Evolutionary Psychology II (102) PDF

PSYCH 102: Evolutionary Psychology II (4) Environment of Evolutionary Adaptiveness (EEA) 1. What is the Environment of Evolutionary Adaptiveness (EEA)? ​ EEA refers to the specific environmental conditions and circumstances that were responsible for the selection pressures that led to pa...

PSYCH 102: Evolutionary Psychology II (4) Environment of Evolutionary Adaptiveness (EEA) 1. What is the Environment of Evolutionary Adaptiveness (EEA)? ​ EEA refers to the specific environmental conditions and circumstances that were responsible for the selection pressures that led to particular adaptations in a species. ​ It helps explain why certain traits evolved based on the challenges and needs in the environment at the time. 2. Examples of Adaptations Fins in Whales ​ Whales, millions of years ago, evolved from land-dwelling creatures (similar to dogs) into sea-dwellers. Initially, these creatures didn’t have fins. As they entered the ocean, fins became a key adaptation for efficient movement through water. ​ The EEA for this adaptation was the ocean, where the need to navigate through water led to the development of fins. Eyes in Animals ​ Eyes have evolved independently multiple times across different species because they are incredibly useful for survival, providing the ability to see distant objects or predators. ​ The EEA for eyes is the presence of light, which has always existed on Earth, driving the evolution of this adaptation across many species over time. The Evolutionary Adaptiveness of Human Psychology What Was the EEA of Human Psychology? ​ The Environment of Evolutionary Adaptiveness (EEA) refers to the conditions in which human psychological traits evolved. By identifying when these traits emerged, we can infer the environmental pressures that shaped them. ​ The human brain underwent massive changes during the evolutionary timeline, and the EEA provides context for understanding the selection pressures that drove these changes. Biological Changes in Humans: Brain Expansion ​ Human brains expanded rapidly in evolutionary terms. ​ While our closest evolutionary relative, the chimpanzee, has a brain size of about 350 cubic centimeters, modern humans have an average brain size of 1,450 cubic centimeters—more than quadruple the size. ​ The most significant brain growth occurred between 2 million and 6 million years ago, with the steepest rise in the last 2 million years. Changes in Brain Shape ​ The human brain evolved to have a higher forehead and a more rounded skull, contrasting with the flatter, angled skulls of early ancestors. ​ This structural change reflects the expansion of specific brain regions, particularly the frontal lobes. Frontal Lobe Development ​ The frontal lobes are responsible for planning, executive function, social intelligence, and morality—traits that distinguish humans from other species. ​ While the overall brain grew, the areas responsible for sensory input (e.g., vision, located in the occipital lobe) did not expand as significantly. The Role of EEA in Brain Expansion ​ The EEA for these biological changes likely involved environmental and social pressures that demanded advanced problem-solving, cooperation, and planning. ​ Early humans lived in the African savannah in small, tight-knit groups (approximately 50 individuals) and subsisted through hunting and gathering. → This environment required ​ The development of tools and strategies for survival. ​ Complex social interactions, such as cooperation, communication, and conflict resolution. ​ Planning for food storage, seasonal changes, and group safety. Neanderthals and Human Brain Comparisons ​ Neanderthals, another closely related species, had even larger brains (1,550–1,600 cubic centimeters), but their brain shapes were different, with less pronounced frontal regions. ​ Despite their larger brain sizes, humans outcompeted Neanderthals, likely due to differences in social intelligence, adaptability, and tool-making skills. Other Observations ​ While human brain sizes have slightly decreased over the last few thousand years, the brain-to-body size ratio is still a strong indicator of intelligence across species.  ​ Larger animals (e.g., blue whales) have bigger brains but are not necessarily more intelligent because intelligence depends on brain specialization and function rather than sheer size. Mismatch Theory Definition: Explains the disconnect between human evolutionary adaptations and the rapid changes in modern environments. Evolutionary Time Lag ​ Evolution is a slow, gradual process that requires many generations for significant genetic changes to occur. ​ For nearly 200,000 years, humans lived in stable environments that shaped both their physical and psychological traits. ​ Over the last 10,000 years, environmental changes—including the advent of agriculture, urbanization, and technology—have occurred at a rate too fast for genetic evolution to keep pace, leading to mismatches between our evolved traits and modern lifestyles. Evolutionary Background Environment of Evolutionary Adaptiveness (EEA) → Humans evolved in small, close-knit groups of about 50–200 individuals. Lifestyles were characterized by ​ Nomadic Movement: Constant relocation to exploit food and natural resources. ​ Survival under Scarcity: Food was often scarce, necessitating efficient energy storage and resourcefulness. ​ Face-to-Face