The Cambridge Handbook of Evolutionary Perspectives on Human Behavior (2020) offers a comprehensive overview of how evolutionary theory helps explain human behavior across domains like mating, cooperation, status, aggression, parenting, and culture. Written by top scholars, it distills decades of research into clear and groundbreaking insights into human psychology and behavior.

SUMMARY

About the Authors:
Different authors, and the main editors are Lance Workman, Will Reader, and Jerome H. Barkow.
Workman and Reader also edited Evolutionary Psychology: An Intro.

Chapter 4: Eusociality in Humans

Laura Betzig opens by tracing the evolution of fully cooperative societies (“eusociality”) in humans, contrasting our species with the eusocial structures of some insects.
She argues that human kinship systems and cooperative breeding foster levels of altruism and division of labor unseen elsewhere, yet still follow principles of inclusive fitness.

• Allomothering & cooperative childcare: human infants receive care from multiple relatives (grandmothers, aunts) boosting offspring survival.
• Division of labor & reproductive skew: though humans lack the morphological caste system of insects, social structures help regulate who reproduces vs. who helps.

Chapter 5: The Nature and Psychological Foundation of Social Universals

Bernard Chapais argues that many cultural universals (e.g. taboos, marriage rules) derive from evolved psychological adaptations for kin recognition, alliance formation, and status acquisition.

He outlines how a small set of cognitive mechanisms gives rise to the vast interlinked web of human social values and norms.

A classification of a large sample of social universals found in Pinker’s (2002) alphabetical list of absolute universals drawn from Brown (1991). Primary social universals are likely to have psychological underpinnings. Derived social universals result from combinations of primary social universals.

• Status‐attainment module: humans possess innate sensitivities to rank and prestige, which drive political alliances and social stratification.
• Kin detection & incest avoidance: cues like coresidence and maternal perinatal association inform inbreeding avoidance.
• Coalition psychology: mechanisms for recognizing and reciprocating support within groups underpin norms of obligation and trust.

Status-seeking

Humans are hard-wired to pay attention to status, and the author lists four motives related to status:

1. opportunistically acquiring and improving one’s competence (in one or more domains of activity);
2. monitoring one’s and others’ relative position in the competence order;
3. seeking to outperform or outrank others whenever this is possible and advantageous – which depends on
   the context (e.g., Anderson et al., 2012) – and to maintain one’s position in the face of challenges;
4. signaling one’s position in the status hierarchy in order to reap the benefits associated with it

Learn more:

• What is social status and why it matters
• How to effectively gain status

Chapter 6: The Study of Culture and Evolution across Disciplines

Alex Mesoudi surveys how cultural evolution has been approached in anthropology, psychology, archaeology, and biology.
He advocates for moving past the evolution/culture dichotomy, and for integrative models that extend the scientific approach to culture (something that sociocultural anthropology isn’t doing, but that cultural evolutionary scientists are).

🙋🏼‍♂️ Lucio’s note: This was a good and well-balanced chapter showing how culture and evolution aren’t two extremes of a continuum, but two mutually-evolving and codependent forces (just added a note to Rogers’ paradox, see analyis below).

The ‘Drift’ Between Evolution & Cultural Evolution Is Thinning, But Differences Persist

The author argues that despite there still being some lingering drift between evolutionary psychologists and cultural constructionists, the field has been moving in the right direction of acknowledging the importance of both evolution/biology, and culture:

This focus on universals was an explicit reaction against what Tooby and Cosmides (1992) called the “Standard Social Science Model,” which they characterized as a denial of human nature and an extreme cultural determinism where evolution played no role in shaping human behavior.

While this was a laudable aim, some have argued that evolutionary psychologists swung too far the other way.
As Laland and Brown (2011) point out, in Buss et al.’s (1990) cross-cultural study of mating preferences, much more variation (around 14 percent) in responses was explained by the cultural background of the participants than was explained by sex (only around 2 percent).
Yet the study is typically cited as evidence for the universality of human mating strategies.

The situation has improved since these early studies, however, with evolutionary psychologists now formulating specific hypotheses about particular patterns of cultural variation and testing them in targeted cross-cultural comparisons (Apicella & Barrett, 2016).

And, most importantly, that cultural variations do not disprove evolution, but confirm it:

In sum, an early focus within evolutionary psychology on human universals (e.g., Brown, 1991) has given way to an appreciation that cultural variation (Definition 3) is not only perfectly consistent with an evolved human psychology (Barrett, 2015), but also that cultural variation can be utilized to test evolutionary predictions (Apicella & Barrett, 2016)

However, while there are plenty of areas of disagreement, there still remain some differences to exactly how much culture matters, and which force is the most ‘potent’ in shaping human psychology, behavior, and society:

In sum, while there are large areas of agreement, evolutionary scholars disagree over how much explanatory power to assign to transmitted culture.

Evolutionary psychologists and human behavioral ecologists typically treat transmitted culture as a proximate mechanism that helps to explain how we arrive at genetically adaptive behavior. Much cultural evolution work is consistent with this, as in the case of genetically evolved content biases.

But many cultural evolutionists argue that transmitted culture also often changes the rules of the human evolutionary game, creating new equilibria (e.g., large-scale cooperation), spreading maladaptive behavior (e.g., copycat suicide, small family sizes), and replacing genetic evolution as a source of adaptation (e.g., resulting in complex technology and institutions or grammatical structure).

In simpler terms, this means that evolutionary psychologists and behavioral ecologists view culture not as an independent force, but as a tool that helps people behave in ways that are aligned with their evolved genetic interests (ie.: use culture to enhance genetic fitness with better survival and reproduction).

The author seems to agree with evolutionary psychologists, and content biases, which are built-in tendencies, shaped by evolution, to focus on certain cultural content we’re most likely to learn and retain, proves that genetic evolution still ultimately drives behavior, and culture just works within that framework — as a channel for expressing evolved adaptations.

In contrast, cultural evolutionists (like Boyd, Richerson, Henrich, etc.) argue that culture can become its own evolutionary force, sometimes even overriding or changing genetic incentives.

My note: both make great points, they’re not antithetical, but cultural evolutionists fielded stronger arguments
The spread of maladaptive behaviors (like copycat suicides or choosing to have fewer children), the importance of culture to survival and reproduction in harsh climates and environments, and culture’s increasing role in human evolution are too compelling to downplay.

Marriage Norms Adapt to Environments

Human behavioral ecologists assume that human behavior is flexible enough to generate adaptive responses to diverse environmental conditions, in contrast to the sociobiological focus on behavioral universals or fixed genetically evolved predispositions.

Consequently, human behavioral ecologists showed how marriage practices may vary in a biologically adaptive manner, with polyandry emerging in harsh environments where more than one man is needed to raise offspring (Crook & Crook, 1988; Smith, 1998) and polygyny emerging when men can monopolize resources and accumulate wealth, particularly via pastoralism (Borgerhoff Mulder, 1990)

Important Concepts

• Dual‐inheritance frameworks: gene–culture coevolution models showing feedbacks between genetic propensities and cultural practices.
• Transmission biases: prestige, conformity, and content biases shape which cultural variants spread.
• Methodological advances: network‐based diffusion analysis (NBDA) and experimental microcultures as tools to quantify cultural‐evolutionary dynamics.

Chapter 7: Are Evolutionary Psychology and the Neuroscience of Motivation Compatible?

Frederick Toates explores how basic human drives like hunger and sex work.
He combines insights from evolutionary psychology with brain research, showing that many of our motivations are shaped by evolved systems in the brain—like the dopamine system—that push us to seek rewards and meet survival and reproduction needs.

Some of these systems, however, evolved for different environments and can turn maladaptive, including our preference for sugary or fatty foods, and our brain receptors that didn’t evolve in a world where getting addicted to drugs was a possibility.

Interesting Notes

• Pregnancy sickness may be an adaptation: Rather than being an example of pathology, pregnancy sickness fits the criteria of being an adaptation (…) It protects the baby from toxins at a time of maximum vulnerability of the developing nervous system (i.e., usually starting at 2–4 weeks of pregnancy and ending at 14 weeks) (Profet, 1992).
• Testosterone ≠ more aggression: in the popular imagination more T = more aggression. However, the evidence suggests a more nuanced view (Archer, 2006; Dreher et al., 2016).
  (…) in keeping with principles of evolutionary function, the secretion of testosterone usually reflects the cost–benefit calculation of aggression in the animal’s present context (Archer, 2006). (…) Testosterone increases aggression tendencies in men who are dominant and/or low in self-control (Carré et al., 2017).
  (…) In men, boosting levels of testosterone increases the punishment given to wrongdoers, but also increases the reward given to a deserving other (Dreher et al., 2016). The authors interpret both of these actions as assertions of status.
• There may be a correlation between testosterone and short-term mating strategy: Archer (2006) predicts that testosterone is positively linked to short-term mating and negatively linked to marital and parental investment. Supporting evidence suggests testosterone is associated with a more extraverted, uninhibited, and dominant personality (Archer, 2006, p. 337), aligning with a short-term mating strategy focused on mating over parenting
• Empathy’s strength is partially associated with in-group belonging (Hein et al., 2016).

Chapter 8: Are We Designed to Be Happy? The Neuroscience of Making Sense of Pleasure

Stark, Berridge, and Kringelbach explain that the brain has separate systems for “liking” and “wanting.” Evolution shaped these systems to help us seek rewards that boost survival and reproduction.

• “Liking” involves small brain areas (hedonic hotspots) that produce pleasure, using opioid and endocannabinoid chemicals.
• “Wanting” is driven by dopamine, which tracks reward cues—not pleasure itself—explaining why we can strongly crave things without enjoying them (as in addiction).

This split helps us stay motivated without becoming overwhelmed by constant pleasure.

Chapter 9: Environmental Pressures on Transgenerational Epigenetic Inheritance

Adhya et al. look at how stress during pregnancy or early life can cause changes in how genes are expressed—without changing the DNA sequence itself.
These are called ‘epigenetic changes,’ and when such changes can be passed on to future generations, it’s called ‘transgenerational epigenetic inheritance’.

They focus especially on links to autism-related traits.

• Timing matters (critical windows): Stress in early stages of pregnancy (like the first trimester) affects gene expression patterns in developing brain cells.
• Lab models: Stem-cell–derived brain cells show abnormal gene activity in genes linked to autism.
• Air pollution is harmful: Maternal exposure to air pollution during pregnancy is also highly associated with autism, and one study showed pregnant mothers living near freeways were more likely to have children with autism (Volk et al., 2011).

I also noticed that the concept of autism as a ‘extreme male brain’ seems to get with these findings:

Steroids are important factors in brain development, and higher levels of circulating sex steroids in the male fetus are positively associated with autism (Baron-Cohen et al., 2011, 2015). Mothers with polycystic ovary syndrome, characterized by hyperandrogenism and elevated levels of androgens during pregnancy, are also at greater risk of having children with autism (Kosidou et al., 2016; Pohl et al., 2014)

Chapter 10: The Problem of Altruism and Future Directions

Colquhoun, Workman, and Fowler revisit classic theories about why people help others—like helping family (kin selection) or expecting favors in return (reciprocal altruism).
They argue that in real life, cooperation often happens in larger social networks, not just one-on-one relationships.

