Evolutionary Psychology I (102) PDF

PSYCH 102: Evolutionary Psychology I (3) Key Points 1.​ The Original Debate within Evolution 2.​ The Naturalistic Fallacy 3.​ How Evolution Works & Has Worked in Recent Human History Introduction Evolutionary psychology seeks to answer "Why?" It explores why certain psychological traits an...

PSYCH 102: Evolutionary Psychology I (3) Key Points 1.​ The Original Debate within Evolution 2.​ The Naturalistic Fallacy 3.​ How Evolution Works & Has Worked in Recent Human History Introduction Evolutionary psychology seeks to answer "Why?" It explores why certain psychological traits and behaviors exist. Why do we have certain emotional responses or preferences, and why do they evolve in certain ways? A Unifying Theory “Nothing in Biology Makes Sense Except in the Light of Evolution.” - Theodosius Dobzhansky 1973 Main Idea: The phrase by Dobzhansky encapsulates the idea that biology, including psychology, only makes sense when viewed through the lens of evolution. Prior to the theory of evolution, biology was a collection of disconnected observations (naturalism) rather than a unified field. Scientists would note patterns, like the shape of leaves or the color of caterpillars, but without understanding the underlying reasons. Evolutionary Psychology: ​ Just like other biological features, our minds and psychology are also products of ​ Our psychological traits, such as emotions and behaviors, have evolved to help us survive and thrive in our environment. Why This Matters: ​ For instance, loving our children is essential for their survival. Ancestors who didn’t form strong bonds with their offspring likely saw fewer of their children survive. ​ Similarly, our preferences, like choosing chocolate over poop, may have evolved because sweetness signals safe, nutritious food. The Original Debate within Evolution: Darwin VS Wallace Alfred Russell Wallace, who co-discovered the theory of evolution, is less recognized than Charles Darwin due to Darwin's earlier start and stronger scholarly connections. Wallace, despite understanding the theory’s implications, hesitated to fully accept them, particularly in relation to human psychology. This hesitation mirrors ongoing debates in evolutionary psychology about whether evolution can entirely explain human behavior. Wallace’s Point of View Wallace resisted the full implications of evolution 1. Wallace’s Skepticism About Evolution – Natural selection could not account Wallace believed natural selection could explain the development of physical traits (like fingers and spleens), but he felt it couldn’t explain higher human faculties like: ​ Mathematics ​ Art ​ Music ​ Humor ​ Spirituality or what he called "metaphysical musings" These complex traits seemed too intricate to be explained by natural selection alone. 2. Spiritual Force Intervention Wallace posited that a spiritual force must have intervened in the evolutionary process at key moments: 1.​ The creation of life from inorganic matter. 2.​ The development of consciousness—self-awareness. 3.​ The development of higher human faculties – like reason and creativity. He believed that this spiritual force went beyond material forces (like natural selection) to shape human evolution. 3. Teleological Evolution ​ Because of his belief in spiritual intervention, Wallace thought that evolution wasn’t just a blind, random process. ​ He proposed that evolution was teleological, meaning it had a purpose and was goal-directed. ​ The goal of this process was to develop the human spirit, and humans were the ultimate product of evolution. Darwin’s Point of View Darwin accepted them ​ Darwin fully embraced natural selection and its implications. ​ In a letter to Wallace, Darwin said, “I go further than you, my dear Wallace.” He expressed confidence that natural selection could explain not just physical traits but also complex psychological traits. 1. Psychology Based on Evolution Darwin predicted that psychology would eventually be grounded in evolutionary theory: ​ "In the distant future, I see an open field for far more important research. Psychology will be based on a new foundation." ​ He saw the implications of evolution in understanding the development of human psychology, suggesting that mental faculties could be understood through the same principles as physical traits (e.g., the finches Darwin studied). 2. Sexual Selection ​ Darwin introduced sexual selection as a mechanism to explain traits that might not directly contribute to survival but serve reproductive purposes: ​ Traits like music, mathematics, and art could be linked to sexual selection—traits that help individuals attract mates and reproduce. 3. Natural Processes and No Need for Metaphysical Forces ​ Darwin rejected the idea of spiritual or metaphysical forces influencing evolution. ​ He believed that natural processes alone were enough to explain the evolution of all life, including mental faculties. ​ Evolution was not directed by any external purpose or goal. 4. Evolution Has No Direction or Purpose Darwin maintained that evolution has no external direction or purpose: ​ It is not guided by a plan and does not aim toward a particular goal. ​ Humans are not the endpoint of evolution; other organisms, like worms, are just as evolved in their own context. 