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PSYC205 Evolutionary Psychology Core Concepts Edison Tan Evolutionary Psychology Singapore Management University  01 Products of Evolutionary Processes Edison Tan Evolutionary Psychology Singapore Management University ...

PSYC205 Evolutionary Psychology Core Concepts Edison Tan Evolutionary Psychology Singapore Management University  01 Products of Evolutionary Processes Edison Tan Evolutionary Psychology Singapore Management University  Products of Evolutionary Processes. Inheritance by genetic transmission Adaptation Most characteristics are coded not by a single gene but by a complex aggregation of many genes Inherited and reliably developing characteristics that came into existence through natural selection Develop reliably to solve adaptive problems. because they helped to solve problems of survival or reproduction better Emerge at appropriate stages of development, not necessarily than alternative designs existing in at birth the population during the period of In a reasonably intact form their evolution Some adaptations are species-typical; others are sex or in subsets of the population. By-products Depending on whether the subgroup faces the recurrent adaptive problem over their evolutionary history Noise Edison Tan Evolutionary Psychology Singapore Management University  Products of Evolutionary Processes Adaptations are functional Function refers to how the adaptation solves adaptive Adaptation problems – the precise solution. Design features of an adaptation refer to the components and Inherited and reliably developing processes of adaptive solutions that contribute to solving the characteristics that came into adaptive problem existence through natural selection Purported adaptations are functional if they are: because they helped to solve problems of survival or reproduction better Adaptation solves than alternative designs existing in Efficient the adaptive problem well the population during the period of their evolution Adaptations are Economic cost-effective By-products Components of adaptation are design to achieve Precise a particular outcome that Noise solves adaptive problems Performs dependably in the specific contexts it Reliable is designed to operate in Edison Tan Evolutionary Psychology Singapore Management University  Products of Evolutionary Processes Adaptations are shaped by natural selection Each adaptation first emerges as a mutation – an error in the Adaptation genetic coding - resulting in a characteristic that deviates from its previous form. Inherited and reliably developing Mutated characteristics that harm the organisms are removed characteristics that came into from the gene pool (sometimes by chance) as they hinder existence through natural selection survival and reproduction. because they helped to solve problems Beneficial mutations are retained and passed down as of survival or reproduction better organisms achieve differential reproductive success. than alternative designs existing in the population during the period of Each adaptation has a unique environment of evolutionary their evolution adaptedness (EEA) Selective forces or adaptive problems responsible for shaping the adaptation over the organism’s evolutionary history By-products Each adaptation has a period of evolution. The timespan natural selection takes to shape the adaptation Noise to its functional form Edison Tan Evolutionary Psychology Singapore Management University Products of Evolutionary Processes Adaptation By-products Characteristics that do not solve adaptive problems and do not have functional design; they are “carried along” with characteristics that do have functional design because they happen to be coupled with those adaptations. Noise Random effects are produced by forces such as chance mutations, sudden and unprecedented changes in the environment, or chance effects during development. It can be harmful or neutral. Edison Tan Evolutionary Psychology Singapore Management University  02 The Evolved Psychological Mechanism Edison Tan Evolutionary Psychology Singapore Management University  The Evolved Psychological Mechanism Decision Algorithm Input Output IF → THEN An evolved psychological mechanism is a set of psychological processes with the following properties: Exist because they solved a recurrent problem of survival or reproduction over our evolutionary history. Their core component (i.e., design features) were shaped in a way they coordinated to overcome specific obstacles to survival or reproduction. An evolved psychological mechanism is designed to take in only a narrow slice of information as inputs. The spectrum of input the psychological mechanisms are sensitive to is relevant for the detection of adaptive problems that are recurring over the EEA – or in modern environments that mimic these inputs The input of an evolved psychological mechanism tells an organism the particular adaptive problem it