• People tend to form clusters of cooperators, which helps keep altruism going even without direct payback
• Altruism for reputation may be a strategy to attract strong, reliable allies.
  Indeed:
  • Altruism increases when behavior is made public from altruism in economic games like public goods or dictator games (Andreoni & Petrie, 2004; Filiz-Ozbay & Ozbay, 2014; Rege & Telle, 2004), to greater engagement in volunteering (Carpenter & Myers, 2010; Linardi & McConnell, 2011), or buying “green” products rather than cheaper alternatives (Griskevicius, Tybur, & Van den Bergh, 2010)
• We help the highest values people when risk is high: In life-or-death scenarios, participants would help young, healthy, and/or wealthy individuals as opposed to very young or old, unhealthy, and/or poor individuals. They also found more help was given to premenopausal as opposed to postmenopausal women.
  • But we help the neediest when risk is low: But in the lower cost situation of everyday favors, the authors found a curvilinear effect for age, with the very young or old receiving more help, and the reverse or diminished effects for health, wealth, and many other factors (Burnstein, Crandall, Kitayama, 1994)
  • It’s not always ‘kin above all’: While there was still found a preference to help close kin, the results demonstrate that it is not sufficient simply to state that kin selection should lead to favoring close relatives; rather, it should lead to the selection of the optimal indirect fitness gain
    Similar results are reported by Essock-Vitale and McGuire (1985)
• Sexual selection may play a role, and men may help others to signal mate value: researchers have proposed that males are more likely to produce costly signals through altruistic behavior, either by aiding females or by aiding males to signal that they are of higher quality. In this way, both intra (within sexes) and inter (between sexes) components of sexual selection may be operating.
  Some evidence supports this theory:
  • And prosociality may support sexual outcomes: Following up on the themes explored by Barclay, Arnocky et al. (2016) found that “altruists” self-reported more sexual partners than “non-altruists.” This was particularly the case for males. In a follow-up study, men who were more willing to donate money to a good cause reported a larger number of lifetime romantic partners (Arnocky et al., 2016). Both of these findings support the notion that altruism increases (male) mating success in humans.
    In addition to recent empirical studies, circumstantial evidence for this position arises from social anthropologists’ studies of hunter–gatherer peoples. It is well established that, in forager societies, men who hunt and share meat enjoy greater reproductive success (Hawkes, 1991; Hill & Hurtado, 1996).
• Selfish genes don’t negate altruism because in repeated interactions like relationships it’s best to cooperate: In the iterated prisoner’s dilemma, we have a microcosm of real-life dilemmas that regularly occur in everyday life – from whether we should offer people a lift in our car, to tipping a waiter (or not), to deciding whether or not to remain faithful to our romantic partner. Do we cooperate or do we defect? In most cases, it will be to our advantage in the long run to cooperate – so long as this is reciprocated, that is.
• Emotional closeness may be the cue to kin altruism: empirical studies demonstrate that kin selection theory stands up to scrutiny, but supporting proximate mechanisms are not as well developed. Emotional closeness may be a proximate cue for kinship, as found it mediates the effect of relatedness and altruistic willingness to help for both low- and high-cost altruistic acts.
  • Nonkin altruism may hijack kinship cues (like emotional closeness): It’s likely that the kin selection heuristic rule of “help those you are emotionally close to” could be selected for, and altruism towards emotionally close nonkin may be hijacking a once-adaptive heuristic.

Also, I found this interesting as a possible friction between individual empowerment and human progress:

• Cooperation is good for everyone, but limits individuals’ freedom: According to new group selectionists, while cooperation is advantageous to the group of cooperators as a whole, it may also curb some individual freedoms

New Group Selection Theories

There are three main overlapping forms of new group selection:

• Multilevel selection (MLS)
• Dual inheritance theory (DIT; or gene–culture coevolution)
• Cultural group selection (CGS)

Let’s quickly review them in relation to cooperation:

1. Multilevel Selection (MLS)

Wilson & Sober (1994); Wilson, 2007; Wilson & Wilson, 2007
This theory argues that natural selection operates not only at the individual level but also at the group level. Groups with more cooperation can outperform less cooperative ones, passing on more genes.

Humans, being highly social, may have evolved group-level traits like altruism.

E.O. Wilson later supported this, arguing that in some species (like social insects), group benefits outweigh kin benefits (Nowak, Tarnita, & Wilson, 2010). However, many scientists remain skeptical, defending Hamilton’s rule (Abbot et al., 2011; Dawkins, 2016).

2. Dual Inheritance Theory (DIT)

Feldman & Cavalli-Sforza, 1976; Henrich & McElreath, 2007; Richerson & Boyd, 2005
DIT proposes that humans evolve through both genetic and cultural transmission. Cultural practices shape the environment in which genes evolve.

For example, imitating a successful farmer may pass on both useful and useless traits (Henrich & McElreath, 2007).
Altruism may evolve not because it’s immediately adaptive, but because group norms favor it—especially when people reward cooperation and punish norm-breakers (a concept called strong reciprocity).

They suggest that our current propensity for altruistic behavior is due to our evolved tendency to gravitate toward group norms.
One of these group norms has been labeled “strong reciprocity.”
Strong reciprocity is based on Trivers’ notion of reciprocal altruism, but is more generalized and culture specific. Strong reciprocity refers to a combination of: 1. Tendencies to reward others for cooperation 2. Norm-abiding behavior 3. Altruistic punishment (i.e., the propensity to impose sanctions on others who violate norms).
(…)
those cultural groups that exhibited strong reciprocity in the past are considered to have outcompeted those cultural groups that did not exhibit strong reciprocity.
This then results in genes that underlie prosocial behavior being selected for, leading ultimately to a form of universal pro-social behavior.

3. Cultural Group Selection (CGS)

Boyd & Richerson, 1982, 1985; Richerson et al., 2016
CGS argues that culture itself—not genes—can drive group-level evolution.

Groups that share norms and cooperate may outcompete others, especially in conflict or war.

Behaviors like building defenses or punishing cheaters help such groups survive and grow (Laland & Brown, 2011).
CGS emphasizes conformity, fast cultural transmission, and clear group boundaries. But while it can promote within-group altruism, it can also lead to between-group hostility (Bowles, 2009).

Boyd and Richerson (2005) argue that cultural group selection (CGS) can promote pro-social behavior, based on studies in New Guinea.
But the authors correctly note that cultural group selection fosters altruism within groups while encouraging selfishness or hostility between them.
Bowles (2009), analyzing ancient death data, found that between-group competition significantly raised mortality.
So the key question becomes: altruism toward whom?
For example, suicide bombers may be seen as altruistic by their own group—but not by outsiders.

I’m glad the author pointed that out since I believe that tribalism stands in the way of both self-development and human development.
Also see:

• Empowered individualism

🙋🏼‍♂️Lucio’s note: cultural evolution is less convincing in explaining the origins of altruism
I so far found the evidence for cultural evolution strong and fascinating, but somewhat less convincing when it comes to explaining cooperation.
At the time of writing, I believe it may have had an impact, but more of a reinforcing one, rather than being a creationist force.

Humans: Not Selfless Altruists, But Still Good Cooperators

As such, the goal of the theories discussed in this chapter is to demonstrate that true altruism, in an evolutionary sense, does not exist. From a gene-centered viewpoint, a gene mutation that encourages true altruistic behaviors will not be selected for. So while it may seem that natural selection and evolutionary explanations for apparent acts of altruism contradict Augustine’s and Aquinas’ views that humans are innately good, remember that the following evidence demonstrates that, while not altruistic from the genes’ eye view, many species – humans included – have evolved to engage in pro-social and cooperative behaviors.

Chapter 11: Can Evolutionary Processes Explain the Origins of Morality?

Dennis Krebs investigates whether moral emotions (guilt, indignation) and judgments arise from adaptive mechanisms (e.g. policing, sanctioning) that enhanced group cohesion.
He critiques “moral‐sense” theories of innate morality for underestimating the importance of culture.

• Commitment devices: moral norms as credible signals of cooperative intent.
• Third‐party punishment: neural and game‐theoretic data show a readiness to incur costs to defend group rules and cooperation.
• Cultural amplification: moral foundations vary by ecology, but rest on shared psychological foundations (Haidt’s Harm/Care, Fairness/Reciprocity).

The 6 Forms of Cross-Cultural Morality

Researchers have found that people from all cultures consider at least six forms of conduct moral (Krebs, 2011):

1. Altruism
2. Group solidarity
3. Respect for rules and authority
4. Fairness
5. Self-control
6. Cleanliness and purity

Cultures vary in which moral norms they prioritize and how they express them. Western societies value care and justice, Orthodox Jewish and Hindu cultures emphasize purity and authority, and Japanese culture highlights group loyalty (Pinker, 2008).

Altruism May Have Evolved Because We Can’t Recognize Kin

Strictly speaking, kin-selected altruistic dispositions should be triggered by kin.

Fortunately for the evolution of altruism, however, members of most species, including our own, are not very good at determining the extent to which they are related to others, let alone the probability that potential recipients possess copies of their altruism genes.

Like other animals, we infer the degree of genetic relatedness by attending to three main correlates of – or cues to – kinship: similarity (e.g., in appearance and smell), familiarity, and proximity.
Because nonrelatives may look like relatives, be familiar to donors, and live in close proximity to them, nonrelatives may trigger kin-selected altruistic dispositions.

Group Selection For Morality & Tribal Instincts

Some forms of altruism—such as self-sacrifice for unrelated group members—aren’t fully explained by kin or reciprocal altruism alone.

Most evolutionary biologists accept that under certain conditions, group selection can support the evolution of altruistic traits when groups with more cooperators outperform more selfish groups (Sober & Wilson, 1998).

This dynamic becomes especially powerful in humans through cultural group selection: cooperative norms, behaviors, and institutions spread because groups that cooperate more tend to outcompete those that don’t, not just in warfare, but also economically and socially (Henrich, 2016; Richerson & Boyd, 2005).

These “tribal instincts” are thought to rest on evolved capacities like emotional bonding, norm enforcement, and loyalty, which are then shaped and reinforced by cultural institutions. This helps explain strong in-group favoritism, including moral concern primarily directed toward group members (Tajfel & Turner, 1985; Greene, 2013).

Together, this body of research suggests that large-scale cooperation in human societies likely emerged not just from individual-level strategies, but also from selection pressures acting on culturally organized groups.

Mental Mechanisms Supporting Kin-Selected Altruism

Research shows that kin-selected a suite of neurochemical and emotional systems support altruism.
Hormones such as oxytocin, vasopressin, prolactin, and endogenous opioids help regulate altruistic behavior toward kin or those perceived as kin (Brown & Brown, 2006).

