Intelligence & Freedom |
Francisco Capella |
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EVOLUTIONARY PSYCHOLOGY Evolution and cognitive adaptation
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Intelligence and ScienceEvolutionary psychologyEvolutionary psychologyEvolutionary psychology researches the organization, design, structure and functioning of the human mind using knowledge and principles from evolutionary biology. It is the application of adaptationist logic to the study of the architecture of the human mind and cognitive processes. It is a way of thinking and a set of general principles about psychology that can be applied to any domain within it (vision, speech, hearing, emotions, social behavior, sex and sexual attraction, reproduction, family, jealousy, parental love, incest avoidance, feeding, foraging, disgust, food aversions and pregnancy sickness, cooperation, competition, rationality, child behavior, conformity, aggression, sleep cycles, aesthetic preferences regarding the natural environment). Human behavior can be explained locating relevant neural circuits in the brain, explaining how they are designed and work, analyzing the information used and how it is processed, and studying what their functionality was in an ancestral environment. The mind is a system of specialized and modular information processing subsystems that were produced and designed gradually and accumulatively by natural selection to solve adaptive problems faced by human hunter gatherer ancestors. The complementary levels of explanation in evolutionary psychology are adaptive problems (faced by human ancestors), cognitive programs (to solve the problems) and neurophysiological bases (implementations of the programs in the human brain). Human instincts constitute human nature. Instincts are produced by specialized neural circuits that are innate and common to every member of a species and are the product of its evolutionary history. Humans are not different and more flexibly intelligent than other instinctive animals because they have lost their instincts and are ruled by reason. Human behavior is more sophisticated because humans have more instincts and more complexly integrated. These instincts work so well (they process information so effortlessly and automatically) and so naturally (they produce normal competent human behavior) that they are often not noticed and therefore not studied and explained (research is usually directed to weird phenomena or to tasks humans find hard to accomplish). Human instinctive skills are possible because there is a huge and heterogeneous array of complex computational machinery supporting and regulating those activities. According to the influential social science standard model (in anthropology, sociology, psychology), the human mind is like a blank slate, virtually free of content until written on and filled by experience (there is nothing in the intellect which was not previously in the senses). Experience, processed through a small set of innate mental procedures (connecting ideas using categories like resemblance, contiguity in time or place, and cause or effect), inscribes content onto the mental slate (like software and data loaded into a general purpose computer): all of the specific content of the human mind comes from the outside, from the physical and biological environment and the social world (unrestricted cultural and social construction of thought and meaning); the evolved architecture of the mind is made up of just a small number of general purpose mechanisms that are content independent (perception, learning, induction, intelligence, imitation, rationality, culture); the same mechanisms govern how one acquires and uses a language, how one learns to recognize and produce emotional expressions, how one thinks about morality. The few basic mechanisms responsible for reasoning, learning, and memory operate uniformly, according to unchanging principles, regardless of content or domain, and have no preexisting content incorporated in their procedures; they are not specialized for processing particular kinds of information. According to this erroneous paradigm, the social sciences are autonomous and disconnected from any evolutionary or psychological foundation. Cognitive psychology, evolutionary biology and neuroscience have shown that this view of the human mind is radically wrong. All normal mature human brains have a standard collection of reasoning and regulatory circuits that are functionally specialized and specific for each domain. These mental subsystems organize the way humans interpret experiences, promote certain recurrent concepts and motivations, and provide universal frames of meaning that permit the understanding of the actions and intentions of others. Beneath the superficial cultural variability, all humans share certain views and assumptions about the nature of the world and human action by virtue of these human universal reasoning circuits. Cognitive functions as learning, reasoning (induction, deduction, statistical and probability analysis) and decision making are not accomplished by a few simple, general purpose and content independent circuits (without domain specific knowledge) that implement formal logic and arithmetic algorithms. The flexibility of human intelligence (the ability to solve many different kinds of problems) is not evidence for the generality of the systems that generate it. Efficient problem solvers are experts in specific