1.​ A naturally selected human nature serves no external purpose 2.​ Adaptations need only be adaptive, they don’t need to be good Evolution and Morality Human Nature Serves No External Purpose: ​ Darwin believed that human nature, shaped by evolution, serves no external purpose. ​ It evolved because it was adaptive to our survival and reproduction in the past, not because it had a spiritual or preordained goal. Adaptations Are Simply Adaptive: ​ Adaptations are not inherently good or morally desirable. ​ Traits evolve because they help organisms survive and thrive, but this does not imply they are morally positive or desirable in a broader sense. ​ Evolution does not guarantee that what evolved is ideal—it just needs to be adaptive for the environment at the time. No Moral or Spiritual Endorsement: ​ There is no moral or spiritual stamp of approval on evolutionary processes. ​ Survival and the traits that help with survival are not necessarily good or just in an ethical sense; they are simply functional for survival in the past. The Naturalistic Fallacy The naturalistic fallacy warns against confusing what "is" (factual claims) with what "ought" to be (moral claims). ​ Just because something is natural does not necessarily mean it is good or desirable, and vice versa. ​ A common mistake is to equate natural with good or unnatural with bad, which leads to logical errors in reasoning. The Ought-Is Problem: Moral Position → Factual Claim → “Natural is the best!” ​ Our moral beliefs (what we think ought to be true) sometimes influence our understanding of facts (what is actually true). ​ Example: We might believe that humans ought to be fair and egalitarian, and therefore assume that this is how humans actually are, even if the facts (e.g., evidence of human behavior) suggest otherwise. The Is-Ought Problem (Naturalistic Fallacy): Factual Claim → Moral Position → “It is, what it is” ​ This occurs when we believe that because something is a certain way, it should be that way. For instance, just because something is evolved or natural, we might assume it is morally good or desirable. ​ Example: Because humans are naturally promiscuous, we may think that this means humans ought to be promiscuous. Example of the Naturalistic Fallacy: ​ The belief that something is better because it is natural (e.g., preferring natural products, like food or medicine, over unnatural alternatives, without evidence supporting that it is actually better for health). ​ The fallacy occurs when we assume that the natural status of something automatically means it is morally good or healthy, even though this is not logically justified. Examples for Practice 1. Men and women should be equal, therefore innate differences in interests don’t exist. Moral Claim: Men and women should be equal. Factual Claim: Therefore, innate differences in interests don’t exist. Type of Problem: Ought-Is Problem Explanation: ​ The moral claim is about equality, suggesting that men and women should be treated equally, which is a normative statement (what ought to be true). ​ The factual claim is about the existence of innate differences in interests between men and women, which is an empirical statement (what is true). ​ Ought-Is Problem: This is an Ought-Is problem because the moral claim about equality is determining the factual claim (that innate differences don’t exist). The moral claim (equality) influences what is believed to be factually true (no innate differences in interests), which leads to a logical fallacy. 2. Because it is more natural than cigarettes, it’s better to smoke pot. Moral Claim: It’s better to smoke pot. Factual Claim: Because it is more natural than cigarettes. Type of Problem: Is-Ought Problem (Naturalistic Fallacy) Explanation: ​ The moral claim is that smoking pot is better, a normative statement about what is morally right or wrong. ​ The factual claim is that pot is more natural than cigarettes, which is a descriptive statement (what is true). ​ Is-Ought Problem (Naturalistic Fallacy): This is an Is-Ought problem, where the factual claim (pot is natural) is being used to justify the moral claim (it’s better to smoke pot). This creates a Naturalistic Fallacy, where something being "natural" is wrongly assumed to make it morally good. 3. Men/women evolved to be promiscuous, therefore men/women should cheat Moral Claim: Men and women should cheat. Factual Claim: Men/women evolved to be promiscuous. Type of Problem: Is-Ought Problem (Naturalistic Fallacy) Explanation: ​ The moral claim is that men and women should cheat, suggesting that cheating is morally acceptable or preferable. ​ The factual claim is that humans evolved to be promiscuous, describing a biological or evolutionary trait (what is true). ​ Is-Ought Problem (Naturalistic Fallacy): This is an Is-Ought problem because the factual claim (evolved promiscuity) is being used to justify the moral claim (cheating is acceptable). It’s a Naturalistic Fallacy because the assumption is made that what is natural (promiscuity) should determine what is morally right (cheating). 