Two key emotions—empathy and sympathy—are central to this process (Batson, 1991).
According to de Waal (2008), these emotions are triggered by cues like similarity, familiarity, social closeness, and shared experiences.

Empathy tends to be activated toward cooperative or close others, while it is suppressed—or even replaced with Schadenfreude—toward strangers or perceived defectors.
Scan shows that empathy activates toward cooperative confederates but reward centers in the brain activate when seeing pain in defectors, at least in men (de Waal, 2008).

Although empathy can sometimes motivate helping to reduce personal distress or avoid disapproval, Batson’s research (1991) supports the idea that empathy and sympathy can produce genuinely altruistic motivation—helping others as an end in itself, not for selfish gain.
This kind of motivation is typically judged as more moral.

Respect for Authority Is Evolved

Respecting authority helps maintain group cohesion, especially in large or structured societies. It supports order by encouraging individuals to follow rules and defer to those who enforce them — such as parents, teachers, and legal authorities.

This tendency serves adaptive functions. Deference helps individuals avoid punishment, access leadership and protection, and ensures smoother group coordination — especially in competitive environments.

In humans, this predisposition appears early. Developmental research shows that young children tend to equate morality with obeying rules and authority figures (Kohlberg, 1984). While later development brings more independent moral reasoning, many still view following legitimate authority as a moral obligation.

Neurobiologically, different pathways may drive respect for authority.
One is fear-based — linked to the threat of punishment. The other stems from admiration or awe, directed at high-status individuals.
Hormones like testosterone and serotonin modulate these tendencies (Cummins, 2005).

As people mature, they gain the cognitive ability to assess authority more critically. This includes distinguishing between legitimate and illegitimate power, questioning unfair rules, and deciding when defiance may be justified — a level of flexibility less common in nonhuman primates.

Origins of Fairness, Justice, & Dislike of Cheats

Trivers (1971) used game theory to show how reciprocal altruism—helping others with the expectation of return—can evolve because it pays off biologically.

Strategies like Tit for Tat outperform selfish ones in repeated exchanges, making fairness not just moral, but adaptive.

Among humans reciprocal altruism is powered by evolved emotions like gratitude, guilt, indignation, and forgiveness. These “moral emotions” promote cooperation, punish cheaters, and help restore valuable relationships:

• Gratitude → Encourages helping those who helped us; reinforces beneficial cooperation.
• Indebtedness → Triggers discomfort when you’ve received help you haven’t yet repaid; pushes to restore balance and avoid being a “free rider
• Guilt→ Discourages selfish or harmful behavior by triggering discomfort after cheating or harming others.
• Indignation (or moral anger) → Motivates punishment or distancing from cheaters; protects the system from exploitation.
• Forgiveness → Allows reconciliation and restoration of cooperation after a breach, when it’s still beneficial long-term.

the biological function of conscience and guilt is to induce members of groups to regret behaving in ways that undermine the cooperative social orders of their groups, to motivate them to right the wrongs they have committed, and to induce them to reform.

These emotions can be so strong that they even invert people’s self-serving biases.
Indeed, Janicki (2004) found that people tend to feel worse when they fail to repay their friends than they do when their friends fail to repay them. The long-term fitness benefits of upholding friendships outweigh the short-term benefits of exploiting one’s friends.

While fairness appears in other species (e.g., capuchins rejecting unfair rewards), humans stand out for their ability to manage complex fairness systems.
Fair behavior works best in small groups, where reputations and repeated interactions keep cheaters in check.

The Original Selfish Gene Approach Was Wrong

As brilliant and renowned as Richard Dawkins is, he reached the wrong conclusion about the evolution of morality, primarily because he conflated genetic selfishness, which pertains to the selection of genes, with biological and psychological forms of selfishness (a mistake that Dawkins corrected in revisions of his books).

In a nutshell, behaving in biologically and psychologically altruistic and moral ways can increase fitness, and behaving in biologically and psychologically selfish and immoral ways can diminish fitness (Krebs, 2011).

Chapter 12: The Evolution and Function of Third‐Party Moral Judgment

Reader and Hughes focus specifically on third-party moral judgment, which is:

Third-party moral judgment is the positive or (probably more usually) negative judgment of a behavior or trait in others that has no material effect on the person judging.

They integrate moral judgment with evolutionary theory, claiming that condemning norm violators serves to maintain group‐wide cohesion and cooperation by broadcasting sanctions and enabling coalitional sorting.

🙋🏼‍♂️ Lucio’s note: did third-party judgment evolve for individual benefit, or group benefit?
The authors claim that it likely evolved as a result of intergroup conflict, something I can partially agree on, but of which I’m not fully convinced.
I believe that the selfish gene point of view also provides a good ultimate explanation via virtue signaling and power signaling (eg.: i’f I can negatively judge others, it means I’m higher status/power’).

• Audience effects: individuals amplify moral outrage when observed, signaling loyalty.
• Proportionality norms: calibrated punishments reflect perceived fitness costs of violations.
• Cognitive underpinnings: fast, intuitive judgments (System 1) followed by deliberative justifications (System 2).

Chapter 13: Evolution of the Human Family

Palmer and Coe argue that the human family isn’t a ‘core social unit’ but a mechanism to transmit traditional behaviors to maximize fitness, eventually enabling the formation of clans.

• Grandmother hypothesis: post‐reproductive women increase inclusive fitness by provisioning grandchildren.
• Stepfamilies & paternity certainty: trade‐offs between male investment and cuckoldry risk shape mating systems and grandparent provisioning, with grandparents from the mother side investing more than from the father side

Chapter 14: The Parasite‑Stress Theory of Cultural Values and Sociality

Thornhill and Fincher propose that pathogen prevalence selects for collectivist norms, stronger in‐group ties, and purity taboos, as behavioral “immunizations.” They integrate cross‐cultural data on parasite load and individualism–collectivism.

• Immune‐behavioral links: the ‘behavioral immune system’ supports the biological immune system with behavior like distancing oneself from sick people and toxic compounds. It’s driven by disgust sensitivity, which is upregulated in high‐pathogen ecologies.
• Fear of infections drives xenophobia and ethnocentrism: Faulkner et al. (2004) and Navarrete and Fessler (2006) provided evidence that the degree of xenophobia and ethnocentrism correspond to chronic individual differences in worry about contracting or catching infectious disease.
  Those who perceive high infectious disease risk are more xenophobic and ethnocentric
• Higher parasites lead to good looks becoming more important: Gangestad and Buss (1993) and Gangestad et al. (2006) empirically reported a positive correlation across countries between human parasite stress and the importance people place on physical attractiveness (good looks) in mate choice.
  It was hypothesized that physical attractiveness is a certification of genetic resistance to parasites
• Social distancing norms (tight/loose): tight‐loose theory says some cultures have strict norms (tight) and others are more permissive (loose). Tight cultures often emerge in places with high threats—like parasite stress—because strict rules help prevent disease spread and protect the group

Parasites Shape Collectivism and Conservatism

The parasite-stress theory of sociality proposes that high levels of infectious disease promote collectivism and conservatism over individualism (especially non-zoonotic infectious diseases transmissible between humans).

Collectivism–individualism is a cultural dimension that closely mirrors the political spectrum of conservatism–liberalism.
Regions with high pathogen stress tend to favor collectivist and conservative values like ethnocentrism, conformity, and xenophobia, which serve as behavioral defenses against disease.

In contrast, individualist and liberal values—such as autonomy, openness, and diversity—thrive in low-pathogen environments, where the risk of infection is lower and the costs of openness are reduced. Thus, disease prevalence helps shape both cultural and political orientations.

In short, high pathogen stress pushes cultures toward collectivism and political conservatism by activating a behavioral immune system aimed at minimizing disease risk. This leads to increased in-group conformity, xenophobia, religiosity, and resistance to social change, forming the cultural and political basis of conservative and authoritarian societies.

Lucio’s Note: This was an incredible, novel insight 🙏🏼
What we may call a ‘aha moment’, or even a mindblown insight. It adds up and passes the ‘logic test’, but it’s so groundbreaking for now that I need to further reflect on it (and I await further future data).
It may be an idea to test and see if more conservative individuals are less healthy, or more health-conscious

Key Findings:

• Collectivism increases with pathogen stress: Cross-national and within-country studies (e.g., across U.S. states and indigenous societies) consistently show that regions with higher pathogen stress display higher collectivism and lower individualism. This includes tighter family ties, traditionalism, and less tolerance for outsiders.
• Non-zoonotic diseases matter most: Diseases that spread human-to-human (as opposed to those contracted from animals) are particularly predictive of collectivist cultures. These findings hold after controlling for wealth, population, and geography.
• Political conservatism and authoritarianism increase with pathogens: Collectivism correlates with right-wing and conservative political ideologies, including authoritarian governance, gender inequality, sexual restrictiveness (especially for women), and limited property rights. This implies that high pathogen stress fosters politically conservative, hierarchical, and closed societies.
• Religiosity as behavioral immunity: Religiosity supports in-group cohesion and moral conformity, making it another collectivist value linked to parasite stress. Highly religious regions tend to have higher disease risk and more collectivist norms.
• Conformity and prejudice rise with perceived infection risk: Both experimental and survey-based studies show that people exposed to disease cues become more conformist, more prejudiced toward non-conformists and out-groups, and more favorable to traditional values. These are immediate, psychological shifts triggered by infection salience.
• Disgust sensitivity links to collectivism and conservatism: People with higher disgust sensitivity—often correlated with disease concerns—are more likely to be collectivist, religious, and prejudiced against sexual and ethnic minorities. This supports the idea that disgust acts as a behavioral immune trigger favoring conservative values.
• Linguistic and cultural fragmentation rise with pathogens: Pathogen stress promotes the rise of new, smaller cultures and languages—a process termed the “parasite-driven wedge.” It suggests that avoidance behaviors (e.g., ethnocentrism and limited dispersal) segment cultures even without geographic barriers.

Chapter 15: The Evolution of Pride and Shame

Beall and Tracy argue that pride and shame are universal self‑conscious emotions that regulate status within hierarchies: pride signals success to others, shame promotes appeasement when status is threatened.