domains, they give precedence to certain expectations and make strong ontological hypotheses and assumptions about what kinds of things the world contains and how they work. Brain and mindPsychology is the branch of biology that studies brains, how brains process information, and how the information processing programs generate behavior. Several basic principles integrate different domains and can be applied to any topic in psychology. The brain is a physical system: its operation is governed solely by the laws of physics and chemistry. Thoughts, dreams, feelings, all are produced by chemical reactions in the brain. The brain functions as a computer (made of organic compounds) that processes information. Its circuits are designed to generate behavior that is appropriate to environmental circumstances. The brain is comprised of cells (mainly neurons and supporting structures). Neurons are cells specialized for the processing and transmission of information: electrochemical reactions cause neurons to fire, and neurons are connected to one another in highly organized networks or circuits whose structure determines how information is processed. Neural circuits in the brain are connected to sensory receptors and muscles by means of neurons that run throughout the body and transmit information. Sensory receptors are cells specialized for gathering information from the outer world and from other parts of the body. Behavior is the coordinated movement or action of different muscles. Multicellular organisms that do not move do not have brains (not only plants but some stages of the life cycles of some animals). Neural networks were designed by natural selection to solve problems (generating appropriate behavior) that human ancestors systematically faced during their evolutionary history. The adequacy of behavior can be radically different for different biological species in the same environmental circumstances (the environment is not enough to determine adequacy, what is food for some is poison for others). In principle an information processor can link any given stimulus in the environment (input) to any kind of behavior (output): which behavior a stimulus activates is a function of the neural circuitry of the organism. Brains were designed by the evolutionary process, and natural selection is the only evolutionary force that is capable of creating complex organized machines. Humans have some mental subsystems rather than other ones because they were better than other possible alternative subsystems at solving problems of human ancestors. During human evolution cognitive systems were transformed or cumulatively added to the brain because they processed information in a way that enhanced the adaptive regulation of behavior and physiology. Natural selection is a process in which a genotype and its associated phenotypic design spread through a population (it does not work for the good of the species but of the genes). Genetic behaviors that do not favor survival and reproduction tend to be eliminated; they can in principle be programmed in the brain, but then the genes responsible for those behaviors do not propagate and disappear from the gene pool. Genetic behaviors that do favor survival and reproduction tend to dominate the gene pool. Evolutionary psychology solves the mind and body problem. Brain and mind are terms that refer to the same system described in two complementary ways: in terms of its physical properties (the brain), or in terms of its information processing operation (the mind). The physical organization of the brain evolved because it produced certain adaptive information processing relationships. The brain is a naturally constructed computational system whose function is to solve adaptive information processing problems. Not all problems are adaptive problems. Adaptive problems are recurrent situations in evolutionary history that affect (strongly or slightly, directly or indirectly) the survival and reproduction of individual organisms: eating, not being eaten (threat interpretation), mating, socializing (face recognition), communicating (language acquisition and use), migration (navigation). There are specialized neural circuits for these tasks. Consciousness is just a small part of the human mind; most of what goes on inside the brain is unconscious, automatic, reliable and fast. Linear and serial conscious experience can deceive and mislead into thinking that the parallel mental circuitry is much simpler than it really is. Intuitions can be deceiving. Most problems that are experienced as easy to solve are in fact very difficult as engineering tasks, they require very complicated neural systems. No single mental subsystem knows all the facts about a situation: they are distributed among many specialized subsystems that work together. Each subsystem knows many details that they do not communicate to other subsystems because they do not need them. Some subsystems gather sensory information from the world (in different modes of perception), some analyze and evaluate that information, some check for inconsistencies and resolve contradictions, some check for completeness, some give interpretations, some coordinate, some produce instructions. Conscious experience is awareness of a few high level conclusions passed on by many specialized mechanisms. Different neural circuits are specialized for solving different adaptive problems. A basic engineering principle is that the same machine or mechanism is