A modern evolutionary perspective emphasizing life history theory and behavioral ecology is brought to bear on the three core patterns of attachment that are identified in studies of infants and young children in the Strange Situation and adults using the Adult Attachment Interview. Mating and parenting correlates of secure/autonomous, avoidant/dismissing, and resistant/preoccupied attachment patterns are reviewed, and the argument is advanced that security evolved to promote mutually beneficial interpersonal relations and high investment parenting; that avoidant/dismissing attachment evolved to promote opportunistic (...) interpersonal relations and low-investment parenting; and that resistant/preoccupied attachment evolved to foster “helper-at-the-nest” behavior and indirect reproduction. (shrink)

The evolutionary origin of human pair-bonds is uncertain. One hypothesis, supported by data from forgers, suggests that pair-bonds function to provision mothers and dependent offspring during lactation. Similarly, public health data from large-scale industrial societies indicate that single mothers tend to wean their children earlier than do women living with a mate. Here we examine relations between pair-bond stability, alloparenting, and cross-cultural trends in breastfeeding using data from 58 “traditional” societies in the Standard Cross-Cultural Sample (SCCS). Analyses show that stable (...) conjugal relationships were associated with significantly later weaning among the societies in the SCCS. The relationship between pair-bond stability and age at weaning was not mediated by women’s ability to provision themselves or women’s kin support. Availability of alloparental care was also inversely related to age at weaning, and the association was not significantly reduced after controlling for frequency of divorce. This study indicates that among a woman’s kin relationships, a pair-bond with a child’s father is especially supportive of breastfeeding. These cross-cultural findings are further evidence that human pair-bonds may have evolved to support lactation. (shrink)

Currently much debate surrounds the significance of cross-cultural variation in mother-infant attachment. Is only one form of attachment “healthy,” or are different types of attachment adaptations to local socioecological conditions? Juvenile mortality rates have been promoted as important features of local environments that shape attachment, which in turn affects later reproductive strategies. To this we add fertility. Fertility changes the environment of a child by influencing the number of potential caregivers and competitors for care, and the cultural ethos regarding the (...) rights of children. Different combinations of fertility and mortality will likely give rise to different attachment forms, and only under one regime (low fertility and mortality) do we expect exclusivity in attachment. (shrink)

This target article presents an integrated evolutionary model of the development of attachment and human reproductive strategies. It is argued that sex differences in attachment emerge in middle childhood, have adaptive significance in both children and adults, and are part of sex-specific life history strategies. Early psychosocial stress and insecure attachment act as cues of environmental risk, and tend to switch development towards reproductive strategies favoring current reproduction and higher mating effort. However, due to sex differences in life history trade-offs (...) between mating and parenting, insecure males tend to adopt avoidant strategies, whereas insecure females tend to adopt anxious/ambivalent strategies, which maximize investment from kin and mates. Females are expected to shift to avoidant patterns when environmental risk is more severe. Avoidant and ambivalent attachment patterns also have different adaptive values for boys and girls, in the context of same-sex competition in the peer group: in particular, the competitive and aggressive traits related to avoidant attachment can be favored as a status-seeking strategy for males. Finally, adrenarche is proposed as the endocrine mechanism underlying the reorganization of attachment in middle childhood, and the implications for the relationship between attachment and sexual development are explored. Sex differences in the development of attachment can be fruitfully integrated within the broader framework of adaptive plasticity in life history strategies, thus contributing to a coherent evolutionary theory of human development. (shrink)

Following from life history and attachment theory, individuals are predicted to be sensitive to variation in environmental conditions such that risk and uncertainty are internalized by cognitive, affective, and psychobiological mechanisms. In turn, internalizing of environmental uncertainty is expected to be associated with attitudes toward risk behaviors and investments in education. Native American youth aged 10–19 years (n = 89) from reservation communities participated in a study examining this pathway. Measures included family environmental risk and uncertainty, present and future time (...) perspective, adolescent attachment, attitudes toward risk, investments in education, and salivary cortisol. Results support the idea that environmental risk and uncertainty are internalized during development. In addition, internalizing mechanisms significantly predicted attitudes toward risk and education: (1) lower scores on future time perspective and higher cortisol predicted higher scores on risk attitudes, and (2) higher scores on future time perspective and lower scores on problems with attachment predicted higher self-reported school performance. Gender differences were seen, with males anticipating a shorter lifespan than females, which predicted higher scores on risk attitudes and lower school performance. Implications for research on adolescent problem behavior and academic achievement are discussed. (shrink)