In evolutionary accounts, emotions are fitness maximizing affective mechanisms that galvanize coordinated suites of physiological and psychological responses to recurrent events of evolutionary significance (Beall & Tracy, 2017; Cosmides & Tooby, 2000; Nesse & Ellsworth, 2009)

• Pride and shame are cross‐cultural prototypical expressions: consistent facial and body language cues for pride and shame
• Pride is associated with high status (Tracy, 2016), shame with low stauts. Pride inclucdes dominant and confident body language, shame with closed off and low power body language
• Two forms of pride conceptualized and experienced as distinct and independent and are associated with highly divergent personality profiles (Tracy & Robins, 2007a, 2014; Tracy et al., 2009)
  • hubristic, marked by arrogance and conceit, more antisocial, associated with disagreeableness, aggression, and lack of conscientiousness, and narcissism
  • authentic, fueled by feelings of accomplishment, confidence, and success
• They both serve an adaptive function: pride motivates dominance behavior, shame deflects aggression
  • Shame displays appease and decreases punishment: researchers found that a hypothetical convicted drug dealer was judged as less guilty and given a weaker penalty when displaying shame and embarrassment compared to contempt or a neutral expression

• There are benefits to reading body language well: Shame displays signal group commitment, helping observers choose trustworthy partners, avoid unnecessary conflict, and understand social hierarchies—key for cooperation and resource-saving
  • It’s especially important for men: in certain contemporary cultures, men must constantly track their own status relative to those around them, whereas for women this is less essential (Tracy et al., 2013)

🙋🏼‍♂️ Lucio’s Note / suggestion: may want to revise the attractiveness of shame/pride
The chapter says that ‘shame expressions are one of the most sexually attractive emotion expressions shown by both men and women (Tracy & Beall, 2011; but see Beall & Tracy, 2014)‘, which seemed strange.
Little later it says that ‘men who displayed pride were found to be highly attractive to women compared to men who gave neutral, shame, or happy displays (male happy displays, in fact, were particularly unattractive)‘.

Chapter 17: Runaway Processes in Modern Human Culture

Miklósi and Konok apply Zahavi’s handicap and runaway sexual selection models to contemporary media, showing how exaggeration of signals (e.g. social‑media personas) fuels escalating patterns of self‑presentation.

• Costly signaling in digital realms: curated online identities used as hard‑to‑fake reputational markers.
• Cascade effects: viral replication amplifies extreme traits through social copying.
• Psychological drivers: reward circuits respond to likes/shares, reinforcing signal inflation.
• Cooperation and cheat punishment may be runaway selection: Nakamaru and Dieckmann (2009) demonstrated mathematically that cooperation and punishment of defectors in human groups underwent runaway selection, with evolution toward enhanced cooperation and ever stricter punishment norms mutually reinforcing each other

🙋🏼‍♂️ Lucio’s Notes On Runaway Selection & Handicap Principle

I had to do some extra research to clarify for myself how runaway selection isn’t withheld by the women who don’t like the runaway trait, and how it fits with the handicap principle.

Here’s what I cam up with:

How Runaway Selection Starts & Works

Three phases:

1. Accidental preferences (sexual selection): A female shows a preference for a male trait (accidentally)
2. Runaway (sexual selection): the bearers of the trait increase their ratio in the population.
   • 👉🏼 Trait competition may limit runaway: sexual selection simultaneously acts on multiple traits that could mutually inhibit the “runaway” of the others. For example, if females like long tails and dancing, then a too long tail hampering dance acts against longer tails
3. Natural selection: the trait that emerges as a result of sexual selection may be subject to factors of natural selection.
   At this point, if the trait is negative, natural selection will ‘cap’ how far the trait can grow

At the beginning, random variation or drift introduces a small number of females who prefer longer tails. These females:

• Choose slightly longer-tailed males → produce sons with slightly longer tails and daughters who prefer them.

Even if the advantage is tiny at first, that correlation between trait and preference builds momentum.
Once a small preference becomes common enough, then:

1. Long-tailed males get more mates,
2. The feedback loop kicks in (runaway), and
3. Short-tail males (and their daughters’ preferences) get outcompeted <— 🙋🏼‍♂️ Lucio’s note: This is not fully clear to me yet and I suggest the authors to dig deeper into it. Why would the short tail males get out-competed as long as females who don’t acquire the taste for longer tails can still pick them to reproduce with? It seems to me there is a missing piece here: a crowding out whereby shorter tales men must compete on other traits, while still never winning the long-tail lovers (a handicap by omission, you may call it)

The text explains that the preference is expressed only in females and the sexually dimorphic trait is expressed only in males.
So only males pay the price of the costly growing ornament.

Zahavi Handicap Principle

Zahavi’s handicap principle says costly traits (like long tails) signal male quality because only the healthiest can afford them.

Studies support this: females prefer such traits, which often reflect good genes or strong immunity. These traits act as honest, hard-to-fake signals of genetic fitness.

Getty (2006) refined this view: rather than just being costly, these traits are strategic investments by high-quality males who benefit more from increased mating opportunities.

Fisher Runaway vs. Zahavi Handicap: They’re Both Right

Both are partially right, and modern evolutionary biology sees them as complementary, not mutually exclusive:

• Fisher explains how female preferences and traits can co-evolve and become exaggerated—even if they start arbitrarily.
• Zahavi explains why a preference might evolve in the first place—because it’s tied to reliable indicators of health or fitness.

In reality, many traits likely involve both mechanisms:

• A preference may start because the trait signals health (Zahavi),
• Then it becomes exaggerated through runaway selection (Fisher).

Chapter 18: Ontogeny of Tactical Deception

LaFreniere and Smith review how children develop deceptive tactics, going from simple feigning to complex deception, against a backdrop of evolving mind‑reading and inhibitory control capacities.

They refer to the theory of Machiavellian intelligence, and claim that deception is a useful skill to succeed in life.

• Stages of deception: spotting opportunities, inhibiting truth, constructing plausible falsehoods.
• Theory of mind refers to knowing what others think and want, and it correlates with false‐belief understanding and lie sophistication.
• Cost–benefit trade‑offs: social learning conditions which deceptions pay off at different ages.

Chapter 20: The Adaptive Problem of Exploiting Resources

Wilke used experiments to show that people make smart choices in problem-solving tasks—similar to foraging—by weighing the cost of searching against the rewards they get.

• Fishing vs. word‐puzzle analogies: similarity in participants’ switching behavior across domains
• Cognitive heuristics: “good‐enough” stopping rules rather than perfect optimization.

Chapter 21: Evolutionary Developmental Psychology

Myers and Bjorklund explain how evolution shapes different behaviors at different ages—like infant attachment or teen risk-taking—through the interaction of genes, environment, and culture.

• Sensitive periods: windows for imprinting and social learning.
• Life‑history calibration: environmental harshness accelerates developmental milestones, shifts towards more risk-taking behavior and prioritize quantity of offspring rather than quality
  Children who are exposed to extrinsic morbidity–mortality cues, such as exposure to violence or harsh childrearing practices, shift their resource allocation toward earlier pubertal maturation and sexual debut, engage in more aggressive and risky behavior, become pregnant earlier, form unstable pair bonds, and provide less parental investment per offspring than children growing up in less harsh and more predictable environments (e.g., Ellis, 2004; Ellis et al., 2009; Nettle, 2010; Nettle & Cockerill, 2010; Placek & Quinlan, 2012; Wilson & Daly, 1997)
• Adaptive plasticity: variation in trait expression shaped by early cues.
• Boys vs Girls show differences from childhood
  • Boys problem solve, girls befriend: Boys are more inclined to use tools for problem-solving, whereas girls are more likely to be oriented toward personal relationships (Gredlein & Bjorklund, 2005).
  • Boys play dominance-related games: Girls’ fantasy play tends to be oriented more toward relationships, such as playing house. Boys’ fantasy play, on the other hand, tends to be more oriented toward dominance themes, such as playing cowboys and Indians or being “superhero crime fighters,” dependent on current cultural themes (Pellegrini, 2013)

Men’s relationships are more based on dominance and status, whereas women’s relationships are more interpersonal and intimate (Bjorklund & Ellis, 2014).

Chapter 22: The Ontogeny and Evolution of Cooperation

Grüneisen and Wyman chart how cooperative behaviors emerge in toddlers—sharing, helping, group cohesion—and link these to ancestral needs for collective action, supported by oxytocin and endorphin systems.

• Early helping: infants as young as 14 months assist adults without reward.
• Punishment & partner choice: toddlers show aversion to unfair peers.

Cooperation is The Secret of Our Success

We propose that a defining human characteristic, which in its scope and flexibility is unparalleled in the animal kingdom, is the ability to coordinate actions with others – even with total strangers – in the pursuit of shared goals

Chapter 23: Genomic Imprinting and Psychological Mechanisms

Brown explains how parent‐of‐origin effects on gene expression (e.g. IGF2, PEG3) shape early brain development and influence behaviors like attachment and resource solicitation, with implications for disorders.

• Conflict theory: paternal genes drive behavior that maximizes infant’s resources while maternal genes ‘defend’ the mother, balancing growth vs. maternal investment.

Also see:

• Sexual conflict theory explained

Chapter 24: Evolutionary Explanations for Bullying Behavior

Smith reviews bullying as an adaptive strategy for social rank acquisition, outlining its costs and benefits in ancestral groups and modern contexts (Table 24.1).

• Frequency‐dependence: bullying pays off only when rare.
• Sex differences: males favor physical intimidation, females relational aggression.
• Intervention implications: reframing anti‑bullying efforts with status‐alternative strategies (e.g. reputation enhancement).

Definition of Bullying

Bullying is generally defined as a subset of aggressive behavior – so, behavior with an intent to harm another
person. But to be called bullying, most researchers agree that two criteria must be satisfied:

• repetition
• imbalance of power

Bullying Roles

Bullying involves different roles:

• Ringleader bullies: Initiate and organize the bullying (Salmivalli et al., 1996)
• Followers: Join in after the ringleader starts the bullying (Salmivalli et al., 1996)
• Reinforcers: Do not directly bully but laugh or encourage the bullying behavior (Salmivalli et al., 1996)
• Victims: The targets of bullying (Smith, 2014)
• Bully–victims (AKA ‘provocative victims’) : Children nominated as both bullies and victims. Often referred to as “provocative victims” because their behavior may provoke others, leading to retaliatory bullying (Smith, 2014)
• Pure bullies / Pure victims: Identified separately to avoid overlap with the bully–victim category, especially in research on outcomes and correlates (Smith, 2014)

Gender Differences in Bullying

Boys’s stategy revolves more around physical power while women more around reputation

The physicality/reputation split is explained based on what’s most effective for each gender:

Physical strength is more important in boys’ peer groups and reputation is more important in girls’ peer groups, so this gender difference has been explained as each gender choosing the most effective method of displaying power and/or damaging a victim (Archer, 2009; Guerra et al., 2011).

Adaptive vs. Maladaptive Bullying

Volk et al. argued that bullying is an adaptation based on its heritable basis and the advantages it provided for survival and reproduction (gaining dominance and social status, and hence access to resources).

The authors ultimately state that it may be too early to judge whether bullying is a specific evolutionary adaptation, also because many bullies operate in a novel environment of ‘evolutionarily unnatural’ classrooms.

Conceivably, it is a by-product of aggression, and pursuing dominance by displaying power against weaker peers may bring payoffs, including gaining or protecting resources and status (Archer, 1988).

While sometimes seen as a sign of poor social skills in children (Crick & Dodge, 1994, 1996), that’s often wrong and some aggressive kids are socially skilled and popular, especially if they use aggression strategically and combine it with prosocial behavior (Hawley, 2003; Bjorklund & Hawley, 2014).
Kaukiainen et al. (1999) also demonstrated that social intelligence correlated positively with relational aggression in particular.

