Becoming DADS Gettler, Lee T.
Current anthropology,
06/2016, Letnik:
57, Številka:
S13
Journal Article
Recenzirano
Men have the capacity to respond to the transition to fatherhood and nurturant investments in their partners and children with shifts in neuroendocrine function (such as decreased testosterone ...production). This capacity may be adaptive, reflecting fitness benefits accrued by some hominin males who responded to partnering and parenting with neuroendocrine shifts promoting cooperation and investment. These patterns are not uniform inter- or intraculturally, suggesting that cultural dimensions and norms that shape men’s developmental experiences as well as their social and economic roles in adulthood are potentially paramount in the expression of diverse biological responses to fatherhood. Here, I draw extensively on animal models and human studies demonstrating the effects of early-life parenting experiences on the function of neuroendocrine systems in adulthood. Based on my team’s research in Cebu, Philippines, and other anthropological studies, I propose a new model (dedication, attitude, duration, and salience DADS) that provides a framework for interpreting diverse human paternal biological profiles by integrating across multiple explanatory scales. Specifically, I use this model as an exemplar to highlight the utility of integrating evolutionary and phylogenetic perspectives with those focusing on the developmental niche, early-life influences on neuroendocrine system function (developmental plasticity and programming), and the broad influence of cultural processes and political economy.
Owing to humans' unique life history pattern, particularly comparatively short interbirth intervals, early weaning, and prolonged support of multiple dependents, human females have greater ...reproductive value and higher lifetime fertility, on average, than do their Great Ape counterparts. As hominin females began weaning their young early and “stacking” dependents of various ages, they must have had cooperative allomaternal care partners already in place or been successful at concurrently soliciting help to ensure a high rate of survival of their offspring. Following Hrdy, I define allomaternal care (and its derivatives, such as “allomothers” and “allomothering”) as “care from anyone other than the mother,” which thus encompasses a wide range of individuals, including fathers. Who the likely allomother candidates mothers were and what form that cooperation took remain intriguing, difficult‐to‐answer questions, which are limited, in some capacity, by the lines of evidence available to us. Here, I present a framework for the ways in which we can integrate neurobiological‐endocrine and social‐behavioral data (“socioendocrinology”) to contribute to this dialogue in terms of evaluating fathers' roles.
In species in which males care for young, testosterone (T) is often high during mating periods but then declines to allow for caregiving of resulting offspring. This model may apply to human males, ...but past human studies of T and fatherhood have been cross-sectional, making it unclear whether fatherhood suppresses T or if men with lower T are more likely to become fathers. Here, we use a large representative study in the Philippines (n = 624) to show that among single nonfathers at baseline (2005) (21.5 ± 0.3 y), men with high waking T were more likely to become partnered fathers by the time of follow-up 4.5 y later (P < 0.05). Men who became partnered fathers then experienced large declines in waking (median: –26%) and evening (median: –34%) T, which were significantly greater than declines in single nonfathers (P < 0.001). Consistent with the hypothesis that child interaction suppresses T, fathers reporting 3 h or more of daily childcare had lower T at follow-up compared with fathers not involved in care (P < 0.05). Using longitudinal data, these findings show that T and reproductive strategy have bidirectional relationships in human males, with high T predicting subsequent mating success but then declining rapidly after men become fathers. Our findings suggest that T mediates tradeoffs between mating and parenting in humans, as seen in other species in which fathers care for young. They also highlight one likely explanation for previously observed health disparities between partnered fathers and single men.
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.
•Non-maternal care occurs in a wide variety of behavioral domains.•It is mediated by a diverse array of physiological processes.•Integrating proximate mechanisms provides important insights on function and costs.•Social neuroendocrinology is a model for integrating other physiological processes.•Current literature biases do not necessarily capture evolutionary relevance.