4. Because we evolved to feel that incest is wrong (factual claim), incest is wrong Moral Claim: Incest is wrong. Factual Claim: Because we evolved to feel that incest is wrong. Type of Problem: Is-Ought Problem (Naturalistic Fallacy) Explanation: ​ The moral claim is that incest is wrong, which is a normative statement about what should be the case. ​ The factual claim is that humans evolved to feel disgusted by incest, which is an empirical claim about human feelings and instincts (what is true). ​ Is-Ought Problem (Naturalistic Fallacy): This is an Is-Ought problem where the factual claim (evolved disgust towards incest) is being used to justify the moral claim (incest is wrong). It’s a Naturalistic Fallacy because it assumes that just because we evolved to feel a certain way, that feeling should dictate moral truth. Simple Mechanics and Complex Dynamics: The Evolutionary Process 3 Necessary and Sufficient Components for Adaptive Evolution Key Idea: To drive adaptive evolution, a system must include three essential components: 1.​ Mechanism of Inheritance 2.​ Variation Within a Population 3.​ Selection Among the Variations 1. Mechanism of Inheritance Explanation: A system must have a way to pass information or traits from one generation to the next. Biological Example: Genes inherited from parents are recombined to create new, unique individuals. Relevance: Without inheritance, advantageous traits cannot persist or spread in subsequent generations. 2. Variation Within a Population Explanation: A population must have diverse traits for evolution to act upon. Biological Example: Genetic differences between individuals in a species, such as height or coloration. Relevance: Without variation, there is nothing for natural selection to act on, and adaptive evolution cannot occur. 3. Selection Among the Variation Explanation: There must be a mechanism that determines which traits are more advantageous, allowing those traits to be better represented in future generations. Biological Example: Traits that increase survival or reproduction (fitness) are passed on more frequently. Relevance: Selection ensures that populations evolve toward better adaptation to their environments. Adaptation Definition: An adaptation is a genetic mutation that has been selected for due to its fitness advantage (i.e., it increases an organism’s ability to survive and reproduce). Genetic Mutations and Adaptations 1. Prevalence of Genetic Mutations: ​ Every individual carries at least 100 genetic mutations. ​ Most mutations are fitness-neutral: They do not impact survival or reproduction. ​ Example: A mutation causing mild discomfort after eating pineapple is unlikely to affect reproductive success. 2. Fitness-Negative Mutations (Deleterious): ​ A significant portion of impactful mutations reduce fitness. ​ These mutations may hinder survival or reproduction. ​ Example: Being born without eyes, a trait vital for survival in many environments, would reduce fitness and likely not persist in a population. 3. Fitness-Positive Mutations (Adaptive): ​ A rare subset of mutations increases survival or reproductive success. ​ These beneficial mutations become adaptations when selected for over time. ​ Example: In fictional terms, Wolverine’s healing factor represents an extreme adaptation, enabling superior survival and reproductive potential (if it didn’t come with other side effects). 4. The Role of Selection in Adaptations: ​ Natural selection ensures that adaptive mutations are passed down more often, increasing their frequency in future generations. ​ This process is the foundation of evolutionary change. Exaptation Definition: An exaptation is a trait that originally evolved for one purpose (its initial function) but later adapted to serve an additional or entirely new purpose. 1. Initial Purpose vs. New Function → Traits selected for a specific purpose may later serve other adaptive roles without losing their original function. Example 1: Feathers ​ Initial Purpose: Temperature regulation. Feathers allowed early feathered species to ventilate or retain heat efficiently. ​ New Function: Facilitating flight. Over time, feathers became critical for powered flight in birds, serving a new adaptive role. 2. Retaining Initial Function → Exaptations can maintain their original purpose even as they serve new functions. Example 2: Pain ​ Initial Purpose: Physical pain evolved as an alarm system to signal tissue damage and motivate individuals to avoid harmful stimuli. ​ New Function: Social pain. As humans evolved in complex social groups, the same pain mechanism adapted to serve as an alarm system for social rejection or threats to group cohesion. This connection between physical and social pain demonstrates how evolution repurposed an existing survival mechanism for a new social context. 