Bullying is a more extreme form of aggression, and although typically labeled harmful or antisocial, bullying can bring real benefits to those who use it effectively:

• Strategic controllers (not emotionally reactive) were the most successful. They mix aggression with prosocial approaches, and tend to:
  • Score high in theory of mind (Sutton et al., 1999b).
  • Are strategically smart (Sutton et al., 1999b).
    they argued that ringleader bullies in particular might deploy skills such as knowing how to choose vulnerable victims, how to choose the right social context to initiate bullying, how best to put down the victim in a way that demonstrated their own power, and how to avoid detection by adults.
  • Be popular, influential, and resourceful

Bullying is usually facultative—children do it when the benefits outweigh the risks. Some researchers suggest victims adapt to avoid further harm, but this idea is controversial.

Outcomes depend on the type of bully:

• Pure bullies:
  • Often popular, athletic, attractive
  • Powerful but not necessarily well-liked (especially ringleaders) are seen as powerful and popular in terms of perceived popularity, though not necessarily well-liked (Peeters et al., 2010; Veenstra et al., 2005).
  • Show few consistent psychological downsides
• Bully–victims (both bully and get bullied):
  • More likely to experience negative outcomes like depression and loneliness

Because bullying can work as a dominance strategy, interventions need to go beyond teaching social skills. A better approach is to redirect status-seeking into prosocial behavior.

Bullies Enjoy Better Dating Outcomes

Research shows that bullies generally start dating earlier, have more dating partners, and engage in more sexual activity.

Physical bullies, especially boys, are particularly more likely to have more dating and sexual partners. However, the quality of their relationships tends to be poorer, with more aggression and less intimacy (Connolly et al., 2000; Espelage & Holt, 2007; Volk et al., 2015; Dane et al., 2017).

Relational bullying alone does not strongly predict dating success, but relational bully–victims (those who both bully and are victimized) may have more dating partners, especially girls (Dane et al., 2017).

Overall, bullies date quantitatively more, there is no information about partners’ mate value, and these relationships often involve more conflict and less emotional closeness.

Health Outcomes Are Generally Poorer for Bullies, But Worse for Victims

Most research suggests that pure bullies—those who bully others but are not themselves victims—tend to have poorer mental and physical health than uninvolved peers, though findings are mixed and depend heavily on the methods used.

Some early studies argued that bullies enjoy better or equal mental health (e.g., Juvonen et al., 2003; Volk et al., 2012), but these conclusions were based on limited evidence. When studies clearly distinguish pure bullies from bully–victims, most show bullies scoring worse on depression, anxiety, psychosomatic complaints, and suicidal ideation, although:

• Some studies report no significant differences or slightly better scores for bullies (e.g., Juvonen et al., 2003; Koh & Wong, 2017).
• In several studies, bullies score better than victims or bully–victims, but still worse than noninvolved children.
• Self-reports are the most common method used, and these often show worse outcomes for bullies.
• Peer nominations, used less often, show smaller or non-significant differences, suggesting self-report data may overstate the negative effects.
• Self-esteem findings vary: bullies may rate themselves low in academic self-worth (due to disapproval from school), but normal or high in areas like athletics or peer relations (O’Moore, 2000; Salmivalli et al., 1999).

Overall, while the picture isn’t entirely uniform, the bulk of evidence—especially from self-report studies—suggests that being a bully is linked to greater internalizing problems and poorer well-being, though not as severely as being a victim.

This applies to self-reported bullies; more evidence is needed for peer-nominated bullies

Outcomes of Bullying Summary

1. Pure bullies are seen as powerful, not necessarily well-liked, but are seen as exercising resource control
2. Pure bullies enjoy better dating, but with more toxic relationships
3. Ringleaders bullies in particular have good theory of mind abilities (the stereotype of the bully as socially incompetent seems radically incorrect)

Genetics and Heritability of Bullying

Twin studies show that both bullying and being victimized are influenced by genetics.

For victimization, genetic influence increases with age, reaching up to 66% by age 10. For bullying others, about 60–70% of the variation is explained by genetic factors.

Genetic traits may make someone more likely to be bullied if they are introverted, emotionally sensitive, or have poor social or emotional regulation.
On the other side, children may be more likely to bully if they are impulsive, thrill-seeking, emotionally cold, or interpret others’ actions as hostile.

“Bully-victims” often show signs of emotional dysregulation, which may also be genetically influenced.

Several heritable personality traits are linked to bullying:

• Low agreeableness and low conscientiousness (Big Five)
• Low honesty–humility and emotionality (HEXACO)
• Traits from the dark triad:
  • Machiavellianism: manipulative, distrusting
  • Narcissism: arrogant, entitled
  • Psychopathy: impulsive, thrill-seeking, uncaring
• Callous–unemotional traits, especially lack of caring

So bullying isn’t just learned—it often reflects inborn tendencies shaped by personality and emotional style, which can either predispose kids to dominate others or make them more vulnerable to being targeted.

How to Stop Bullying

Bullying should not be viewed simply as pathological behavior since many bullies are socially skilled and gain real status and resources from it.

Because bullying can provide benefits and low costs in certain contexts, interventions need to address this balance.
Successful reduction of bullying must consider the bully, the victim, and the social environment.

For bullies:

• Recognize that popular bullies may not respond well to standard anti-bullying programs.
• Provide alternative, pro-social, status-enhancing roles such as organizing activities, leading sports events, or peer tutoring to replace bullying as a way to gain respect (the “meaningful roles” approach).

For victims:

• Teach friendship skills and coping strategies through assertiveness training.
• Use buddying schemes to provide social support.
• Encourage high-status peer defenders to intervene on behalf of victims.

For the peer group and school context:

• Improve the overall peer group climate to reduce the perceived popularity of bullies.
• Apply clear sanctions and enforce effective school policies against bullying.
• Consider the bully’s social competence and motivation for status, rather than just labeling bullying as “wrong,” to avoid counterproductive effects.

Chapter 25: Birth Order and Evolutionary Psychology

Sulloway presents evidence that firstborns tend toward conformity and authority‐orientation, laterborns toward rebellion and risk‐taking, framing this as parent–offspring conflict over niche differentiation.

• Resource dilution & niche partitioning: siblings diversify strategies to reduce competition.
• Personality correlations: meta‐analysis shows consistent but small effects across cultures.
• Historical shifts: family‐size decline may amplify birth‑order effects.
• Later-borns are more likely to be homosexual: Among males (but not females), higher birth rank is correlated with an increasing likelihood of homosexual orientation (Blanchard, 1997, 2004)
  Explanation: About 15% of mothers develop antibodies to male-specific antigens, which can interfere with the masculinization of later male fetuses. As a result, the likelihood of homosexuality increases by roughly 33% for each older brother.
• IQ scores increase slightly among lastborns growing up in large families

Birth Order Affects Investment & Emotional Bond

Since the last child can’t be replaced, we could expect mothers to invest more in lastborns.
And indeed older mothers report that they feel more emotionally attached to their lastborn children (Suitor & Pillemer, 2007)

Trivers (1972) has defined parental investment as any investment in time, energy, or resources that benefits one offspring at a cost to another offspring. Among humans, biases in parental investment are well documented and have often been based on differences in birth order, gender, and offspring quality (Daly & Wilson, 1988; Hrdy & Judge, 1993)

Chapter 26: Survival, Selection, and Sex Differences in Fear

Campbell integrates meta‑analytic data on dot‑probe tasks and fear conditioning to argue that women’s greater fear sensitivity evolved as protection for offspring.

Summarized in one great quote:

The benefits for women lie in lower mortality and greater longevity, which enhance mothering and enable grandmothering. Among women, living slow and dying late has been a winning strategy.

• Preparedness theory: faster conditioning to ancestral threats (snakes), stronger in females.
• Hormonal modulation: estrogen amplifies amygdala reactivity.
• Clinical relevance: sex differences in anxiety disorders reflect these evolved mechanisms.

Remember: the overlap is still larger than the difference

It bears repeating that any sex difference is a matter of degree, not kind.
For example, even with a large effect size of d = 1.00 (as found by Campbell et al., 2016), 62 percent of the male and female fear distributions overlap. Men and women are, after all, morphs of the same species, and selection pressures “nudge” rather than “shove.”

But she reminds us that the differences become more noticeable and impactful at the extreme ends of the distribution.

Increasing Male Aggression Is Capped By Risks, and May Increase Monogamy

Traditional sex-role theory claims male aggression evolved to attract mates and beat rivals—but this view is problematic, claims Campbell.

Higher aggression means higher risk.
When competition gets intense or unwinnable, increasing aggression increases the payoffs of monogamy.
Males benefit more from sticking with one mate and helping raise kids (Gangestad & Simpson, 2000).

Aggression is not on a runaway trajectory, but on a tradeoff.
Data show aggression rises as more males compete, but drops once it gets too extreme—replaced by courtship and mate guarding (Weir et al., 2011).

A model also shows monogamy can evolve if women prefer resource-giving men. Low-status males adopt this to reproduce, and since they’re the majority, the strategy spreads (Gavrilets, 2012).

Chapter 27: The Enigmatic Urge: How Sexual Desire Works

Toates dissects desire into drive (homeostatic), incentive (external cues), and cognitive (expectations) components, showing how each relates to certain reward circuitry and how they relate to evolved mating strategies.

• Dual‐control model: balance of excitatory vs. inhibitory inputs varies by sex and context.
• Sociosexuality: individual differences in desire linked to mating market variables.

And I found interesting from a relationship power dynamics point of view:

• Women seek confirmation in relationships: After time in an established relationship, women tend to place more weight upon associations with their regular partner, such as to receive confirmation of their desirability (Basson et al., 2003).

Sexual Desire And Dominance

There is a link between dominance and sexuality.

Sexual violence is mostly male behavior and often driven by a mix of sexual desire and dominance—not just one or the other.

Desire is usually present, but the role of aggression varies: from calculated use of force to outright violent acts. Testosterone fuels both sexual and dominance motives.

Some men find women more attractive when primed with dominance cues, suggesting a link between power and sexual desire.

Rape victim age data clusters around 15, suggesting physical features and perceived vulnerability at that age may trigger these drives.

To explore this topic also see our article:

• The role of dominance in dating, courtship, and sexual success

🙋🏼‍♂️ Lucio’s suggestion: Revist the claim on bigger penis = bigger pleasure
The author states that ‘the male penis is much larger than the female clitoris as a source of self-generated pleasure, deliberately induced or accidentally‘.
I’m not sure I understood the ‘accidental’ bit, and I don’t think that women necessarily derive less pleasure from masturbation.

Chapter 28: Are Humans Peacocks or Robins?

Stewart‑Williams evaluates whether human traits (e.g. ornamental displays, courtship rituals) align better with Darwin’s runaway signal theory (peacock) or Zahavi’s handicap model (robin), concluding both processes operate in mating domains.