Interaction: All social bonds, cooperation, and hierarchies were formed within small groups, with no exposure to larger societal structures. → These conditions shaped traits such as ​ Strong cravings for calorie-dense foods. ​ Stress responses to acute physical threats. ​ The need for strong social connections and belonging. Modern Environment Approximately 10,000 years ago, the development of agriculture marked a significant shift: ​ Humans began living in settled communities. ​ Population sizes grew exponentially. ​ Resource abundance and specialization replaced scarcity and generalist survival. Industrialization and technological revolutions over the last few centuries accelerated these changes even further. ​ Globalization, urbanization, and digital connectivity created environments that humans are not biologically equipped to handle. Examples of Mismatch → Diet and Cravings EEA Context: Calorie-dense foods (rich in sugar, fat, and salt) were rare but critical for survival. Evolution rewarded humans with cravings for such foods to ensure energy needs were met. Modern Context: These foods are now readily abundant, leading to overconsumption and health issues like obesity, diabetes, and cardiovascular diseases. Mismatch: Our brains still interpret these foods as "rare and essential," even though they are now harmful in excess. → Social Interaction EEA Context: Humans evolved for intimate, face-to-face interactions within small groups. Social bonds and cooperation were crucial for survival. Modern Context: Social media and global interconnectedness expose individuals to thousands of people, creating unrealistic comparisons, feelings of inadequacy, and loneliness. Mismatch: The brain is not adapted to handle large, impersonal networks or the pressures of online interactions. → Stress Responses EEA Context: Stress responses evolved to handle immediate, short-term threats (e.g., predators or conflicts). The fight-or-flight response was adaptive in these scenarios. Modern Context: Chronic stressors, such as work deadlines, financial struggles, or constant notifications, trigger the same physiological responses, but without resolution. Mismatch: Chronic activation of the stress response leads to burnout, anxiety, and physical health problems. → Cognitive Challenges EEA Context: The brain evolved to solve survival-based problems in relatively simple environments, such as hunting, gathering, and avoiding predators. Modern Context: Modern humans face complex societal systems, like navigating cities, working office jobs, or understanding global issues like climate change. Mismatch: Our Stone Age brains struggle to process these abstract, large-scale challenges, often resulting in decision fatigue, anxiety, or avoidance. Key Insights ​ Humans are biologically equipped with "Stone Age brains" that were optimized for small-scale, resource-scarce environments. ​ Rapid advancements in technology, lifestyle, and societal organization have created numerous mismatches between our instincts and modern realities. ​ Examples like overeating, chronic stress, and struggles with digital connectivity illustrate how these mismatches impact physical and mental health. ​ By understanding mismatch theory, we can better design interventions to align modern environments with our evolutionary heritage, improving overall well-being. Mismatch Theory Overview ​ Evolutionary mismatch occurs when human traits, adapted to ancestral environments, fail to align with modern environments. ​ The past 10,000 years, although significant in terms of technological and societal changes, is considered a very short time for major evolutionary changes, especially in complex traits like brain function. Small Changes Over Time → While large-scale brain changes are unlikely, small biological adaptations have occurred: Lactose Tolerance: Populations that domesticated milk-producing animals developed lactose tolerance in adulthood, a notable digestive adaptation. Spleen Adaptations: In populations reliant on underwater activities, changes in spleen function improved diving capacity. Environment vs. Evolution → Modern humans have begun shaping their environments to fit existing traits, slowing down natural selection pressures. For example: Vision Correction: Glasses and contact lenses mitigate the disadvantage of poor eyesight, removing selection pressure against this trait. Wisdom Teeth: The absence of wisdom teeth in some individuals could be a microevolutionary adaptation, as those without them avoid complications. Addiction and Behavioral Traits Addiction: Populations with longer exposure to substances like alcohol may exhibit increased tolerance and reduced susceptibility to addiction compared to populations with limited exposure. ADHD: Variability in attention spans may have always existed but is now classified and understood in different ways, possibly reflecting a spectrum of natural variation rather than a new adaptation. Art and Creativity Artistic expression (e.g., cave paintings, figurines) may not necessarily reflect new adaptations. Instead, it could be a byproduct of other evolved traits, such as the appreciation of patterns, symmetry, or storytelling. Evolutionary Timeframes ​ Short timeframes, such as a few centuries, are insufficient for substantial physical evolution. Traits must persist under consistent selection pressure over millennia for significant changes to occur. ​ Technologies and cultural practices, like typing or key usage, are unlikely to shape physical traits (e.g., finger adaptations) due to their rapid obsolescence and limited generational impact.  