The assumption that the onset of puberty is a context-sensitive marker of a reproductive strategy is tested by comparing parental and filial childhood context and somatic development in West and East Germany. Sixty-eight mother-daughter dyads and 35 father-son dyads were taken from two samples of families from Osnabrück in West Germany and Halle in East Germany. According to the observed context discontinuity between the generations in the male dyads, linear regression models show that no indicator of male sexual maturation was (...) influenced significantly by the somatic development of the father. Instead of an inherited timing of maturation, antecedent distal factors like socioeconomic childhood context variables and critical life events lead to an acceleration of male sexual maturation. Finally we test the effect of two different conditions of childhood context continuity on daughter’s age at menarche with maternal age at menarche controlled. Linear regression models show that mother’s age at menarche predicts daughter’s age at menarche only under the condition of contextual continuity between generations, which was the case in the West German sample only. In East Germany, where mother’s age at menarche had no significant effect, the amount of variance explained by childhood context variables was almost the same. These results indicate the context sensitivity of somatic development which seems to follow an evolutionary rationale. (shrink)

Adolescence signifies a transition from the use of prereproductive to reproductive strategies in the life history of Homo sapiens. Insofar as human generations overlap, events at adolescence, surrounding the onset of puberty, offer a unique glimpse into human adaptation from the point of view of the changing strategies of both parents and offspring. The timing of puberty is an important life history trait that varies between species, but also between and within the sexes in human beings. The onset of puberty (...) marks the beginning of the reproductive life, is affected by previous experience, and serves as a trigger for behavioral change. Surbey (1988, 1990) reported relationships between father absence, heightened levels of childhood stress, and early menarche and considered them within the context of human evolutionary history. Subsequently, similar findings have been reported in a number of human populations and have been interpreted from several evolutionary perspectives. This article discusses the extent to which these and related findings regarding alterations in the timing of human puberty reflect evolved parental or offspring strategies. It entails a consideration of the applicability of the concepts of phenotypic plasticity, nonadaptive genetic variation, and conditional and alternative reproductive strategies in describing the interwoven nature of strategies employed by parent and child in the transition at adolescence. (shrink)

Attachment is an emotional bond between two people where one seeks care from the other. In the prototypical case, the child attaches to their mother. The most recent theoretical developments point out that attachment is multidimensional – meaning that the phenomenon pertains to multiple domains related to the relationship with the caregiver. However, researchers have so far modeled attachment computationally by mostly adopting a classical categorical (as opposed to dimensional) standpoint that sees the system as controlling caregiver proximity. In contrast, (...) we adopt here adimensional perspective(DP) and consider dimensions to be the system’s set-goals. We hypothesize that the resulting multidimensional controller should lead to valid (or even better) models of the phenomenon. To start testing this hypothesis, we built a DP-informed agent-based model of attachment inspired by the widely-studied Strange Situation Procedure. In this context, child and mother show the nature of attachment bonds through their behavioral and emotional expressions. By modeling them as point-agents moving in a two-dimensional arena, we simulated child-mother interactions for the avoidant and ambivalent attachment dimensions. The generated dynamical patterns – characterized by the alternation between approach and exploration – matched those described in the attachment literature, thereby confirming the implementability and validity of the DP. (shrink)

The current paper synthesizes theory and data from the field of life history (LH) evolution to advance a new developmental theory of variation in human LH strategies. The theory posits that clusters of correlated LH traits (e.g., timing of puberty, age at sexual debut and first birth, parental investment strategies) lie on a slow-to-fast continuum; that harshness (externally caused levels of morbidity-mortality) and unpredictability (spatial-temporal variation in harshness) are the most fundamental environmental influences on the evolution and development of LH (...) strategies; and that these influences depend on population densities and related levels of intraspecific competition and resource scarcity, on age schedules of mortality, on the sensitivity of morbidity-mortality to the organism’s resource-allocation decisions, and on the extent to which environmental fluctuations affect individuals versus populations over short versus long timescales. These interrelated factors operate at evolutionary and developmental levels and should be distinguished because they exert distinctive effects on LH traits and are hierarchically operative in terms of primacy of influence. Although converging lines of evidence support core assumptions of the theory, many questions remain unanswered. This review demonstrates the value of applying a multilevel evolutionary-developmental approach to the analysis of a central feature of human phenotypic variation: LH strategy. (shrink)

