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Evolutionary psychology

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Evolutionary psychology (abbreviated ev-psych or EP) is a theoretical approach to psychology that explains many mental traits as adaptations in the sense of evolutionary biology, as a product of natural or sexual selection. This is to bring the functional way of thinking about biological mechanisms, such as the heart or the immune system, into the psychological field, and to approach psychological mechanisms, such as perception or language acquisition, in the same way.

Though applicable to any organism with a nervous system, most research in Evolutionary Psychology focuses on humans. Specifically, Evolutionary Psychology most strongly supports the Massive Modularity hypothesis, which proposes that the human brain comprises many functional mechanisms, called psychological adaptations or evolved psychological mechanisms (EPMs), that evolved by natural selection. Uncontroversial examples of EPMs include vision, hearing, memory, and motor control. More controversial examples include language acquisition modules, incest avoidance mechanisms, cheater detection mechanisms, and sex-specific mating preferences, mating strategies, and spatial cognition. Most evolutionary psychologists argue that EPMs are universal in a species, excepting those specific to sex or age.

Evolutionary psychology has roots in cognitive psychology and evolutionary biology. It also draws heavily on behavioral ecology, artificial intelligence, genetics, ethology, anthropology, archeology, biology, and zoology. Evolutionary psychology 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 behaviour. Many evolutionary psychologists, however, argue that the mind consists of both domain-specific and domain-general mechanisms, especially evolutionary developmental psychologists. Most sociobiological research is now conducted in the field of behavioral ecology.

The term evolutionary psychology was probably coined by Ghiselin in his 1973 article in Science. Jerome Barkow, Leda Cosmides and John Tooby popularized the term in their highly influential 1992 book [The Adapted Mind: Evolutionary Psychology and The Generation of Culture]. Evolutionary psychology has been applied to the study of many fields, including economics, aggression, law, psychiatry, politics, literature, and sex.

Contents

General evolutionary theory

''Main article: Evolution
The idea that organisms are composed of a number of parts that serve different functions (i.e., living things are, in some sense, machines) goes back at least to Aristotle. This idea is the foundation of modern medicine and biology. William Paley, drawing upon the work of many others, argued that organisms are machines designed to function in particular environments. Paley believed that this evidence of 'design' was evidence for a designer—God. Darwin appears to have been impressed with Paley's argument that organisms are designed for particular environments. The theory of natural selection, created by Darwin and Wallace, provided a scientific account of the origins of functional design in the natural world that did not invoke a supernatural designer.

Evolutionary psychology is ultimately rooted in the basic theoretical principles of evolutionary theory. It is sometimes seen not simply as a sub-discipline of psychology but as a way in which evolutionary theory can be used as a meta-theoretical framework within which to examine the entire field of psychology.#redirect

Evolutionary theory involves three main ingredients:

Many traits that are selected for can actually hinder survival of the organism at the same time as they are increasing its reproduction. Consider the classic example of the peacock's tail. It is metabolically costly, cumbersome, and essentially a "predator magnet." What the peacock's tail does do is attract mates. Thus, the type of selective process that is involved here is what Darwin called sexual selection. Sexual selection can be divided into two types:

Ultimately, no matter how much an organism reproduces, that organism dies, and it is genetic information that gets passed on from one generation to the next. Since it is genetic information that matters, there can also be selection pressures that favor an organism aiding in the reproduction of its genetic relatives, since they carry some of the organism's genes. Such pressures are called kin selection.

Inclusive fitness

Inclusive fitness theory, which was proposed by William D. Hamilton in 1964 as a revision to evolutionary theory, is basically a combination of natural selection, sexual selection, and kin selection. It refers to the sum of an individual's own reproductive success plus the effects the individual's actions have on the reproductive success of their genetic relatives. General evolutionary theory, in its modern form, is essentially inclusive fitness theory.

Inclusive fitness theory resolved the issue of how "altruism" evolved. The dominant, pre-Hamiltonian view was that altruism evolved via group selection: the notion that altruism evolved for the benefit of the group. The problem with this was that if one organism in a group incurred any fitness costs on itself for the benefit of others in the group, (i.e. acted "altruistically"), then that organism would reduce its own ability to survive and/or reproduce, therefore reducing its chances of passing on its altruistic traits. Furthermore, the organism that benefitted from that altruistic act and only acted on behalf of its own fitness would increase its own chance of survival and/or reproduction, thus increasing its chances of passing on its "selfish" traits. Inclusive fitness resolved "the problem of altruism" by demonstrating that altruism can evolve via kin selection as expressed in Hamilton's rule:

:::cost < relatedness × benefit
In other words, altruism can evolve as long as the fitness cost of the altruistic act on the part of the actor is less than the degree of genetic relatedness of the recipient times the fitness benefit to that recipient. This perspective reflects what is referred to as the gene-centered view of evolution and demonstrates that group selection is a very weak selective force. However, in recent years group selection has been making a comeback, (albeit a controversial one), as multilevel selection, which posits that evolution can act on many levels of functional organization, (including the "group" level), and not just the "gene" level.

