The aim of this article is to examine the relations between two approaches to the measurement of life history (LH) strategies: A traditional approach, termed here the biodemographic approach, measures developmental characteristics like birthweight, gestation length, interbirth intervals, pubertal timing, and sexual debut, and a psychological approach measures a suite of cognitive and behavioral traits such as altruism, sociosexual orientation, personality, mutualism, familial relationships, and religiosity. The biodemographic approach also tends not to invoke latent variables, whereas the psychological approach typically relies heavily upon them. Although a large body of literature supports both approaches, they are largely separate. This review examines the history and relations between biodemographic and psychological measures of LH, which remain murky at best. In doing so, we consider basic questions about the nature of LH strategies: What constitutes LH strategy (or perhaps more importantly, what does not constitute LH strategy)? What is gained or lost by including psychological measures in LH research? Must these measures remain independent or should they be used in conjunction as complementary tools to test tenets of LH theory? Although definitive answers will linger, we hope to catalyze an explicit discussion among LH researchers and to provoke novel research avenues that combine the strengths each approach brings to this burgeoning field.

One of the fundamental concerns of developmental psychology is the nature of continuity and change across development. The present study investigated the continuity of social competence across developmental periods, paying special attention to the transition from middle childhood to adolescence. Using a birth cohort of youths (277 males, 315 females), I examined the stability of social competence across developmental periods, assessed the relation between quality of early parenting and later competence, and tested how timing of pubertal maturation and school transition impact the stability of social competence, using both variable-centered and person-centered analyses. It was expected that social competence would be highly stable across development, but less stable across the transition to adolescence, and that higher quality parenting would predict greater competence among males and females. Furthermore, I expected that pubertal maturation and school transition would deflect trajectories of social competence over time, accentuating individual differences (e.g., socially competent youths would become more competent, whereas incompetent youths would become less competent). As expected, the nature of social competence was fairly stable from early childhood to adolescence, although there is evidence that social competence is less stable as youth transition from early childhood to middle childhood and from middle childhood to adolescence. Moreover, individuals with warm parenting evinced greater social competence across time. Consistent with my hypothesis, off-time pubertal maturation and school transition accentuated individual differences in social competence, increasing social competence among more competent youths, and further diminishing social competence among less competent youths. Finally, I find evidence that experiencing both off-time pubertal maturation and a school transition simultaneously incurred more risk for females, particularly among less competent females, than experiencing only off-time maturation or a school transition. / Psychology

Puberty is the process of becoming sexually mature and it has fundamental somatic and psychosocial implications. The focus of this dissertation was the short and long term developmental significance, concerning both soma et psyche, of female pubertal timing. Four studies were designed to accomplish these aims. Six samples of different ages from different countries and from different time points, comprising several thousand females some of which were followed longitudinally, were used. Age at menarche was used as the primary measure of pubertal maturation. The first main aim of this dissertation was to explore the mechanisms that might explain the well-established link between female pubertal timing and problem behavior, and to identify contextual conditions at which associations are stronger or weaker. Existing explanations are unsatisfactory and little is known about conditions that might affect the strength of the associations. In Paper I, we tested and confirmed a peer socialization hypothesis as a satisfactory explanation for the link between early puberty and problematic adjustment. In short, this hypothesis posits that early developing girls associate with older peers and boyfriends because they feel more mature than their same age peers, and through these peers and boyfriends the early developed girls are channeled into more socially advanced behaviors, including normbreaking. This should be particularly true in contexts where heterosexual relationships are sanctioned and where there is an abundance of deviant youth. In Paper II, I used a biopsychosocial approach and studied pubertal timing along with self-perceptions of maturity and early romantic relationships. The findings revealed that early puberty had very different implications depending on the psychological and social contexts in which it was embedded. For instance, when early puberty was coupled with feeling mature and having early romantic relationships, it was associated with adjustment problems. When early puberty was coupled with neither, it was not linked to particularly high levels of problem behavior. In stark contrast to the vast literature on the role of female pubertal timing in adolescence, the literature on long-term implications is remarkably limited. For this reason, the second main aim of this dissertation was to study the adult implications of female pubertal timing. In Papers III and IV, we examined long term implications of pubertal timing, particularly as it relates to somatic development. The findings suggested that pubertal timing does have future implications for women’s body perception and composition, with early developing females having higher body mass indexes in adulthood, but only under certain circumstances. The findings of this dissertation help further understanding of the soma et psyche implications of female pubertal timing. They indicate that pubertal timing has concurrent and future implications. It seems, however, that timing is not everything. The developmental significance of female pubertal timing appears to be very different under different contextual conditions. Thus, it is only when girls’ psychological and social contexts are considered that fruitful predictions can be made. As such, the findings have important implications for prevention, policy, and practice.