• Mate choice experiments: women prefer indicators of genetic quality under high‑risk contexts, ornamental cues under low‑risk.
• Signal costs: costly self‑disclosure and creative displays function as honesty assurances.
• Low-investing sex develops ornamentation, high-investing one lives longer because they avoid risk and take care for children
• Cultural variation: relative importance shifts across ecologies.

The Difference Between Sexes Isn’t Smaller Than Some Evolutionary Psychologists Claim

While Stewart‑Williams acknowledges that some differences between men and women are real, he shows they are often exaggerated.

He demonstrates that men and women’s mating psychology tends to overlap more than it diverges, and that large, attention-grabbing claims often rest on modest differences in averages—differences that shrink further when placed in a broader biological and statistical context.

Let’s review the domains:

Reproductive Variability

• Common assumption: Men can have many more children than women (e.g., Ismail the Bloodthirsty with 888 offspring), suggesting stronger male desire for multiple partners.
• Reality: Such reproductive extremes are historical anomalies, not typical.
  In small-scale societies, which better reflect most of human history, the difference in reproductive variability is usually small—and sometimes even favors women.
• Implication: Modest sex differences in reproductive outcomes mean we should expect only modest differences in sexual psychology.

Polygynous Desires & Short-Term Interest

• Claim: Men are more interested in casual sex and short-term mating.
• Reality: True across all cultures studied, but the effect size (d = 0.74) is still modest when compared to more intuitive sex differences like height (d = 1.63).
• Implication: The differences are real but relatively modest. This is expected on the assumption that our primary reproductive pattern was pair-bonding and biparental care.

Mate Preferences: Physical Attractiveness

• Claim: Men care far more about physical attractiveness than women.
• Reality: Men rate it slightly higher on average, but both sexes value it. In Buss’s influential study, men ranked it only 10th, women 13th. The difference from a meta-analysis was moderate (d = 0.54), implying around 80 percent overlap between the male and female distributions.
  This makes evolutionary sense: women as the choosier sex are expected to care for looks
• Implication: Attractiveness matters to both sexes, and the average difference is meaningful but far from stark.

Similarly, Kanazawa (2003) observed that, “In every society, men prefer young and attractive women for mates, and women prefer wealthy and powerful men” (p. 292).
Such descriptions suggest substantial, dichotomous differences. The evidence for these differences, however, invariably consists of relatively modest differences in the central tendencies of highly variable and overlapping distributions. There is thus a mismatch between the data and the verbal descriptions of the data: we are comparing apples but concluding oranges.

Mate Preferences: Wealth and Status

• Claim: Women are hypergamous and strongly prioritize wealth/status in a mate.
• Reality: Women rank wealth slightly higher than men, but often below other traits like love, character, and intelligence. In many real-world cases, women prioritize attractiveness over wealth.
• Implication: While the sex difference is consistent, it’s moderate in size (d = 0.69), with a lot of overlap. Many women don’t strongly prioritize wealth or status.

Jealousy

• Claim: Men are more distressed by sexual infidelity, women by emotional infidelity.
• Reality: In the classic Buss’ study, only 60% of men chose sexual infidelity as more upsetting, and in some cultures (like Germany or Japan), a majority of men picked emotional infidelity instead.
  We cannot conclude that men are more concerned about sexual infidelity when only a little more than half of men do and in some samples, more men are upset by emotional infidelity.
• Implication: The difference is not accurately described by statements such as “men find sexual infidelity more upsetting, women emotional infidelity.” A more accurate description would be that “a larger proportion of men than women find sexual infidelity more upsetting, whereas a larger proportion of women are more upset by emotional infidelity.”
  Buss’ ‘forced choice option’ also exaggerated the differences, while the reality is that most men and women are upset by both

The ‘menopause for women’, ‘retained virility for men’ is an exaggeration

Although men do not experience the complete cessation of fertility in middle age that women do, their fertility declines more precipitously than was once believed.

To begin with, men’s testosterone levels tend to nosedive with age (Harman et al., 2001), which may lead to a reduction in courtship effort and intrasexual competition. In addition, the quality and quantity of men’s sperm declines throughout adulthood (Kong et al., 2012).

The implication is this: the sex difference in age-related fertility is smaller than previously thought, which provides a theoretical rationale for thinking that the sex difference in the importance of physical attractiveness will be smaller than previously thought.

🙋‍♂️Lucio’s Take: Let’s all be more careful in not over-stating the differences

Lucio:
I loved this chapter, and I had noticed a similar trend to overstate the differences, including among some scholars.

Just as an example, the “men seek looks, women resources” not only didn’t seem to square too well with the data, but also not with my personal experience of successful dating with limited resources.

I believe that stressing the differences may have been a knee-jerk reaction to decades of the “standard social science model” and of downplaying genetic differences.

However, it’s now time to start being more balanced.
Balance is also important given the general public’s (and pop authors’) tendency to over-focus on the differences while forgetting the overlap.

Chapter 29: Human Mate Selection: A Multidimensional Approach

Conroy‑Beam and Buss integrate mate‐value indices, preference hierarchies, and mating market constraints to model real‐world pairings.

• Euclidean metric: potential mates evaluated across multiple preference dimensions (Table 29.1 below)
• Preferences reflect choice: People’s actual long-term mates tend to fall close to their ideal preferences through the multidimensional preference space, exactly as they would if mate preferences were integrated according to a Euclidean algorithm (Conroy-Beam & Buss, 2016b)
• Preferences reflect choice when people can afford to select: people who are themselves higher in mate value according to Euclidean calculations – that is, who are closer to the opposite sex’s aggregate preference point in the preference space – tend to be mated to partners closer to their own mate preferences
• Market dynamics: sex ratio skews and operational sex ratio modulate selectivity, as do other sexual market variables and localized dynamics
• Preference fulfillment: trade‑offs between ideal standards and available options.

The Three Key Constraints in Realistic Human Mating Markets

While people have ideal mate preferences, real-life mating markets are complex, and several constraints significantly weaken the link between those preferences and actual partner choices. Agent-based models show that three main dynamics explain why preference fulfillment is often limited:

1. Availability

• Constraint: People can only choose partners from those who are locally available.
• Impact: Even if someone has strong preferences, they may not encounter partners who match them well.
• Finding: This was the most impactful constraint in reducing both preference fulfillment and predictive power.

2. Competitiveness

• Constraint: People compete for the same desirable mates, and each person can only form a limited number of relationships (especially in monogamous settings).
• Impact: Even if a preference-fulfilling partner is available, a rival might pair with them first.
• Note: Competitiveness alone had no strong effect, but it amplified the impact of other constraints.

3. Mutual Mate Choice

• Constraint: Attraction must be mutual—it’s not enough to prefer someone; they have to prefer you back.
• Impact: Ideal partners may not reciprocate interest, forcing people to settle for less ideal matches.
• Interaction: This constraint becomes harsher in competitive markets.

Overall Findings

In fully constrained markets, predictive power of mate preferences dropped to r = 0.24, close to real-world findings like Campbell et al.’s r = 0.14.

These constraints don’t mean mate preferences are unimportant, but rather that their influence is embedded in complex, dynamic systems.

Chapter 31: Integrating Feminist Perspectives

Fisher, Garcia, and Burch argue that evolutionary psychology must incorporate perspectives on gender inequality, intersectionality, and power dynamics, proposing revisions to standard mate‐ preference models to account for patriarchal cultural overlays.

There is an enduring uneasy relationship between evolutionists and feminists when it comes to the study of human behavior. In general, feminists tend to view work incorporating an evolutionary perspective as being somewhat anti-feminist, unnecessarily reductionist, or at least neglecting to be inclusionary of sociocultural and gendered factors

However, things are changing for the positive say the authors, and there are now even ‘feminist evolutionists’.

🙋‍♂️Lucio’s Take: I couldn’t agree more. Some feminist scholars are spot on power dynamics

Lucio:
The easiest way to spot a scholar biased by gender is a woman who rejects evolutionary psychology’s universal tendencies, or a man who rejects feminist contributions to social and interpersonal power dynamics (social dominance theory also backs up some feminist theories).

From my perspective, evolutionary psychology is the foundation of all psychology-related disciplines—and feminists are spot on when they highlight the drive of some men to control and disempower women (which makes perfect sense to anyone who understands evolution and power dynamics).

Evolutionary Psychology’s Reliance On Self-Reports Is Problematic

Eagly and Wood (2013), among others, note that evolutionary psychology’s reliance on self-reports raises concerns.

While such studies often find sex differences (e.g., men reporting a stronger preference for casual sex or more sexual partners), these results may partly reflect social desirability and adherence to gender role norms, rather than innate differences.

For example, Alexander and Fisher (2003) used a bogus pipeline method (a fake lie detector) and found that men reported more sexual experiences only when they believed their answers would be seen by others.
When they thought lying could be detected, the sex differences nearly vanished.

Similarly, Eastwick et al. (2011) argue that implicit measures tend to reveal smaller sex differences than explicit self-reports.

These findings suggest that some evolutionary psychology claims may overstate innate sex differences, and that more reliable methods are needed—especially in light of broader replicability concerns in psychology (Camerer et al., 2018).

🙋🏼‍♂️ Lucio’s note: I agree, it’s something to keep in mind
I also suspect, for example, that people, and potentially women in particular, may rate the importance of looks lower than what they truly are.

The Main Issue Is Social Constructionism: Here’s Why It Shouldn’t Be

Feminist scholars often emphasize social constructionism, while criticizing evolutionary psychology for being biologically deterministic.

Social constructionism is the idea that much of what we consider to be “reality” — including concepts like gender, morality, or even intelligence — is not purely objective or natural, but shaped by social interactions, cultural norms, and shared beliefs.

However, the authors argue that social construction is itself enabled by evolved traits—humans are a culture-bearing species, and our capacity for social learning is biologically rooted.
Rather than opposing each other, social and biological explanations can be integrated.

Yet both fields have historically missed this opportunity to cooperate and build upon each other.

Chapter 32: Psychopathology from an Evolutionary Perspective

William J. Ray surveys theories of depression (analytical rumination, social competition), anxiety (smoke‐detector principle), and more, emphasizing that many pathologies may be misfirings of once‐adaptive defense mechanisms.

• Autism may be an extreme case of understanding and developing systems: Coupled with the inability to empathize in autism is the superior ability to systemize. Systemizing is the ability to analyze objects or events in terms of their structures and future behaviors. These deficits and abilities make up the empathizing–systemizing theory of autism (Baron-Cohen & Belmonte, 2005)

Histrionics and Psychopathy Are An Adaptive Cheater Strategy

From an evolutionary perspective, psychopathy may be understood not simply as a disorder, but as a possible adaptive strategy—specifically, a “cheater” strategy in reproductive and social life.

Psychopaths, characterized by manipulativeness, lack of empathy, dishonesty, and disregard for social rules, may exploit others for short-term gains without remorse.