Middle-level evolutionary theories

Middle-level evolutionary theories are theories that encompass broad domains of functioning. They are compatible with general evolutionary theory but not derived from it. Furthermore, they are applicable across species. During the early 1970's, three very important middle-level evolutionary theories were contributed by then Harvard graduate student, Robert Trivers:

However, if all things are not equal, a parent may engage in discriminative investment towards one sex or the other, depending on the parent's condition. Recall that females are the heavier parental investors in our species. Because of that, females have a better chance of reproducing at least once in comparison to males. Thus, according to the Trivers-Willard hypothesis, parents in good condition are predicted to favor investment in sons, and parents in poor condition are predicted to favor investment in daughters.

Products of the evolutionary process

There are three products of the evolutionary process:

Adaptive problems

Evolutionary psychologists attempt to identify the adaptive problems that humans face... that is, those problems that correlate with humans' survival and reproduction, (i.e., humans' inclusive fitness). These problems can be broadly categorized as problems of survival, (i.e., growth, development, differentiation, and maintenance), mating, parenting, kin, non-kin, and group-living. Adaptive problems also include those dealing with cooperation, competition, and conflict. Adaptive problems that have occurred consistently over evolutionary history are recurrent adaptive problems, while those that have not are novel adaptive problems.

Evolved psychological mechanisms: the core of evolutionary psychology

''Main article: Evolved psychological mechanisms
Evolutionary psychology is based on the belief that, just like hearts, lungs, livers, kidneys, and immune systems, cognition has functional structure that has a genetic basis, and therefore has evolved by natural selection. Like other organs and tissues, this functional structure should be universally shared amongst a species, and should solve important problems of survival and reproduction. Evolutionary psychologists seek to understand psychological mechanisms by understanding the survival and reproductive functions they might have served over the course of evolutionary history.

Evolutionary psychologists subdivide the concept of psychological mechanisms into two general categories:

The Environment of evolutionary adaptedness

The term environment of evolutionary adaptedness, often abbreviated EEA, was coined by John Bowlby within attachment theory. It refers to the environment in which an organism or mechanism evolved, adapting to interact with its surroundings. In the environment in which ducks evolved, the first moving being that a duckling was likely to see was its mother. A psychological mechanism that evolved to form an attachment to the first moving being would therefore properly function to form an attachment to the mother. In novel environments, however, the mechanism can malfunction by forming an attachment to a dog or human instead.

For modern man, this environment is the Pleistocene, in where a significant part of human evolution was spent in hunter–gatherer societies. Evolutionary psychology predicts that human psychology is adapted to the Pleistocene EEA, and therefore will exhibit “mismatches” similar to the attachment patterns of ducks. One example is the fact that although cars kill over 40,000 people in US annually, whereas spiders and snakes kill only a handful, people nonetheless much more readily learn fear of spiders and snakes than they do fear of cars, guns, electric outlets, and other novel dangers. An explanation is that spiders and snakes were a threat to human ancestors, whereas cars were not. There is thus a mismatch between our evolved fear learning psychology and the modern environment. In contrast, an explanation that does not appeal to EEA is that encounters between humans and snakes result in harm to humans much more often than do encounters between humans and cars.

Evolutionary psychology argues that in order to understand an evolved psychological mechanism, one must similarly understand the properties of the environment in which the psychological mechanism evolved. For another example, the fact that women got pregnant and men did not is an essential aspect of the EEA of human mating preferences.

Controversies

Animal behavior studies have long recognized the role of evolution; the application of evolutionary theory to human psychology, however, is controversial. There are many families of criticism of the idea. 
How knowable is the early environment (EEA)?

Some critics of evolutionary psychology claim that because little is known about the Pleistocene, the evolutionary context in which humans developed (including population size, structure, lifestyle, eating habits, habitat, and more), there is little basis on which evolutionary psychology may operate.  Most EP research is thus confined to certainties about the past, such as pregnancies only occurring in women, and that humans lived in groups.

Many evolutionary psychologists argue that this criticism is based on a misunderstanding. Evolutionary psychologists argue that they use knowledge of the environment of evolutionary adaptedness to generate hypotheses regarding possible psychological adaptations, and subsequently, these hypotheses can be tested and evaluated against the empirical evidence in just the same way that any other hypothesis generated from any other theoretical perspective can be assessed. 


Furthermore, evolutionary psychologists posit that there are many environmental features that we can be sure played a part in our species' evolutionary history. They argue that our hunter-gatherer ancestors most certainly dealt with predators and prey, food acquisition and sharing, mate choice, child rearing, interpersonal aggression, interpersonal assistance, diseases and a host of other fairly predictable challenges that constituted significant selection pressures.For an outline of the current state of knowledge in this area, see: Mithen, Steven. After The Ice: A Global Human History 20000-5000 BC. Harvard Uni. Press, 2004).


There also exists debate within evolutionary psychology about the nature of the EEA. Many evolutionary psychologists contend that many aspects of the EEA were not as consistent as other evolutionary psychologists would argue. This argument is used to support the notion that the mind consists of not only domain-specific psychological mechanisms but of domain-general ones as well, that deal with environmental novelty.



