Evolutionary Psychology: Summary & Review

evolutionary psychology book cover

Evolutionary Psychology (2019) provides a thorough overview of evolutionary psychology.
David Buss, the author, distills hundreds of researches and experiments to provide the readers with the quickest possible way to understand who we are and why we are the way we are.


About The Author: David Buss is an evolutionary psychologist and researcher, currently teaching at the University of Texas. He is a well known and respected voice in evolutionary psychology, authored and performed an incredible amount of field research, and has written several books, including “The Evolution of Desire“.

Milestones of Human Evolution

  • 15 billion years ago (bya) The Big Bang
  • 4.7 bya Earth forms
  • 3.7 bya First life emerges
  • 1.2 bya Sexual reproduction evolves
  • 500–450 million years ago (mya) First vertebrates
  • 365 mya Fish evolve lungs and walk on land
  • 248–208 mya First small mammals and dinosaurs evolve
  • 208–65 mya Large dinosaurs flourish
  • 114 mya Placental mammals evolve
  • 85 mya First primates evolve
  • 65 mya Dinosaurs go extinct
  • mammals then increase in size and diversity
  • 35 mya First apes evolve
  • 6–8 mya Common ancestor of humans and African apes evolves
  • 4.4 mya First primate with bipedal locomotion (Ardipithecus ramidus)
  • 3.0 mya The australopithecines evolve in savannas of Africa
  • 2.5 mya Earliest stone tools develop—Oldowan (found in Ethiopia and Kenya, Africa); linked with Homo habilis
  • 1.8 mya Hominids (Homo erectus) spread beyond Africa to Asia—first major migration
  • 1.6 mya Fire evidence; likely hearths; linked with African Homo erectus
  • 1.5 mya Invention of Acheulean hand ax; linked with Homo ergaster
  • 1.2 mya Brain expansion in Homo line begins
  • 1.0 mya Hominids spread to Europe
  • 800 thousand years ago (kya) Crude stone tool kit used—found in Spain, linked with Homo antecessor
  • 600–400 kya Long, crafted wooden spears; linked with Homo heidelbergensis found in Germany
  • 500–100 kya Period of most rapid brain expansion
  • 200–30 kya Neanderthals flourish in Europe and western Asia
  • 150–120 kya Common ancestor for all modern humans (Africa) evolves
  • 100–50 kya Exodus from Africa—second major migration [“Out of Africa”]
  • 50–35 kya “Creative Explosion”, explosion of diverse stone tools, bone tools, blade tools, well–designed fireplaces, elaborate art; increased population density. Mainly among Homo sapiens, rarely among Neanderthals
  • 40–35 kya Homo sapiens (Cro–Magnons) arrive in Europe
  • 30 kya Neanderthals go extinct
  • 27 kya–present Homo sapiens colonize entire planet; all other hominid species are now extinct

What happened to other hominids? 

Up until 100.000 years ago there still were three hominids on earth: Homo Sapiens in Africa, Homo Neanderthalensis in Europe, and Homo Erectus in Asia.

What happened to the Neanderthals and Erectus is still up to debate, with two main theories: 

  • Multiregional continuity theory (MRC): 
  • Out of Africa theory (OOA): modern humans evolved in Africa, then migrated all over the world and replaced the other hominids

The archeological and genetical evidence supports the OOA theory.

What caused us to become smart?

There are many theories as to what caused our major feature: brain size. 
Some of the theories link our brain expansion to toolmaking and use, social challenges and social competition, cooperative large-game hunting, complex communication.
Buss says that all of them might have played a role.

My Note: How About Sexual Selection?
I was surprised David Buss doesn’t list sexual selection and sexual competition as a possible cause of brain expansion.
Geoffrey Miller in “The Mating Mind” makes a compelling case for sexual selection and brain development.

Behaviorism Debunked: Enter Evolutionary Psychology

Behaviorists believed that the human mind had little or no innate properties.
The only innate property of the brain was general intelligence and the ability to learn anything via “reinforcement and punishment”. 

This has sometimes been referred to as “tabula rasa” or “blank slate” theory and, in the past decades, Western culture loved the idea.
Anthropologists hunted different cultures, and the more different they were, the more supposedly they proved there were no inborn adaptations, and the more they were celebrated.

See Margareth Mead and the Samoa debacle as an example.
Even to this day, the Wikipedia top summary entry still mentions no bias, ideology or doubt over the quality of Mead’s accounts. And it talks about “controversy” over Mead VS Friedeman without mentioning controversies on Mead’s work.

David Buss suggests that the tabula rasa theory was based on ideology more than on data, and he says:

If tropical paradises existed in other cultures, then perhaps our own problems of jealousy, conflict, and competition were due to U.S. culture, Western values, or capitalism.

However, as time went by, psychology research and science left little wiggling room for behaviorism and “tabula rasa” theories.
Evidence started mounting that the external environment is not the sole determinant of behavior and that humans all share some commonalities, and predispositions.
Starting with Martin Seligman, for example, it became clear that humans can easily learn to develop certain types of fear, like snakes, but it’s difficult to make them develop other types of fears, like cars or electrical outlets.

David Buss says that three forces combined to usher in what’s been called the “cognitive revolution” that eventually supplanted behaviorism as the dominant trend in psychology:

  • Violation of the “fundamental” laws of learning
  • The study of language, with Chomsky arguing for universal invariants across languages
  • The rise of computer and the “information processing metaphor” 

Do Domain-General Mechanisms Even Exist?

