Search Results

This chapter presents an interdisciplinary study on the effect of parental care on the psychology and biology of offspring. The research program, conducted with rodents, provides a detailed model of how early environmental influences can induce profound changes in the biology of the offspring at the level of gene expression. These changes in gene expression then have a cascading effect and alter the physiology of the offspring in ways that are enduring, probably lifelong.

This chapter examines the neuromolecular and plastic brain. Ideas about plasticity and the openness of brains to environment influences, from initial evidence about nerve development, through the recognition that synaptic plasticity was the very basis of learning and memory, to evidence about the influence of environment on gene expression and the persistence throughout life of the capacity to make new neurons—all this made the neuromolecular brain seem exquisitely open to its milieu, with changes at the molecular level occurring throughout the course of a human life and thus shaping the growth, organization, and regeneration of neurons and neuronal circuits at time scales from the millisecond to the decade. This was an opportunity to explore the myriad ways in which the milieu got “under the skin,” implying an openness of these molecular processes of the brain to biography, sociality, and culture, and hence perhaps even to history and politics.

Environmental modifiers of the effects of genetic variants, or gene-environment interactions, have received increased attention in recent years due to the recognition that genetic variants alone are unlikely to explain most of the recent increases in chronic diseases. Such increases are more likely due to environmental and behavioral changes interacting with a genetic predisposition, suggesting that failing to identify and control environmental modifiers of disease risk could mask important associations with genetic variants or misestimate the magnitude of their effects. Identifying environmental modifiers of these variants may also be essential in mitigating the risk conferred by these variants. Population-based genetic association studies with detailed characterization of environmental exposures are critical and underused resources for identifying potential interacting factors. This chapter explores the substantial and complementary strengths offered by the two main approaches to these studies — case-control and cohort designs — in the search for the genetic and environmental influences on common diseases.

People vary in personality and social behavior. It is generally accepted that some of this variation is due to differences in genes and some to “environment”—that is, to differences in people's experiences. This chapter is about the latter source of individual differences, the variation that is not due to genes. More precisely, it is about theories designed to account for environmental influences on personality and social behavior by specifying some of the ways these outcomes are affected by people's experiences. The chapter begins by summarizing some of the findings that a theory of environmental influences on human behavior should be called upon to explain. It then describes a new theory designed to account for these findings. The final section examines some alternative theories.

This concluding chapter highlights several key findings from the preceding chapters and discuss a few particularly important topics for the next generation of research studies on violence and prevention. The chapter refers to comments made elsewhere in the book about the need for broader, more inclusive definitions of violence; for more knowledge of social, structural and environmental influences; and for advances in prevention to bring about lasting changes in real world settings.

This chapter explores how cultural and economic circumstances shape the nature, meaning, and consequences of strivings for autonomy in adolescence. It highlights research that demonstrates that the ways in which parents respond to adolescent strivings for autonomy have been linked to multiple aspects of adolescent adjustment. The challenge, however, is to recognize that there are variations across cultural groups in the degree to which autonomy is valued relative to loyalty and deference to the family. In addition to variations across cultural groups in the degree to which autonomy is a cherished goal, some parents are likely to find themselves in circumstances in which environmental influences, such as dangerous neighborhoods, may propel them to exert greater control over their adolescent children in order to protect their well-being. The chapter provides a roadmap for understanding how seemingly universal goals, such as the promotion of autonomy during adolescence, may take on different meanings and be accomplished in different ways depending on context and culture.