is facing. Perception can happen consciously or unconsciously. Edison Tan Evolutionary Psychology Singapore Management University  The Evolved Psychological Mechanism Decision Algorithm Input Output IF → THEN An evolved psychological mechanism is a set of psychological processes with the following properties: The input of an evolved psychological mechanism is transformed through an algorithmic decision rule or procedure into outputs. The decision rules are sets of procedures —“if, then” statements—for guiding an organism down one response or another. The output of an evolved psychological mechanism can be a physiological activity, information about other psychological mechanisms, or manifest behavior. Outputs of psychological mechanisms can act as inputs to other psychological mechanisms or as manifest behaviors The output of an evolved psychological mechanism is directed toward the solution to a specific adaptive problem. The output of the mechanisms may not always be successful, but on average, it tends to solve adaptive problems. Edison Tan Evolutionary Psychology Singapore Management University Important Notes about Evolved Psychological Mechanism Evolved Psychological Mechanisms are Problem Specific Adaptations are solutions that need to be specific to addressing the problem faced Generalized solutions, even if they work, they are unreliable and imprecise because they are not designed for a specific problem Every solution, including adaptations, can fail. Errors are more likely to arise from solutions not designed for the problem. ○ When errors occur, they present themselves as a threat to survival and reproduction ○ Organisms evolved to process mechanisms specifically designed for correcting errors (e.g., vomiting) Edison Tan Evolutionary Psychology Singapore Management University Important Notes about Evolved Psychological Mechanism Humans Possess a Complex Array of Evolved Psychology Mechanisms Humans have faced a large number of adaptive problems throughout our evolutionary history. Each adaptive problem requires a specific psychological solution Consequently, we possess just as many evolved psychological mechanisms to address the multitude of adaptive problems. Edison Tan Evolutionary Psychology Singapore Management University Important Notes about Evolved Psychological Mechanism Specificity, Complexity, and Numerousness of Evolved Psychological Mechanism Confers Humans High Level of Behavioral Flexibility Behaviors are not rigid “instinct.” Without environmental stimuli acting as triggers (IF), there will be no behavioral response (THEN) Some mechanisms feed input to another mechanism as outputs The huge number of mechanisms humans possess allows us to generate a huge range of behavioral responses. Response can be altered by changing the input, by changing the environment, or by the operation of a psychological mechanism producing an input as output. Edison Tan Evolutionary Psychology Singapore Management University Important Notes about Evolved Psychological Mechanism Learning, Socialization, Cultural Influence Describe Proximate Operations of Evolved Learning Mechanism Learning requires an environmental input surrounding the individual to generate an output mimicking Learning, socialization, and endorsement of culture require an evolved psychological mechanism to attend to environmental cues to generate functional, socially learned, or culturally influenced behaviors Edison Tan Evolutionary Psychology Singapore Management University  03 Research Methods in Evolutionary Psychology Edison Tan Evolutionary Psychology Singapore Management University  General Evolutionary Theory Levels of Analysis in Evolutionary Middle-Level Evolutionary Psychology Theories Research in Evolutionary Psychology involves (a) Generating hypotheses (b) Empirically testing predictions based on Specific Evolutionary those hypotheses Hypotheses (c) Interpreting study results Evolutionary Psychology does so by organizing evolutionary principles into hierarchical levels of analysis. Specific Prediction Derived from Hypotheses Each level must be consistent with higher levels of analysis without being wholly derived from it. Edison Tan Evolutionary Psychology Singapore Management University  General Evolutionary Theory Levels of Analysis in i.e., Evolution by Natural Selection Evolutionary Middle-Level Evolutionary Psychology Theories General Evolutionary Theory describes the evolutionary principle Specific Evolutionary Hypotheses that natural selection is the core engine of the evolutionary process by which adaptations emerge. Specific Prediction Derived from Hypotheses Edison Tan Evolutionary Psychology Singapore Management University  General Evolutionary Theory Levels of Analysis in i.e., Evolution by Natural Selection Evolutionary Middle-Level Evolutionary For example, genes can increase their own replicative success by Psychology Theories E.g., Kin-Selection Theory promoting the reproduction of