rarely capable of solving different problems equally well. As the body is divided into cooperative specialized organs, human minds consist of a large number of independent modules that are functionally specialized for different cognitive tasks. The brain is a collection of dedicated computers whose operations are functionally integrated to produce behavior. The human brain has independent specialized circuits for reasoning about objects, physical causality, number, the biological world, the beliefs and motivations of other individuals, and social interactions. Some circuits are specialized for integrating the output of all the dedicated modules to produce behavior. A cognitive system that is very efficient in a domain can be very wrong if applied in a different one (knowledge about intentions, beliefs and desires allows the inference of the behavior of persons, but is misleading if applied to inanimate objects). Different problems require different specialized solvers with domain specific knowledge. Some problem solvers may embody rational methods that use logical forms, but most need to have special purpose inference procedures that respond efficiently to particular information types and contents. The more specialists a system has, the more problems it can solve. A brain equipped with a multiplicity of specialized inference engines can generate sophisticated behavior that is sensitively tuned to its environment. Experts (specific problem solvers) can solve problems more efficiently than novices (general problem solvers) because they already know a lot about the problem domain. General purpose methods that can produce valid inferences in all domains are computationally weak and insufficient for biological survival: having no privileged restrictive hypotheses about a domain, there is little they can induce before their operation fails due to combinatorial explosion. Instincts are not the polar opposite of reasoning and learning. Humans are not rational animals because instincts, obviated by culture, have been erased by evolution. Most mental subsystems are instincts for reasoning and learning: they are complexly structured for solving specific types of adaptive problems; they reliably develop in all normal human beings without any conscious effort and without formal instruction; they are applied without any conscious awareness of their underlying logic; they are distinct from more general abilities to process information or behave intelligently. Human babies have an innate intelligence made up of privileged hypotheses (about faces, objects, physical causality, other minds, word meanings) that permit the developing child to learn about its environment. Newborns expect faces to be present in the environment (they turn their eyes and head in response to facial patterns). Babies assume that the world contains rigid objects that are continuous in space and time and impenetrable; they have preferred ways of analyzing the world, treating things that are cohesive, bounded, and move as a unit as single separate objects (ignoring shape, color, texture). Babies distinguish causal and non causal events and interactions; they distinguish animate objects (capable of self generated motion) from inanimate objects (they move only when acted upon); they infer that the self-propelled movement of animate objects is due to invisible internal states (intentions, goals). Babies have a well developed intuitive psychology or theory of mind that uses eye direction and movement to infer what other people want, know and believe (autism happens when these cognitive systems are impaired). When an adult speaks and points to an object, babies assume that the word refers to the object. Emotions and cognition are not split. An emotion is an integrated mode of operation of the entire cognitive system caused by programs that structure interactions among different mechanisms so that they function harmoniously when confronting recurrent problems (especially situations in which errors are so costly that individual learning by trial and error is not adaptive, the first response must be right). Evolution and cognitive adaptationFunctional explanations are essential to understand how natural selection designs organisms. The brain is an information processing device whose function is to produce behavior using information from the environment of the organism. Neuroscience studies the physical structure of brains; cognitive psychology studies the information processing programs realized by that physical structure. The function of a device and its structure are strongly related. In evolved systems structure reflects function: the physical structure exists because it embodies a set of programs that solved a particular problem in the past. The phenotype of an organism is a system of functional components. During evolution new design features are added to or discarded from the genotype and phenotype of a species because of their good or bad consequences. A phenotypic trait spreads over generations if it solves recurrent adaptive problems, promoting survival and reproduction. Natural selection is a feedback process that chooses among possible alternative designs on the basis of how well they function and solve adaptive problems. It is a progressive process that has produced exquisitely engineered biological machines: a design feature that solves an adaptive problem well can be beaten by a new design feature that solves it better. Proximate explanations refer