The aim of this study is an analysis of the possible adaptive consequences of delivery of low birth weight infants. We attempt to reveal the cost and benefit components of bearing small children, estimate the chance of the infants’ survival, and calculate the mothers’ reproductive success. According to life-history theory, under certain circumstances mothers can enhance their lifetime fitness by lowering the rate of investment in an infant and/or enhancing the rate of subsequent births. We assume that living in a (...) risky environment and giving birth to a small infant may involve a shift from qualitative to quantitative production of offspring. Given high infant mortality rates, parents will have a reproductive interest in producing a relatively large number of children with a smaller amount of prenatal investment. This hypothesis was tested among 650 Gypsy and 717 non-Gypsy Hungarian mothers. Our study has revealed that 23.8% of the Gypsy mothers had low birth weight (<2,500 g) children, whose mortality rate is very high. These mothers also had more spontaneous abortions and stillbirths than those with normal weight children. As a possible response to these reproductive failures, they shortened birth spacing, gaining 2–4 years across their reproductive lifespan for having additional children. Because of the relatively short interbirth intervals, by the end of their fertility period, Gypsy mothers with one or two low birth weight infants have significantly more children than their ethnic Hungarian counterparts. They appear to compensate for handicaps associated with low birth weights by having a larger number of closely spaced children following the birth of one or more infants with a reduced probability of survival. The possible alternative explanations are discussed, and the long-term reproductive benefits are estimated for both ethnic groups. (shrink)

Life history theory suggests that in risky and uncertain environments the optimal reproductive strategy is to reproduce early in order to maximize the probability of leaving any descendants at all. The fact that early menarche facilitates early reproduction provides an adaptationist rationale for our first two hypotheses: that women who experience more risky and uncertain environments early in life would have (1) earlier menarche and (2) earlier first births than women who experience less stress at an early age. Attachment theory (...) and research provide the rationale for our second two hypotheses: that the subjective early experience of risky and uncertain environments (insecurity) is (3) part of an evolved mechanism for entraining alternative reproductive strategies contingent on environmental risk and uncertainty and (4) reflected in expected lifespan. Evidence from our pilot study of 100 women attending antenatal clinics at a large metropolitan hospital is consistent with all four hypotheses: Women reporting more troubled family relations early in life had earlier menarche, earlier first birth, were more likely to identify with insecure adult attachment styles, and expected shorter lifespans. Multivariate analyses show that early stress directly affected age at menarche and first birth, affected adult attachment in interaction with expected lifespan, but had no effect on expected lifespan, where its original effect was taken over by interactions between age at menarche and adult attachment as well as age at first birth and adult attachment. We discuss our results in terms of the need to combine evolutionary and developmental perspectives and the relation between early stress in general and father absence in particular. (shrink)

Since the seminal works of Draper and Harpending (1982) and Belsky et al. (1991) there has been considerable interest in the link between the family environment experienced as a child and consequent mating and reproductive strategy of females. In this paper, predictions from the hypothesis were tested using postal survey data from a cross-section of 415 women in Merseyside, UK. No relationships were found between father-absence, unrelated male-presence, parental divorce or parental death with age at first coitus, number of sexual (...) partners, mean length of sexual relationships or mean length of relationships prior to coitus occurring. (shrink)

The hypothesis that father absence during childhood, as well as other forms of childhood psychosocial stress, might influence the timing of sexual maturity and adult reproductive behaviors has been the focus of considerable research. However, the majority of studies that have examined this prediction have used samples of women of European descent living in industrialized, low-fertility nations. This paper tests the father-absence hypothesis using the Cape Area Panel Study (CAPS), which samples young adults in Cape Town, South Africa. The sample (...) contains multiple racial groups (blacks, coloureds [mixed race], and whites) and includes both males and females. Dependent variables include age at menarche, age at first sexual intercourse, and age at first pregnancy. Childhood stress is measured by father absence by age six (either never lived with father or lived with father some but not all years) and an index of childhood exposure to violence (measuring threatened or actual verbal or physical abuse). The hypothesis received no support for effect on age at menarche but was supported for age at first sex and first pregnancy. The model showed stronger support for coloureds and whites than blacks and had no predictive power at all for black males. (shrink)

We hypothesize that rapid eye movement or REM sleep evolved, in part, to mediate sexual/reproductive behaviors and strategies. Because development of sexual and mating strategies depends crucially on early attachment experiences, we further hypothesize that REM functions to mediate attachment processes early in life. Evidence for these hypotheses comes from (1) the correlation of REM variables with both attachment and sexual/reproductive variables; (2) attachment-related and sex-related hormonal release during REM; (3) selective activation during REM of brain sites implicated in attachment (...) and sexual processes; (4) effects of maternal deprivation on REM; (5) effects of REM deprivation on sexual behaviors; and (6) the REM-associated sexual excitation. To explain why we find associations among REM sleep, attachment, and adult reproductive strategies, we rely on recent extensions of parent-offspring conflict theory. Using data from recent findings on genomic imprinting, Haig (2000) and others suggest that paternally expressed genes are selected to promote growth of the developing fetus/child at the expense of the mother, while maternally expressed genes counter these effects. Because developmental REM facilitates attachment-related outcomes in the child, developmental REM may be regulated by paternally expressed genes. In that case, REM may have evolved to support the “aims” of paternal genes at the expense of maternal genes. (shrink)

