Sexing the baby: Part 2--Applying dynamic systems theory to the emergences of sex-related differences in infants and toddlers

Parents' mental state language and child gender: A scoping review of developmental evidence

Mental state language (MSL) is an important mechanism through which children learn about their social world and place within it. Previous research has suggested that parents may use MSL differently towards children based on their child's gender. However, findings are inconsistent. This scoping review explores the consistency of reported differences in parents' MSL use as a function of children's gender while exploring the methodological variables that may provide insights into these differences. Based on a review of the 27 studies included, 12 found a significant relationship between child gender and parents' MSL, while the remaining did not. The included studies used a range of methodological approaches to elicit MSL. This scoping review allows researchers and practitioners to reflect upon assumptions regarding the associations between child gender and parents' MSL. Further, we call for the use of diverse and informed approaches when studying these associations from a developmental perspective in the future.

Challenging the binary: Gender/sex and the bio-logics of normalcy

BACKGROUND

We are witnessing renewed debates regarding definitions and boundaries of human gender/sex, where lines of genetics, gonadal hormones, and secondary sex characteristics are drawn to defend strict binary categorizations, with attendant implications for the acceptability and limits of gender identity and diversity.

AIMS

Many argue for the need to recognize the entanglement of gender/sex in humans and the myriad ways that gender experience becomes biology; translating this theory into practice in human biology research is essential. Biological anthropology is well poised to contribute to these societal conversations and debates. To do this effectively, a reconsideration of our own conceptions of gender/sex, gender identity, and sexuality is necessary.

METHODS

In this article, we discuss biological variation associated with gender/sex and propose ways forward to ensure we are engaging with gender/sex diversity. We base our analysis in the concept of "biological normalcy," which allows consideration of the relationships between statistical distributions and normative views. We address the problematic reliance on binary categories, the utilization of group means to represent typical biologies, and document ways in which binary norms reinforce stigma and inequality regarding gender/sex, gender identity, and sexuality.

DISCUSSION AND CONCLUSIONS

We conclude with guidelines and methodological suggestions for how to engage gender/sex and gender identity in research. Our goal is to contribute a framework that all human biologists can use, not just those who work with gender or sexually diverse populations. We hope that in bringing this perspective to bear in human biology, that novel ideas and applications will emerge from within our own discipline.

A Dynamic Systems Framework for Gender/Sex Development: From Sensory Input in Infancy to Subjective Certainty in Toddlerhood

From birth to 15 months infants and caregivers form a fundamentally intersubjective, dyadic unit within which the infant's ability to recognize gender/sex in the world develops. Between about 18 and 36 months the infant accumulates an increasingly clear and subjective sense of self as female or male. We know little about how the precursors to gender/sex identity form during the intersubjective period, nor how they transform into an independent sense of self by 3 years of age. In this Theory and Hypothesis article I offer a general framework for thinking about this problem. I propose that through repetition and patterning, the dyadic interactions in which infants and caregivers engage imbue the infant with an embodied, i.e., sensori-motor understanding of gender/sex. During this developmental period (which I label Phase 1) gender/sex is primarily an intersubjective project. From 15 to 18 months (which I label Phase 2) there are few reports of newly appearing gender/sex behavioral differences, and I hypothesize that this absence reflects a period of developmental instability during which there is a transition from gender/sex as primarily inter-subjective to gender/sex as primarily subjective. Beginning at 18 months (i.e., the start of Phase 3), a toddler's subjective sense of self as having a gender/sex emerges, and it solidifies by 3 years of age. I propose a dynamic systems perspective to track how infants first assimilate gender/sex information during the intersubjective period (birth to 15 months); then explore what changes might occur during a hypothesized phase transition (15 to 18 months), and finally, review the emergence and initial stabilization of individual subjectivity-the period from 18 to 36 months. The critical questions explored focus on how to model and translate data from very different experimental disciplines, especially neuroscience, physiology, developmental psychology and cognitive development. I close by proposing the formation of a research consortium on gender/sex development during the first 3 years after birth.