other bodies likely to carry copies of themselves. When the core principle of natural selection is applied to specific Specific Evolutionary domains of life, it yields middle- Hypotheses level theories E.g., kin-Selection theory is an extension of natural selection Specific Prediction Derived to the context of altruism from Hypotheses amongst kin. Edison Tan Evolutionary Psychology Singapore Management University  General Evolutionary Theory Levels of Analysis in i.e., Evolution by Natural Selection Evolutionary Middle-Level Evolutionary For example, genes can increase their own replicative success by Psychology Theories E.g., Kin-Selection Theory promoting the reproduction of other bodies likely to carry copies of themselves. Using Middle-level theories, For example, natural researchers can generate specific Specific Evolutionary selection favored the Hypotheses existence of a hypotheses about the operation of psychological e.g., Kin-Recognition hypothesis mechanism that allows evolved psychological mechanisms. individuals to estimate the genetic relatedness between themselves and others. Specific Prediction Derived from Hypotheses Edison Tan Evolutionary Psychology Singapore Management University  General Evolutionary Theory Levels of Analysis in i.e., Evolution by Natural Selection Evolutionary Middle-Level Evolutionary For example, genes can increase their own replicative success by Psychology Theories E.g., Kin-Selection Theory promoting the reproduction of other bodies likely to carry copies of themselves. Researchers can then use For example, natural hypotheses to generate testable Specific Evolutionary selection favored the Hypotheses existence of a empirical predictions. psychological e.g., Kin-Recognition hypothesis mechanism that allows For example, older individuals to estimate siblings will exhibit the genetic relatedness greater altruism between themselves toward younger and others. siblings if they observe Specific Prediction Derived them nursing from from Hypotheses their own mother. Edison Tan Evolutionary Psychology Singapore Management University  General Evolutionary Theory Levels of Analysis in i.e., Evolution by Natural Selection Evolutionary Middle-Level Evolutionary Psychology Theories E.g., Kin-Selection Theory Predictions in Evolutionary Psychology were generated based on specific hypotheses, which in Specific Evolutionary turn were inspired by the middle-level theory of Hypotheses kin selection, which was itself generated based on e.g., Kin-recognition hypothesis evolutionary theory. Applying a simple insight at a broad level, such as that of a middle-level theory like kin selection, can Specific Prediction Derived yield rich and diverse downstream hypotheses from Hypotheses and a priori predictions readily testable in empirical research. Edison Tan Evolutionary Psychology Singapore Management University  Hypothesis Generation Steps Top Down (Theory Drive) Bottoms-Up (Observation Driven) Developing Hypotheses from Existing Developing Hypotheses by Observing Theory Behavioral, Physiological, or Psychological Phenomenon 1 Identify an adaptive problem Observe a phenomenon 2 Hypothesize an adaptation via a task Hypothesize an adaptation via a reverse analysis task analysis – asking if psychological adaptation may be responsible for producing that phenomenon and what adaptive problem that mechanism may be designed to solve. 3 Make predictions regarding the core Make predictions regarding the core design features design features 4 Conduct empirical studies to test Conduct empirical studies to test predictions predictions Edison Tan Evolutionary Psychology Singapore Management University Identifying Adaptive Problems Recurrent adaptive problems must be present to shape adaptations; genes of an individual who solved the adaptive problem are passed down: Useful tools: Existing knowledge about the ancestral environment Using well-established data from disciplines such as anthropology, geology, primatology, and biology, assuming physical laws are unchanging For example, in the Social Brain Hypothesis (Dunbar, 1998), primate seems to have comparatively larger brain sizes than other organisms. Primate, including humans, are known to be social-living organisms Social interactions require neurological infrastructure to support – brain size correlates with group size. Humans likely lived in approximately 150 individuals Edison Tan Evolutionary Psychology Singapore Management University Identifying Adaptive Problems Recurrent adaptive problems must be present to shape adaptations; genes of an individual who solved the adaptive problem are passed down: Useful tools: Applying middle-level theories to the EEA to identify who is most likely to face adaptive problems Sociometer Theory (Leary & Downs, 1995; later Kirkpatrick & Ellis, 2001) – Humans have an innate need to feed included in their group and relationship, and exclusion is detrimental to survival (e.g., predation) and