The aim of this project is to examine the relationships between two approaches to the measurement of life history strategies. The traditional method, termed here the biodemographic approach, measures developmental characteristics like birthweight, gestation length, inter-birth intervals, pubertal timing, and sexual debut. The alternative method under exploration, termed here the psychological approach, measures a suite of cognitive and behavioral traits such as altruism, sociosexual orientation, personality, mutualism, familial relationships, and religiosity. Although both approaches are supported by a large body of literature, they remain relatively segregated. This study draws inspiration from both views, integrating measures that assess developmental milestones, including birthweight, prematurity, pubertal timing, and onset of sexual behavior, as well as psychological life history measures such as the Mini-K and a personality inventory. Drawing on previous theoretical work on the fundamental dimensions of environmental risk, these measures are tested in conjunction with several scales assessing the stability of early environmental conditions, including both "event-based" measures that are defined with an external referent, and measures of internal schemata, or the predicted psychological sequelae of early events. The data are tested in a three-part sequence, beginning with the measurement models under investigation, proceeding to an exploratory analysis of the causal network, and finishing with a cross-validation of the structural model on a new sample. The findings point to exciting new directions for future researchers who seek to integrate the two perspectives.

<p>Puberty is the process of becoming sexually mature and it has fundamental somatic and psychosocial implications. The focus of this dissertation was the short and long term developmental significance, concerning both soma et psyche, of female pubertal timing. Four studies were designed to accomplish these aims. Six samples of different ages from different countries and from different time points, comprising several thousand females some of which were followed longitudinally, were used. Age at menarche was used as the primary measure of pubertal maturation. The first main aim of this dissertation was to explore the mechanisms that might explain the well-established link between female pubertal timing and problem behavior, and to identify contextual conditions at which associations are stronger or weaker. Existing explanations are unsatisfactory and little is known about conditions that might affect the strength of the associations.</p><p>In Paper I, we tested and confirmed a peer socialization hypothesis as a satisfactory explanation for the link between early puberty and problematic adjustment. In short, this hypothesis posits that early developing girls associate with older peers and boyfriends because they feel more mature than their same age peers, and through these peers and boyfriends the early developed girls are channeled into more socially advanced behaviors, including normbreaking. This should be particularly true in contexts where heterosexual relationships are sanctioned and where there is an abundance of deviant youth. In Paper II, I used a biopsychosocial approach and studied pubertal timing along with self-perceptions of maturity and early romantic relationships. The findings revealed that early puberty had very different implications depending on the psychological and social contexts in which it was embedded. For instance, when early puberty was coupled with feeling mature and having early romantic relationships, it was associated with adjustment problems. When early puberty was coupled with neither, it was not linked to particularly high levels of problem behavior.</p><p>In stark contrast to the vast literature on the role of female pubertal timing in adolescence, the literature on long-term implications is remarkably limited. For this reason, the second main aim of this dissertation was to study the adult implications of female pubertal timing. In Papers III and IV, we examined long term implications of pubertal timing, particularly as it relates to somatic development. The findings suggested that pubertal timing does have future implications for women’s body perception and composition, with early developing females having higher body mass indexes in adulthood, but only under certain circumstances. The findings of this dissertation help further understanding of the soma et psyche implications of female pubertal timing. They indicate that pubertal timing has concurrent and future implications. It seems, however, that timing is not everything. The developmental significance of female pubertal timing appears to be very different under different contextual conditions. Thus, it is only when girls’ psychological and social contexts are considered that fruitful predictions can be made. As such, the findings have important implications for prevention, policy, and practice.</p>

The timing of pubertal development has important mental and physical health consequences. Individuals who enter puberty off-time are at greater risk for psychological disorders, social difficulties, and physical morbidity. One variable associated with early pubertal development is marital conflict. Life History Theory proposes that marital conflict signals an unreliable environment and promotes advanced pubertal timing to enhance reproductive fitness. Such calibrations allow individuals to unconsciously invest more resources in reproduction, following a quantity over quality approach. Despite research supporting the role of marital conflict in early-onset puberty, research has struggled to find a mechanism for this relationship. The current study examined two possible mediators: emotional insecurity and cortisol levels in a sample of children aged 6-12 years from 2-parent families. Neither variable was supported as a mediator of this relationship. However, parental depression significantly predicted pubertal development for girls. Findings regarding the role of parental depression in the timing of girl’s puberty support life history theory.