Epistemic Injustice in Brain Studies of (Trans)Gender Identity

This study undertakes an analysis of the conceptualization of gender identity in neuroscientific studies of (trans)gender identity that contrast the brains of cisgender and transgender participants. The analysis focuses on instances of epistemic injustice that combine scientific deficiencies and the exclusion of relevant bodies of knowledge. The results of a content analysis show how the ignoring of biosocial, developmental, mosaicist, contextualist, and depathologizing approaches leads to internal conceptual inconsistencies, hermeneutical deficiencies and the upholding of questionable paradigms in the research field. Interviews with researchers involved in these brain studies reveal targeted and diffuse forms of testimonial injustice against alternative approaches, promoted by the hierarchical arrangements of research teams in combination with the careerist and economic logic of research. The analysis points to the exclusion of critical epistemologies of science and the historical oppression of trans people as epistemic agents as the underlying hermeneutical deficiencies.

Effects of maternal and paternal postnatal depressive symptoms on infants' parasympathetic regulation in low-income, Mexican American families

Mothers and fathers are at elevated risk for developing depression during the first postnatal year, especially among families from marginalized communities. Although a number of studies demonstrate that exposure to maternal depressive symptoms can undermine infants' regulatory development, less is known about the extent to which paternal depressive symptoms may also contribute. The current study investigated whether maternal and paternal depressive symptoms were uniquely associated with infants' physiological regulation, and whether associations varied depending on infant sex. Participants included 90 low-income Mexican American families. Fathers and mothers self-reported their depressive symptoms when infants were 15 weeks old, and infants' resting parasympathetic activity (i.e., respiratory sinus arrhythmia [RSA]) was assessed at 6 and 24 weeks. Results indicated that, after controlling for infant 6-week RSA and depressive symptoms in the other parent, paternal depressive symptoms were associated with lower 24-week RSA for both girls and boys, but maternal depressive symptoms were only associated with lower 24-week RSA for boys. Findings highlight a potential mechanism through which the consequences of parent depressive symptoms may reverberate across generations, and suggest that considerations of both infants' and parents' sex may lend insight into how best to intervene.

The Epistemology of Evolutionary Psychology Offers a Rapprochement to Cultural Psychology

Many detractors of evolutionary psychology (EP) presume that adaptive arguments are nothing more than whimsical and unfalsifiable just-so stories. The reality though is that the epistemology of EP is precisely the opposite of this antiquated canard in that it fixes the evidentiary threshold much higher than is typically achieved by most scientists. EP amasses evidence across cultures, time periods, disciplines, paradigms, methodologies, and units of analyses in validating a given scientific explanation. These nomological networks of cumulative evidence stimulate greater interdisciplinarity, lesser methodological myopia, and increased consilience (unity of knowledge). A component in building such nomological networks is to examine phenomena that are cross-culturally invariant (human universals) versus those that vary cross-culturally as adaptive responses (the domain of behavioral ecologists and gene-culture coevolution modelers). The epistemological efficacy of this unique approach is highlighted using two cases studies, the sex-specificity of toy preferences and men’s preference for the hourglass figure.

Transgender embodiment: a feminist, situated neuroscience perspective

The policing of boundaries of acceptable sexual identities and behaviour is a recurring theme in numerous marginalities. Gender (especially womanhood) is often instantiated socially through the harms to which members of that gender are subjected. For transgender people, the assumption that genitals define gender translates the ubiquitous misapprehension that genitals and sex are binary into an assumption that gender must also be binary. This circumscribes the potentiality of cultural intelligibility for trans gender identities, and may interfere with the ability of transgender people to select the most appropriate medical and social means of expressing their authentic identities, even altering what is possible or appropriate, thereby curtailing trans people’s authenticity and freedom. We therefore distinguish social from bodily aspects of gender dysphoria, proposing a model of their distinct, intersecting origins. We explore ways in which transgender medicine reflects aspects of other gendered surgeries, proposing a biopsychosocial understanding of embodiment, including influences of culture on the neurological representation of the body in the somatosensory cortex. This framework proposes that cultural cissexism, causes trans people to experience (neuro)physiological damage, creating or exacerbating the need for medical transition within a framework of individual autonomy. Our social-constructionist feminist neuroscientific account of gendered embodiment highlights the medical necessity of bodily autonomy for trans people seeking surgery or other biomedical interventions, and the ethical burden therein.