3. Evolutionary Efficiency ​ Exaptations highlight how evolution repurposes existing structures or systems instead of creating entirely new mechanisms, demonstrating efficiency in adaptation. ​ Exaptations show how evolution creatively builds upon existing traits, adapting them to serve new purposes while often preserving their original function. Vestigial Traits Definition: Vestigial traits are ancestral traits that no longer provide any fitness advantage to a population. These traits once served an important role in the survival or reproduction of ancestors but have since lost their function due to changes in lifestyle, environment, or evolutionary pressures. These traits remain present despite their loss of adaptive function because they do not significantly harm an organism’s survival or reproduction. Examples of Vestigial Traits: Example 1: Wisdom Teeth ​ Initial Function: Humans used to have larger jaws to chew tough, uncooked food like raw meat or fibrous plants. ​ Current State: As humans evolved to cook food and consume softer diets, jaw size decreased, but the number of teeth remained constant. Wisdom teeth now often cause overcrowding or other dental issues but persist because they do not strongly affect overall fitness. Example 2: Whale Hind Limbs (Pelvic Bones) ​ Initial Function: Whale ancestors were land-dwelling mammals with legs used for walking. ​ Current State: Over millions of years, whales adapted to aquatic life, and their hind legs became unnecessary for swimming. While the visible limbs disappeared, remnants of pelvic bones remain. Why Vestigial Traits Persist ​ Vestigial traits are not strongly selected against because they do not significantly hinder survival or reproduction. ​ Evolution often acts to eliminate traits only when they pose a notable disadvantage. Evolutionary Byproducts Definition: Evolutionary byproducts are traits or characteristics that exist not because they serve a direct adaptive purpose, but because they are incidental outcomes of other traits that were naturally selected for adaptive reasons. 1. Not Every Trait Is Adaptive While many traits arise through natural selection because they improve survival or reproduction, some traits exist as unintended side effects of other adaptive features. 2. Examples of Evolutionary Byproducts Belly Button ​ Adaptive Trait: The umbilical cord is essential for nourishing a fetus during development. ​ Byproduct: The belly button remains after the umbilical cord is detached, serving no adaptive purpose. Male Nipples ​ Adaptive Trait: Female nipples are essential for nursing offspring. ​ Byproduct: Male nipples persist because early fetal development follows a shared blueprint for both sexes before diverging due to hormonal differences. Higher Human Psychology (Hypothetical) ​ Adaptive Trait: The human brain evolved to solve complex survival and social problems. ​ Byproducts: Abilities like abstract mathematics, music, fine art, or spiritual musings might not have direct survival advantages but are incidental outcomes of having a highly complex and adaptable brain. 3. Why Byproducts Persist: ​ These traits often remain because there is no strong selective pressure to remove them, as they do not significantly harm survival or reproduction. Summary: Evolutionary byproducts remind us that not every trait exists for a direct purpose. Traits like the belly button and male nipples are incidental outcomes of vital adaptive traits, while higher human psychology might represent a fascinating byproduct of the evolution of complex brains. Recognizing the role of byproducts helps deepen our understanding of evolutionary processes beyond simple adaptation. Summary of Concepts Adaptation: A trait that is currently adaptive and serves the same purpose for which it was originally selected. → Example: Opposable thumbs for grasping objects. Exaptation: A trait that is currently adaptive but now serves a different purpose than originally intended. → Example: Feathers (initially for temperature regulation, later for flight). Vestigial Trait: A trait that is no longer adaptive but was adaptive in the past. → Example: Wisdom teeth (useful for larger jaws in ancestral diets). Evolutionary Byproduct: A trait that was never adaptive but exists as a byproduct of another adaptive trait. → Example: Belly button (a byproduct of the umbilical cord). The Gene's-Eye View Definition: the idea that evolution works at the level of genes, not individuals or species. It means that genes get passed down through generations if they help the gene survive and reproduce, even if they aren't always good for the individual or group. In other words, genes "want" to spread, and they can do so even if it harms the organism carrying them. 1. Level of Selection ​ The primary unit of selection in evolution is the gene, not the species or the individual organism. ​ This perspective focuses on how traits or behaviors spread based on whether they increase the survival and reproduction of the gene itself, even if it negatively impacts the individual or group. 