The specific circumstances in which an individual encounters their mate options may influence how she chooses and, ultimately, whom she chooses. In particular, the choice environment may affect the cues we pay attention to, how we combine them and, ultimately (and significantly), our reproductive fate. This chapter consolidates the current state of knowledge regarding choice environment effects on mating behavior. This chapter's thesis is that human mate choice is adapted to the choice environment in which it is made: We are sensitive to changes in the environment and adapt our judgments and choice strategies accordingly, thereby exhibiting ecological and social rationality—the topic of this volume. This chapter promotes the view that mating-related judgment and choice depend very much on the environmental conditions facing the chooser, while also being shaped by the past recurring conditions in which these behaviors evolved. To substantiate this perspective, the chapter describes anthropological, sociological, and psychological research showing that human mating-related judgments and choice are context-sensitive in meaningful ways. In particular, the chapter shows how the cues and strategies used in mate choice are influenced by environmental structure, considered first at the population level and second at the level of individual choosers. The chapter concludes by focusing in on one important aspect of the mate choice environment in specific modern settings and its impact on heuristic and cue use: the number of potential mates available.

To determine what encourages young local scientists and engineers to follow entrepreneurial paths in the Greater Boston area, this chapter provides a broad discussion of the influences of the Greater Boston environment, and especially the Massachusetts Institute of Technology (MIT) environment, on the formation of new companies. It traces the evolution of Boston's high technology community. The author cites in this chapter Cooper's argument for six different potential environmental influences and provides support for all of Cooper's variables in his discussion. Further, this chapter identifies several more critical aspects of culture and attitude that have built a local environment that fosters entrepreneurship. Some environmental forces that “push” young local scientists and engineers away from entrepreneurship are also demonstrated in this chapter.

We survey three interlocking talent development models: the Differentiating Model of Giftedness and Talent (DMGT), the Developmental Model for Natural Abilities (DMNA), and their merging into a Comprehensive Model of Talent Development (CMTD). The authors use the CMTD framework to analyse the phenomenon of musical prodigiousness, defined as a quantitatively extreme level of talent (T component). We then explore the gifts (G component) that contribute to musical prodigiousness, as well as its typical developmental process (D component). Two types of catalytic causal influences are explored: intrapersonal characteristics (I component) and environmental influences (E component). Within each section, we briefly discuss the biological foundations of the various constructs. We finally integrate these five analyses into a dynamic developmental perspective and propose a tentative answer to the key question: “Which causal influences better ‘explain’ the early manifestation and development of musical prodigiousness?” In other words: “What makes a difference?”

This chapter discusses social-environmental approaches to studying human behavior, covering methods, scope, and assumptions. Social-environmental approaches seek to understand the environmental contribution to the development and expression of various behaviors. The aim is to identify aspects of the social environment that may have an effect on the behavior of interest. Some studies focus on the familial environment, considering, for example, parents' attitudes and interactions with their children. Others look beyond to the school environment, and peer relations, or media exposure.

This chapter reviews the influences of environmental factors on sex determination, sex ratios, and reproductive behavior in the Crustacea, focusing in particular on amphipod and isopod examples. A range of abiotic and biotic environmental factors influence reproduction in Crustacea, including temperature, day length, pollutants, and parasites. Individual crustaceans may benefit from these environmental influences, but in other cases, reproductive biology responses to biotic and abiotic environments may be detrimental to individual fitness. Environmental Sex Determination (ESD) falls into the former category. ESD is an adaptive mechanism of sex determination that is rare, but has evolved in diverse taxa. Evidence from gammarid amphipods is used to explore the evolution of ESD in response to a patchy environment. While ESD is an adaptive mechanism of sex determination, the impact of other environmental factors can be very costly. Parasitic castrators can lead to a reduction or total cessation of reproduction in crustacean hosts, driving population declines. In contrast, parasitic feminizers convert male hosts into females, enhancing maternal parasite transmission but also leading to sex ratio distortion in the host population. The chapter discusses parasite-host coevolutionary conflict and reviews evidence that selection on the host in response to parasitic sex ratio distortion has led to altered mate choice in amphipods, and to the evolution of a novel system of sex determination in isopods. Human-induced environmental influences can also be seen in Crustacea, and the chapter discusses how parasites, ESD, and endocrine-disrupting chemicals can each affect sex determination and lead to abnormal intersex phenotypes. It ends by highlighting areas for future research on the diverse world of crustacean reproduction.