reproduction (e.g., access to mates). Self-esteem is an output of an evolved psychological mechanism that regulates relational investment All humans face the adaptive problem of inclusion given that we are group-living organisms – all humans should possess this mechanism. Edison Tan Evolutionary Psychology Singapore Management University Identifying Adaptive Problems Other useful heuristics to identify adaptive problems: Must-solve vs. Beneficial-to-solve adaptive problems Must-solve Adaptive problems that, if not solved, will singlehandedly result in organisms failing to survive and reproduce. Beneficial-to-solve Problems that did not necessarily have to be solved but whose solution would nonetheless have increased the organism’s fitness improving the performance of an extant adaptive solution increasing the economy of an existing adaptation, such as by decreasing its costs increasing the reliability of the development of an adaptation increasing the number of cues that the adaptation takes as increasing and diversifying the repertoire of outputs that an adaptation can produce to improve the functional match between behavior and the specific cause of the problem Edison Tan Evolutionary Psychology Singapore Management University Identifying Adaptive Problems Other useful heuristics to identify adaptive problems: Must-solve vs. Beneficial-to-solve adaptive problems Aid development of hypotheses that also consider adaptive problems that are less obvious but likely just important in shaping adaptations E.g., Bullying as an adaptation (Volk et al., 2012, 2022) Aggression against peers offers benefits such as access to social and material resources, deterrence from being aggressed against, and some conferences of prestige. People do not NEED TO bully their peers to gain resources, but occasionally, bullying can yield benefits Edison Tan Evolutionary Psychology Singapore Management University Identifying Adaptive Problems Other useful heuristics to identify adaptive problems: Threats vs. Opportunities A threat is a feature or characteristic of the physical, ecological, or social environment with the potential to compromise an individual’s survival or reproduction (see The Hostile Forces of Nature, next week) An opportunity is a previously unexploited situation that could enhance survival or reproduction if taken advantage of. Attending to these “opportunities” and sometimes, their trade-off with “threats” (see “Cost- Benefit Analysis later) can lead to hypotheses, predictions, and findings that might otherwise remain undiscovered. Edison Tan Evolutionary Psychology Singapore Management University  Identifying Adaptive Problems Weak selective Extraordinarily Other useful heuristics to identify pressure but strong selection occurs often pressure adaptive problems: enough to be Often shapes beneficial for complex organism to adaptations Magnitude of impact and Frequency of overcome encounter Low Impact, High Impact, High High Frequency Frequency Adaptive problems that generate strong selective pressures drive the evolution of adaptations. The strength of an adaptive problem depends on: Low Impact, High Impact, Low Low 1. the magnitude of its impact on survival or Frequency Frequency Strong Selective reproduction Pressure Unlikely to shape Adaptation 2. the frequency at which it was faced. adaptation emerges even if an organism did not encounter the adaptive problem in its lifetime. Edison Tan Evolutionary Psychology Singapore Management University Task Analysis Specify the (a) relevant end state—the solution to the adaptive problem— and proceed by (b) detailing the specific design feature of the psychological mechanism capable of producing that end state. “How would an evolved psychological mechanism operate to solve this adaptive problem?” Consider this question at all stages of processing (Inputs → IF-THEN → outputs) What are the inputs? (Identifying the social, cultural, or other environmental inputs that the mechanism is expected to process) What is the IF-THEN rule? (describing the algorithmic processing of these inputs) What are the outputs? (predicting the mechanism’s psychological, physiological, or behavioral outputs) e.g., The Behavioral Immune System Decision Algorithm Input Output IF → THEN Probabilistic cues of IF – Detected (real or Affective: Disgust pathogens (e.g., corpse, perceived) Behavioral: Avoid feces) Then – Manifest Output Physiological: Nausea Edison Tan Evolutionary Psychology Singapore Management University Task Analysis The importance of postulating specific design features: Specification is necessary to confirm that the proposed adaptation could plausibly solve the adaptive problem. Predicting numerous, specific design features enables a researcher to design studies that test for their existence and thereby test for the existence of the adaptation itself. Renders the hypothesized psychological adaptation empirically testable and, consequently, falsifiable. Detailed