The neurobiology of human allomaternal care; implications for fathering, coparenting, and children's social development

Conflict and Father Involvement: The Unique Role of Postpartum Destructiveness for Fathers' Direct Care in Toddlerhood

Father involvement in childcare is associated with positive outcomes for children. Growing evidence supports many predictors of fathers' involvement, including maternal gatekeeping and father characteristics. The present study focuses on fathers' postpartum experiences, exploring parallel insights from environmental, interpersonal, and internal factors after having a baby to predict later involvement. We investigated how early household chaos, couple conflict, and father depressive symptoms in infancy predict later direct involvement in toddler care. The current study utilized data from 202 families participating in a parenting intervention program. We longitudinally assessed father reports of household chaos and their depressive symptoms, and employed an observational measure of conflict, at 6, 12, and 18 months postpartum to predict mother and father reports of father direct contributions to childcare at 18 months. Latent variables were created for household chaos, depressive symptoms, and destructiveness to incorporate reports 6 months apart. A structural equation model indicated father appraisals of household chaos were positively associated with depressive symptoms over time. Furthermore, couple destructiveness was negatively predictive of mothers' reports, but not fathers' reports of father direct care at 18 months after controlling for direct care behavior within 6 months postpartum. These results suggest that although father appraisals of his environment likely relate to his mental health, couple functioning played a greater role over time in direct care. We emphasize including fathers' appraisals of their experience in future research and underscore the potential impact of intervening at the couple level postpartum to support fathers' direct involvement in childcare over time.

Fathers' lived experiences of fatherhood during the child's first 1000 days: a qualitative systematic review protocol

OBJECTIVE

The objective of this review will be to synthesize the best available evidence on fathers' lived experiences of fatherhood during the child's first 1000 days of life.

INTRODUCTION

Involved and caring fatherhood is crucial for the healthy cognitive, physical, social, and emotional development of children; however, fatherhood is a challenging process for most men. It is characterized by profound changes that require the development of a new identity and the assumption of new roles within the family. Understanding adult fathers' lived experiences during this stage of life can provide valuable knowledge to families, health care professionals, and policymakers.

INCLUSION CRITERIA

This review will include studies on the experiences of fatherhood during the child's first 1000 days of life. It will include heterosexual biological fathers of healthy infants, who are 18 years or over, and belong to an intact family.

METHODS

This review will be conducted in accordance with the JBI methodology for systematic reviews of qualitative evidence. The search strategy will aim to locate both published and unpublished qualitative studies published in English, Spanish, and Portuguese. Ten databases or gray literature sources will be searched, with no date limitations. Study selection, critical appraisal, and data extraction will be performed by 2 independent reviewers. Any disagreements that arise between the reviewers will be resolved through discussion or with an additional reviewer. Data will be presented in narrative format, and data synthesis will follow the JBI meta-aggregation approach. A ConQual Summary of Findings will be presented.

REVIEW REGISTRATION

PROSPERO (CRD42023487167).

EEG responses to infant faces in young adults can be influenced by the quality of early care experiences with caregivers

BACKGROUND

The quality of early experiences with caregivers affects individual adjustment and can modulate adults' responses to salient social stimuli, like infant faces. However, in the framework of Interpersonal Acceptance-Rejection Theory (IPARTheory), no research to date has examined whether early experiences of acceptance or rejection from caregivers are associated with individual differences in the electrophysiological (EEG) responses to infant faces.

OBJECTIVE

This study examined the associations between the perceived quality of care during childhood and the behavioral and EEG responses to infant and adult faces in non-parent young adults.

METHODS

N = 60 non-parent young adults (30 males; 30 females) completed an Emotion Recognition task displaying emotional and unemotional infant and adult faces during an EEG recording. Memories of past care experiences with mothers and fathers were collected using the short form version of the Parental Acceptance-Rejection scale.

RESULTS

At the behavioral level, slower Reaction Times (RTs) in recognizing all faces were related to higher levels of perceived maternal rejection in young adults; in particular, males who reported higher levels of maternal rejection displayed longer RTs in recognizing faces compared to females. At the neurophysiological level, as the level of perceived paternal rejection increased, the N170 amplitude to infant faces increased. Females who reported higher levels of paternal rejection, compared to males, had a larger increase in the N170 amplitude and a larger decrease in the LPP amplitude in response to emotional faces.

CONCLUSIONS

While a higher perception of maternal rejection hindered the behavioral responses of adults in recognizing faces, those who felt more rejected by their own father during childhood showed an enhanced N170 amplitude to infant faces. This might reflect a greater need for discrimination resources, at a very early stage of infant face processing, in those adults who perceived higher levels of paternal rejection. Adults' sex modulated the associations found at the behavioral and neurophysiological levels. Overall, our findings extended the IPARTheory postulates that being neglected during childhood might trigger perceptual changes in adults, hindering the elaboration of social cues like infant and adult faces at different levels.

Development of the Parent-to-Infant Bonding Scale: Validation in Swedish Mothers and Fathers in Community and Clinical Contexts

Valid measurement instruments are needed to investigate the impact of parental bonding on child health development. The aim was to develop and validate a self-report questionnaire, the Parent-to-Infant Bonding Scale (PIBS) to measure bonding in both mothers and fathers. Internal consistency and construct validity were analysed using data from Swedish parents from both clinical (N = 182), and community (N = 122) population samples. Overall, good or acceptable internal consistency of the PIBS appeared. Convergent validity (against the Postpartum Bonding Questionnaire, analysed in the clinical sample) and discriminant validity (against the mental health constructs of depressive symptoms and anxiety) were demonstrated. The results support the PIBS as a measure of maternal and paternal bonding in community and clinical populations. Assessments of criterion validity in these populations are desirable. The similarities in PIBS measurement properties between the parent groups suggest its usefulness for comparisons between mothers and fathers, and for future investigations of unique and interactive impacts of maternal and paternal bonding on child outcomes using community and clinical cohorts.

Single parent adoption in India: Mental health and legal perspectives and the way forward

Single parent adoption (SPA) is a relatively new construct worldwide and in India. The Ministry of Women and Child Development, Government of India, has laid down criteria for adoption in general and SPA in particular, in conjunction with the Juvenile Justice Act (Care and Protection of Children), 2015. There is scant literature on this topic of SPA, more so in India, that looks into the various psychological nuances of SPA from a mental health professional's (MHP) perspective. This review paper aims to assess SPA from the perspective of a MHP that will focus on its various legal nuances as well as the psychological connotations attached to it. For this, a search strategy was employed that included a thorough literature search from two databases (PubMed and Google Scholar) with relevant keywords related to the topic. The various legal issues pertaining to SPA in the current scenario, the psychological issues and challenges faced by single parents, the behavioral outcomes of adoptees who are adopted by single parents, and ways to deal with the various obstacles of SPA are discussed.