In the class Mammalia, most young are cared for exclusively by their mothers. In species where mothers receive help, however, non-maternal caregivers may play a crucial role in development and life ...history trajectories. In turn, recipients of such care may have important impacts on caregivers of all types. In Part I of this overview, we briefly review the evolutionary barriers to widespread non-maternal care in mammals, and explain why the exceptions are of particular theoretical importance. We also summarize the current understanding of the selective forces leading to non-maternal care, and the taxa and types of caretakers amongst which it occurs. Finally, we argue for a fresh look at the categorization schemes that have traditionally been used to separate various types of mammalian non-maternal caregivers. This two-part introduction is aimed at scientists from multiple disciplines who study diverse organismal systems. It draws from the social and biological sciences literatures to provide an overview of this special issue of Physiology and Behavior's suite of methodological offerings and theoretical underpinnings.
•In most mammals, only mothers care for young.•Exceptions are important for understanding sociality and reproductive strategies.•Kin selection, outside options, reciprocity, life history traits are key determinants.•Fathers share key characteristics and tradeoffs with other non-maternal caretakers.•Physiological processes unite diverse socioecologies in which such care occurs.
Unlike most mammals, human fathers cooperate with mothers to care for young to an extraordinary degree. Human paternal care likely evolved alongside our unique life history strategy of raising ...slow-developing, energetically costly children, often in rapid succession. Adaptive frameworks generally assume that paternal provisioning played a critical role in this pattern's emergence. We draw on nonhuman primate data to propose that nonprovisioning forms of low-cost hominin male care were potentially foundational and ratcheted up through evolutionary time, helping facilitate social contexts for later subsistence specialization and sharing. We then argue for expanding the breadth of anthropological research on paternal effects in families, particularly in three domains: direct care and teaching;social capital cultivation; and reduction of family conflict. Anthropologists can greatly contribute to conversations about the determinants of children's development across contexts, but we need to ask more expansive questions about the pathways through which caregivers (including fathers) affect child outcomes.
As the human-primate interface expands, many nonhuman primate (NHP) populations exploit anthropogenic foods to survive, while some populations opportunistically target them. Though anthropogenic food ...consumption is sometimes associated with greater reproductive output and survival in these populations, there is a dearth of research on possible health effects. We explore how differential exposure to anthropogenic foods is linked to variation in isotopic compositions (δ
C and δ
N) and body weights in Barbary macaques (Macaca sylvanus) in the Upper Rock Nature Reserve, Gibraltar. We placed monkeys into three categories based on anthropogenic food exposure. We then analyzed individuals for isotopic signatures (N = 147) and body weight measurements (N = 80). Using the lowest exposure category as the comparison, we found body weights and δ
N values, but not δ
C values, significantly differed across key categories. Within categories, we found no significant associations between sex and δ
C or δ
N values, suggesting that individuals within categories consumed similar foods regardless of sex. We found a significant interaction effect between category and sex for predicting body weights. These results suggest that sex plays a role in how anthropogenic foods are accessed and consumed regardless of exposure, which may result in differential health profiles for female and male macaques.
Developmental plasticity is particularly important for humans and other primates because of our extended period of growth and maturation, during which our phenotypes adaptively respond to ...environmental cues. The hypothalamus–pituitary–gonadal (HPG) and hypothalamus–pituitary–adrenal (HPA) axes are likely to be principal targets of developmental “programming” given their roles in coordinating fitness‐relevant aspects of the phenotype, including sexual development, adult reproductive and social strategies, and internal responses to the external environment. In social animals, including humans, the social environment is believed to be an important source of cues to which these axes may adaptively respond. The effects of early social environments on the HPA axis have been widely studied in humans, and to some extent, in other primates, but there are still major gaps in knowledge specifically relating to males. There has also been relatively little research examining the role that social environments play in developmental programming of the HPG axis or the HPA/HPG interface, and what does exist disproportionately focuses on females. These topics are likely understudied in males in part due to the difficulty of identifying developmental milestones in males relative to females and the general quiescence of the HPG axis prior to maturation. However, there are clear indicators that early life social environments matter for both sexes. In this review, we examine what is known about the impact of social environments on HPG and HPA axis programming during male development in humans and nonhuman primates, including the role that epigenetic mechanisms may play in this programming. We conclude by highlighting important next steps in this research area.
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