Chapters 1 (and 2) provide a common basis and a vocabulary for appreciating the contours of behavioral and psychiatric genetics. There are three dialogues between a behavioral geneticist and an appeals court judge who wishes to find out more about behavioral genetics for eventual use in her court cases. The distinction between classical quantitative genetics and modern molecular genetics is introduced. In the former, no specific genes are identified, though heritability estimates are provided. The contentious concept of "heritability" is analyzed in detail and its limitations delineated in the first dialogue. A simple mathematical argument is sketched to show how twin studies yield heritabilities and environmental influences for both traits and disorders, and the critical assumptions of such studies are summarized. The chapter closes with an analysis of the shared and nonshared environment issue and a sketch of what is known as an ACE diagram.

The Conclusion draws together the findings concerning music and speech that are explored in the book, and the insights derived from these findings. Much of the book is concerned with illusions. Some of the illusions reflect huge differences between people in how they perceive simple musical patterns. These differences suggest variations in brain organization and environmental exposure. Another way in which these illusions shed light on hearing involves illusory conjunctions. These lead to the conclusion that, normally, the process of analyzing sound includes the operation of specialized modules that each analyze a particular attribute, and that we combine the outputs of these modules to obtain an integrated percept. This process usually leads us to perceive sounds correctly, but it breaks down under certain circumstances, producing illusions. Further threads that run through the book involve relationships between music and speech; the importance of unconscious inference, or “top-down processing” on our perception of sound; and extremes of musical ability, which are shown to be the products of both innate and environmental factors. It is also shown that earworms and musical hallucinations highlight the vital role played by the inner workings of our musical minds in determining what we hear. The extraordinary phenomena explored in this book lead us to conclude that the hearing mechanism did not arise as a coherent, integrated whole, but rather developed as a set of different, though interconnected, mechanisms. From another perspective, they elucidate factors involved in listening to music in everyday life.

This chapter argues that addiction is inherently a chronic, relapsing disease, not much different from diseases such as hypertension, diabetes, or asthma. Similar to those diseases, the risk for developing addiction has a strong genetic component. Likewise, the development and course of addiction are determined by an intricate interplay among genetic risk factors, environmental influences, and behavioral choices. Addiction cannot currently be cured but can be managed with a degree of success that is sufficient to allow patients to live a good life. If not managed, it disables, kills, and leads to significant costs and suffering. For these conditions, long-term disease management that combines pharmacological and behavioral approaches is an undisputed norm, and success is hardly assessed by the number of people completely cured of their ailment. At the same time, we continue to debate whether addiction really is a medical condition; focus on short-term fixes such as detoxification or twenty-eight-day residential programs; see anything other than complete abstinence as a failure; and frequently view the harm caused by addiction as self-inflicted.

This chapter concludes with the major theme that ran through the previous chapters; how much of each of these skeletal activity reconstruction features are a result of environmental influences (i.e., activities) and how much of the variation in these features are a result of genes. Biological confounds, which are largely genetic, have been found in all of the skeletal features covered in the previous chapters. For example, evolutionary body type rules (i.e., Bergmann’s and Allen’s Rules) affect measures of cross-sectional geometries. Plus, age is known to increase entheseal change scores. Furthermore, twin studies have revealed hereditary etiologies for osteoarthritis and Schmorl’s nodes. Yet, not all of the variance is genetic and, thus, the question remains whether skeletal indicators of activity can still be used to reconstruct activity patterns. Methods that avoid circular reasoning and aim to use only skeletal features with predictive validity should be the ultimate goal for those studying skeletal remains. If skeletal indicators of activity cannot be used to reconstruct what people did in the past, then perhaps these skeletal features can help in other ways, such as improving age estimates or drawing better conclusions about biological relatedness.