The impact of mode of delivery on parent-infant-bonding and the mediating role of birth experience: a comparison of mothers and fathers within the longitudinal cohort study DREAM

BACKGROUND

The association between mode of delivery (MOD) and parent-infant-bonding has only been studied in mothers and findings have been inconclusive. The aim of this study was to prospectively investigate how MOD relates to postpartum parent-infant-bonding in both mothers and fathers and whether these associations are mediated by birth experience.

METHODS

This study is part of the prospective cohort study "Dresden Study on Parenting, Work, and Mental Health" (DREAM). Our sample comprised N = 1,780 participants who completed quantitative questionnaires during pregnancy as well as 8 weeks and 14 months postpartum. MOD was dummy coded, contrasting spontaneous vaginal delivery against vaginal delivery induced by drugs, operative vaginal delivery, planned, and unplanned cesarean section. Parent-infant bonding and birth experience were assessed using validated scales. A moderated mediation analysis based on ordinary least square (OLS) regression and bootstrapped estimates was conducted, considering relevant confounding variables.

RESULTS

Compared to spontaneous vaginal delivery, all categories of MOD predicted more negative birth experiences in both parents. A more positive birth experience predicted stronger parent-infant-bonding at 8 weeks, but not at 14 months postpartum. Mothers who delivered via cesarean section (planned or unplanned) reported stronger parent-infant-bonding at 8 weeks and 14 months postpartum. In fathers, only unplanned cesarean section was associated with stronger parent-infant-bonding at 8 weeks postpartum. At 8 weeks postpartum, birth experience mediated the association between a vaginal delivery induced by drugs and a planned cesarean section and mother-infant-bonding and between a vaginal delivery induced by drugs, an operative vaginal delivery, and planned cesarean section and father-infant-bonding. At 14 months postpartum, birth experience mediated the association between a vaginal delivery induced by drugs, operative vaginal delivery, and planned cesarean section and parent-infant-bonding in both parents.

CONCLUSIONS

The results emphasize the importance of the birth experience for parent-infant-bonding in both mothers and fathers. Further research should address the mechanisms by which parents with an unplanned cesarean section establish stronger parent-infant-bonding compared to parents whose baby was delivered via spontaneous vaginal delivery, despite their overall more negative birth experiences.

Paternal postpartum depression, coparenting, and father-infant bonding: Testing two mediated models using structural equation modeling

BACKGROUND

Impaired father-infant bonding is a mental health issue that has been understudied. The current study aimed to examine the extent to which fathers' depression symptoms and coparenting relationship, respectively, are associated with infant bonding, as well as how these two variables mediate in the association with infant bonding.

METHODS

Cross-sectional data from 612 fathers of infants (0-24 months) were used in this study. Path analyses on two competing mediation models were used to examine the direct and indirect associations between fathers' depression symptoms, coparenting relationship, and infant bonding, after controlling for several known covariates.

RESULTS

Whether fathers reported depression symptoms (Model 1) or reported lower levels of coparenting relationships (Model 2), they also reported higher levels of impaired infant bonding, rejection and anger, and anxiety about care after controlling for the covariates. The analysis further found significant indirect associations between father depression symptoms and father-infant bonding via the coparenting relationship (Model 1) as well as significant indirect associations between the coparenting relationship and father-infant bonding via father depression symptoms (Model 2).

LIMITATIONS

The cross-sectional data cannot show causal links. Specific efforts were made to recruit fathers with depression symptoms, and therefore prevalence rates may appear skewed.

CONCLUSIONS

Decreasing depression symptoms and improving coparenting quality can potentially improve father-infant bonding. Fathers' depression symptoms and coparenting quality can be bi-directionally related in the association with father-infant bonding. Early detection and preventive treatments for paternal depression symptoms and coparenting are warranted.

Proximate and Ultimate Mechanisms of Human Father-child Rough-and-tumble Play

The aim of this contribution is to attempt to understand the adaptive functions of father-child rough-and-tumble play (RTP) in humans. We first present a synthesis of the known proximate and ultimate mechanisms of peer-peer RTP in mammals and compare human parent-child RTP with peer-peer RTP. Next, we examine the possible biological adaptive functions of father-child RTP in humans, by comparing paternal behavior in humans versus biparental animal species, in light of the activation relationship theory and the neurobiological basis of fathering. Analysis of analogies reveals that the endocrine profile of fathers is highly variable across species, compared to that of mothers. This can be interpreted as fathers' evolutionary adjustment to specific environmental conditions affecting the care of the young. Given the high unpredictability and risk-taking features of RTP, we conclude that human adult-child RTP appears to have a biological adaptive function, one of 'opening to the world'.

Testosterone, oxytocin and co-operation: A hypothesis for the origin and function of music

Since the time of Darwin, theories have been proposed on the origin and functions of music; however, the subject remains enigmatic. The literature shows that music is closely related to important human behaviours and abilities, namely, cognition, emotion, reward and sociality (co-operation, entrainment, empathy and altruism). Notably, studies have deduced that these behaviours are closely related to testosterone (T) and oxytocin (OXT). The association of music with important human behaviours and neurochemicals is closely related to the understanding of reproductive and social behaviours being unclear. In this paper, we describe the endocrinological functions of human social and musical behaviour and demonstrate its relationship to T and OXT. We then hypothesised that the emergence of music is associated with behavioural adaptations and emerged as humans socialised to ensure survival. Moreover, the proximal factor in the emergence of music is behavioural control (social tolerance) through the regulation of T and OXT, and the ultimate factor is group survival through co-operation. The "survival value" of music has rarely been approached from the perspective of musical behavioural endocrinology. This paper provides a new perspective on the origin and functions of music.

Major depression, temperament, and social support as psychosocial mechanisms of the intergenerational transmission of parenting styles

In this three-generation longitudinal study of familial depression, we investigated the continuity of parenting styles, and major depressive disorder (MDD), temperament, and social support during childrearing as potential mechanisms. Each generation independently completed the Parental Bonding Instrument (PBI), measuring individuals' experiences of care and overprotection received from parents during childhood. MDD was assessed prospectively, up to 38 years, using the semi-structured Schedule for Affective Disorders and Schizophrenia (SADS). Social support and temperament were assessed using the Social Adjustment Scale - Self-Report (SAS-SR) and Dimensions of Temperament Scales - Revised, respectively. We first assessed transmission of parenting styles in the generation 1 to generation 2 cycle (G1→G2), including 133 G1 and their 229 G2 children (367 pairs), and found continuity of both care and overprotection. G1 MDD accounted for the association between G1→G2 experiences of care, and G1 social support and temperament moderated the transmission of overprotection. The findings were largely similar when examining these psychosocial mechanisms in 111 G2 and their spouses (G2+S) and their 136 children (G3) (a total of 223 pairs). Finally, in a subsample of families with three successive generations (G1→G2→G3), G2 experiences of overprotection accounted for the association between G1→G3 experiences of overprotection. The results of this study highlight the roles of MDD, temperament, and social support in the intergenerational continuity of parenting, which should be considered in interventions to "break the cycle" of poor parenting practices across generations.