Using Vector Autoregression Modeling to Reveal Bidirectional Relationships in Gender/Sex-Related Interactions in Mother-Infant Dyads

Vector autoregression (VAR) modeling allows probing bidirectional relationships in gender/sex development and may support hypothesis testing following multi-modal data collection. We show VAR in three lights: supporting a hypothesis, rejecting a hypothesis, and opening up new questions. To illustrate these capacities of VAR, we reanalyzed longitudinal data that recorded dyadic mother-infant interactions for 15 boys and 15 girls aged 3 to 11 months of age. We examined monthly counts of 15 infant behaviors and 13 maternal behaviors (Seifer et al., 1994). VAR models demonstrated that infant crawling predicted a subsequently close feedback loop from mothers of boys but a subsequently open-ended, branched response from mothers of girls. A different finding showed that boys' standing independently predicted significant later increases of four maternal behaviors: rocking/jiggling, lifting, affectionate touching, and stimulation of infant gross-motor activity. In contrast, crawling by girls led mothers to later decrease the same maternal behaviors. Thus, VAR might allow us to identify how mothers respond differently during daily interactions depending on infant gender/sex. The present work intends to mainly showcase the VAR method in the specific context of the empirical study of gender/sex development.

Gender/Sex, Sexual Orientation, and Identity Are in the Body: How Did They Get There?

In this review, I explore theoretical and empirical approaches to the development of gender/sex and sexual orientation (SO). Leaving behind the nature versus nurture opposition, I look at both identities as deeply embodied. My approach intertwines sex, gender, orientation, bodies, and cultures without a demand to choose one over the other. First, I introduce basic definitions, focusing on how intertwined the concepts of sex and gender really are. I affirm recent trends to consider a new term-gender/sex-as the best way to think about these deeply interwoven bodily traits. I introduce several literatures, each of which considers the processes by which traits become embodied. These points of view offer a basis for future work on identity development. Specifically, and selectively, I provide insights from the fields of phenomenology, dyadic interaction and the formation of presymbolic representations in infancy, and dynamic systems in infant development. I consider how thinking about embodied cognition helps to address intersubjectivity and the emergence of subjective identity. Next, I review what we currently know about the development of complex sexual systems in infancy and toddlerhood. Finally, I discuss the few existing theories of SO development that consider the events of infancy and childhood.

Polifonia na Produção do Binarismo de Gênero em Brincadeiras na Primeira Infância

Resumo: Estudos sobre desenvolvimento de identificação de gênero têm indicado a presença de estereotipias na escolha de cores, brinquedos e objetos nos primeiros três anos de vida, suscitando discussões sobre método. O objetivo deste artigo é analisar o uso de objetos e sua relação com dinâmicas polifônicas na produção de significados de gênero em brincadeiras. Foram utilizados multimétodos qualitativos com foco em interações diádicas (criança-objeto) e triádicas (adulto-criança-objeto) com quatro meninas de 30 a 36 meses. Uma etapa de entrevista com as cuidadoras também foi incluída. Os dados foram submetidos à análise dialógica temática e relacionados às expectativas de gênero convencionais. Os resultados indicam como os processos de convencionalização ocorrem nas interações orientados para a manutenção do binarismo como dinâmica dominante na produção de subjetividades, em brincadeiras que envolvem: ações de cuidar de si e do outro; regulação de significados e usos de objetos pelas cuidadoras orientadas para o convencional; e ambivalências entre enunciados de gênero.

Sex differences in nonhuman primate behavioral development

Sex differences in behavior and developmental trajectories in human children are of great interest to researchers in a variety of fields, and a persistent topic of discussion and debate is the relative contribution of biological vs. social influences to such differences. Given the potentially large effects of cultural and social influences on human child development, nonhuman primates are important model species for investigating the biological and evolutionary roots of sex differences in human development. This Mini-Review briefly summarizes the existing literature on sex-biased behavior toward infant nonhuman primates by mothers and other social partners, followed by a review of findings on sex differences (or lack thereof) in primate behavioral development from a variety of species in wild and naturalistic settings. These include differences in physical and social development, including play, grooming, and object manipulation patterns, as well as nursing and the development of foraging behavior. The Mini-Review concludes by providing potential avenues for future research. © 2016 Wiley Periodicals, Inc.