specification is necessary to submit alternative hypotheses to discriminative tests and adjudicate between them. Edison Tan Evolutionary Psychology Singapore Management University  Cost-Benefit Analysis Context may vary the fitness cost and benefit of manifested output. For example, when e.g., The Behavioral Immune System facing contaminated food: Stress increases pathogen cost (cortisol is an immunosuppressant) Stressed individuals are more Contextual Input: likely to feel disgusted by Stressor contaminated food Hunger indicates potential survival cost due to potential nutritional deficit Hungry individuals are more likely to benefit from eating Input: Decision Algorithm contaminated food Output Contaminated Food IF → THEN Cost and Benefit Analysis allows for a nuanced prediction regarding the operation Stress: ↑ Disgust Hunger: ↓ Disgust of the evolved psychological mechanism – across different cultural contexts, individuals, Contextual Input: and sex. Hunger Al-Shawaf & Lewis (2013) Edison Tan Evolutionary Psychology Singapore Management University Data for Testing Hypothesis and Predictions Paleontological Archeological Records Anthropological Hunter-Gatherer Societies Human Products Sociological/Psychological This is particularly Observation (Field and Lab) important when Self-Report assessing unobservable Public Archives psychological variables! Edison Tan Evolutionary Psychology Singapore Management University The Importance of Triangulation Triangulation in research involves using multiple methods, datasets, and theories (recall Tinbergen's four questions) to increase scientific validity. Multiple data and methods allow researchers to overcome critical limitations associated with specific methods or types of data. Convergence in findings increases our confidence that conclusions are robust, valid, and reliable in the face of a replication crisis in science. Edison Tan Evolutionary Psychology Singapore Management University Interpreting General Evolutionary Theory Research at Different Levels of Middle-Level Evolutionary Theories Analysis A single adaptive problem may have multiple solutions. Hence, a middle-level theory can generate various hypotheses. Specific Hypotheses A Specific Hypotheses B It is possible for a hypothesis about the existence of an adaptation to be falsified without falsifying a middle-level theory. Interpret individual research in the context of other findings within the broader body of research. Science is a cumulative enterprise Specific Prediction Derived Specific Prediction Derived Evaluation of the theory depends on independent from Hypothesis A from Hypothesis B verification and falsification from multiple research Edison Tan Evolutionary Psychology Singapore Management University Interpreting General Evolutionary Theory Research at Different Levels of Middle-Level Evolutionary Theories Analysis All observed findings are open to alternate interpretations, including multiple evolutionary explanations that compete with one another. Specific Hypotheses A Specific Hypotheses B The observed phenomenon might be the output of an adaptation designed to solve a different adaptive problem other than the one proposed or even a non-functional by-product of an adaptation. Consider alternative functions an output may serve and Specific Prediction Derived Specific Prediction Derived make testable predictions about their design feature. from Hypothesis A from Hypothesis B Design studies with robust methods to test competing hypotheses Edison Tan Evolutionary Psychology Singapore Management University  Discussion Edison Tan Evolutionary Psychology Singapore Management University Persistence of Negative Traits “How do evolved psychological mechanisms explain psychological or mental health disorders that appear maladaptive in modern societies?” Edison Tan Evolutionary Psychology Singapore Management University  Why do negative traits and characteristics exist and persist? A trait, cognition, affect, and behavior Natural selection selects for Costly traits may be generally beneficial for are adaptive insofar as fitness characteristics and traits that fitness approaching the extreme but benefits outweigh the cost. enhance reproductive odd, not health maladaptive at the extreme. and well-being. Cost of anxiety, for example, may include: Damage from physiological Costly traits may be adaptive for the genes but distressing for the effects underlying anxiety, individual. e.g., the effect of adrenaline and cortisol. Opportunity cost from Sexual jealousy is an output of a mate-defending mechanism avoidance of potential benefits Motivates attentiveness to potential infidelity Benefits of anxiety include: Ensure offspring belongs to Avoidance of danger that self, aid monopoly of mate’s would have resulted in resource death May cause sleepless nights, anxiety, and interference Benefit of Anxiety > Cost of Anxiety with daily life Edison Tan Evolutionary Psychology Singapore