First-time fathers show longitudinal gray matter cortical volume reductions: evidence from two international samples

Emerging evidence points to the transition to parenthood as a critical window for adult neural plasticity. Studying fathers offers a unique opportunity to explore how parenting experience can shape the human brain when pregnancy is not directly experienced. Yet very few studies have examined the neuroanatomic adaptations of men transitioning into fatherhood. The present study reports on an international collaboration between two laboratories, one in Spain and the other in California (United States), that have prospectively collected structural neuroimaging data in 20 expectant fathers before and after the birth of their first child. The Spanish sample also included a control group of 17 childless men. We tested whether the transition into fatherhood entailed anatomical changes in brain cortical volume, thickness, and area, and subcortical volumes. We found overlapping trends of cortical volume reductions within the default mode network and visual networks and preservation of subcortical structures across both samples of first-time fathers, which persisted after controlling for fathers' and children's age at the postnatal scan. This study provides convergent evidence for cortical structural changes in fathers, supporting the possibility that the transition to fatherhood may represent a meaningful window of experience-induced structural neuroplasticity in males.

Is paternal oxytocin an oxymoron? Oxytocin, vasopressin, testosterone, oestradiol and cortisol in emerging fatherhood

How do hormonal levels in men change from pregnancy to after the birth of their firstborn child, and what is the role of oxytocin, alone or in interplay with other hormones, in explaining variance in their parenting quality? We explored in 73 first-time fathers the development of five hormones that have been suggested to play a role in parenting: oxytocin (OT), vasopressin (AVP), testosterone (T), oestradiol (E2) and cortisol (Cort). In an extended group of fathers (N = 152) we examined associations with fathers' behaviour with their 2-month-old infants. OT and E2 showed stability from the prenatal to the postnatal assessments, whereas AVP and T decreased significantly, and Cort decreased marginally. OT on its own or in interplay with other hormones was not related to paternal sensitivity. Using an exploratory approach, the interaction between T and E2 emerged as relevant for fathers' sensitive parenting. Among fathers with high E2, high T was associated with lower sensitivity. Although we did not find evidence for the importance of OT as stand-alone hormone or in interplay with other hormones in this important phase in men's lives, the interaction between T and E2 in explaining variation in paternal behaviour is a promising hypothesis for further research. This article is part of the theme issue 'Interplays between oxytocin and other neuromodulators in shaping complex social behaviours'.

The Neurobiology of Infant Attachment-Trauma and Disruption of Parent-Infant Interactions

Current clinical literature and supporting animal literature have shown that repeated and profound early-life adversity, especially when experienced within the caregiver-infant dyad, disrupts the trajectory of brain development to induce later-life expression of maladaptive behavior and pathology. What is less well understood is the immediate impact of repeated adversity during early life with the caregiver, especially since attachment to the caregiver occurs regardless of the quality of care the infant received including experiences of trauma. The focus of the present manuscript is to review the current literature on infant trauma within attachment, with an emphasis on animal research to define mechanisms and translate developmental child research. Across species, the effects of repeated trauma with the attachment figure, are subtle in early life, but the presence of acute stress can uncover some pathology, as was highlighted by Bowlby and Ainsworth in the 1950s. Through rodent neurobehavioral literature we discuss the important role of repeated elevations in stress hormone corticosterone (CORT) in infancy, especially if paired with the mother (not when pups are alone) as targeting the amygdala and causal in infant pathology. We also show that following induced alterations, at baseline infants appear stable, although acute stress hormone elevation uncovers pathology in brain circuits important in emotion, social behavior, and fear. We suggest that a comprehensive understanding of the role of stress hormones during infant typical development and elevated CORT disruption of this typical development will provide insight into age-specific identification of trauma effects, as well as a better understanding of early markers of later-life pathology.

Attachment-based parent–adolescent interaction linked to visual attention and autonomic arousal to distress and comfort stimuli

In infancy and in the early years of life, emotion regulation and attachment relationships with parents are tightly intertwined. However, whether this link persists into adolescence has not yet been established and requires exploration. This pilot study utilizes an experimental design to assess the patterns of parent–adolescent interactions that are hypothesised to be related to two specific aspects of adolescents’ emotion regulation, namely: visual attention and autonomic arousal to distress and comfort stimuli. Two innovative and ecologically valid methodologies were utilized to assess (a) patterns of attachment-based parent–adolescent interactions among 39 adolescent–parent dyads from the general population, using the Goal-corrected Partnership in Adolescence Coding System (Lyons-Ruth et al. Goal corrected partnership in adolescence coding system (GPACS), 2005) applied to a conflict discussion task; (b) the two aspects of adolescent emotion regulation were assessed with the Visual/Autonomic Regulation of Emotions Assessment (VAREA) (Vulliez-Coady et al. Visual/Autonomic Regulation of Emotions Assessment, VAREA) paradigm, an attachment-related, emotionally arousing experimental procedure, using a distress-then-comfort paradigm, in conjunction to an eye-tracker synchronized with a physiological device that measured gaze and skin conductance response, (SCR), or emotional reactivity. In line with research in infancy, as predicted, markers of secure parent–adolescent interaction were linked to higher amplitude of SCR for distress and comfort pictures, and with longer attention to comfort pictures. On the other hand, parental role-confusion was associated with less time spent on comfort pictures by the adolescent. Overall, this pilot study suggests that interventions supporting collaborative communication between adolescents and their parents, as well as working to reduce parental role-confusion, may improve adaptive adolescent emotion regulation as assessed via physiological measures.

Do empathy and oxytocin predict responsiveness to a crying infant simulator in expecting and non-expecting couples? A multilevel study

Infant crying is a strong emotional stimulus that elicits caregiving responses in adults. Here we examine the role of empathy (measured with the Polish version of Interpersonal Reactivity Index) and salivary oxytocin in modulating sensitive responsiveness to a crying infant simulator in two groups of heterosexual couples: 111 expecting or 110 not expecting a baby. Sensitive responsiveness was observed during a standardized procedure using the Ainsworth Sensitivity Scale while participants took care of the infant simulator, both individually and as a couple. Other-oriented empathy predicted elevated levels of individual but not couple sensitive responsiveness. More OT reactivity to crying predicted less responsiveness in non-expecting couples, which might be explained by their stronger focus on task performance. This study uniquely combined hormonal, observational and self-report measures in couples, and showed that personality and hormonal correlates of sensitive responsiveness might be studied before the child's birth with the use of infant simulators.