2. Gene Variants Spread If ​ They contribute to the survival of the gene (directly or indirectly). ​ This can occur even if: ​ The gene harms the individual carrying it. ​ The gene negatively affects the group the individual belongs to. 3. Examples Mandrill Alpha Male ​ When a mandrill becomes the alpha male, physiological changes occur, such as the development of brightly colored face pads. ​ Being the alpha male increases stress levels and reduces life expectancy. ​ However, the alpha male has greater access to mates and reproduces more, ensuring the transmission of its genes. ​ This behavior is selected for because it benefits the gene, not the individual. Homosexuality (as briefly mentioned) ​ While homosexuality may superficially appear to decrease direct reproduction, there are multiple theories (six or seven) about how it might still benefit genetic fitness in indirect or non-obvious ways. 4. Implications for Fitness ​ Fitness is not about individual survival alone—it’s about maximizing the chances of gene propagation across generations. ​ Traits that harm the individual but help propagate the gene will still be favored by natural selection. The Genes-eye View: Key Concepts on 'Selfishness' and Life History Trade-offs 1. ‘Selfishness' of a Gene ​ In the gene's view, 'selfishness' refers to the selection process aimed at maximizing the fitness of the gene itself, not the organism's behavior or observed traits. ​ The term doesn't suggest that genes behave in a selfish way toward their hosts. It simply describes how genes are selected based on their ability to maximize their own survival and reproduction. 2. Unselfishness and Reproductive Success ​ Unselfish behavior can also be advantageous from a gene's perspective. ​ If genes producing unselfish behaviors increase the reproductive success of individuals who carry them (for example, helping relatives pass on genes), those genes will be selected for, even if they seem unselfish in their actions. 3. Life History Trade-offs ​ Trade-offs between fast and slow life histories affect organisms' strategies for reproduction and survival. ​ Fast life history: Organisms invest in having many offspring in a short lifespan but with lower investment in each individual offspring. ​ Slow life history: Organisms invest more in fewer offspring with a longer lifespan, improving the quality of each offspring. → Example ​ Higher testosterone levels can lead to traits that are preferred in male-male competition (such as strength), but this comes at a cost to brain development. ​ Such trade-offs show how life history strategies shape evolutionary outcomes, even when it may reduce an organism's individual longevity or health. 4. The Black Lace Spider Example ​ In the Black Lace Spider, mothers allow their offspring to consume them after giving birth. ​ This is a trade-off between the mother's longevity and the reproductive success of her genes—sacrificing herself to ensure the survival of her offspring. ​ This behavior illustrates how genes prioritize their propagation over individual survival. 5. Suicide and Evolution: ​ The question of suicide and whether it could have an adaptive function is complex. ​ From an evolutionary perspective, suicide doesn't seem to serve a direct survival function. However, in some extreme cases (like self-sacrifice for offspring), it might be seen as indirectly benefiting the gene pool. → Example: ​ Suicide bombers might, from a genes-eye perspective, increase the fitness of their genes by ensuring the welfare of their offspring or community through their death, as the offspring or family may receive resources and protection from the state. Genetic Inclusive Fitness Definition: Genetic inclusive fitness is the total genetic contribution of an individual, including both their direct offspring and their relatives (such as siblings or cousins), because these relatives share a portion of their genetic material. The greater the genetic overlap, the more likely it is that unselfish behaviors toward these relatives will increase an individual's genetic fitness. ​ A useful measure of genetic-inclusive fitness is the number of grandchildren an individual has. This reflects how many generations their genes continue to influence, as grandchildren represent the propagation of shared genetic material. The "Selfish Gene" Concept ​ Richard Dawkins' "The Selfish Gene" concept, introduced nearly 50 years ago, asserts that genes behave as though they are "selfish" because they seek to maximize their own survival and replication, sometimes at the expense of the individual organism. ​ The idea of the selfish gene does not mean that organisms themselves are selfish. Instead, it refers to how genes act in their own interest to be passed down, even if the host organism exhibits behaviors that seem to undermine its own survival. For example, the Black Lace Spider's maternal sacrifice is an example of a gene ensuring its propagation at the cost of the mother's survival, as the gene benefits through the offspring's survival. Unselfish Behavior and Genetic Fitness ​ Interestingly, being unselfish can increase genetic fitness. This may occur in situations like kin selection, where an