To date, no prior research has examined the combined roles of childhood family adversity and pubertal timing in longitudinal pathways to depressive symptomatology in adulthood. The present study was conducted with 225 men and 225 women to explore the unique and combined roles of childhood family adversity and pubertal timing on depressive symptoms in a community sample of married adults. Results for both men and women indicated significant main effects of a cumulatively risky family environment on depressive symptoms, as well as main effects of families with higher levels of abuse and neglect, chaos and disorganization, and interpersonal family conflict. A significant moderating relation was found for women with earlier pubertal timing and higher levels of childhood interpersonal family conflict on greater levels of depressive symptoms in adulthood. No other significant relations were determined in other moderation and mediational analyses. This project furthers our understanding of how the combined roles of pubertal timing and childhood family experiences can clarify the developmental, evolutionary, and clinical theories that link childhood and adolescent experiences to depression in adulthood. Specifically, childhood home environments defined by frequent interpersonal conflict (quarreling, arguing, and shouting), combined with early pubertal development, may play an important role in predicating depressive symptomatology among adult women.

In an attempt to understand girls' involvement conduct problems, this dissertation first reviews two existing theoretical approaches that provide an explanation for the development of conduct problems. Specifically, the available literature on the development and correlates of conduct problems in boys suggests the subtypes of conduct disorder represent two developmental trajectories. The adolescent-onset pathway is associated with deviant peers and few characterological problems, where as the childhood-onset pathway is associated with emotion regulation deficits, negative parenting, callous and unemotional traits, and neurological deficits. Research also suggests a gender-specific model, the delayed-onset model, for the development of conduct problems in girls. Following this theoretical review, differential predictions made by the competing theoretical models are tested in a community sample of school-aged girls and boys. Participants were 202 children (87 males and 115 females) in grades 5-9. The students ranged in age from 10 to 17 years old (M = 13.16). Similar to the total student body, the ethnic breakdown of the sample was as follows: African-American (60%), Caucasian (24%), Hispanic (6%), and Other (5%). Data was also collected from the students' parents and teachers. Results indicated that girls conduct problems did not follow either model in a consistent manner. Specifically, adolescent-onset conduct problem girls, childhood-onset conduct problem boys, and adolescentonset conduct problem boys differed from non-conduct problem children but did not differ significantly amongst themselves on study variables (e.g., deviant peer association, hyperactivity/impulsivity, emotional dysregulation, callous/unemotional traits). However, results suggest that gender-specific risk factors should be taken into account when developing theoretical models for girls' conduct problems. For example, early pubertal maturation is a particularly salient risk factor for conduct problems in girls, and pubertal development interacts with emotion regulation problems to place girls at high risk for deviant behavior. Finally, implications for prevention and intervention as well as future research are discussed.

<p>This thesis outlined a novel operationalization and extension of the thrifty phenotype and fetal overnutrition hypotheses, two evolutionary developmental hypotheses stemming from the developmental origins of health and disease perspective, for developmental pathways from prenatal risk through child growth to early puberty. Support has accumulated for both, but previous studies have not clearly determined which hypothesis better predicts early puberty. Using the Fragile Families and Child Wellbeing Study (<i>n</i>=4898), the thrifty phenotype and fetal overnutrition pathways were tested against each other, separately by sex, and race/ethnicity for adrenal, and gonadal pubertal markers. Results indicated that in general, both hypotheses were supported. Contrary to hypotheses, the thrifty phenotype pathway did not predict perceived pubertal timing better in boys and the fetal overnutrition pathway did not predict perceived pubertal timing best in girls. Instead, both pathways predicted puberty equally well between girls and boys and the fetal overnutrition pathway stemming from maternal gestational weight gain was stronger than the pre-pregnancy BMI pathway. Individual paths of the hypothesized pathways were generally supported when analyzed by race/ethnicity group separately, but support for the entire pathways were sparse. Implications of this work are that pubertal timing may be similarly programmed by restrictive and overnutrition prenatal risks, both should be prioritized, and that interventions for maternal gestational weight should be prioritized over interventions for pre-pregnancy BMI for reducing rates of early puberty. </p>

The genes that regulate pubertal timing in the general population are not well understood. Recently, genome-wide association studies have demonstrated that genetic variants near LIN28B associate with variation in pubertal timing in humans. To investigate where within the hypothalamic-pituitary-ovarian (HPO) axis Lin28b, and its homologue Lin28a, regulate pubertal timing, expression of these genes was assessed across the pubertal transition. The finding that Lin28a/b expression decreases only in the ovary suggests that the Lin28 pathway may exert its regulatory effects with respect to puberty in the ovary. Another aim of this thesis was to examine the effect of estrogen on Lin28b expression in immortalized GnRH neuronal cells, but the data remains equivocal and detailed future studies are needed to make definitive conclusions. The ovarian expression data lay the foundation for further studies using conditional knockout mice to verify the importance of the tissue and age specific developmental pattern that was identified.