The Neural Basis of Human Fatherhood: A Unique Biocultural Perspective on Plasticity of Brain and Behavior

With the growing involvement of fathers in childrearing and the application of neuroscientific tools to research on parenting, there is a need to understand how a father's brain and neurohormonal systems accommodate the transition to parenthood and how such neurobiological changes impact children's mental health, sociality, and family functioning. In this paper, we present a theoretical model on the human father's brain and the neural adaptations that take place when fathers assume an involved role. The neurobiology of fatherhood shows great variability across individuals, societies, and cultures and is shaped to a great extent by bottom-up caregiving experiences and the amount of childrearing responsibilities. Mechanisms of mother-father coparental brain coordination and hormonal correlates of paternal behavior are detailed. Adaptations in the father's brain during pregnancy and across the postpartum year carry long-term implications for children's emotion regulation, stress management, and symptom formation. We propose a new conceptual model of HEALthy Father Brain that describes how a father's brain serves as a source of resilience in the context of family adversity and its capacity to "heal", protect, and foster social brain maturation and functionality in family members via paternal sensitivity, attunement, and support, which, in turn, promote child development and healthy family functioning. Father's brain provides a unique model on neural plasticity as sustained by committed acts of caregiving, thereby affording a novel perspective on the brain basis of human affiliation.

Early Life Adversity and Males: Biology, Behavior, and Implications for Fathers' Parenting

Fathers have an important and unique influence on child development, but influences on fathers' parenting have been vastly understudied in the scientific literature. In particular, very little empirical research exists on the effects of early life adversity (ELA; e.g. childhood maltreatment, parental separation) on later parenting among fathers. In this review, we draw from both the human and non-human animal literature to examine the effects of ELA, specifically among males, in the following areas: 1) neurobiology and neurocognitive functioning, 2) hormones and hormone receptors, 3) gene-environment interactions and epigenetics, and 4) behavior and development. Based on these findings, we present a conceptual model to describe the biological and behavioral pathways through which exposure to ELA may influence parenting among males, with a goal of guiding future research and intervention development in this area. Empirical studies are needed to improve understanding of the relationship between ELA and father's parenting, inform the development of paternal and biparental interventions, and prevent intergenerational transmission of ELA.

Parental Reflective Functioning as a Moderator of the Link Between Prematurity and Parental Stress

We examined group differences between parents, both mothers and fathers, of premature and full-term infants to determine whether they differed in their reports of subjective parenting stress and in their level of parental reflective functioning (PRF). We also tested whether each parent's reflective functioning moderated the links between birth status (prematurity vs. full-term) and parenting stress. A sample of 73 cohabiting, heterosexual Israeli families with a premature (28-36th week gestational age, N = 34) or full-term infant (37th week and above gestational age, N = 39) participated, comprising the two parents' groups. Infants' age averaged 7.07 months (SD = 1.28). Each parent completed the Parent Stress Inventory (PSI) individually to determine his/her subjective personal and childrearing stress levels. The Parent Development Interview (PDI-R2-S) was used to obtain each parent's PRF (self and child/relation-focused) level. Findings showed that the premature and full-term parents did not differ in their PSI scores or PRF levels. However, mothers' self-focused PRF moderated the link between prematurity and personal parenting stress, whereas fathers' self-focused PRF moderated the link between prematurity and childrearing parenting stress. Furthermore, fathers' and mothers' PRF operated differently in the premature and full-term parents' groups. The findings highlight the importance of mothers' and fathers' PRF in predicting parents' subjective stress in general and particularly in the case of infant prematurity. We discuss these findings and their relevance for preventive and therapeutic perinatal interventions.

Recent Neuroscience Advances in Human Parenting

The transition to parenthood entails brain adaptations to the demands of caring for a newborn. This chapter reviews recent neuroscience findings on human parenting, focusing on neuroimaging studies. First, we describe the brain circuits underlying human maternal behavior, which comprise ancient subcortical circuits and more sophisticated cortical regions. Then, we present the short-term and long-term functional and structural brain adaptations that characterize the transition to motherhood, discuss the long-term effects of parenthood on the brain, and propose several underlying neural mechanisms. We also review neuroimaging findings in biological fathers and alloparents (such as other relatives or adoptive parents), who engage in parenting without directly experiencing pregnancy or childbirth. Finally, we describe perinatal mental illnesses and discuss the neural responses associated with such disorders. To date, studies indicate that parenthood is a period of enhanced brain plasticity within brain areas critical for cognitive and social processing and that both parenting experience and gestational-related factors can prime such plasticity.

Neural Representation of the Parent-Child Attachment from Infancy to Adulthood

Attachment theory is built on the assumption of consistency; the mother–infant bond is thought to underpin the life-long representations individuals construct of attachment relationships. Still, consistency in the individual’s neural response to attachment-related stimuli representing his or her entire relational history has not been investigated. Mothers and children were followed across two decades and videotaped in infancy (3–6 months), childhood (9–12 years) and young adulthood (18–24 years). In adulthood, participants underwent functional magnetic resonance imaging while exposed to videos of own mother–child interactions (Self) vs unfamiliar interactions (Other). Self-stimuli elicited greater activations across preregistered nodes of the human attachment network, including thalamus-to-brainstem, amygdala, hippocampus, anterior cingulate cortex (ACC), insula and temporal cortex. Critically, self-stimuli were age-invariant in most regions of interest despite large variability in social behavior, and Bayesian analysis showed strong evidence for lack of age-related differences. Psycho–physiological interaction analysis indicated that self-stimuli elicited tighter connectivity between ACC and anterior insula, consolidating an interface associating information from exteroceptive and interceptive sources to sustain attachment representations. Child social engagement behavior was individually stable from infancy to adulthood and linked with greater ACC and insula response to self-stimuli. Findings demonstrate overlap in circuits sustaining parental and child attachment and accord with perspectives on the continuity of attachment across human development.

Maternal chemosignals enhance infant-adult brain-to-brain synchrony

Maternal body odors serve as important safety-promoting and social recognition signals, but their role in human brain maturation is largely unknown. Utilizing ecological paradigms and dual- electroencephalography recording, we examined the effects of maternal chemosignals on brain-to-brain synchrony during infant-mother and infant-stranger interactions with and without the presence of maternal body odors. Neural connectivity of right-to-right brain theta synchrony emerged across conditions, sensitizing key nodes of the infant’s social brain during its maturational period. Infant-mother interaction elicited greater brain-to-brain synchrony; however, maternal chemosignals attenuated this difference. Infants exhibited more social attention, positive arousal, and safety/approach behaviors in the maternal chemosignals condition, which augmented infant-stranger neural synchrony. Human mothers use interbrain mechanisms to tune the infant’s social brain, and chemosignals may sustain the transfer of infant sociality from the mother-infant bond to life within social groups.