What a Peculiar Time to be Alive We Only Know This Society: The world we live in today feels normal to us because it’s the only environment we’ve experienced. Our daily routines, technologies, and societal norms are so deeply ingrained that we rarely question how unusual they are in the broader context of human history. The Water We Swim In: Like fish unaware of water, we often fail to notice the profound ways modern society shapes our lives. This environment feels natural because we were born into it, yet it’s vastly different from the conditions that shaped our species over hundreds of thousands of years. A World Unlike What We Evolved For: For the majority of human history, our ancestors lived in small, nomadic groups, relying on hunting, gathering, and close-knit social bonds. Modern urban living, sedentary lifestyles, and technological dependence would seem alien to them—and biologically, our brains and bodies are still wired for that earlier way of life. Peculiar Becomes Normal: The structures of our modern world—cities, screens, and even the pace of life—are radically different from what humans were adapted to survive in. Yet, because we’ve grown up in this environment, these peculiarities feel ordinary and unremarkable to us. Sex and Sex Differences Sex and Death: The Two Drivers of Evolution ​ Evolutionary success hinges on two fundamental processes: survival (avoiding death) and reproduction (sex). ​ Survival ensures that an individual can live long enough to reproduce, while reproduction ensures the continuation of genes into the next generation. ​ Metaphorically, sex and death act as the "gas pedal" and "brake" of evolution. Reproduction Is Complex Avoiding death involves straightforward strategies (e.g., finding food, and avoiding predators), but reproduction is much more psychologically complex. → Reproduction requires individuals to: ​ Convince others to mate with them. ​ Select the "right" mates—those whose genetic traits will increase the chances of survival and reproductive success for their offspring (referred to as inclusive fitness). Male & Female Differences Across Species Size Differences ​ In many species, males are larger than females (common in mammals). ​ In some species, such as spiders, females are larger than males. Sexual Motivation and Behavior ​ Males tend to be more sexually motivated and exhibit behaviors that are competitive for mates. ​ Females are generally more selective in choosing their mates, often focusing on quality over quantity. Sexual Ornamentation ​ Males often possess elaborate physical traits (such as bright colors, feathers, or other ornaments) to attract females. These traits can be quite conspicuous and sometimes extravagant. ​ Females, in contrast, are often more drab or subdued in appearance. Aggression and Weaponry ​ Males are often equipped with aggressive weaponry (e.g., antlers, tusks, larger muscles) and show more aggressive behavior toward rivals. ​ Females typically do not exhibit such aggression and are less likely to be outfitted with weaponry. Parental Care ​ In many species, females do most of the caring for the young (e.g., nurturing, protecting, and feeding). Parental Investment Theory (Robert Trivers, 1971) Parental Investment Theory, proposed by Robert Trivers in 1971, explains the differences in male and female behaviors and traits across species by focusing on the division of labor during reproduction and the investment each sex makes in their offspring. Division of Labor in Reproduction Reproduction often involves a division of labor between males and females. This means that each sex plays a different role in the reproductive process, which leads to different evolutionary pressures. Parental Investment Parental investment refers to the time, energy, and resources that a parent devotes to raising their offspring. Typically, the parent investing more resources will be more selective in choosing a mate, as they want to ensure that the mate they choose will contribute to the survival and success of their offspring. ​ For many species, females tend to invest more in offspring care, either through pregnancy, egg-laying, or post-birth care, which makes them more discriminating in mate choice. ​ On the other hand, males usually have lower parental investment, especially in species where they do not participate in raising offspring, leading to higher competition among males to win over females. Sexual Selection and Mating Strategies ​ The difference in parental investment drives sexual selection. Males, with their lower investment in offspring, compete more intensely for mating opportunities, often showing elaborate traits (such as aggression, ornamentation, or displays) to attract females. ​ Females, with their higher investment, are more choosy and tend to prioritize quality over quantity in selecting mates. Evolution of the Theory ​ Initially, Charles Darwin (in 1871) observed the differences between males and females in the animal kingdom but did not provide a concrete explanation. ​ Robert Trivers' theory provided a much-needed explanation for these differences, showing that the costs of reproduction and investment are key factors in understanding sexual behavior and evolution. This theory helped explain many observed patterns, like why males are more likely to be aggressive or possess ornamentation to attract females. Implications in Human Behavior ​ In humans, the theory suggests that women may be more selective in choosing mates due to higher parental investment (e.g., pregnancy, caregiving). Men, with lower initial investment, may be more inclined to compete for mates. ​ These differences can explain some of the gendered behaviors we see today, such as mate competition and sexual jealousy. The Sexual Division of Labor in Reproductive Costs Parental Investment Theory, as expanded here, highlights how reproductive costs are divided between parenting costs and mating costs, with distinct roles for males and females. 