Sociobiology is a field of biology that aims to examine and explain social behavior in terms of evolution. It draws from disciplines including psychology, ethology, anthropology, evolution, zoology, archaeology, and population genetics. Within the study of human societies, sociobiology is closely allied to evolutionary anthropology, human behavioral ecology, evolutionary psychology, and sociology.
Nature versus nurture is a long-standing debate in biology and society about the balance between two competing factors which determine fate: genetics (nature) and environment (nurture). The alliterative expression "nature and nurture" in English has been in use since at least the Elizabethan period and goes back to medieval French.
Biological determinism, also known as genetic determinism, is the belief that human behaviour is directly controlled by an individual's genes or some component of their physiology, generally at the expense of the role of the environment, whether in embryonic development or in learning. Genetic reductionism is a similar concept, but it is distinct from genetic determinism in that the former refers to the level of understanding, while the latter refers to the supposedly causal role of genes. Biological determinism has been associated with movements in science and society including eugenics, scientific racism, and the debates around the heritability of IQ, the basis of sexual orientation, and sociobiology.
Pleiotropy occurs when one gene influences two or more seemingly unrelated phenotypic traits. Such a gene that exhibits multiple phenotypic expression is called a pleiotropic gene. Mutation in a pleiotropic gene may have an effect on several traits simultaneously, due to the gene coding for a product used by a myriad of cells or different targets that have the same signaling function.
Human genetics is the study of inheritance as it occurs in human beings. Human genetics encompasses a variety of overlapping fields including: classical genetics, cytogenetics, molecular genetics, biochemical genetics, genomics, population genetics, developmental genetics, clinical genetics, and genetic counseling.
Hereditarianism is the doctrine or school of thought that heredity plays a significant role in determining human nature and character traits, such as intelligence and personality. Hereditarians believe in the power of genetics to explain human character traits and solve human social and political problems. Hereditarians adopt the view that an understanding of human evolution can extend the understanding of human nature.
A genetic predisposition is a genetic characteristic which influences the possible phenotypic development of an individual organism within a species or population under the influence of environmental conditions. In medicine, genetic susceptibility to a disease refers to a genetic predisposition to a health problem, which may eventually be triggered by particular environmental or lifestyle factors, such as tobacco smoking or diet. Genetic testing is able to identify individuals who are genetically predisposed to certain diseases.
Gene–environment interaction is when two different genotypes respond to environmental variation in different ways. A norm of reaction is a graph that shows the relationship between genes and environmental factors when phenotypic differences are continuous. They can help illustrate GxE interactions. When the norm of reaction is not parallel, as shown in the figure below, there is a gene by environment interaction. This indicates that each genotype responds to environmental variation in a different way. Environmental variation can be physical, chemical, biological, behavior patterns or life events.
Dual inheritance theory (DIT), also known as gene–culture coevolution or biocultural evolution, was developed in the 1960s through early 1980s to explain how human behavior is a product of two different and interacting evolutionary processes: genetic evolution and cultural evolution. Genes and culture continually interact in a feedback loop, changes in genes can lead to changes in culture which can then influence genetic selection, and vice versa. One of the theory's central claims is that culture evolves partly through a Darwinian selection process, which dual inheritance theorists often describe by analogy to genetic evolution.
Evolutionary developmental psychology (EDP) is a research paradigm that applies the basic principles of evolution by natural selection, to understand the development of human behavior and cognition. It involves the study of both the genetic and environmental mechanisms that underlie the development of social and cognitive competencies, as well as the epigenetic processes that adapt these competencies to local conditions.
Developmental systems theory (DST) is an overarching theoretical perspective on biological development, heredity, and evolution. It emphasizes the shared contributions of genes, environment, and epigenetic factors on developmental processes. DST, unlike conventional scientific theories, is not directly used to help make predictions for testing experimental results; instead, it is seen as a collection of philosophical, psychological, and scientific models of development and evolution. As a whole, these models argue the inadequacy of the modern evolutionary synthesis on the roles of genes and natural selection as the principal explanation of living structures. Developmental systems theory embraces a large range of positions that expand biological explanations of organismal development and hold modern evolutionary theory as a misconception of the nature of living processes.
Evolutionary psychology seeks to identify and understand human psychological traits that have evolved in much the same way as biological traits, through adaptation to environmental cues. Furthermore, it tends toward viewing the vast majority of psychological traits, certainly the most important ones, as the result of past adaptions, which has generated significant controversy and criticism from competing fields. These criticisms include disputes about the testability of evolutionary hypotheses, cognitive assumptions such as massive modularity, vagueness stemming from assumptions about the environment that leads to evolutionary adaptation, the importance of non-genetic and non-adaptive explanations, as well as political and ethical issues in the field itself.
Developmental psychobiology is an interdisciplinary field, encompassing developmental psychology, biological psychology, neuroscience and many other areas of biology. The field covers all phases of ontogeny, with particular emphasis on prenatal, perinatal and early childhood development. Conducting research into basic aspects of development, for example, the development of infant attachment, sleep, eating, thermoregulation, learning, attention and acquisition of language occupies most developmental psychobiologists. At the same time, they are actively engaged in research on applied problems such as sudden infant death syndrome, the development and care of the preterm infant, autism, and the effects of various prenatal insults on the development of brain and behavior.