Prenatal mother-father cortisol linkage predicts infant executive functions at 24 months

The present study investigated associations between prenatal mother-father cortisol linkage and infant executive functions. Data come from an international sample (N = 358) of predominantly white and middle- to upper-class first-time parents. During late pregnancy, parents collected diurnal salivary cortisol samples and reported on levels of psychological stress. At 24 months, children completed a battery of executive function tasks. Parent cortisol linkage was operationalized as the time-dependent, within-dyad association between maternal and paternal diurnal cortisol. Results indicated that prenatal linkage was positively related to infant executive functions, suggesting that stronger mother-father cortisol linkage was associated with higher executive function scores. Additionally, this relation was moderated by paternal average cortisol levels such that executive function scores were lower when fathers had higher average cortisol levels and linkage was weak. This association suggests that elevated paternal cortisol amplifies the negative relation between lower cortisol linkage and lower infant executive function scores. Importantly, these findings were observed while controlling for observational measures of caregiving and self-report measures of psychosocial functioning and infant social-emotional behavior. These results suggest that prenatal linkage of mother's and father's stress physiology plays a potentially important part in programming and regulating infant neurocognitive development.

Developmental trajectories of infant nighttime awakenings are associated with infant-mother and infant-father attachment security

This longitudinal study examined developmental trajectories of infant sleep problems from 3 to 24 months old and investigated associations with infant-parent attachment security and dependency. In a sample of 107 Israeli families, number and duration of infant nighttime awakenings were measured at 3, 6, 9, and 24 months old, using mothers' and fathers' reports on the Brief Infant Sleep Questionnaire (BISQ). Infant-parent attachment security and infant-parent dependency was assessed at 24 months old, using the observer Attachment Q-Sort procedure (AQS) with both parents. Latent growth curve models showed a non-linear decline in number and duration of infant nighttime awakenings over time. A higher number and longer duration of infant nighttime awakenings at 3 months were associated with higher infant-father attachment security at 24 months. In contrast, longer infant nighttime awakenings at 3 months were predictive of lower infant-mother attachment security at 24 months. A steeper decrease in duration of infant nighttime awakenings was associated with higher infant-father attachment security and lower infant-mother attachment security. As a potential mechanism, paternal involvement in nighttime caregiving was explored in relation to infant-father attachment security. Results of our post-hoc analyses revealed no significant associations between paternal involvement in nighttime caregiving and infant-father attachment security. Our results highlight the need to examine potential mechanisms explaining the divergent associations of infant sleep problems with infant-mother and infant-father attachment security in future research.

How do expectant fathers respond to infant cry? Examining brain and behavioral responses and the moderating role of testosterone

Expectant parents’ responses to infant cry may indicate future risk and resiliency in the parent-child relationship. Most studies of parental reactivity to infant cry have focused on mothers, and few studies have focused on expectant fathers, although fathers make important contributions to parenting. Additionally, although different responses to infant cry (behavioral, psychological and neural) are hypothesized to track together, few studies have analyzed them concurrently. The current investigation aimed to address these gaps by characterizing multimodal responses to infant cry within expectant fathers and testing whether prenatal testosterone moderates these responses. Expectant fathers responded to infant cry vs frequency-matched white noise with increased activation in bilateral areas of the temporal lobe involved in processing speech sounds and social and emotional stimuli. Handgrip force, which has been used to measure parents’ reactivity to cry sounds in previous studies, did not differentiate cry from white noise within this sample. Expectant fathers with higher prenatal testosterone showed greater activation in the supramarginal gyrus, left occipital lobe and precuneus cortex to cry sounds. Expectant fathers appear to interpret and process infant cry as a meaningful speech sound and social cue, and testosterone may play a role in expectant fathers’ response to infant cry.

Early maternal and paternal caregiving moderates the links between preschoolers' reactivity and regulation and maturation of the HPA-immune axis

While early caregiving and child's temperamental dispositions work in concert to shape social-emotional outcomes, their unique and joint contribution to the maturation of the child's stress and immune systems remain unclear. We followed children longitudinally from infancy to preschool to address the buffering effect of early parenting on the link between temperamental dysregulation and hypothalamic-pituitary-adrenal (HPA)-immune axis in preschool-aged children. Participants included 47 typically developing children and their 94 parents in both mother-father and two-father families followed across the first 4-years of family formation. In infancy, we observed parent-infant synchrony and measured parental oxytocin; in preschool, we observed temperamental reactivity and self-regulation and assessed children's cortisol and secretory Immunoglobulin A (s-IgA), biomarkers of the stress and immune systems. Greater self-regulation and lower negative emotionality were associated with lower baseline s-IgA and cortisol, respectively. However, these links were defined by interactive effects so that preschoolers with low self-regulation displayed higher s-IgA levels only in cases of low parent-infant synchrony and negative emotionality linked with greater baseline cortisol levels only when parental oxytocin levels were low. Results emphasize the long-term stress-buffering role of the neurobiology of parental care, demonstrate comparable developmental paths for mothers and fathers, and delineate the complex developmental cascades to the maturation of children's stress-management systems.

Differences in mother-child and father-child RSA synchrony: Moderation by child self-regulation and dyadic affect

Parents and preschoolers show respiratory sinus arrhythmia (RSA) synchrony, but it is unclear how child self-regulation and the dyadic affective climate shape RSA synchrony and how synchrony differs for mothers and fathers. We examined child average RSA, externalizing problems, and dyadic positive affect as moderators of the synchrony of dynamic, within-epoch child and parent RSA reactivity during a challenging task. Mothers (N = 82) and fathers (N = 60) oversampled for familial risk participated with their 3-year-olds. For mothers, when children showed either higher externalizing or lower average RSA, negative RSA synchrony was observed as dynamic coupling of maternal RSA augmentation and child RSA withdrawal, suggesting inadequate support of the child during challenge. However, when children showed both higher externalizing and lower average RSA, indicating greater regulatory difficulties overall, positive synchrony was observed as joint RSA withdrawal. The same patterns were found for father-child RSA synchrony but instead with respect to the moderators of higher externalizing and lower dyadic positive affect. Findings suggest moderators of RSA synchrony differ by parent and shared positive affect plays a robust role in fathers' RSA reactivity and synchrony. Mothers may be more attuned to children's regulatory capacities, whereas fathers may be more influenced by the immediate behavioral context.

Transgender fathering: Children's psychological and family outcomes

Medical advances in assisted reproductive technology have created new ways for transgender persons to become parents outside the context of adoption. The limited empirical data does not support the idea that trans-parenthood negatively impacts children’s development. However, the question has led to lively societal debates making the need for evidence-based studies urgent. We aimed to compare cognitive development, mental health, gender identity, quality of life and family dynamics using standardized instruments and experimental protocols in 32 children who were conceived by donor sperm insemination (DSI) in French couples with a cisgender woman and a transgender man, the transition occurring before conception. We constituted two control groups matched for age, gender and family status. We found no significant difference between groups regarding cognitive development, mental health, and gender identity, meaning that neither the transgender fatherhood nor the use of DSI had any impact on these characteristics. The results of the descriptive analysis showed positive psycho-emotional development. Additionally, when we asked raters to differentiate the family drawings of the group of children of trans-fathers from those who were naturally conceived, no rater was able to differentiate the groups above chance levels, meaning that what children expressed through family drawing did not indicate cues related to trans-fatherhood. However, when we assessed mothers and fathers with the Five-Minute Speech Sample, we found that the emotions expressed by transgender fathers were higher than those of cisgender fathers who conceived by sex or by DSI. We conclude that the first empirical data regarding child development in the context of trans-parenthood are reassuring. We believe that this research will also improve transgender couple care and that of their children in a society where access to care remains difficult in this population. However, further research is needed with adolescents and young adults.

