Evolutionary psychology


Evolutionary psychology is a theoretical approach in psychology that examines cognition and behavior from a modern evolutionary perspective. It seeks to identify human psychological adaptations with regard to the ancestral problems they evolved to solve. In this framework, psychological traits and mechanisms are either functional products of natural and sexual selection or non-adaptive by-products of other adaptive traits.
Adaptationist thinking about physiological mechanisms, such as the heart, lungs, and the liver, is common in evolutionary biology. Evolutionary psychologists apply the same thinking in psychology, arguing that just as the heart evolved to pump blood, the liver evolved to detoxify poisons, and the kidneys evolved to filter turbid fluids, there is modularity of mind in that different psychological mechanisms evolved to solve different adaptive problems. These evolutionary psychologists argue that much of human behavior is the output of psychological adaptations that evolved to solve recurrent problems in human ancestral environments.
Some evolutionary psychologists argue that evolutionary theory can provide a foundational, metatheoretical framework that integrates the entire field of psychology in the same way evolutionary biology has for biology.
Evolutionary psychologists hold that behaviors or traits that occur universally in all cultures are good candidates for evolutionary adaptations, including the abilities to infer others' emotions, discern kin from non-kin, identify and prefer healthier mates, and cooperate with others. Findings have been made regarding human social behaviour related to infanticide, intelligence, marriage patterns, promiscuity, perception of beauty, bride price, and parental investment. The theories and findings of evolutionary psychology have applications in many fields, including economics, environment, health, law, management, psychiatry, politics, and literature.
Criticism of evolutionary psychology involves questions of testability, cognitive and evolutionary assumptions, importance of non-genetic and non-adaptive explanations, as well as political and ethical issues due to interpretations of research results.

Scope

Principles

Its central assumption is that the human brain is composed of a large number of specialized mechanisms that were shaped by natural selection over a vast period of time to solve the recurrent information-processing problems faced by our ancestors. These problems involve food choices, social hierarchies, distributing resources to offspring, and selecting mates. Proponents suggest that it seeks to integrate psychology into the other natural sciences, rooting it in the organizing theory of biology, and thus understanding psychology as a branch of biology. Anthropologist John Tooby and psychologist Leda Cosmides note:
Just as human physiology and evolutionary physiology have worked to identify physical adaptations of the body that represent "human physiological nature," the purpose of evolutionary psychology is to identify evolved emotional and cognitive adaptations that represent "human psychological nature." According to Steven Pinker, it is "not a single theory but a large set of hypotheses" and a term that "has also come to refer to a particular way of applying evolutionary theory to the mind, with an emphasis on adaptation, gene-level selection, and modularity." Evolutionary psychology adopts an understanding of the mind that is based on the computational theory of mind. It describes mental processes as computational operations, so that, for example, a fear response is described as arising from a neurological computation that inputs the perceptional data, e.g. a visual image of a spider, and outputs the appropriate reaction, e.g. fear of possibly dangerous animals. Under this view, any domain-general learning is impossible because of the combinatorial explosion. Evolutionary Psychology specifies the domain as the problems of survival and reproduction.
While philosophers have generally considered the human mind to include broad faculties, such as reason and lust, evolutionary psychologists describe evolved psychological mechanisms as narrowly focused to deal with specific issues, such as catching cheaters or choosing mates. The discipline sees the human brain as having evolved specialized functions, called cognitive modules, or psychological adaptations which are shaped by natural selection. Examples include language-acquisition modules, incest-avoidance mechanisms, cheater-detection mechanisms, intelligence and sex-specific mating preferences, foraging mechanisms, alliance-tracking mechanisms, agent-detection mechanisms, and others. Some mechanisms, termed domain-specific, deal with recurrent adaptive problems over the course of human evolutionary history. Domain-general mechanisms, on the other hand, are proposed to deal with evolutionary novelty.
Evolutionary psychology has roots in cognitive psychology and evolutionary biology but also draws on behavioral ecology, artificial intelligence, genetics, ethology, anthropology, archaeology, biology, ecopsychology and zoology. It is closely linked to sociobiology, but there are key differences between them including the emphasis on domain-specific rather than domain-general mechanisms, the relevance of measures of current fitness, the importance of mismatch theory, and psychology rather than behavior.
Nikolaas Tinbergen's four categories of questions can help to clarify the distinctions between several different, but complementary, types of explanations. Evolutionary psychology focuses primarily on the "why?" questions, while traditional psychology focuses on the "how?" questions.

Premises

Evolutionary psychology is founded on several core premises.
  1. The brain is an information processing device, and it produces behavior in response to external and internal inputs.
  2. The brain's adaptive mechanisms were shaped by natural and sexual selection.
  3. Different neural mechanisms are specialized for solving problems in humanity's evolutionary past.
  4. The brain has evolved specialized neural mechanisms that were designed for solving problems that recurred over deep evolutionary time, giving modern humans stone-age minds.
  5. Most contents and processes of the brain are unconscious; and most mental problems that seem easy to solve are actually extremely difficult problems that are solved unconsciously by complicated neural mechanisms.
  6. Human psychology consists of many specialized mechanisms, each sensitive to different classes of information or inputs. These mechanisms combine to produce manifest behavior.