According to Harpending and Sobus (1987), both male psychopaths and female histrionics can be seen as different forms of sexual cheater strategies:

• Male psychopaths deceive women about commitment to gain sexual access while avoiding investment in offspring.
• Female histrionics exaggerate emotional neediness and helplessness to attract male attention and secure resources, potentially even at the cost of their offspring’s well-being.

This view frames certain personality disorders not merely as dysfunctions, but as extreme or context-dependent evolutionary strategies shaped by environmental pressures and individual reproductive incentives.

🙋🏼‍♂️ Lucio’s note: psychopathy may be seen as an extreme end of a short-term and uncommitted sexual strategy (player strategy)
And unfortunately, the sexual deception strategy goes beyond ‘deceiving about commitment’. This is an exposé article on a psychopath openly discussing his cheater strategy:

• Psychopaths’ cheater strategy in dating: a shocking revelation from an actual psychopath

Chapter 34: The Evolution of Prosocial Behavior: From Caring to Compassion

Gilbert outlines the phylogeny of care‐giving systems.

The Benefits of Caring

Compassion training has been shown to positively affect physiology (e.g. nervous system, immune function, neuroplasticity) and mental health (reducing depression/anxiety) (Kirby et al., 2017b; Goleman & Davidson, 2017).
Various training models now exist, including those based on Mahayana Buddhism and modern psychotherapy (Gilbert, 2010).

However, modern societies often promote competitive self-interest and narcissism, especially in schools and businesses, which can suppress compassionate instincts.

The evolutionary lens shows that while self-interest and tribalism are natural, so are empathy and cooperation. The challenge is to create individual and cultural environments that activate and reinforce pro-social motives over competitive or exploitative ones (Gilbert & Mascaro, 2017).

A Case For Working Toward A More Compassionate Society

One is mental health:

There are concerns as to whether we should allow our schools to drift further and further into narcissistic, competitive self-interest, with consequences for vulnerability to mental health and reducing community values, or whether schools should be the grounding for the teaching of ethical and compassionate values and behavior (Weissbourd & Jones, 2014)

And the other is the future of humanity:

This is important because we cannot simply rely on the emergence of contexts to create the kinds of justice, fairness, ecological sensitivity and compassion we may wish to see. Indeed, self-interest and tribalism can equally recruit new brain competencies, and they have done so for thousands of years, with some very horrific consequences. We may be vehicles for our genes and for different algorithms and strategies that are “battling” for the control of the minds

Wealth May Decrease Compassion & Cooperation

In environments where resources are scarce—such as in small-scale, low-resource hunter–gatherer societies—people tend to adopt strategies centered on caring and sharing.
In these settings, survival depends on mutual reliance and cooperation, so compassion and generosity are adaptive.
Reputation for helping matters, and group interdependence fosters empathy and support.

In contrast, in wealthy, high-resource societies, the strategy shifts toward controlling and holding.
As people can store resources, grow wealth, and live in larger, more anonymous groups, the adaptive approach becomes one of accumulation, protection, and self-interest.
Compassion becomes less central, and individuals are more likely to prioritize themselves or their close kin.

Research supports this shift:

• Lower socioeconomic classes are more charitable, often more trusting, and helpful than those from higher classes—despite having less to give.
• Entitlement grows with wealth: as wealth and power increase, individuals tend to show reduced empathy, greater entitlement, and less sensitivity to others’ suffering.

This evolution poses a challenge: compassion evolved to function in small, kin-based groups, but modern societies are large, unequal, and often driven by competitive, individualistic, or nationalistic agendas.

Prosocial Adaptation Can Be Co-Opted For Selfish Purposes

As evolution modifies physiological systems that facilitate different competencies, these competencies can begin to be utilized for a range of different purposes.

For example, it is well known that human empathy can be used to be caring or for Machiavellian self-advancement or to cause harm (Gilbert et al., 2017b; Zaki, 2014).
Similarly, caring behavior can be used for a whole variety of purposes, one being to advance one’s reputation (Catarino et al., 2014; Goetz et al., 2010).

We Need Science to Develop A Better Future For Humanity

It is very easy to inspire humans to violence and the enjoyment of narcissistic self-interest with a toning down of empathic concern for the misfortune of others.
(…)
Although many might like to see humanity as a compassionate species – and we can be – we can also be one of the nastiest, most brutal, and most exploitative species to have ever walked this planet.
(…)
Our challenges are to try to create a more compassionate mind in a more compassionate and pro-social world.

🙋‍♂️Lucio’s Take: I agree, and humanity’s future may be at stake

Lucio:
I consider ingroup/outgroup tribalism—and humans’ tendency to band together to attack others—one of the major risks to humanity’s future.

If we are to survive and thrive, and hopefully expand into the universe, some form of “cooperation and compassion engineering” may be necessary.

Chapter 36: A Bridge Too Far? Evolutionary Psychology and Social Problems

Buunk assesses evolutionary psychology‐based interventions for social issues (e.g. aggression, obesity), warning against genetic determinism and urging policies that modify environments to align proximate incentives with adaptive goals.

Evolutionary Psychology More Useful In Telling Us What Not to Do, Than What to Do

For example, it’s useless to tell or expect men to commit more if women far outnumber men, or if men have been raised in difficult environment and already adopted a fast life strategy.

Similarly, policies to bring more women to the to of organizations may fail or be misguided because, given women’s different psychological makeup from men, it is unrealistic to assume that complete equality in the workplace is a reachable goal.

🙋🏼‍♂️ Lucio’s note: potentially too critical and potentially underestimating the impact of Evolutionary Psychology
I was surprised to find this chapter rather critical of evolutionary psychology’s contribution to solving modern problems.
Every field may need internal criticism to avoid touting its horns and some of Buunk’s points are valid. I agreed for example that some criticism of cognitive or social psychology may be taken too far.
However, I remain more optimistic about the value evolutionary psychology can bring to the table.

Chapter 37: The Evolution of Personality

Furnham and Kanazawa review Big Five traits as fitness‐relevant dimensions balancing costs & benefits across environments, proposing that personality diversity is maintained by fluctuating selection (ie.: selection pressure change over time and contexts) and pleiotropy (ie.: one mutation affects many traits, so even sub-optimal traits may stick around even if they’re not always helpful).

All credits to Adrian Furnham and Satoshi Kanazawa

• 50-0-50 rule of personality: for many personality traits roughly 50 percent of the variance in individual differences in personality is heritable (determined by genes), roughly 0 percent is attributable to the shared environment, and roughly 50 percent is due to the nonshared environment, including peer socialization (Harris, 1995, 1998).

🙋🏼‍♂️ Lucio’s note: I still don’t see how this squares with other evidence, and may be potentially misleading
The 50-0-50 rule doesn’t reconcile perfectly with what I’ve learned and observed so far.
For example, Life History Theory says the early environment cues people into fast or slow strategies, often through perceived harshness or unpredictability (see next chapter and not for more 👇🏼). That’s often a shared environment heavily shaped by parents, including the simple presence or absence of a father.
I suspect the misunderstanding may be related to what counts as ‘trait’, and many authors may refer to the Big 5. But a fast life history approach more closely resembles that of individuals high in psychopathic traits, so I struggle to see how that’s not a highly significant impact on personality.

Intelligence Predicts The Acquisition of Novel Preferences

The idea is that intelligence is essential to comprehending and responding to complex and evolutionarily novel situations, but not necessarily to evolutionarily familiar situations. Thus, it is possible to explain a whole range of individual differences from television watching to political attitudes in terms of the intelligence of individuals. More intelligent individuals are more likely to acquire and espouse evolutionarily novel preferences and values such as political liberalism, atheism, and nocturnal lifestyles

There is no ‘best’ personality, only contextually better

The fluctuating selection model highlights the fact that few personality traits have unqualified and universal reproductive benefits under all circumstances;
instead, their benefits depends on contexts and circumstances. Every personality trait has trade-offs in terms of costs and benefits. Different geographical locations and different historical times may select for different personality types.

And this is why social calibration is crucial.

🙋🏼‍♂️ Lucio’s suggestion: expand this great chapter!
This chapter was great, and with even bigger potential for more. It mentions the limitations of random mutation and natural selection in driving evolution toward a single optimum, due to factors such as shifting environments, niche specialization, pleiotropy, and the fact that most traits are not simply present or absent, but continuously distributed—potentially with adaptive advantages near the middle and maladaptive effects at the extremes—making them difficult to eliminate entirely
These are concepts I’ve been grappling with for some time and I’d love for the authors to explain them even more deeply.

Chapter 38: Applying Evolutionary Principles to Criminality

Taylor and Workman apply life‑history theory to antisocial behavior, showing that “fast‐life” strategies (early reproduction, high risk) correlate with Cluster B personality disorders and propensity for crime.

• Secure attachment is rare for psychopathic offenders (Frodi et al., 2001), and such offenders were far more likely to have been physically abused as children

🙋🏼‍♂️ Lucio’s note: sometimes a good family can’t put a bad seed on a good path
The authors compare psychopathic researcher James Fallon‘s good upbringings and a psychopathic killer who had a bad childhood, suggesting that the contingent shift theory (ie.: adjusting to a different environment) explains the diverging paths. However, I’d note that we can’t be sure that was the case, and the main difference may still be genetic, with Fallon having stronger impulse control, or stronger long-term thinking propensities. Or, simply, Fallon may score lower in psychopathic traits (eg.: psychopathy factor 1).
Finally, as per note above, this seems to defy the 50-0-50 ‘rule’ that discounts the early shared environment.

Chapter 39: Substitute Parenting

Daly and Perry analyze stepfamily fertility and child‐investment patterns, revealing higher mortality rates in stepchildren (the “Cinderella effect”) and proposing evolutionary explanations for kin‐selective caregiving.

Existing (dependent) children may decrease a mate’s value:

From a suitor’s perspective, the prospect of becoming a stepparent to a predecessor’s child is treated as a cost, not a benefit, in remarriage negotiations, and stepchildren are sources of marital instability, conflict, and violence (Becker, Landes, & Michael, 1977; Campbell et al., 2003; Daly & Wilson, 1996; Daly, Singh, & Wilson, 1993; White & Booth, 1985;)

The authors also state that ‘stepparental investment has to be understood as a form of mating effort, not parental effort (Rohwer, Herron, & Daly, 1999)’.

Chapter 40: Historians and the Evolutionary Approach

Hanlon critiques historical narratives for ignoring biological factors, illustrating how warfare, state formation, and economic cycles are shaped by evolved incentives and collective action dilemmas.

