. In this connection, Whiffen's (1990) study is of particular interest since it shows depressed mothers' ratings of infant crying and temperamental difficulty to be considerably higher than fathers' ratings. Although Whiffen takes this to be an indication of parental discord when the mother is dysphoric, it may also indicate the mother 's enhanced sensitivity to infant crying such that her responses are not directly related to its "objective" level.

8. For a brief but illuminating discussion of the evolutionary perspective on emotional illness, see Nesse and Williams 1994.

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