1. Parenting Costs Definition: Parenting costs involve the energy and resources required to raise offspring. ​ Primarily borne by females: Across most species, females bear the majority of parenting costs, investing heavily in pregnancy, nurturing, and caregiving. ​ Variation by species: While females generally shoulder these costs, the degree varies across species. 2. Mating Costs Definition: Mating costs are the efforts invested in finding and securing a mate. ​ Primarily borne by males: Males generally focus on mating efforts rather than parenting. This includes behaviors and traits aimed at maximizing reproductive success. Two Types of Mating Costs 1. Intersexual Selection (Between the Sexes) Focus: One sex selects mates based on traits that indicate genetic fitness. → Examples ​ Male peacocks display elaborate feathers to attract females. ​ Adaptations evolve to showcase the desirability of the opposite sex. 2. Intrasexual Selection (Within the Same Sex) Focus: Individuals of the same sex compete for access to mates. → Examples ​ Gorillas engage in physical competition to establish dominance. ​ Traits like increased testosterone levels in male mandrills promote competitive behaviors. Humans and the Blurred Distinction → Humans diverge from many species in the division of reproductive costs Increased male parental investment: Human males contribute more to parenting than males in most primate species. ​ Female mating efforts: Women invest more in mating costs compared to females in other species, including efforts to attract mates. ​ Mutual mate selection: Unlike other species, human males are more selective than most male primates, though females remain choosier overall. This results in more balanced mutual selection compared to other species. Men and Women Have Large Differences Male Aggression ​ Men commit 95% of convicted homicides ​ Men victims in 79% of convicted homicides ​ Male chimps commit 92% of chimpicides ​ Male chimps victims in 73% of chimpicides → These consistent trends across species suggest a deep-rooted origin of male aggression. → The parallels between human and chimpanzee behavior point to shared evolutionary traits rather than random or purely cultural phenomena. Biological Continuity ​ Aggression differences are evolutionarily inherited from a common ancestor. ​ Biological mechanisms, such as testosterone levels, influence aggression and dominance behaviors across species. ​ This perspective highlights that these traits are innate and adaptive in nature, shaped over generations. Cultural Reinvention Hypothesis ​ Humans are culturally shaped blank slates, and societies have independently constructed these patterns. ​ This explanation is less plausible, given the remarkable consistency in sex-based aggression across species. Interaction of Biology and Culture → Human aggression results from an interplay of biology and culture: ​ Biological predispositions provide a foundation. ​ Cultural norms and societal structures shape how aggression is expressed or suppressed. → For example, cultural norms may tolerate or reward male aggression, reinforcing natural tendencies, while also influencing societal outcomes. Human Uniqueness ​ Unlike other species, humans display more variability in how aggression is expressed due to greater cultural influence and social complexity. Men and Women Have Small Differences – Sexual Dimorphism Definition: Refers to physical differences between males and females, particularly in body size and related traits. Example 1 – Silverback Gorilla (Huge difference): ​ Males are twice as large as females. ​ Larger male sizes evolved due to the intense competition for reproductive dominance. ​ Highly hierarchical social structure dominated by an alpha male. ​ The alpha male sires 85% of the offspring in his group. ​ Large male size is a product of competition among males for dominance, where physical strength determines reproductive success. ​ Smaller females avoid the cost of unnecessary size since they do not engage in a similar competition. Example 2 – Bonobo (Moderate Difference): ​ Much less sexual dimorphism in size (males ~25% larger than females). ​ Egalitarian and polyamorous social structure. ​ Polyamorous, gender-balanced societies reduce the need for size-based competition. ​ Less intense selective pressure for larger males results in reduced size differences. ​ Distinguishing males from females is more difficult compared to other great apes. Humans (Least Amount of Difference): ​ Have the least sexual dimorphism among great apes, with males on average 15% larger than females. Overlapping height distributions: Many females are taller than shorter males, making differences less pronounced. ​ Social structures and environmental influences play a larger role compared to purely biological traits. Physical Traits: ​ Sexual dimorphism in humans is smaller compared to other apes. ​ Male height advantage (~6–7 inches on average) is modest and varies significantly, with considerable overlap between male and female height distributions. Behavioral Traits: ​ Male aggression and traits like throwing force show more pronounced differences with minimal overlap. ​ Traits like general intelligence or creativity often show significant overlap between sexes, reflecting small or negligible differences. The Challenge is to Neither Overstate Nor Understate those Differences → Differences between sexes exist but are often exaggerated or understated: ​ Some traits, like physical strength, show clear distinctions. ​ Other traits, such as cognitive abilities, have overlapping distributions with small average differences. More Similarities Than Differences ​ Both men and women highly value intelligence, humor, and honesty in romantic partners, indicating a significant overlap in preferences. ​ Differences in ranking exist but are relatively minor. → For example ​ Kindness and values are prioritized by women, while good looks and facial attractiveness are emphasized more by men. Humor ​ Women often describe humor as the ability of a partner to make them laugh. ​ Men, in contrast, might view humor as a partner appreciating their jokes or comedic sense. ​ Despite this difference, humor remains a universally important trait. Main Finding: Both Lippa's study (2007) and class results show that men and women are more alike than different in mate preferences, with significant overlap in top traits. Key Observations ​ Kindness: Ranked higher by both men and women in the class data compared to Lippa’s findings. ​ Facial Attractiveness: Appears in both lists for men and women but is ranked lower than traits like kindness, honesty, and humor. ​ Honesty/Kindness: Both men and women in class data ranked kindness and honesty as their top two traits. Lippa’s findings emphasized humor and intelligence more highly for both genders. → The differences between UBC class data and Lippa's study may reflect shifts in cultural values or sociability norms in different contexts. Sex Differences in Good Looks Key Point: Across various countries, men consistently prioritize good looks more than women in mate preferences. Class Observations Men's Preferences: ​ Intelligence ranked higher for men in the class data than for women, which was unexpected. ​ Men also emphasized good bodies and facial attractiveness. Women's Preferences: ​ Women placed slightly more emphasis on earning potential than men. Global Data on Good Looks ​ Data shows systematic and predictable gender differences in preferences. ​ Across all countries analyzed (from Argentina to Venezuela, including Canada): ​ Men consistently ranked good looks as more important than women did. ​ Lower rankings indicate higher importance, and men’s rankings for good looks were systematically lower than women’s. Main Takeaways Gendered Differences: ​ While both genders share many similarities in mate preferences, good looks are a gendered element with men placing significantly more importance on this trait. Cultural Consistency: ​ The preference for good looks in men is consistent across cultures and countries, reinforcing it as a predictable pattern in mate preferences. Evolutionary Psychology Critique: ​ Evolutionary psychology tends to emphasize differences (e.g., men value good looks more and women value earning potential).  ​ However, the shared priorities (e.g., kindness, honesty, intelligence) often outweigh these differences in importance. Sex Differences in Earning Potential Key Points ​ Women consistently prioritize earning potential in men across cultures. ​ Even women who earn more than men (including their partners) still prioritize earning potential in their mate. Evolutionary Perspective ​ The preference for earning potential may have evolutionary roots, as financial stability historically provided resources for offspring. Alternate Explanation ​ Women may prioritize earning potential due to systematic gender disadvantages (e.g., economic inequality). Pairing with a higher-earning mate could offset these disadvantages. Global Data on Gender Equality A massive study examined gender equality and its impact on mate preferences: → Prediction: ​ If economic parity reduces this preference, the importance of earning potential should diminish in gender-equal countries. → Findings: ​ The preference for earning potential remains consistent across countries, regardless of gender equality. ​ Data from the Gender Development Index showed no convergence in mate preferences between men and women as gender equality improved. Main Takeaways Persistent Gendered Pattern: ​ Women, even in modern and gender-equal societies (e.g., 2025 college students), consistently prioritize earning potential. Cultural Consistency: ​ This gender difference is observed universally, showing little variation across different levels of gender equality. Complex Influences: ​ While evolutionary explanations may partly account for the trend, societal factors (e.g., economic disparities) could also contribute to its persistence. Sex Differences in Age Preferences