to the structure of a device (genetic, biochemical, physiological, developmental, cognitive, social, and all other immediate causes of behavior in psychology). Ultimate explanations refer to the adaptive function of a device (causes that operated over evolutionary time). Knowledge of adaptive function is necessary to understand biology. Phenotypic traits can be adaptations (present because they were selected for), byproducts (present because they are causally coupled to adaptations, side effects of adaptations), and random noise (evolution is partly stochastic). Not all aspects of biological machines are functional and adaptive: selection creates functional organization, but not all traits of organisms are functional. Not all organic behavior is adaptive, especially if the environment changes fast. Existing structures can be used for activities that are unrelated to their original function (exaptations), and the new functionalities are not the original selection factor. Artificial man made machines and adaptive natural biological machines are reliable and efficient problem solving devices that show common evidence of complex functional engineering organization: many coordinated specialized design features that are unlikely to have arisen by chance alone and that are not better explained as the byproduct of mechanisms designed to solve some alternative problem. Design evidence is important for explaining why a known mechanism exists, and also for discovering new mechanisms. Engineers have problems they want to solve, and then design machines that are capable of solving these problems efficiently; evolutionary biologists figure out what adaptive problems a given species encountered during its evolutionary history, and then investigate what organic devices could have solved them. Definitions of adaptive problems do not in general uniquely determine the design of the mechanisms that solve them: there are often multiple ways of achieving a solution, so empirical studies are needed to decide which one nature has actually adopted. The more precisely and clearly an adaptive information processing problem can be defined, the more easily can its solving mechanism be determined. Human past and presentMaximization of fitness is a not a mental goal (conscious or unconscious): the mind cannot decide what is an adequate behavior in any environment, especially evolutionarily novel ones. Modern human brains house a stone age mind. Biological machines are calibrated to the environments in which they evolved, and they embody information about the relevant stable properties of those ancestral worlds. Natural selection takes a long time to design a complex system that is suited to a given task and environment. The environment in which humans evolved was very different from the modern environment. Human ancestors lived during most of human evolution in hunter gatherer societies, small nomadic bands with a small number of individuals who got all their food daily gathering plants or hunting and scavenging animals. The modern world (farming, industry, technology, capital accumulation) has been very short and the changes very fast when compared to the entire human evolutionary history. Natural selection has not had time to design systems that are well adapted to modern life. Human minds are adapted to ancestral environments and their problems, not to present civilization and its problems: humans deal easily with small sized groups of people than with crowds of thousands or societies of millions; fears refer to predators and poisonous animals, not to dangerous artificial tools; hunger and taste adjust to scarcity of food, not to present abundance. Evolutionary psychology refers to the past to explain the present of humanity. Present behavior is generated by information processing mechanisms that exist because they solved adaptive problems in the ancestral environments in which the human line evolved. Cognitive mechanisms that solved problems efficiently in the past do not necessarily generate adaptive behavior in the present. The environment of evolutionary adaptation is not just one specific place and time, but the statistical composite of selection pressures that produced different adaptations that may refer to different places and times. Many human adaptations are shared by many animals, some only by a few closer species. Modern humans are able to solve problems that no ancestor ever had to solve (modern science and technology), partly as a side effect (byproduct) of systems that were designed to solve other adaptive problems, and mainly because of the imitation instinct (memetics, cultural transmission of ideas). Nature and nurtureEvolutionary psychology attempts to characterize the universal architecture of mental mechanisms typical of the human species. There is biochemical individuality (no two cells, or organs, or individuals are exactly alike), but every biological species has its own abstract universal functional constitution. Evolutionary psychology rejects the usual nature against nurture dichotomies: instinct or reasoning, innate or learned, biological or cultural. Every aspect of the phenotype of an organism is the joint product of its genes and its environment. Genes allow the environment to influence the development of phenotypes. The developmental mechanisms of some organisms produce different phenotypes in different environments. Responding to some environmental variation is part of the design, but this does not mean that