    History

Evolutionary psychology has its historical roots in Charles Darwin's theory of natural selection. In On The Origin of Species, Darwin predicted that psychology would develop an evolutionary basis:
Once the Origin was complete, Darwin turned to developing an evolution-based psychology, for, from the inception of his theory of evolution in the late 1830s, Darwin had seen the task of developing an evolutionary account of the higher human faculties as his most important challenge. He devoted more than a decade to study of the evolutionary origins of key aspects of human behaviour, in particular: the human intellect; rationality; human sexual behaviour; emotional expressions; moral behaviour; language; culture; and conscience—several of which Darwin argued had originated due to the unusual ways natural selection operates in social animals, that is, by different kinds of group selection, including kin selection and reciprocal altruism.
Initially conceived as groundwork for one book, Darwin's psychological project became so large and fruitful that he split it into two parts, the first being published as The Descent of Man, and Selection in Relation to Sex in 1871 and the second as The Expression of the Emotions in Man and Animals in 1872. Darwin also published pathbreaking evolutionary monographs on insect and invertebrate behaviour, and—believing that infant behaviour gives us privileged access to humans' evolutionary endowment—a seminal case-study of his baby son William's behaviour, containing many observations confirmed by recent research, including those on: infant-adult communication and meta-communication; infant emotional expressions; early reasoning; the experimental study of infant jealousy; and the origins of self-knowledge.
Darwin's evolutionary psychological publications inspired many of the founders of modern psychology, including: Sigmund Freud and his theories of psychoanalysis, particularly as relating to the Oedipus complex and group psychology; both the physiological and folk psychologies of Wilhelm Wundt; William James's functionalist approach to psychology; the genetic psychology of James Mark Baldwin and thus, indirectly, Jean Piaget; the social behaviourism or symbolic interactionism of George Herbert Mead which set out from Mead's appropriation of Darwin's treatment of gesture and attitude in his book on Expression; and the study of evolved 'instinctive' behaviour in animals—a major topic in On the Origin of Species—known today as ethology and pioneered by Konrad Lorenz, Karl von Frisch and Niko Tinbergen. More recently, Darwin's research on his baby son inspired Colwyn Trevarthen's observational approach to infancy and his theory of innate intersubjectivity. Overall, Darwin's theories of evolution, adaptation, and natural selection have provided and continue to provide many insights into why minds and brains function the way they do.
20th century evolutionary psychologies mostly bypass Darwin's extensive evolutionary treatment of human psychology, drawing instead from: the biological sciences of their day—especially 20th century evolutionary theory as it is imagined to relate to ancient human environments; the study of paleoanthropology; ethology; and various human sciences, most obviously cognitive psychology. For example, writing from a gene-centred perspective on evolution, W.D. Hamilton's papers on inclusive fitness and Robert Trivers's theories on reciprocity and parental investment helped to re-establish evolutionary thinking in psychology and the other social sciences, though without reference to the place of parental investment, reciprocal altruism and kin selection in Darwin's psychology. Likewise, in 1975, Edward O. Wilson combined evolutionary theory with studies of animal and social behavior, principally referencing the works of Lorenz and Tinbergen, in his book Sociobiology: The New Synthesis.
In the 1970s, two major branches developed from ethology. Firstly, the study of animal social behavior generated sociobiology, defined by its pre-eminent proponent Edward O. Wilson in 1975 as "the systematic study of the biological basis of all social behavior" and in 1978 as "the extension of population biology and evolutionary theory to social organization." Secondly, there was behavioral ecology which placed less emphasis on social behavior; it focused on the ecological and evolutionary basis of animal and human behavior.
In the 1970s and 1980s university departments began to include the term evolutionary biology in their titles. The modern era of evolutionary psychology was ushered in, in particular, by Donald Symons' 1979 book The Evolution of Human Sexuality and Leda Cosmides and John Tooby's 1992 book The Adapted Mind. David Buller observed that the term "evolutionary psychology" is sometimes seen as denoting research based on the specific methodological and theoretical commitments of certain researchers from the Santa Barbara school, thus some evolutionary psychologists prefer to term their work "human ecology", "human behavioural ecology" or "evolutionary anthropology" instead.
From psychology there are the primary streams of developmental, social and cognitive psychology. Establishing some measure of the relative influence of genetics and environment on behavior has been at the core of behavioral genetics and its variants, notably studies at the molecular level that examine the relationship between genes, neurotransmitters and behavior. Dual inheritance theory, developed in the late 1970s and early 1980s, has a slightly different perspective by trying to explain how human behavior is a product of two different and interacting evolutionary processes: genetic evolution and cultural evolution. DIT is seen by some as a "middle-ground" between views that emphasize human universals versus those that emphasize cultural variation.