Key Points: ​ Women generally prefer older men as partners. ​ Men generally prefer younger women as partners. Men's Preferences (Class Survey): ​ Most men preferred partners of the same age or younger. ​ A smaller portion of men preferred slightly older partners. Women’s Preferences (Class Survey): ​ Most women preferred partners of the same age or slightly older. ​ Women were less likely to prefer younger partners than men. Lifespan Trends (Broader Data): → At younger ages (e.g., late teens to early 20s): ​ Women prefer partners slightly older than themselves (e.g., 18-year-old women tend not to date younger teenagers). ​ Men prefer partners younger than themselves. → As women age: ​ They become more flexible in their preferences and are open to younger partners. ​ Men’s preferences remain relatively consistent throughout life, showing a persistent preference for younger partners. Sex Differences in Attractiveness According to Age Women’s Definition of Attractiveness ​ Younger women tend to find men slightly older than themselves more attractive, but this preference evolves over time. ​ As women age, their definition of attractiveness aligns more with their own age group. They gradually prefer men around their own age rather than significantly younger men. ​ By the mid-40s, women begin to perceive younger men as less attractive, and aging in both genders becomes less of a focus for women when it comes to attractiveness. Men’s Definition of Attractiveness ​ Men’s preference for youthful attractiveness remains consistent across their lifespan. ​ Regardless of age, men consistently find younger women (20s-early 30s) to be the most attractive. ​ This preference doesn't change as men age, meaning even older men in late adulthood still find young women attractive. Key Takeaway ​ Men's attraction to youth remains constant throughout their lives, while women’s perception of attractiveness changes over time, often favoring partners closer to their age. ​ As women age, they tend to focus less on youth and more on qualities like maturity, compatibility, and intelligence in a partner. Why Do Men Like Younger Women? ​ Men’s attraction to younger women can be understood through evolutionary psychology. ​ Facial attractiveness in women is often linked to symmetry and gender typicality (features that are indicative of youth and fertility). Symmetry ​ Men are generally more attracted to symmetrical faces, as symmetry is often associated with genetic health. → Features that signal youthfulness are key, such as: Neoteny (exaggerated youthful features) – big eyes, full lips, small chin, and small nose. ​ These features are considered fertility cues, signaling youth and reproductive potential. ​ Makeup serves to exaggerate these cues of neoteny (e.g., enhancing eye size, lip fullness) and sexual maturity, both of which align with the evolutionary cues men are attracted to. Evolutionary Explanation ​ Men’s preferences for youthful attractiveness align with their instincts for maximizing reproductive success. ​ Men unconsciously prioritize fertility cues (youthfulness, neoteny) as part of their genetic fitness strategy. ​ Historically, men who were attuned to recognizing youth and fertility (through physical cues like facial features) were more likely to leave descendants compared to those who were less sensitive to these cues. Sources of Sexual Conflict in Relationships Sexual conflict between the sexes often arises due to evolved differences in sexual behavior. These differences can create tension in heterosexual relationships, particularly in the following areas: 1.​ Differences in desire for sexual novelty 2.​ Differences in desires for sexual variety 3.​ Differences in sexual willingness 4.​ Differences in perception of sexual interest 1. Desire for Sexual Novelty ​ Men tend to have a stronger desire for sexual novelty, meaning they are more likely to seek out new sexual partners. ​ Research shows that when asked about their ideal number of new sexual partners in the next month, year, or 30 years, men report a significantly higher number than women. On average: ​ Women desire about 2.5 new sexual partners over the next 30 years. ​ Men desire about 6 or more, reporting higher numbers ​ This difference is consistent across cultures and sexual orientations, where gay men also report a higher desire for sexual novelty compared to gay women. 2. Desire for Sexual Variety When asked about wanting more than one sexual partner in the next month, research consistently shows that men have a higher preference for sexual variety across various cultures and continents. → This difference remains significant regardless of whether individuals identify as straight or gay. ​ Men, both straight and gay, show a much stronger preference for new partners compared to women, who generally express a desire for fewer sexual partners within the same time frame. ​ This highlights the evolutionary difference in sexual preferences between men and women, with men more likely to seek out sexual variety and novelty. 