DEVELOPMENT AND SOCIALIZATION OF PHYSICAL AGGRESSION IN VERY YOUNG BOYS

The expression of physical aggression is normative in early child development; it peaks in the second year of life, with steep declines for most children by the third and fourth years as children learn alternatives to aggression. Some children, however, fail to demonstrate declines in aggressive acts, and many of these are boys. The current review uses a dynamic systems (DS) approach to identify early individual and contextual factors that may dynamically influence trajectories of aggression as a characteristic way of engaging within communities and relationships. Within the DS framework, we focus on the parent-infant relationship as central to the development of adaptive emotion-regulation capacities of the infant and young child. Biological sex differences that may influence this early relationship are highlighted, as is the influence of contextual processes such as family violence. Clinical implications suggested by both the empirical and theoretical literatures are then described.

PSYCHOLOGY OF BOYS AT RISK: INDICATORS FROM 0-5

In utero and during the first 5 years of life, boys face unique risks as a result of neurobiological and environmental factors. This introductory article to the Special Issue describes the background of this gender-specific inquiry and outlines some of those risks, drawing attention to the areas that will be covered in depth in the following contributions. We also describe the basis of this inquiry as the link between early life and the subsequent difficulties that adolescent boys and many young men face, and pay particular attention to the circumstances of young men of color and to the growing knowledge about the contributions of fathers to boys' development.

Personality and gender differences in global perspective

Men's and women's personalities appear to differ in several respects. Social role theories of development assume gender differences result primarily from perceived gender roles, gender socialization and sociostructural power differentials. As a consequence, social role theorists expect gender differences in personality to be smaller in cultures with more gender egalitarianism. Several large cross-cultural studies have generated sufficient data for evaluating these global personality predictions. Empirically, evidence suggests gender differences in most aspects of personality-Big Five traits, Dark Triad traits, self-esteem, subjective well-being, depression and values-are conspicuously larger in cultures with more egalitarian gender roles, gender socialization and sociopolitical gender equity. Similar patterns are evident when examining objectively measured attributes such as tested cognitive abilities and physical traits such as height and blood pressure. Social role theory appears inadequate for explaining some of the observed cultural variations in men's and women's personalities. Evolutionary theories regarding ecologically-evoked gender differences are described that may prove more useful in explaining global variation in human personality.

Multimodal sex-related differences in infant and in infant-directed maternal behaviors during months three through twelve of development

Using the concepts of sensory and affective experience, this work relates the concepts of socialization and cognitive development to the embodiment of gender in the human infant. Evidence obtained from biweekly observations from 30 children and their mothers observed from age 3 months to age 12 months revealed measurable sex-related differences in how mothers handle and touch their infants. This work offers novel approaches to visualizing combinations of behaviors with the aim of encouraging researchers to think in terms of suites of action rather than singular sensory or motor systems. New avenues of research into the mechanisms which produce sex-related differences in behavior are suggested.

Social Determinants and Health Behaviors: Conceptual Frames and Empirical Advances

Health behaviors shape health and well-being in individuals and populations. Drawing on recent research, we review applications of the widely applied "social determinants" approach to health behaviors. This approach shifts the lens from individual attribution and responsibility to societal organization and the myriad institutions, structures, inequalities, and ideologies undergirding health behaviors. Recent scholarship integrates a social determinants perspective with biosocial approaches to health behavior dynamics. Empirical advances model feedback among social, psychological and biological factors. Health behaviors are increasingly recognized as multidimensional and embedded in health lifestyles, varying over the life course and across place and reflecting dialectic between structure and agency that necessitates situating individuals in context. Advances in measuring and modeling health behaviors promise to enhance representations of this complexity.