• Mothers don’t automatically accept newborns: nor do they treat all of their children equally. It is lactation, with its attendant nurturing and cooing, that establishes the bond between mother and infant, who quickly responds (Hrdy, 1999).
• Abortion and infanticide have been common in history: Abortion and infanticide appear to be part of the universal repertoire of human behavior and are much more widespread than we thought. The mothers appear everywhere to be the authors of them, and midwives are active or complicit in the phenomena with various degrees of concealment.
  • Christianity decreased infanticide: The long-standing opposition of Christianity to infanticide is held to represent the dominance of culture over nature
• The certitude of punishment, not the severity, reduces crime: teaching that the short-term advantages aren’t worth it is key to deter people from pursuing a life of crime
• Crime statistics are only as good as the bureaucracy that produced them, and many crime go unreported, unregistered, or unprosecuted.
  The authors also imply that Pinker’s work in The Better Angels of Our Nature was questionable
• Battles are a game of posturing until one faction quits: The actual battle among men at close quarters is a process of posturing until one side turns and runs. “It is in the subsequent pursuit of a broken or defeated enemy that the vast majority of the killing happens. Dogs understand this too, and you will be pursued if you run from them” (Grossman, 2004).
• The desire for dominance drives status acquisition: All primate communities form status hierarchies, and individuals with a strong desire for dominance generally rise to the top.

Chapter 41: The Psychology of Extraterrestrials: The New Frontier?

Barkow speculates on universal cognitive architectures and adaptive behaviors of hypothetical alien intelligences, using human evolutionary constraints to predict likely forms of extraterrestrial sociality and technology.

• We don’t know what they compete on, but if they reproduce sexually, they’re competitive: Because we are a cultural species, the criteria in terms of which we compete and then allocate prestige – relative standing – can vary enormously (Barkow, 1975, 1980b, 1989, 2014a). What is universal is not the specific kind of competition, but competition itself, competition in terms of a standard of excellence

Chapter 45: Evolution and the Media

In this finale, Workman et al. note that modern media exploit ancient biases (supernormal stimuli, gossip networks) to hijack attention and drive status hierarchies. They argue for “media hygiene” practices grounded in evolutionary insight.

• Law of least effort got us hooked: people do what’s easiest, and modern media makes it easy for most people to get entertained, without having to move or do much at all

The principle of least effort has implications for all forms of media: why people may (…) pass up a chance to meet a woman in order to surf porn, pass up a chance to meet a man to read a romance novel
(…) And he can do this while indulging the “rest when you don’t need to move” impulse in a padded lounge chair and consuming supernormal stimuli for hunger or enjoying endogenous feel-good chemicals.

And just wait for AI and sex robots, I’d add…

SHARPEST INSIGHTS

These are the insights that struck us the most.
We use the authors’ quotes and research, but the titles and interpretations are our own—and may not reflect the authors’ intent.
Credit for the insight goes to them; blame for the interpretation is on us.

Tribal Altruists Are Humanity’s Enemies

From Colquhoun et al.:

Based on observations of pro-social behavior of various groups in New Guinea, Boyd and Richerson (2005) claim that CGS can work.

There is, however, a downside to this, since CGS can lead to altruism within the group, but simultaneously promote selfishness between groups.
In fact, Bowles (2009) looked at archaeological data on causes of death during the late Pleistocene and the early Holocene and concluded that between-group competition led to a large increase in mortality rates.

In a sense, the claim that cultural group selection can lead to altruism in humans really raises the question: Altruism toward whom?

From this perspective, suicide bombers may be thought of as altruists to the cause of their group by other group members, but to non-group members they are anything but.

Communism Is Failure to Understand Human Nature

one might argue – with reason – that communist regimes were based on the assumption that the human mind was completely malleable and that society could strongly influence, if not completely change human nature.
Indeed, many social scientists have been guilty of actively supporting this notion and the dictatorial regimes based on it.

And, I’d add, the failure of communism and its chronic underperformance in output, quality of life, and progress, is also the natural consequence of not maximizing the human drive to status and wealth accumulation in the same way that (regulated!) capitalism does.

Society Replaced Alpha Males With Institutions

Taylor and Workman, citing Dennis Krebs, say:

Showing deference ensured survival, whereas defiance may have resulted in injury or death if the challenger was overwhelmed by the alpha male.
Today, the concept of the alpha male has largely been replaced by societal infrastructure and, in particular, by the laws of the land. This means that whereas we once paid deference to the alpha male, we now do so to organizations such as the police force

However, I wouldn’t say that the ‘alpha male‘ has been suppressed, but more like it’s been supplemented.
Social hierarchies haven’t gone anywhere and are still part of our social architecture and internalized psychology.

Lower mate value men may drive monogamy

Quoting Campbell:

Although the selective forces that led to widespread human pair-bonding are debated, Gavrilets (2012) found support for a plausible model that showed that, if females were willing to forego extra-pair matings and preferred males who provided resources, male provisioning would increase driven chiefly by low-ranking males who would otherwise fail to reproduce at all. Because these males outnumbered elite males, selection would have acted more strongly on them and their strategy, causing it to spread through the male population

This recalls the mantra of ‘alpha fux, beta bucks‘.

But the same author then notes:

Monogamy may make for better societies

Humans’ basically monogamous mating system, through its effects on individual behavior, brings with it societal rewards in terms of reduced crime rates and stronger within-group alliances.

For women, it reduces gender inequality and domestic conflict while increasing child survival (Henrich, Boyd, & Richerson, 2012).

Monogamy also means that mate selection becomes a two-way street: when men constrain their (potentially) high reproductive output to that of a single woman, they become much choosier

I agree with this, and even made it a step on our ‘how to build an empire‘ article, since it stabilizes society.
But, importantly, I believe it may also make for a better quality of life for many, and children may benefit from monogamy and a present father.

Some aggressive men may find aggression exciting

Quoting from Toates’ chapter:

For those males who have a desire to dominate, the subliminal presentation of dominance-related words tends to increase the attractiveness rating of the female being viewed (Bargh et al., 1995).

Lying is part of being human

Quotes from the chapter on deception:

lying is just a solution to the ecological circumstances of being human. We have to forge alliances with others, conceal important personal information, and manage multiple – often mutually antagonistic – relationships, none of which would be possible if we were obligate truth-tellers

Lying is so commonplace that it may be the default, and it’s functional:

We used to consider truth-telling to be the default position and deception to be deviant, but evolutionary research is increasingly demonstrating that deception is not only ubiquitous, but functional.

However, not all lies are mean and self-serving:

The lies need not be directly malign, and unlike psychopaths and other pathological liars, they are motivated to grease the wheels, pour oil on troubled water, and generally manage social situations, albeit often for the ultimate benefit of the deceiver.

The best liars may believe in their lies

It should be noted that it has been suggested that human cheats could employ complex methods of hiding their intentions, such as Trivers’ (2011) theory of selfdeception, in which humans are not consciously aware that they will cheat, allowing them to hide dishonest cues

QUOTES

On how researchers still can end up on opposite side of the spectrum when it comes to the role of culture:

Evolutionary scholars often appear to disagree strikingly about the value of “culture” in explaining human behavior.
John Tooby (…_ responded to the Edge.org question “What scientific idea is ready for retirement?” with the answer “Learning and culture” (Tooby, 2014).
At around the same time, Joseph Henrich published ‘The Secret of Our Success: How Culture Is Driving Human Evolution‘.
How can two highly reputable scholars, both committed to understanding human behavior within an evolutionary framework, come to such apparently opposing conclusions? Should the concept of “culture” be retired, or should it be heralded as the secret to humanity’s evolutionary success?

My note:
I disagree with Tooby here, unfortunately, he spoke like a biology/evolutionary determinist

On the misplaced criticism against simple models being ‘too simplistic’:

Simple models do not imply that the modeler thinks that the real world really is simple.
(…) simple models are the best way of understanding a complex reality (Servedio et al., 2014; Smaldino, 2016).

On the relative importance between mothers and fathers:

through our evolutionary past from an infant’s viewpoint, mothers have always been essential while fathers have been an optional extra (Campbell, 2013) (p. 73)

On the cost and inheritability of honor:

He who was ready to sacrifice his life, as many a savage has been, rather than betray his comrades, would often leave no offspring to inherit his noble nature (Darwin, 1871)

On sexual selection supporting human cooperation:

The reason we’re nice is that, throughout the course of our evolution, kind, loyal, and generous people attracted more romantic interest than their cruel, traitorous, or selfish peers, and therefore did better in the reproductive sweepstakes. (2018, p. 200)

On our natural morality:

Mental mechanisms that disposed early humans to behave in moral ways were selected and shaped as humans evolved. Modern humans are naturally disposed to uphold culturally universal and culturally relative moral norms. We are moral by nature.

On women’s ‘slow life’ winning strategy:

The benefits for women lie in lower mortality and greater longevity, which enhance mothering and enable grandmothering. Among women, living slow and dying late has been a winning strategy.

Lucio’s Analysis

Roger’s Paradox Could Be Expanded: Cultural Learning Deserves Better Defense

Mesoudi introduces the Rogers’ paradox, showing that undirected social learning can evolve without improving average fitness, due to frequency dependence.

However, as Mesoudi and others have clarified, this result applies only to non-selective copying. Human learners typically use strategic, selective learning—copying successful individuals or deferring to social learning when individual learning is costly—which can and does enhance fitness.

More importantly, cumulative culture allows humans to build on prior knowledge across generations, achieving innovations no individual could invent alone. This cumulative aspect—not modeled in Rogers’ original framework—is central to culture’s adaptive power.

Finally, human learners are not passive. They can selectively learn, evaluating and refining what they copy with some reverse engineering, filtering out outdated or maladaptive behaviors. These richer learning dynamics resolve the paradox and reaffirm the role of culture in human success.

More Structured Presentation of Main vs Speculative Theories

To improve clarity on complex topics, I believe it’s best to first present the main, most well-supported drivers—those with the strongest empirical backing and largest effect sizes—before introducing additional or more speculative contributors.

Otherwise, readers can get lost in a dense web of interwoven theories, all technically valid, but lacking a coherent narrative or hierarchy of importance.

I recommend authors adopt a top-down structure from most important to least.
Start with the key explanatory drivers, then layer in secondary mechanisms and less supported hypotheses.

For example:

🔎 Ranking the drivers of altruism, morality, & cooperation

For example, despite several chapters dedicated on the topic, I wasn’t able to gain the level of clarity I wanted.

What I wanted was a ranked explanation:

• What are the largest, most widely accepted evolutionary drivers of altruism and cooperation?
• And what are the possible, but less substantiated or narrower-scope, contributors?

This is what I would have liked to see:

“Evolutionary Drivers of Altruism, Morality, and Cooperation: A Ranked Framework”
(by Lucio Buffalmano)

REVIEW

The Cambridge Handbook of Evolutionary Perspectives on Human Behavior is an authoritative, comprehensive, and wide-ranging source of insights into human psychology and behavior.

I’ve reviewed and studied many evolutionary psychology textbooks, and yet the best ones still manage to deliver new and fresh insights.

This Cambridge Handbook ranks among the very best.
It helped me improve several articles, and I learned a ton in the process.

From chapters on cooperation and altruism to bullying, parasite-stress theory, and beyond—there’s so much value here that it’s hard to even pick a favorite.

So instead, I’ll just express my gratitude to every contributing author:
Thank you for the excellent work you do 🙏🏼

Check the best evolutionary psychology books or get this book on Amazon.