just any aspect of the environment can affect any trait of the organism. Genes are regulatory elements that when expressed in an environment arrange their surrounding elements into an organism. Sufficiently intense and specific environmental manipulations can change some phenotypic traits. The cognitive architecture, like all aspects of the phenotype, is the joint product of genes and environment. Its development depends on common genetic and environmental factors: it is produced uniformly across the normal range of ancestral human environments. Evolutionary psychology is not behavior genetics, the study of how differences between people in a given environment can be accounted for by differences in their genes. Evolutionary psychology studies the underlying cognitive architecture shared by all human beings. The genetic basis for the human cognitive architecture is universal (psychic unity of humankind). Genetic variations can cause individuals to differ slightly in quantitative properties that do not disrupt the functioning of complex cognitive adaptations. The initial state of an organism at birth is not the same as its evolved architecture, which can develop gradually during life. Many phenotypic aspects are not present at birth but it makes no sense to say that they are culturally learned (teeth, female breasts): their production is activated at different life stages, partially because different life stages have different adaptive problems to solve. Different aspects of the human evolved cognitive architecture can mature at different points in the life cycle. Cultural descriptions or expectations of behavior need not be the causes for those behaviors. Nature and nurture interact in a positive sum game. Instincts and learning are not opposite: the brain must have a certain kind of structure and mechanism in order to learn. The ability to learn is an innate instinct, since it cannot be learned. Learning is not an explanation: it is a phenomenon that demands and explanation. Understanding learning implies knowing the computational structure of the diverse cognitive mechanisms that cause it. More nature allows more nurture. The richer the complexity of these mechanisms, the more an organism is capable of learning. Social exchange reasoningThe human cognitive system contains specialized subsystems for reasoning about adaptive social problems in the world of human ancestors. Regarding social interactions there are two basic consequences humans can have on each other: helping or hurting, providing benefits or inflicting costs. Some social behavior is unconditional (nursing an infant without asking it for a favor in return), but most social actions are conditionally performed. There is a selection pressure for cognitive designs that can reliably, precisely, and economically detect and understand social conditionals: exchange (conditional helping) and threat (conditional hurting) by individuals or groups on other individuals or groups. Social exchange (cooperation, reciprocal altruism, reciprocation, trade, mutually beneficial interactions) is a situation in which one obtains a benefit only if one has fulfilled a requirement. It is an ancient, pervasive, universal and central part of human social life. Situations involving social exchange have constituted a long enduring selection pressure on the hominid line, so complex adaptations have been constructed in response to them. The evolutionary theory of the functional logic of social exchange is well understood: it is based on a common cognitive mechanism whose development does not require cultural stimulation. Social exchange cannot evolve in a species or be stably sustained in a social group unless the cognitive machinery of the participants allows a potential cooperator to detect individuals who cheat, so that they can be excluded from future interactions in which they would exploit cooperators. A cheater is an individual who accepts a conditioned benefit without satisfying the conditioning requirements. The human mind does not develop general reasoning procedures for detecting abstract logical violations of conditional rules. People are not very good at these tasks, even when the rules deal with familiar content from everyday life; even formal training in logical reasoning helps little. But people who ordinarily cannot detect violations of conditional rules can do so easily and accurately when that violation represents cheating on a social exchange contract (without formal training and even when the situation described is culturally unfamiliar). Human reasoning includes domain specific inference procedures specialized for detecting cheaters in situations of exchange, analyzing social conditionals, interpreting their meaning, and successfully solving their problems. People are much better at social exchange problems than at logically equivalent reasoning problems. Human minds instinctively distinguish social exchange situations and their fundamental generic elements: agent, intentionality, benefit, cost, obligation, entitlement. Relevant inference procedures are automatically activated if the thinking subject represents the situation as an intentional agent entitled to a benefit only if one has satisfied a requirement (obligation, duty, cost). The cognitive procedures activated by social contract rules do not behave as if they were designed to just detect general logical violations; they produce choices that process information useful for detecting cheaters, whether