individual helps their relatives, increasing the chances of shared genes surviving. For example, altruistic behaviors like caring for kin can be seen as "selfish" from a gene’s perspective if they promote the survival of genetically related individuals. ​ This concept challenges the idea that selfish behavior is always the most adaptive. In some cases, cooperation and altruism are favored because they enhance the survival of relatives who share genetic material. Environmental Influences on Behavior ​ Environmental conditions can play a significant role in determining whether selfish or unselfish behaviors are expressed. For instance, in harsh environments, individuals may exhibit cooperative behaviors to ensure the survival of the group or family. ​ These behaviors can be adaptive in that they ensure the survival of genes shared among close relatives. Genetic Drift and Non-Adaptive Traits ​ Genetic drift refers to the random changes in gene frequencies within a population, often due to small population sizes or random events. These changes can lead to traits that do not have adaptive value but still persist in the population because they were not selected against. ​ Traits that evolve without any clear adaptive benefit may remain in the gene pool simply due to random genetic fluctuations. These traits may not contribute to the organism’s survival or reproductive success, but they don’t necessarily harm the species either, allowing them to persist. Summary: Genetic inclusive fitness highlights that the survival of genes can extend beyond direct offspring to include relatives, reinforcing behaviors that promote family survival. The selfish gene theory emphasizes the gene's drive for survival, even when it leads to behaviors that seem unselfish. Unselfish behavior, such as cooperation with relatives, can increase an individual’s genetic fitness, while genetic drift can result in traits that persist despite lacking adaptive value. Evolutionary Psychology and Genetic Selection  1.​ Gene Selection Theory: ○​ In evolutionary psychology, the key idea is gene selection theory, which suggests that the unit of selection in evolution is not the individual or the species, but the gene itself. ○​ Organisms (like humans) are viewed as "machines" created by genes to ensure their survival and replication. In this view, our bodies are vehicles for genes, and natural selection acts on genes rather than the individual organisms. 2.​ Selfish Gene Concept: ○​ The selfish gene theory doesn't refer to selfishness in the way we typically think about it (i.e., individual selfishness). Instead, it refers to how genes act to maximize their survival and replication, sometimes even at the expense of the individual or species. ○​ An example of this is how human parents might sacrifice their well-being for the sake of their children. While this seems like an act of love, it can be understood as an adaptive strategy from a genetic perspective. The sacrifice may harm the individual, but it benefits the gene's survival by increasing the survival of offspring, who carry the same genes. 3.​ Unselfishness as a Gene Strategy: ○​ Unselfishness can be seen as a strategy for gene propagation. If a gene can cause a host organism (like a parent) to act unselfishly and care for its offspring, the gene's survival is more likely, even if this behavior is "bad" for the individual. ○​ The individual's sacrifice is not a failure of evolution, but rather an adaptation that contributes to the success of the gene. 4.​ Genetic Inclusive Fitness: ○​ Genetic inclusive fitness refers to the total genetic contribution an individual makes to future generations, including through their children, grandchildren, and other close relatives who share some portion of their genes. ○​ Rather than measuring fitness in terms of an individual's longevity or happiness, genetic fitness is assessed by looking at how effectively the individual passes on their genes. A useful metric for this is the number of grandchildren an individual has, since grandchildren represent a further propagation of the individual's genetic material. 5.​ Importance of Grandchildren in Measuring Fitness: ○​ Focusing on grandchildren instead of just children provides a clearer picture of an individual's genetic contribution to future generations. If a parent has many children but invests little in their survival or success, the children may not survive to pass on the parent's genes. However, by the time the next generation (grandchildren) is reached, it provides a better measure of the gene's long-term success in the evolutionary process. Summary:Gene selection theory in evolutionary psychology emphasizes that genes are the true units of selection. Organisms serve as vehicles to propagate genes, and behaviors that seem unselfish (such as parental sacrifice) can be seen as strategies for gene survival. The concept of genetic inclusive fitness provides a measure of an individual's genetic success, focusing on the survival of their genes in future generations, with grandchildren serving as a key indicator of this success.