3. High Sexual Willingness An attractive graduate student approaches people on campus and asks: Would you go on a date with me? Would you come back to my apartment? Would you have sex with me? Results Going on a Date: Both men and women were equally likely (about 50%) to agree to go on a date. Coming Back to My Apartment: Women (5%) Men (70%) Having Sex: Women (0%) Men (75%) ​ No women agreed to this request in the studies before a recent replication. ​ Even then, only a few women showed willingness, indicating a clear gender difference in sexual willingness. Safety Considerations ​ While safety concerns could explain some of the hesitancy from the women, the overall trend strongly supports the idea that women tend to be less willing than men when it comes to engaging in sexual activity with strangers. This highlights an important aspect of sexual willingness and how it differs between the sexes. Differences in Sexual Willingness Across Cultures General Findings for Men ​ Men typically want more sexual partners over time than women. ​ Married men are more likely to seek extra-marital affairs or have a "side piece." ​ Men are more likely to actually have affairs and have fantasies about short-term sex or sex with strangers. ​ Men are less likely to regret a one-night stand. ​ They are less likely to view a one-night stand as a potential pathway to a long-term relationship. ​ Men often consume porn that focuses on short-term sex devoid of emotional connections. ​ Men are more likely to be patrons of prostitutes. ​ More attractive men tend to have more short-term relationships but fewer long-term relationships compared to less attractive men (Rhodes et al., 2005). ​ Conversely, more attractive women have long-term relationships but fewer short-term relationships than less attractive women. Findings for Women ​ When women pursue short-term mating, they tend to have different motives than men: ​ Their goal is often securing the possibility of a future long-term relationship or "mate-switching" (finding someone better for a long-term partnership). ​ When women engage in affairs, it's often because they are unhappy in their current relationship, as opposed to men who may engage in affairs for opportunity rather than dissatisfaction. Attractiveness and Relationship Types Attractive men tend to take advantage of their high market value for short-term relationships, while attractive women leverage their status for long-term relationships. Perception of One-Night Stands ​ For women, a one-night stand may often be viewed as a "failure" to initiate a long-term relationship or as a test for a potential future partner. ​ Men may view these encounters more casually and not expect them to lead to long-term commitment. The Eerie Fact About Affairs The eerie fact is that when men engage in affairs, they don’t necessarily do so because they are unhappy in their current relationship. In fact, there’s no difference in the happiness levels between men who have affairs and those who don’t, across all ages. Men typically don’t engage in affairs due to dissatisfaction but rather because the opportunity presents itself and they feel they can get away with it. Evolutionary Perspective on Mating Behaviors Short-Term Mating: ​ More adaptive for men due to fewer costs and greater evolutionary benefits. ​ Men are likely evolutionarily equipped with motivations to pursue short-term mating more than women. → Reasons: ​ Men can father multiple offspring simultaneously with different partners ​ Women can only be pregnant with one child at a time. ​ Men are less involved in child-rearing, especially when offspring are distributed across multiple partners. Affair Patterns: ​ Women: Tend to have affairs with people similar to their existing partners. ​ Men: Tend to have affairs with individuals different from their long-term partners. Partner Preferences: ​ Both men and women prioritize traits like intelligence, kindness, and honesty when selecting long-term partners. ​ Women also value these traits in short-term partners. ​ Men, however, exhibit an evolved tendency to prioritize different traits in short-term partners that women do not. Evolutionary Explanation: ​ Men's system is "tuned" toward short-term mating for reproductive success. ​ This is consistent across heterosexual and homosexual dynamics, from an inclusive fitness standpoint. Long Term v.s Short Term Relationships - Class Data Men in the class ​ 50% said they were primarily looking for a long-term partner ​ 34% said they were open to both short-term and long-term partners ​ 19% said they were primarily interested in short-term relationships Women in the class ​ 65% said they were primarily looking for a long-term partner. ​ 35% said they were open to both short-term and long-term partners ​ Not a single woman in the class reported primarily looking for short-term relationships. Key Observations: ​ Men prioritize intelligence more for marriage and long-term relationships, but the requirement decreases significantly for casual sex. ​ Women, on the other hand, maintain a relatively high standard of intelligence, even for casual sex. Evolutionary Perspective: ​ For women, engaging in casual sex poses higher evolutionary risks, such as the potential for pregnancy and the possibility of passing on undesirable genes. ​ For men, casual sex involves fewer evolutionary costs due to reduced responsibility for potential offspring. ​ Women’s focus on intelligence even for casual relationships reflects a strategy to mitigate risks associated with pregnancy and undesirable genetic traits. 