Handbook of Parenting

Volume 2: Biology and Ecology of Parenting, Third Edition

Marc H. Bornstein

• Publisher: Routledge
• Year: 2019
• Print ISBN:
  9781138228696
• eBook ISBN:
  9780429685880
• Topic: Psychology
• Subtopic: Developmental Psychology
• Index: Psychology

This highly anticipated third edition of the Handbook of Parenting brings together an array of field-leading experts who have worked in different ways toward understanding the many diverse aspects of parenting. Contributors to the Handbook look to the most recent research and thinking to shed light on topics every parent, professional, and policymaker wonders about. Parenting is a perennially "hot" topic. After all, everyone who has ever lived has been parented, and the vast majority of people become parents themselves. No wonder bookstores house shelves of "how-to" parenting books, and magazine racks in pharmacies and airports overflow with periodicals that feature parenting advice. However, almost none of these is evidence-based. The Handbook of Parenting is. Period. Each chapter has been written to be read and absorbed in a single sitting, and includes historical considerations of the topic, a discussion of central issues and theory, a review of classical and modern research, and forecasts of future directions of theory and research. Together, the five volumes in the Handbook cover Children and Parenting, the Biology and Ecology of Parenting, Being and Becoming a Parent, Social Conditions and Applied Parenting, and the Practice of Parenting.

Volume 2, Biology and Ecology of Parenting, relates parenting to its biological roots and sets parenting in its ecological framework. Some aspects of parenting are influenced by the organic makeup of human beings, and the chapters in Part I, on the Biology of Parenting, examine the evolution of parenting, the psychobiological determinants of parenting in nonhumans, and primate parenting, as well as the genetic, prenatal, neuroendocrinological, and neurobiological bases of human parenting. A deep understanding of what it means to parent also depends on the ecologies in which parenting takes place. Beyond the nuclear family, parents are embedded in, influence, and are themselves affected by larger social systems. The chapters in Part II, on the Ecology of Parenting, examine the ancient and modern histories of parenting as well as epidemiology, neighborhoods, educational attainment, socioeconomic status, culture, and environment to provide an overarching relational developmental contextual systems perspective on parenting.

Part I
Biology of Parenting

1
The Evolution of Parenting and Evolutionary Approaches to Childrearing

David F. Bjorklund and Alyson J. Myers

Introduction

Child and developmental psychologists, sociologists, educators, and policy makers have long viewed parenting and the family as the most significant influence on the developing child. As such, parenting has traditionally been viewed as an important source of “environmental” variability in the long debated (and still controversial) nature/nurture dichotomy. At one level, of course, parenting is a potent part of a child’s environment. An infant’s very survival depends on parents. There is nothing in the external world so critical to a child’s success in life as her or his parents. Yet, parenting also straddles the nature side of the traditional continuum. Parenting is not only important to humans, but it is central to the survival of many species of animals, including all mammals and many birds (Rosenblatt, 2002). Evolutionary biologists have long recognized this fact, arguing that, in order for individuals to get their genes into the next generation, they must make investments in mating and, following conception, parenting (Hamilton, 1964; Trivers, 1972). How much is invested in mating versus parenting will vary among species and between females and males within a species, depending on characteristics of the developing offspring and ecological conditions. But parenting—the care and nurturing of offspring between conception and independence—is universal among mammals and, depending on the species-typical pattern of such investment, influences how offspring are reared.

Homo sapiens, however, have taken parenting to new heights, not simply because of our use of language, advanced cognition, cultural transmission of knowledge, or societal institutions, but also because of the extended period of immaturity of our young. As all mammals, human children are conceived within their mothers’ bodies, fed after birth with mother-produced milk, and eventually mature to be able to fend for themselves. But the period of immaturity and dependency is extended in humans relative to other primates. This prolonged period of youth is seemingly necessitated by the intellectual demands of human society; children cannot learn enough in a decade of life to function effectively in any human group. This intellectual immaturity is accompanied by physical immaturity of offspring that puts extraordinary demands on human parents, surpassing those of any other land mammal. Such pressures have shaped how parents around the world treat children, the structure of the human family, and relationships between women and men.