Exploring the hormonal and neural correlates of paternal protective behavior to their infants

Infant protection is an important but largely neglected aspect of parental care. Available theory and research suggest that endocrine levels and neural responses might be biological correlates of protective behavior. However, no research to date examined associations between these neurobiological and behavioral aspects. This study, preregistered on https://osf.io/2acxd, explored the psychobiology of paternal protection in 77 new fathers by combining neural responses to infant-threatening situations, self-reported protective behavior, behavioral observations in a newly developed experimental set-up (Auditory Startling Task), and measurements of testosterone and vasopressin. fMRI analyses validated the role of several brain networks in the processing of infant-threatening situations and indicated replicable findings with the infant-threat paradigm. We found little overlap between observed and reported protective behavior. Robust associations between endocrine levels, neural responses, and paternal protective behavior were absent.

Paternal Deprivation and Female Biparental Family Rearing Induce Dendritic and Synaptic Changes in Octodon degus: I. Medial Prefrontal Cortex

In most mammalian species parent-offspring interactions during early life periods primarily comprise social contacts with the mother, whereas the role of males in parental care is one of the most overlooked and understudied topics. The present study addressed the hypothesis that the complete deprivation of paternal care delays or permanently retards synaptic connectivity in the brain, particularly in the medial prefrontal cortex (mPFC) of the offspring in a sex-specific manner. Another aim of this study was to address the question whether and in which way replacing the father with a female caregiver (in our experiments the “aunt”) can “buffer” the detrimental effects of paternal deprivation on neuronal development. The comparison of: (a) single mother rearing; (b) biparental rearing by father and mother; and (c) biparental rearing by two female caregivers revealed that: (i) paternal care represents a critical environmental factor for synaptic and dendritic development of pyramidal neurons in the vmPFC of their offspring; (ii) a second female caregiver (“aunt”) does not “buffer” the neuronal consequences of paternal deprivation; and that (iii) neuronal development in the vmPFC is differentially affected in male and female offspring in response to different family constellations.

Pathways linking childhood trauma to rural, unmarried, African American father involvement through oxytocin receptor gene methylation

Father involvement contributes uniquely to children's developmental outcomes. The antecedents of father involvement among unmarried, African American fathers from rural areas, however, have been largely overlooked. The present study tested a conceptual model linking retrospective reports of childhood trauma and early adulthood social instability to father involvement among unmarried, African American men living in resource-poor, rural communities in the southeastern United States. We hypothesized these factors would influence father involvement indirectly, via DNA methylation of the oxytocin receptor gene (OXTR). A sample of 192 fathers participated in 3 waves of data collection in early adulthood. Fathers reported on social instability at Wave 1; OXTR methylation was assessed via saliva samples at Wave 2; and measures of father involvement, retrospective childhood trauma, and quality of the fathers' relationships with their children's mothers were collected at Wave 3. Structural equation modeling indicated that childhood trauma was related directly to reduced levels of father involvement and to increased social instability. Social instability was associated with elevated levels of OXTR methylation, which in turn predicted decreased father involvement. The indirect effect from social instability to father involvement via OXTR methylation was significant. These associations did not operate through fathers' relationship with the child's mother and remained significant even accounting for associations between interparental relationship quality and father involvement. Findings suggest that OXTR methylation might be a biological mechanism linking social instability to father involvement among unmarried, African American fathers in vulnerable contexts and underscore the detrimental influence of childhood trauma on father involvement. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

What is resilience: an affiliative neuroscience approach

Resilience - a key topic in clinical science and practice - still lacks a clear conceptualization that integrates its evolutionary and human-specific features, refrains from exclusive focus on fear physiology, incorporates a developmental approach, and, most importantly, is not based on the negation (i.e., absence of symptoms following trauma). Building on the initial condition of mammals, whose brain matures in the context of the mother's body and caregiving behavior, we argue that systems and processes that participate in tuning the brain to the social ecology and adapting to its hardships mark the construct of resilience. These include the oxytocin system, the affiliative brain, and biobehavioral synchrony, all characterized by great flexibility across phylogenesis and ontogenesis. Three core features of resilience are outlined: plasticity, sociality and meaning. Mechanisms of sociality by which coordinated action supports diversity, endurance and adaptation are described across animal evolution. Humans' biobehavioral synchrony matures from maternal attuned behavior in the postpartum to adult-adult relationships of empathy, perspective-taking and intimacy, and extends from the mother-child relationship to other affiliative bonds throughout life, charting a fundamental trajectory in the development of resilience. Findings from three high-risk cohorts, each tapping a distinct disruption to maternal-infant bonding (prematurity, maternal depression, and early life stress/trauma), and followed from birth to adolescence/young adulthood, demonstrate how components of the neurobiology of affiliation confer resilience and uniquely shape the social brain.

Oxytocin and CD38 in the paraventricular nucleus play a critical role in paternal aggression in mice

In mammals, the development of healthy offspring requires maternal care. Behavior by lactating mothers toward other individuals is an important component of maternal aggression. However, it is unclear whether fathers display aggression primed by pups (an external factor), and the protection mechanism is poorly understood. To address this question, we examined paternal aggression in the ICR mouse strain. We found that sires exposed to cues from pups and lactating dams showed stronger aggression toward intruders than did sires that were deprived of family cues or exposed to nonlactating mates. c-Fos immunohistochemistry showed that cells in both the paraventricular and supraoptic nuclei (PVN and SON, respectively) in the hypothalamus of sires exposed to any cues were highly activated. However, c-Fos activation in oxytocinergic neurons was increased only in sires exposed to pup cues and solely in the PVN. In Cd38-knockout sires, the presence of pups induced no or reduced parental aggression; however, this phenotype was recovered, that is, aggression increased to the wild-type level, after intraperitoneal administration of oxytocin (OT). Specific c-Fos activation patterns induced by pup cues were not found in the PVN of knockout sires. These results demonstrate that the PVN is one of the primary hypothalamic areas involved in paternal aggression and suggest that a CD38-dependent OT mechanism in oxytocinergic neurons is critical for part of the behavior associated with the protection of offspring by nurturing male mice.