3. High Sexual Interest Error Management Theory (EMT) Error management theory explains how humans have evolved psychological systems to minimize the costs of errors in uncertain situations. → Key Premise: When making decisions with incomplete information, errors are inevitable. These errors are categorized as: Type 1 Error (False Positive): Acting as if there’s a signal or threat when none exists. ​ Example: Hearing a car alarm when the car isn’t being stolen. ​ Consequence: Inconvenience, embarrassment, or annoyance (relatively minor harm). Type 2 Error (False Negative): Failing to detect a real signal or threat. ​ Example: Car alarm not going off when the car is being stolen. ​ Consequence: Significant harm, such as loss of the car. EMT’s Guiding Principle: When the costs of errors are asymmetric, our decision-making systems are biased to favor the less costly error (even if it means making that error more often). Differences in Sexual Interest: Men’s Perspective ​ Due to evolution missing out on sexual opportunities (Type 2 error) would have been more costly for men in terms of reproductive success. ​ Bias: Men are more likely to overestimate women’s sexual interest to avoid the costly Type 2 error of missing a potential mating opportunity. ​ Consequence: False positives (Type 1 errors) may lead to embarrassment or rejection, but the evolutionary "cost" is lower than missing a genuine opportunity. Women’s Perspective: ​ Due to evolution, women faced higher costs from casual mating (e.g., pregnancy, and childcare). Thus, their decision-making systems are tuned to be more cautious. ​ Bias: Women are less likely to overestimate men’s interests and tend to interpret ambiguous signals conservatively. ​ Example: A woman might interpret a man’s friendly behavior as just friendliness rather than romantic interest. ​ Consequence: Women are less prone to false positives but may miss genuine signals (Type 2 errors), which are less evolutionarily costly for them. The Sexual Abyss Dick Pics Study – “I’ll Show You Mine so You’ll Show Me Yours” ​ 53% of millennial women have received a dick pic, with 78% of those being unsolicited. ​ Common Reactions from Women: ○​ Gross (49%) ○​ Stupid (48%) ○​ Sad (24%) ○​ Sexy (17%) Why Do Men Send Them? 1. Aggressive Motive: to upset the woman ​ Some men might send dick pics with the intention to upset the woman or provoke a reaction. ​ This aligns with a more hostile or aggressive attitude toward women. 2. Selfish Motive: to please themselves ​ For some men, sending these images may simply be about self-gratification, without regard for the recipient’s feelings. ​ This is driven by exhibitionism or a desire to show off, with little concern for how the woman might feel. 3. Misguided Motive (Most Common): to please the woman ​ The majority of men sending dick pics do so with the misguided belief that women would appreciate or desire such images. Psychological Missteps ​ Men often assume that women would want to receive a nude image the same way they might. ​ This belief is rooted in a projection of their own desires onto women, without considering the differences in how women may view such acts. ​ Men may think, "I would like to receive nude images, so they would too" Evolutionary Factors ​ Men may have developed biases that lead them to overestimate sexual interest in ambiguous situations. ​ This cognitive bias leads men to misread signals, mistakenly assuming that women share the same desires. ​ Women generally do not appreciate unsolicited sexual advances and tend to value boundaries. ​ The core issue here is that men and women often live in different psychological worlds when it comes to sexual behavior and desires. People’s Perspectives on The Sexual Abyss The “Sexual Abyss” Psychologist Steven Pinker: “The sexual abyss [may] come from a parochial inability of men to conceive of a mind unlike theirs, a mind that finds the prospect of abrupt, unsolicited sex with a stranger to be repugnant rather than appealing.” ​ Argues that the "sexual abyss" stems from men's inability to understand that women may find unsolicited, abrupt sexual advances repugnant rather than appealing. ​ Believes men often fail to appreciate the vast differences in sexual desires and behaviors between the sexes. Psychologist Catherine Salmon and Anthropologist Donald Symon: "To encounter erotica designed to appeal to the other sex is to gaze into the psychological abyss that separates the sexes... The contrasts between romance novels and porn videos are so numerous and profound that they can make one marvel that men and women ever get together at all, much less stay together and successfully rear children.” ​ The psychological divide between men and women is evident in the contrasting ways they consume erotica—romance novels for women and porn videos for men. ​ These differences are so profound that it’s surprising men and women ever form lasting relationships or raise children together. Balancing Gender Differences Overstating Differences ​ Risk: This leads to stereotypes and viewing the other gender as completely separate. ​ Consequence: Fails to recognize common humanity. Understating Differences ​ Risk: Fails to acknowledge real differences, leading to misunderstanding and conflict. ​ Consequence: Treats others as you want to be treated, not as they want. The Balance ​ Challenge: Neither overstate nor understate differences. ​ Goal: Recognize differences without creating stereotypes and respect individual preferences. → Important Point: Treat people as they want to be treated, not as you would want to be treated.