Too many alternative hypotheses


Critics claim that many valid hypotheses, including contradictory ones, can be drawn from the same evolutionary principles. Evolutionary psychology can predict many, or even all, behaviours for a given situation, including contradictory ones. Therefore many human behaviours will always fit some hypotheses. The central paradigm of evolutionary psychology is impossible to prove, and the predicting power of evolutionary psychology is doubtful. For example, kin selection predicts that humans will be altruistic toward relatives in proportion to their relatedness, while reciprocal altruism predicts that we will be altruistic toward people from whom we can expect altruism in the future (not strangers). However, altruism towards a complete stranger fits the handicap principle. Thus altruism toward every class of person fits some well-known hypothesis. This doesn't seem to give us any way to predict how a human will act in a given situation.


Evolutionary psychologists respond that their discipline is not primarily concerned with explaining the behavior of specific individuals, but rather broad categories of human behaviors across societies and cultures. It is the search for species-wide trends in behavior that distinguishes evolutionary psychology from cultural or social explanations. Thus hypotheses will attempt to explain contradictory human behavior because human behavior is often contradictory.



Falsifiability


Critics claim that many of the propositions of evolutionary psychology are not falsifiable. It is not possible to conduct definitive experiments on humans on an evolutionary timescale.


The methods that evolutionary psychologists actually use for testing include comparing different species, comparing males and females, comparing individuals within a species and comparing the same individuals in different contexts. Their sources of data for testing evolutionary hypotheses include archeological records, data from hunter-gatherer societies, observations, self-reports, life-history data and public records, and human products. Source: Evolutionary Psychology: The New Science of the Mind by David Buss.



Biology versus environment


Some studies have been criticized for their tendency to attribute to evolutionary processes elements of human cognition that may be attributable to social processes (e.g. preference for particular physical features in mates). 


Evolutionary psychologists respond that many traits have been shown to be universal in humans and that social processes are related to evolutionary processes. They argue that statements such as "biology vs. environment" and "genes vs. culture" amount to false dichotomies. Evolutionary psychologists justify this claim by arguing that behavior results from an organism interacting with its environment. Psychological mechanisms, they argue, are created by genes, (which, in turn, were selected for by the evolutionary process), and those mechanisms help the organism negotiate its environment. Furthermore, they assert that many aspects of the environment, (e.g. culture and social institutions), are rested upon those mechanisms. In short, evolutionary psychologists argue that there is a bidirectional influence between things like "biology and environment" and "cognition and social processes."



Reductionism


Some opponents of evolutionary psychology maintain that elements of human  behavior are irreducible to their component parts. On the other hand, it is quite possible that a study of the component parts can lead to new insights about how they function as part of an integrated whole.




Ethical justification


Some people worry that evolutionary psychology will be used to justify harmful behavior, and have at times tried to suppress its study #redirect . For example, people may be more likely to cheat on their spouse if they believe their mind evolved to be that way.


Evolutionary psychologists respond by saying that they only state what is, not what ought to be.  Knowing how something works, they argue, is the first step to fixing it if it's broken, or changing how it works (if we should or not is an argument commonly left to philosophers). They further suggest that if people understand the system that "makes" them promiscuous--not for their happiness, not because it is right or moral, but because of the blind causal process of natural selection--they can become better consumers of their own consciousness, and other people may be able to use this understanding to intervene and change their behaviour. 


See: naturalistic fallacy



Empirical evidence


Some commentators, like philosopher David Buller, agree with the general argument that the human mind has evolved over time but disagree with the specific claims evolutionary psychologists make. Buller has argued, among other things, that the so-called Cinderella Effect, the argument that there are gender differences with respect to sexual jealousy and the contention that the mind consists of thousands of modules, are unsupported by the available empirical evidence. [link]  


An alternative to the "mental module" view of how human minds evolved is offered by cognitive psychologist Merlin Donald.  He argues that over evolutionary time the mind has gained adaptive advantage from a general problem solver.  Donald articulates this view in his book "A Mind So Rare: The Evolution of Human Consciousness" [link].


Another criticism regarding empirical evidence is a perceived lack of cross-cultural proofs. Many empirical studies come from a single culture. In these cases it is unknown if discoveries hold across all cultures.



Lack of genetic evidence


There is no direct evidence of genetic basis of human behaviors like altruism, maternal care, mate selection etc.. There are no genes identified, no mutants, no inheritance patterns, no gene polymorphism matching behavioral differences. If the supposed behaviors are polygenic, this raises doubt on how they could be effectively subject to directional selection. Genetic basis is the cornerstone to the proposed evolutionary origin of human behavior.



Some references for rebuttals to criticisms of evolutionary psychology







Image gallery


Image:Leda Cosmides.jpg|Leda Cosmides
Image:StevePinker.jpg|Steven Pinker
Image:RDawkins.jpg|Richard Dawkins




References











Also see books listed at the [Human Behavior and Evolution Society].



See also





External links


Introductory Reading:




Evolutionary Psychology Societies and Centres:




Evolutionary Psychology Journals:




Papers and reasearch concerning Evolutionary Psychology:



Evolutionary Psychology challenged:




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