Levers and barriers to success in the use of translational neuroscience for the prevention and treatment of mental health and promotion of well-being across the lifespan

Neuroscientific tools and approaches such as neuroimaging, measures of neuroendocrine and psychoneuroimmune activity, and peripheral physiology are increasingly used in clinical science and health psychology research. We define translational neuroscience (TN) as a systematic, theory-driven approach that aims to develop and leverage basic and clinical neuroscientific knowledge to aid the development and optimization of clinical and public health interventions. There is considerable potential across basic and clinical science fields for this approach to provide insights into mental and physical health pathology that had previously been inaccessible. For example, TN might hold the potential to enhance diagnostic specificity, better recognize increased vulnerability in at-risk populations, and augment intervention efficacy. Despite this potential, there has been limited consideration of the advantages and limitations of such an approach. In this article, we articulate extant challenges in defining TN and propose a unifying conceptualization. We illustrate how TN can inform the application of neuroscientific tools to realistically guide clinical research and inform intervention design. We outline specific leverage points of the TN approach and barriers to progress. Ten principles of TN are presented to guide and shape the emerging field. We close by articulating ongoing issues facing TN research. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Dads: Progress in understanding the neuroendocrine basis of human fathering behavior

We outline the progress on the hormonal basis of human paternal behavior during the past twenty years. Advances in understanding the roles of testosterone, prolactin, oxytocin and vasopressin in fathering behavior are described, along with recent research on hormonal interactions, such as those between testosterone and cortisol, and testosterone and the peptide hormones. In addition, we briefly describe the recent leaps forward in elucidating the neurobiological and neuroendocrine basis of fatherhood, made possible by fMRI technology. Emerging from this literature is a developing and complicated story about fatherhood, highlighting the need to further understand the interplay between behavior, physiology, social context, and individual genetic variation. Given the changing roles of parents in many societies, the continued growth of this research area will provide a strong empirical knowledge base about paternal behavior on which to create policies promoting fathers' involvement in their infants' lives.

Preventing Postpartum Depression With Mindful Self-Compassion Intervention: A Randomized Control Study

Mindfulness and self-compassion are reported to have a preventive effects on depression and anxiety disorders. In the present study, we aimed to assess the effect of mindful self-compassion intervention on preventing postpartum depression in a group of symptomatic pregnant women. Participants were screened and assigned to the intervention and control groups randomly. A 6-week Internet-based Mindful Self-Compassion Program was used to train the participants. Multiple scales were used to assess depressive and anxiety symptoms, mindfulness, self-compassion, and mother and infant well-being. All assessments were performed at three time points: baseline, 3 months, and 1 year postpartum. Compared with the control group, the intervention group showed significant improvement in depressive and anxiety behaviors. In addition, the intervention group became more mindful and self-compassionate at 3 months and 1 year postpartum. More importantly, both mothers and infants experienced substantial improvement in well-being. Our findings indicate that mindful self-compassion intervention is effective in preventing postpartum depression and promoting mother and infant well-being.

Vasopressin and parental expressed emotion in the transition to fatherhood

In the last decades, parenting researchers increasingly focused on the role of fathers in child development. However, it is still largely unknown which factors contribute to fathers' beliefs about their child, which may be crucial in the transition to fatherhood. In the current randomized within-subject experiment, the effect of nasal administration of vasopressin (AVP) on both Five Minute Speech Sample-based (FMSS) expressed emotion and emotional content or prosody was explored in 25 prospectivefathers. Moreover, we explored how the transition to fatherhood affected these FMSS-based parameters, using prenatal and early postnatal measurements. Analyses revealed that FMSS-based expressed emotion and emotional content were correlated, but not affected by prenatal AVP administration. However,child's birth was associated with an increase in positivity and a decrease in emotional prosody, suggesting that the child's birth is more influential with regard to paternal thoughts and feelings than prenatal AVP administration.

Father Involvement in Infant Parenting in an Ethnically Diverse Community Sample: Predicting Paternal Depressive Symptoms

Early paternal involvement in infant care is beneficial to child and maternal health, and possibly for paternal mental health. The purpose of the present study was to examine the relationship between fathers' involvement in early infant parenting and their depressive symptoms during the infant's first year in a sample of 881 low-income Black, Hispanic, and White fathers recruited from five sites in the United States (urban, mixed urban/suburban, rural). Home interviews at 1 month after birth assessed three concepts based on prior research and community input: (1) time spent with the infant, (2) parenting self-efficacy, (3) material support for the baby. Paternal depressive symptoms at 1, 6, and 12 months after the birth of a child were assessed with the Edinburgh Postpartum Depression Scale. Generalized estimating equations tested whether the three indicators of father involvement at 1 month after birth predicted lower subsequent paternal depressive symptoms controlling for social and demographic variables. For fathers, greater time spent with the infant, parenting self-efficacy, and material support were all significantly associated with lower paternal depressive symptoms during the first year. When risk of depression (scores > 9) was examined, only parenting self-efficacy among fathers was associated with higher likelihood of clinical depression. Findings have implications for future research on mechanisms linking paternal involvement and paternal mental health, and for possible paid paternal leave policies in the future.

The neural mechanisms and consequences of paternal caregiving

In recent decades, human sociocultural changes have increased the numbers of fathers that are involved in direct caregiving in Western societies. This trend has led to a resurgence of interest in understanding the mechanisms and effects of paternal care. Across the animal kingdom, paternal caregiving has been found to be a highly malleable phenomenon, presenting with great variability among and within species. The emergence of paternal behaviour in a male animal has been shown to be accompanied by substantial neural plasticity and to be shaped by previous and current caregiving experiences, maternal and infant stimuli and ecological conditions. Recent research has allowed us to gain a better understanding of the neural basis of mammalian paternal care, the genomic and circuit-level mechanisms underlying paternal behaviour and the ways in which the subcortical structures that support maternal caregiving have evolved into a global network of parental care. In addition, the behavioural, neural and molecular consequences of paternal caregiving for offspring are becoming increasingly apparent. Future cross-species research on the effects of absence of the father and the transmission of paternal influences across generations may allow research on the neuroscience of fatherhood to impact society at large in a number of important ways.

Birth of a Father: Fathering in the First 1,000 Days

As a result of societal changes, fathers participate more actively in child care than they used to. In this article, we propose a context-dependent biobehavioral model of emergent fatherhood in which sociocultural, behavioral, hormonal, and neural factors develop and interact during the first 1,000 days of fatherhood. Sociocultural factors, including different expectations of fathers and varying opportunities for paternal caregiving through paid paternal leave, influence paternal involvement. Levels of hormones (e.g., testosterone, vasopressin, oxytocin, cortisol) predict fathers' parenting behaviors, and involvement in caregiving in turn affects their hormones and brain responses to infant stimuli. The birth of the first child marks the transition to fatherhood and may be a critical period in men's lives, with a smoother transition to fatherhood predicting more optimal involvement by fathers in subsequent years. A focus on prenatal and early postnatal fathering may pave the way for developing interventions that effectively support fathering during pregnancy and in the first years of their children's lives.