Some of the research that is conducted in the field of psychology is more "fundamental" than the research conducted in the applied psychological disciplines, and does not necessarily have a direct application. The subdisciplines within psychology that can be thought to reflect a basic-science orientation include biological psychology, cognitive psychology, neuropsychology, and so on. Research in these subdisciplines is characterized by methodological rigor. The concern of psychology as a basic science is in understanding the laws and processes that underlie behavior, cognition, and emotion. Psychology as a basic science provides a foundation for applied psychology. Applied psychology, by contrast, involves the application of psychological principles and theories yielded up by the basic psychological sciences; these applications are aimed at overcoming problems or promoting well-being in areas such as mental and physical health and education.
Behavioural genetics, also referred to as behaviour genetics, is a field of scientific research that uses genetic methods to investigate the nature and origins of individual differences in behaviour. While the name "behavioural genetics" connotes a focus on genetic influences, the field broadly investigates the extent to which genetic and environmental factors influence individual differences, and the development of research designs that can remove the confounding of genes and environment. Behavioural genetics was founded as a scientific discipline by Francis Galton in the late 19th century, only to be discredited through association with eugenics movements before and during World War II. In the latter half of the 20th century, the field saw renewed prominence with research on inheritance of behaviour and mental illness in humans, as well as research on genetically informative model organisms through selective breeding and crosses. In the late 20th and early 21st centuries, technological advances in molecular genetics made it possible to measure and modify the genome directly. This led to major advances in model organism research and in human studies, leading to new scientific discoveries.
Inclusive fitness in humans is the application of inclusive fitness theory to human social behaviour, relationships and cooperation.
Probabilistic epigenesis is a way of understanding human behavior based on the relationship between experience and biology. It is a variant form of epigenetics, proposed by American psychologist Gilbert Gottlieb in 1991. Gottlieb’s model is based on Conrad H. Waddington's idea of developmental epigenesis. Both theories examine the complexity of the ways in which the brain develops and explore factors that occur outside the genome. However, probabilistic epigenesis differs from Waddington’s model as it relies much more heavily on the potential developmental impacts of experience and environment and how they interact with an individual’s genes. Probabilistic epigenesis takes into account developmental, hormonal, environmental, neuropsychological, and genetic factors in order to explain various forms of behavior.
David Scott Moore is an American developmental psychologist and Professor of Psychology at Pitzer College, where he is the Director of the Claremont Infant Study Center. He is also Professor of Psychology at Claremont Graduate University. His research focuses on cognitive development and mental rotation in infants, as well as behavioral epigenetics. His 2002 book, The Dependent Gene, criticized some of the fundamental assumptions underlying the nature-nurture debate. His 2015 book, The Developing Genome: An Introduction to Behavioral Epigenetics, received positive reviews, and was awarded the American Psychological Association's Eleanor Maccoby and William James Book Awards in 2016. A short précis of the book was subsequently published in WIREs Systems Biology and Medicine. Moore's work has been profiled in The Wall Street Journal,The New York Times, Scientific American, and Parents.
In the context of the nature-nurture debate, interactionism is the view that all human behavioral traits develop from the interaction of both "nature" and "nurture", that is, from both genetic and environmental factors. This view further holds that genetic and environmental influences on organismal development are so closely interdependent that they are inseparable from one another. Historically, it has often been confused with the statistical concept of gene-environment interaction. Historically, interactionism has presented a limited view of the manner in which behavioral traits develop, and has simply demonstrated that "nature" and "nurture" are both necessary. Among the first biologists to propose an interactionist theory of development was Daniel Lehrman. Since then, numerous interactionist perspectives have been proposed, and the contradictions between many of these perspectives has led to much controversy in evolutionary psychology and behavioral genetics. Proponents of various forms of interactionist perspectives include Philip Kitcher, who refers to his view as "causal democracy", and Susan Oyama, who describes her perspective as "constructive interactionism". Critics of interactionism include major figures in behavioral genetics such as Arthur Jensen, Robert Plomin, and philosopher Neven Sesardic.
In adoption studies, selective placement refers to the practice by which adoption agencies tend to deliberately match certain characteristics of an adopted child's adopted parents with those of his or her biological parents. When this occurs, it results in a correlation between environments between biological relatives raised in different homes. It has the potential to bias the conclusions of such studies, because twins who were reared in separate environments may in fact have been reared in much more similar environments than assumed. This can result in an inflated estimate of heritability. There is evidence that selective placement was a major confound in many early studies of twins reared apart. Some adoption studies report little or no evidence of selective placement. For example, a 1979 study by Ho et al. reported a generally low level of selective placement in adopted children for either physical or behavioral traits. The authors concluded that to the extent that selective placement occurred for such traits, "our data suggest that it is based largely on characteristics of the birth father," rather than those of the adoptee. Carey (2003) concluded that selective placement was "moderate" for physical characteristics and typically "small or nonexistent" for behavioral characteristics.