In this chapter, we provide an evolutionary view of human parenting. In a first section, we review briefly the basic tenets of evolution by natural selection and some of the major ideas of the field of evolutionary psychology, particularly evolutionary developmental psychology. We then review a more specific evolutionary theory, Trivers’s (1972) parental investment theory, which accounts for the amount of investment females and males put into parenting (all actions related to rearing an offspring to reproductive age) versus mating (including the seeking, attaining, and maintaining of a mate). We next examine some of the selection pressures that produced our species, and how those pressures led to patterns of parenting and the structure of the family that characterize our species today. We then take a closer look at some of the factors influencing the decisions parents and other people make for investing in children. The final major section of the chapter examines some of the evolved psychological mechanisms—genetically coded “messages” that, following epigenetic rules, interact with the environment over time to produce behavior—associated with infant-mother attachment, evolved mechanisms underlying neglect, abuse, and infanticide, and how an evolutionary perspective questions the very concept of “parenting” as conventionally defined. In all, we argue that an evolutionary perspective not only tells us where patterns of childrearing came from, but where they may head in the future as ecological conditions change, and how many problems of contemporary parenting can be understood, and perhaps solved.

Principles of Evolution and Evolutionary Developmental Science

Evolution by Natural Selection

The basic ideas behind Charles Darwin’s (1859) great theory of “descent with modification” are surprisingly simple yet frequently misunderstood, particularly when applied to human behavior. The core of evolutionary theory is the concept of natural selection, which, simply stated, refers to individuals who are well suited to their environment leaving more progeny than less well-suited (or less fit) individuals. Natural selection works because there is variation among members of a generation; that is, there are different combinations of physical and behavioral traits among individuals within a species. Critically, these traits, as well as individual differences in these traits, are heritable. Characteristics that result in an individual surviving and reproducing are passed down from one generation to the next, whereas characteristics that are associated with early death or low levels of reproduction decrease in frequency in the population. Characteristics of the individual interact with features of the local ecology, and it is this interaction that is responsible for increases and decreases in characteristics over time. This is the process of selection, and through this process, adaptive changes in individuals, and eventually species, are brought about.

Natural selection is a highly interactive process, involving an active organism’s response to a sometimes changing environment. Evolutionary theorists often use phrases such as “the trait was selected by the environment” as a shorthand to refer to this complex interaction among an organism, heritable traits of that organism, and the environment. However, the term “selection” does not imply some deliberate or foresighted process (e.g., selecting for more “advanced” individuals). Natural selection, and thus evolution, is blind to the future; individuals who fit well with a current environment survive, and those who fit less well die. Nevertheless, the process, although blind, is an active one, reflecting the bidirectional relation between an organism with heritable traits and the environment.

Darwin used the term reproductive fitness to refer to the likelihood that an individual will become a parent and a grandparent. Contemporary evolutionary theorists, taking advantage of the scientific advances in genetics that have occurred since Darwin’s time, use the concept of inclusive fitness (Hamilton, 1964) to take into consideration the influence that an individual may have in getting additional copies of her or his genes into subsequent generations. For example, a child possesses 50% of a parent’s genes. Thus, it is in the parent’s best genetic interest to see that an offspring survives so that copies of the parent’s genes are passed on to grandchildren (each of whom will possess 25% of a grandparent’s genes). A person can further benefit the transmission of her or his genes by helping relatives, who share a smaller percentage of genes. For example, by helping to rear a sister’s four children, each of whom shares, on average, 25% of her genes, a woman can further increase her genetic contribution to the next generation, thereby increasing her inclusive fitness. Of course, none of this happens intentionally or consciously. After all, people do not walk around calculating exactly how related they are to one another before deciding to act altruistically. Rather, the underlying mechanisms are in terms of unconscious evolved “strategies.” Moreover, such patterns are observed in nonhuman mammals, birds, and social insects, indicating that self-awareness is not ordinarily involved.

Principles of Evolutionary Developmental Science

Although the principles of evolution should be the same for physical, behavioral, or cognitive characteristics, psychologists investigating the evolution of behavior or cognition, particularly human behavior or cognition, have made explicit some of these principles. Moreover, developmentalists have added to or modified slightly some of these principles to achieve a better understanding of the role of evolution in contemporary human behavior (e.g., Bjorklund and Ellis, 2014; Bjorklund, Hernández Blasi, and Ellis, 2016; Bjorklund and Pellegrini, 2000, 2002; Geary and Bjorklund, 2000), and we examine briefly some of these principles here.