The gestational foundation of sex differences in development and vulnerability

Despite long-standing interest in the role of sex on human development, the functional consequences of fetal sex on early development are not well-understood. Here we explore the gestational origins of sex as a moderator of development. In accordance with the focus of this special issue, we examine evidence for a sex differential in vulnerability to prenatal and perinatal risks. Exposures evaluated include those present in the external environment (e.g., lead, pesticides), those introduced by maternal behaviors (e.g., alcohol, opioid use), and those resulting from an adverse intrauterine environment (e.g., preterm birth). We also provide current knowledge on the degree to which sex differences in fetal neurobehavioral development (i.e., cardiac and motor patterns) are present prior to birth. Also considered are contemporaneous and persistent sex of fetus effects on the pregnant woman. Converging evidence confirms that infant and early childhood developmental outcomes of male fetuses exposed to prenatal and perinatal adversities are more highly impaired than those of female fetuses. In certain circumstances, male fetuses are both more frequently exposed to early adversities and more affected by them when exposed than are female fetuses. The mechanisms through which biological sex imparts vulnerability or protection on the developing nervous system are largely unknown. We consider models that implicate variation in maturation, placental functioning, and the neuroendocrine milieu as potential contributors. Many studies use sex as a control variable, some analyze and report main effects for sex, but those that report interaction terms for sex are scarce. As a result, the true scope of sex differences in vulnerability is unknown.

Neurofeminism and feminist neurosciences: a critical review of contemporary brain research

To date, feminist approaches to neurosciences have evaluated the debates surrounding practices of knowledge production within and research results of contemporary brain research. Consequently, neurofeminist scholars have critically examined gendered impacts of neuroscientific research. Feminist neuroscientists also develop research approaches for a more gender-appropriate neuroscientific research on several levels. Based on neurofeminist critique feminist neuroscientists aim to enrich neuroscientific work by offering methodological suggestions for a more differentiated setup of categories and experimental designs, for reflective result presentations and interpretations as well as for the analysis of result validity. Reframing neuro-epistemologies by including plasticity concepts works to uncover social influences on the gendered development of the brain and of behavior. More recently, critical work on contemporary neurocultures has highlighted the entanglements of neuroscientific research within society and the implications of ‘neurofacts’ for gendered cultural symbolisms, social practices, and power relations. Not least, neurofeminism critically analyses the portrayal of neuro-knowledge in popular media. This article presents on overview on neurofeminist debates and on current approaches of feminist neurosciences. The authors conclude their review by calling for a more gender-appropriate research approach that takes into account both its situatedness and reflections on the neuroscientific agenda, but also questions neurofeminist discourse in regards to uses and misuses of its concepts.

Central gender theoretical concepts in health research: the state of the art

Despite increasing awareness of the importance of gender perspectives in health science, there is conceptual confusion regarding the meaning and the use of central gender theoretical concepts. We argue that it is essential to clarify how central concepts are used within gender theory and how to apply them to health research. We identify six gender theoretical concepts as central and interlinked-but problematic and ambiguous in health science: sex, gender, intersectionality, embodiment, gender equity and gender equality. Our recommendations are that: the concepts sex and gender can benefit from a gender relational theoretical approach (i.e., a focus on social processes and structures) but with additional attention to the interrelations between sex and gender; intersectionality should go beyond additive analyses to study complex intersections between the major factors which potentially influence health and ensure that gendered power relations and social context are included; we need to be aware of the various meanings given to embodiment, which achieve an integration of gender and health and attend to different levels of analyses to varying degrees; and appreciate that gender equality concerns absence of discrimination between women and men while gender equity focuses on women's and men's health needs, whether similar or different. We conclude that there is a constant need to justify and clarify our use of these concepts in order to advance gender theoretical development. Our analysis is an invitation for dialogue but also a call to make more effective use of the knowledge base which has already developed among gender theorists in health sciences in the manner proposed in this paper.

Sexing the baby: Part 1--What do we really know about sex differentiation in the first three years of life?

The most common paradigm used to analyze health differences between men and women, is to divide the body from the social environment. In such a model, the bodily contribution and the social contribution add up to 100%. A few health science researchers offer more sophisticated approaches. None, however, offer an intensive study of the first several years of life in order to offer a model which integrates biology and culture in a fashion that demonstrates the productive processes by which gender itself emerges. In this article, we identify the earliest known sex-related biological and behavioral differences in young infants, toddlers and their parents and indicate how these might relate to health and disease. We frame these differences using unifying concepts from the study of neuroplasticity and dynamic systems theory.