or not they correspond to the logically correct selections (some responses that are functionally correct from the point of view of cheater detection can be logically incorrect). The programs involved do not detect potential altruists (individuals who pay costs but do not take benefits), are not activated in social contract situations in which errors would correspond to innocent mistakes rather than intentional cheating, and do not help to solve problems in different domains (threats, safety rules). Social threat is a conditional damage relationship: an aggressor threatens a victim with inflicting some damage or hurt if he does not fulfill some requirement. It is a typical human situation that people understand instinctively. There are cognitive mechanisms to understand the threat and assess its authenticity and danger: the aggressor must face the risk that the threatened person prefers to defend himself, he must show his superiority in strength and his willingness to fight; it is not adaptive to obey those who imitate aggressors without the ability or the intention to do damage. Reproductive behaviorHuman sexual preferences and strategies are the result of natural selection favoring those that were more efficient at propagating the genes responsible for them. All humans try to get the most attractive possible sexual partner (considering different aspects as beauty, wealth, health, intelligence), and therefore people tend to pair with others that approximately match their attractiveness (if there is a big difference in attractiveness between the two members of a couple the more attractive one is not following an optimal strategy, it is lowering its chances of long term propagation of its genes). Men and women consider different aspects of attractiveness and take different reproductive strategies due to their biological differences regarding sexual reproduction: men find young and fertile women attractive (beauty tends to indicate health and fertility); women pay more attention to status (strength, wealth, intelligence). The main sexual difference in humans is in resources invested in producing offspring: women produce the eggs (few, large and expensive to make), get pregnant and look after children (parental care, altriciality, babies require much attention for a long time), while men basically produce the sperm (many, small and cheap to make). Male parental investment is higher in humans than in other mammals (providing food and protection for the family) but it is significantly smaller than female parental investment. A fertile woman can produce at most a baby a year, and she cannot increase her reproductive rate mating more frequently or with more men. A man can produce a large number of offspring by mating with many women and relying on the mother to provide the needed care (if the sexual intercourse fails to produce children the experience has been usually pleasurable and the biological cost for him is very little). The optimal reproductive strategy for a man is to mate frequently with many different women without being selective; the optimal reproductive strategy for a woman is to mate selectively with a man with good genes (sexual appeal as indicator of health and strength) and willing to provide food and protection, avoiding ugly, lazy, incompetent or careless men. The result of the interaction of groups of men and women competing to reproduce is usually long term couples in which the man protects the woman and her offspring and tries to exclude her from sex with other men while trying himself to have sex with other women without getting caught by their men, and the woman raises her children and may have occasional selective sex with very attractive men. Men are more eager to have sex and are excited by the idea of sex with many women; women are more selective and prefer one reliable partner. Women want to receive something in exchange for sex (food, money, compromise); men are willing to give something in exchange for sex. Men are attracted to beautiful (healthy) young women (many fertile years) with broad hips (wide birth canal), small waist (not pregnant) and big breasts (abundant food). Women pay less attention to physical appearance (strength is important for a good hunter and fighter) and more to wealth, power and status that indicate the ability to provide food and protection. A woman can be certain that a baby is hers (she is pregnant) and can be quite sure about the father, while men cannot be certain about fatherhood (not all sexual intercourses are reproductively successful and the woman might have sex with other men). This might explain concealed ovulation in women: she can trick a man into caring for the child of another one and couples are more stable because sex is not limited to a short period. A man has several ways to increase the probability that a baby is his: marriage with female premarital chastity and marital fidelity, mutilation of female genitals (decreases the female desire), control of female sexuality, punishment for adultery. Jealousy is related to reproduction and parental certainty: a man fears most that his woman has sex with another man (sexual infidelity), because this might mean that he does not invest resources in his own offspring; a woman fears most that her man gets romantically attached to another woman (emotional infidelity) and spends time and resources on her.
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Inteligencia y Libertad |
Francisco Capella |