First, an evolutionary account of behavioral or cognitive characteristics does not imply genetic determinism. Certainly, evolutionary change implies change in the frequency of genes within a population; but evolutionary psychologists argue that behavioral change occurs as a result of a transactional relation between an organism and its environment and that the eventual behavioral phenotype of an organism is not predetermined by its genes. From this perspective, development involves the expression of evolved, epigenetic programs, from conception through old age, as described by the developmental systems approach (e.g., Bjorklund, Ellis, and Rosenberg, 2007; Gottlieb, 2007; Gottlieb, Wahlsten, and Lickliter, 1998). Development occurs as a result of the bidirectional relations between all levels of biological and experiential factors, from the genetic through the cultural. “Experience,” from this perspective, involves not only exogenous events but also self-produced activity, as reflected by the firing of a nerve cell in response to solely endogenous factors. Functioning at one level (e.g., the genetic) influences functioning at adjacent levels (e.g., neuronal) with constant feedback between levels.

Because the experiences of each individual are unique, there should be substantial plasticity in development. Yet, there is much that is universal about humans (or any species), and this seeming discrepancy is resolved when one recognizes that infants of a species, beginning at conception, inherit not only a species-typical genome but also a species-typical environment. To the extent that individuals grow up in environments similar to those of their ancestors, development should follow a species-typical pattern. From the developmental systems perspective, there are no simple cases of either genetic or environmental determinism. Infants are not born as blank slates; evolution has prepared them to “expect” certain types of environments and to process some types of information more readily than others (Bjorklund, 2015). Yet, it is the constant and bidirectional interaction between various levels of organization, which changes over the course of development, that produces behavior. For example, differences in the quality and quantity of parental investment affect children’s development and influence their subsequent reproductive and childcare strategies (e.g., Belsky, Steinberg, and Draper, 1991; Ellis et al., 2012, see discussion to follow).

Second, there is a need for an extended childhood to learn the complexities of human communities. Homo sapiens spend a disproportionate amount of time as prereproductives. From an evolutionary perspective, the benefits associated with an extended period of immaturity must have outweighed the costs. We believe that the most important and difficult things children need to learn are related to the social complexity of human groups (e.g., Alexander, 1989; Bjorklund and Pellegrini, 2002; Dunbar, 2010), although the time to master tool use and food acquisition techniques (e.g., Kaplan and Gangestad, 2005; Kaplan, Hill, Lancaster, and Hurtado, 2000) would also require an extended juvenile period.

Third, many aspects of childhood serve as preparations for adulthood and were selected over the course of evolution. Many sex differences in social and cognitive abilities are good examples (Geary, 2010). Evolutionary psychologists have often focused on sex differences (Hyde, 2014), proposing that women and men have different self-interests and thus have evolved different psychologies. This focus is reflected especially in sex differences with regard to mating, childrearing, and intra-sex competition. However, these behaviors, dispositions, and cognitions do not appear with the first blast of pubertal hormones or on hearing the cries of one’s newborn infant, but have developmental histories, with children adapting their gender-specific behavior to local norms, based on evolved predispositions. Such sex differences should not be viewed as a form of biological determinism, destining women and men to narrow and unchanging roles. Rather, girls and boys are biased toward different environments and experiences via evolved epigenetic rules, and, to the extent that one’s environment supports those biases, children will develop in a species-typical fashion. Although these epigenetic rules may be necessary, they are not sufficient to produce a particular developmental pattern (Bjorklund, 2015; Bjorklund et al., 2007). Human behavior is highly flexible, and although some outcomes are more likely than others, all require environmental support to be realized.

Fourth, different selection pressures operate on organisms at different times in ontogeny. Although some aspects of infancy and childhood can be seen as preparations for adulthood, other features have been selected in evolution to serve an adaptive function at that time in development only and not to prepare the child for later life (Bjorklund, 1997, 2007). For example, some aspects of infancy may serve to foster the attachment between an infant and mother to increase the chances of survival at that time in ontogeny, and not only to prepare the child for later adult relationships. Evolution, we propose, has endowed children (and the juveniles of other species) with many characteristics that adapt them well to their immediate environments and not solely to prepare them for a future one.

Fifth, simply because some social, behavioral, or cognitive tendency was adaptive for our ancestors, does not mean that it continues to be adaptive for modern humans. Similarly, just because some tendencies (such as violence among young adult males) are “natural” based on evolutionary examination, does not mean that they are morally “good,” excusable, or inevitable. For example, humans’ penchant for sweet and fatty foods can be seen as a formerly adaptive disposition that, in modern environments with grocery stores and Ben and Jerry’s Rocky Road Ice Cream, produces increased risk of obesity and heart attacks. S...

Table of contents

• Cover
• Half Title
• Title
• Copyright
• Dedication
• Contents
• Preface to the Third Edition
• About the Editor
• About the Contributors
• Part I Biology of Parenting
• Part II Ecology of Parenting
• Index