Challenging the challenge hypothesis on testosterone in fathers: Limited meta-analytic support

In fathers testosterone levels are suggested to decrease in the context of caregiving, but results seem inconsistent. In a meta-analysis including 50 study outcomes with N = 7,080 male participants we distinguished three domains of research, relating testosterone levels to parental status (Hedges' g = 0.22, 95% CI: 0.09 to 0.35; N = 4,150), parenting quality (Hedges' g = 0.14, 95% CI: 0.03 to 0.24; N = 2,164), and reactivity after exposure to child stimuli (Hedges' g = 0.19, 95% CI: -0.03 to 0.42; N = 766). The sets of study outcomes on reactivity and on parenting quality were both homogeneous. Parental status and (higher) parenting quality were related to lower levels of testosterone, but according to conventional criteria combined effect sizes were small. Moderators did not significantly modify combined effect sizes. Results suggest that publication bias might have inflated the meta-analytic results, and the large effects of pioneering but small and underpowered studies in the domains of males' parental status and parenting quality have not been consistently replicated. Large studies with sufficient statistical power to detect small testosterone effects and, in particular, the moderating effects of the interplay with other endocrine systems and with contextual determinants are required.

Observed infant-parent attachment and brain morphology in middle childhood- A population-based study

Poor quality of the early infant-parent bond predicts later child problems. Infant-parent attachment has been suggested to influence brain development, but this association has hardly been examined. In adults, larger amygdala volumes have been described in relation to early attachment disorganization; neuroimaging studies of attachment in children, however, are lacking. We examined the association between infant-parent attachment and brain morphology in 551 children from a population-based cohort in the Netherlands. Infant-parent attachment was observed with the Strange-Situation Procedure at age 14 months and different brain measures were collected with magnetic resonance imaging at mean age 10 years. Children with disorganized infant attachment had larger hippocampal volumes than those with organized attachment patterns. This finding was robust to the adjustment for confounders and consistent across hemispheres. The association was not explained by cognitive or emotional and behavioral problems. Disorganized attachment did not predict any other difference in brain morphology. Moreover, children with insecure organized infant attachment patterns did not differ from those who were securely attached in any brain outcome. Causality cannot be inferred, but our findings in this large population-based study provide novel evidence for a long-term association between the quality of infant-parent attachment and specific brain differences in childhood.

Mothers, Fathers, and Others: Neural Substrates of Parental Care

Parental care is essential for the survival of offspring in altricial mammalian species. However, in most mammals, virgin females tend to avoid or attack infants. Moreover, most males demonstrate avoidance and aggression toward infants, and have little to no involvement in parental care. What mechanisms suppress avoidance, and support approach towards pups, to promote maternal care? In biparental and cooperatively breeding species, what mechanisms allow nonmothers (i.e., fathers and alloparents) to demonstrate parental care? In this review we consider the mechanisms that subserve parental care in mothers, fathers, and others (i.e., alloparents). We emphasize recent discoveries and research trends with particular emphasis on neuroendocrinology, neuroplasticity, transcriptomics, and epigenetics. Finally, we consider outstanding questions and outline opportunities for future research.

With a little help from her friends (and family) part II: Non-maternal caregiving behavior and physiology in mammals

The diversity of competing frameworks for explaining the evolution of non-maternal care in mammals (Part I, this issue) reflects the vast range of behaviors and associated outcomes these theories attempt to subsume. Caretaking comprises a wide variety of behavioral domains, and is mediated by an equally large range of physiological systems. In Part II, we provide an overview of how non-maternal care in mammals is expressed, the ways in which it is regulated, and the many effects such care has on both recipients and caretakers. We also discuss the two primary ways in which closer integration of ultimate and proximate levels of explanation can be useful when addressing questions about non-maternal caretaking. Specifically, proximate mechanisms provide important functional clues, and are key to testing theory concerning evolutionary tradeoffs. Finally, we highlight a number of methodological and publication biases that currently shape the literature, which provide opportunities for knowledge advancement in this domain going forward. In this conclusion to our two-part introduction, we provide a broad survey of the behavior and physiology that the contributions to this special issue represent.

Single men seeking adoption

It was once impossible anywhere in the world for single adults to adopt children, and this is still the case in many jurisdictions. Elsewhere, however, single adults are now being actively recruited primarily because they are more willing than are married couples to adopt older or disabled children or to adopt across racial or other barriers. This is true for single men as well as for single women, but single men seeking to adopt continue to be widely viewed with skepticism and are reportedly often judged to be inappropriate parents. This paper reviews the sparse fostering and adoption literature on single heterosexual males and addresses the evident ambivalence with which parenting by single men is held among both child and adult mental health professionals. The paper also discusses the parenting styles of mothers and fathers, the ways that the central nervous system in both sexes has been found to respond to parenthood, the similarity of outcomes between single male and single female parenting, and the availability in North America of support and training for foster and adoptive single parents. The paper concludes that, in general, single men have as much to offer an adopted child as do single women and that seeming discrimination against them by childcare agencies requires investigation.

Explaining individual variation in paternal brain responses to infant cries

Crying is the principal means by which newborn infants shape parental behavior to meet their needs. While this mechanism can be highly effective, infant crying can also be an aversive stimulus that leads to parental frustration and even abuse. Fathers have recently become more involved in direct caregiving activities in modern, developed nations, and fathers are more likely than mothers to physically abuse infants. In this study, we attempt to explain variation in the neural response to infant crying among human fathers, with the hope of identifying factors that are associated with a more or less sensitive response. We imaged brain function in 39 first-time fathers of newborn infants as they listened to both their own and a standardized unknown infant cry stimulus, as well as auditory control stimuli, and evaluated whether these neural responses were correlated with measured characteristics of fathers and infants that were hypothesized to modulate these responses. Fathers also provided subjective ratings of each cry stimulus on multiple dimensions. Fathers showed widespread activation to both own and unknown infant cries in neural systems involved in empathy and approach motivation. There was no significant difference in the neural response to the own vs. unknown infant cry, and many fathers were unable to distinguish between the two cries. Comparison of these results with previous studies in mothers revealed a high degree of similarity between first-time fathers and first-time mothers in the pattern of neural activation to newborn infant cries. Further comparisons suggested that younger infant age was associated with stronger paternal neural responses, perhaps due to hormonal or novelty effects. In our sample, older fathers found infant cries less aversive and had an attenuated response to infant crying in both the dorsal anterior cingulate cortex (dACC) and the anterior insula, suggesting that compared with younger fathers, older fathers may be better able to avoid the distress associated with empathic over-arousal in response to infant cries. A principal components analysis revealed that fathers with more negative emotional reactions to the unknown infant cry showed decreased activation in the thalamus and caudate nucleus, regions expected to promote positive parental behaviors, as well as increased activation in the hypothalamus and dorsal ACC, again suggesting that empathic over-arousal might result in negative emotional reactions to infant crying. In sum, our findings suggest that infant age, paternal age and paternal emotional reactions to infant crying all modulate the neural response of fathers to infant crying. By identifying neural correlates of variation in paternal subjective reactions to infant crying, these findings help lay the groundwork for evaluating the effectiveness of interventions designed to increase paternal sensitivity and compassion.