Management University Why does costly traits and characteristic persist? Edison Tan Evolutionary Psychology Singapore Management University Universality Given that evolutionary psychology asserts the universality of psychological mechanisms across cultures, to what extent do these variations suggest that psychological mechanisms are more shaped by specific ecological and social contexts rather than being universally consistent? Edison Tan Evolutionary Psychology Singapore Management University What is Universal? The Psychological Mechanism or the Output? Evolutionary Psychology advances the universality of psychological mechanisms, not the manifest behavior generated by the psychological mechanism. Systematic variability in social and cultural input should lead to systematic variability in psychological output. E.g.., Varying pathogen loads in local ecology predict cultural differences in the importance of physical attractiveness in mate preference Edison Tan Evolutionary Psychology Singapore Management University Domain-Specificity and Flexibility “How do specialized mechanisms enhance behavioral flexibility in humans, and why might having many specialized mechanisms broaden rather than limit the range of possible behaviors, especially in comparison to domain-general mechanisms?” Edison Tan Evolutionary Psychology Singapore Management University Evolved Psychological Mechanisms are Unlikely to be Domain General (Confer et al., 2007) Failure-to-Predict Domain-General explanation typically assumes humans “just figured it out.” Does not explain why humans are so sensitive to specific inputs Does not explain why sex differences exist Combinatorial Explosion Domain-General explanation will require the organism to have a trial-and-error response to the adaptive problem There are potentially exponential numbers of output that can be generated in the face of the adaptive problem Not efficient Not economic Not precise Not reliable Edison Tan Evolutionary Psychology Singapore Management University Evolved Psychological Mechanisms are Unlikely to be Domain General (Confer et al., 2007) Poverty-of-the-Stimulus Domain-General explanation requires an organism to sample a large number of observations to determine the regularity in the occurrence of an adaptive problem E.g., Men need to continuously observe how sexual infidelity leads to paternal uncertainty Unlikely to occur Adaptive Problems are Context-Dependent The most effective solution to an adaptive problem depends on the cost-benefit of output considering the context. Risk-taking during hunting for a childless man vs. risk-taking for a man with mates and offspring There are no “one-size-fits-all” solutions to adaptive problems – what is “rational” in one context may be irrational in another. Edison Tan Evolutionary Psychology Singapore Management University Evolved Psychological Mechanisms are Unlikely to be Domain General (Confer et al., 2007) Purported Domain-General mechanisms are better explained by the existence of a Domain-Specific mechanism. General Intelligence may be an evolved psychological mechanism that solves adaptive problems of novelty – adaptive problems that are not common over the EEA Possibly as low-frequency, high-impact problems Key evidence (Kanazawa, 2004) Intelligence does not seem to boost reproductive success Intelligence does not seem to predict kin-investment or cooperation with non-kin positively Intelligence predicts better performance in an area of life that does not exist in the ancestral past (e.g., standardized education) Edison Tan Evolutionary Psychology Singapore Management University Domain-Specificity Assuming that humans possess domain-general mechanisms would mean that humans would often be completely paralyzed by the ineffective and highly iterative means of generating output. In contrast, having numerous domain-specific evolved psychological mechanisms allows for flexibility of response because: Specialized psychological mechanisms are sensitive to specific inputs, efficiently generating specific output in cognition, affect, and behavior. When multiple psychological mechanisms are engaged, they collectively generate a myriad of outputs that can interact with each other or give feedback to other downstream psychological mechanisms as inputs. Each interaction between psychological mechanisms allows for a wide range of potential outputs that would manifest as a highly flexible range of possible responses to a given situation. Edison Tan Evolutionary Psychology Singapore Management University  Open Floor Discussion Edison Tan Evolutionary Psychology Singapore Management University NEXT WEEK: The Hostile Forces of Nature Additional Readings: Lewis, D. M. G., Al-Shawaf, L., Conroy-Beam, D., Asao, K., & Buss, D. M. (2017). Evolutionary psychology: A how- to guide. American Psychologist, 72(4), 353–373. https://doi.org/10.1037/a0040409 Edison Tan Evolutionary Psychology Singapore Management University