This paper investigates hypotheses drawn from two sources: (1) Belsky, Steinberg, and Draper’s (1991) attachment theory model of the development of reproductive strategies, and (2) recent life history models and comparative data suggesting that environmental risk and uncertainty may be potent determinants of the optimal tradeoff between current and future reproduction. A retrospective, self-report study of 136 American university women aged 19–25 showed that current recollections of early stress (environmental risk and uncertainty) were related to individual differences in adult time (...) preference and adult sexual behavior, and that individual differences in time preference were related to adult attachment organization and sexual behavior. These results are consistent with the hypothesis that perceptions of early stress index environmental risk and uncertainty and mediate the attachment process and the development of reproductive strategies. On this view individual differences in time preference are considered to be part of the attachment theoretical construct of an internal working model, which itself is conceived as an evolved algorithm for the contingent development of alternative reproductive strategies. (shrink)

We present a psychometric test of life history theory as applied to human individual differences using MIDUS survey data (Brim et al. 2000). Twenty scales measuring cognitive and behavioral dimensions theoretically related to life history strategy were constructed using items from the MIDUS survey. These scales were used to construct a single common factor, the K-factor, which accounted for 70% of the reliable variance. The scales used included measures of personal, familial, and social function. A second common factor, Covitality, was (...) constructed from scales for physical and mental health. Finally, a single general factor, Personality, was constructed from scales for the “Big Five” factors of personality. The K-factor, covitality factor, and general personality factor correlated significantly with each other, supporting the prediction that high K predicts high somatic effort and also manifests in behavioral display. Thus, a single higher-order common factor, the Super-K factor, was constructed that consisted of the K-factor, covitality factor, and personality factor. (shrink)

The well-established finding that siblings growing up in the same family turn out to be very different from one another has puzzled psychologists and behavior geneticists alike. In this theoretical note we describe the possible ontogeny and phylogeny of a sibling differentiation mechanism. We suggest that sibling competition for parental investment results in sibling differentiation on a number of characteristics, producing different developmental trajectories within families. Variations in developmental trajectories within families may have had fitness advantages in ancestral environments because(a) (...) sibling competition for extrafamilial resources would be reduced and(b) these variations would be suited to environments containing a variety of niches or to changing environments. Predictions derived from this model and an example of an application to attachment theory are presented. (shrink)

Models of risk-taking as used in the social sciences may be improved by including concepts from life history theory, particularly environmental unpredictability and life expectancy. Community college students completed self-report questionnaires measuring these constructs along with several well-known correlates. The frequency of risk-taking was higher for those with higher future unpredictability beliefs and shorter lifespan estimates (as measured by the Future Lifespan Assessment developed for this study), and unpredictability beliefs remained significant after accounting for standard predictors, such as sex and (...) temperament. The results demonstrate the usefulness of applying concepts from life history theory to enhance our understanding of human behavior. (shrink)

If parenting behavior influences attachment, then parental investment (PI) theory can predict sex differences and distributions of attachment styles across cultures. Trivers-Willard, local resource competition, and local resource enhancement models make distinct predictions for sex-biased parental responsiveness relevant to attachment. Parental investment and attachment probably vary across cultures in relation to for status, wealth, and well-being.

Life history data, attractiveness ratings of male photographs, and attitudes towards partnership and child-rearing of 321 women were used to test four evolutionary models (quantitative reproductive strategy, male short-age, polygyny indication, and maternal reproductive interests) which attempt to explain the influence of family composition on reproductive strategies. Links between early menarche and other markers of reproductive strategy were investigated. Childhood stress and absence of a father figure, whether genetically related or not, were found to have accelerated menarche whereas having younger (...) siblings decelerated it. Early menarche was associated with attractiveness ratings, the number of partners desired for the immediate future, and the early onset of intimate relationships. It was not linked with sociosexual orientation, mate choice criteria, and investment in the subjects’ own children, but these three markers were interrelated. The implications of the findings for the four evolutionary models are discussed. (shrink)

The mechanism proposed by Del Giudice by which adult attachment style is adapted to the extrinsic risk in the local environment via attachment style during the early years does not fulfill important criteria of an adaptation. The proposed mechanism is neither specific, nor developmentally reliable, nor effective. Therefore, it should not be considered an adaptation.