Some evolutionary psychologists believe that, on top of our evolved specific mechanisms to deal with our evolutionary problems, we also have domain-general mechanisms such as general intelligence, analogical reasoning, concept formation, and working memory.

For sure domain-specific mechanisms communicate to each other and are not walled-off, so to speak.

But while we can be fairly certain about the presence of domain-specific mechanisms, we cannot yet be sure of domain-general ones.

Evolution and The 3 Products of Evolution

Among the 3 theories of life on earth -seeding, creationism, and natural selection-, natural selection is the most widespread among scientists.

There are three products of the evolutionary process:

  • Adaptations: inherited and common to the whole population because they proved better at ensuring survival and/or reproduction (example: umbilical cord)
  • By-products: they have no functional designs and don’t (directly) solve any evolutionary problem (example: belly button)
  • Noise: random effects produced by mutations and chance (example: the shape of a person’s belly button)

The “noise” is the engine of evolution.
Most of the noise will be unhelpful. But eventually, someone will stumble upon a mutation that helps the organism survive and reproduce. And it will spread out until it becomes an adaptation.

Evolutionary Psychology Misunderstanding

David Buss lists the following as the most frequent misunderstanding people have about evolutionary psychology:

  • Human behavior is genetically determined: genes interact with the environment
  • If it’s evolutionary, we cannot change it: we can change it, and we might argue one of the goals of studying evolutionary psychology is to gain more personal power on ourselves
  • Current mechanisms are optimally designed: no they’re not, evolution can be chaotic as it reacts to the environment. A good design builds from scratch, but evolution has to “add” new things on top of what’s already there

How to Test Evolutionary Hypotheses

A common criticism of evolutionary psychology is that it’s not a science because it’s not falsifiable.

Well, that is not the case.
Buss says there are several ways with which a hypothesis can be empirically tested:

  • Comparisons: measure if groups that are supposed to differ do indeed differ (comparing species, groups of people, genders reactions to stimuli, etc.)
  • Archeological records
  • Contemporary hunter-gatherer societies: supposedly living closer to the circumstances of our evolution
  • Laboratory experiments
  • Public data and records
  • Products and artifacts
  • Behavior: self-reported or observed

The Inclusive Fitness Revolution

Classical Darwinian fitness is focused solely on parent-children, and Hamilton expanded it to include kins as well.

The simple yet revolutionary idea of Hamilton was that, I quote Buss:

An organism can also increase the reproduction of its genes by helping brothers, sisters, nieces, or nephews to survive and reproduce.

One implication of the inclusive fitness hypothesis is that people will be more altruistic and helpful towards their kins, and that’s been proven by several studies.

This is how Buss explains the Hamilton’s rule:

Hamilton’s rule, stated more formally, is that natural selection favors mechanisms for altruism when c < rb In this formula, c is the cost to the actor, r is the degree of genetic relatedness between the actor and the recipient

What’s crucial to remember here, and what many people get wrong, is that the Hamilton’s rule is not an adaptation per se.
The Hamilton rule simply predicts that altruism among kin can arise and, if it does, it will be favored by evolutionary forces.
Altruism that goes against Hamilton’s rule instead will have to buck the evolutionary forces, and is more likely to be rooted out (evolvability constraint).

David Buss goes on to describe all the types of relationship directly linked to Hamilton’s rule, including parent–child. sibships, half sibships, aunt–niece, uncle–nephew, grandparent–grandchild, and others.

We recognize kins in the following ways:

  1.  Through association (having grown together)
  2. Through odor
  3. Through kin classification (all cultures have special names for kins)
  4. Through facial similarity 

People are also good at spotting clusters of kins from strangers, which could have been helpful to recognize who is allied with whom.

Why Families Evolved

Families are uncommon in the animal kingdom.

Only 3% of mammals and birds form families.
It makes sense, because remaining in the parental nest incurs high costs, including delayed reproduction and concentration of resource competition.

Two models have been proposed:

  • Ecological constraint: families emerge when there is a lack of mating opportunities
  • Familial benefits: families emerge when they can provide benefits to the offspring
    • Enhanced survival from family’s protection
    • Enhanced ability to better compete later in life
    • Inheriting or sharing the family resources
    • Inclusive fitness gains by helping genetic relatives

Non-Kin Altruism

David Buss also goes into the evolution of non-kin altruism.
The theories developed to explain the puzzle of altruism are:

  1. reciprocal altruism
  2. indirect reciprocity: people benefit when others seem them being altruist and they gain a reputation for reciprocators
  3. need-based transfer systems: risk pooling, a form of social insurance
  4. costly signaling: increases reputation and status through the handicap system of (similar to “conspicuous consumption” in mating)

I liked his summary of Axelrod’s techniques to increase cooperation:

  1. Enlarge the shadow of the future: if people think you’ll be dealing with each other again, they’ll be more likely to cooperate
  2. Teach reciprocity
  3. Insist on no more than equity: greed is the downfall of the many, when people know fairness is the goal, they’ll be more likely to trust and cooperate
  4. Respond quickly to provocation: sends a signal you don’t tolerate exploitation, which will not work with you or within your team (also see: “how to be a great leader“)
  5. Cultivate a personal reputation as a reciprocator

There are several psychological adaptations showing that we evolved to compute social exchange barters:

  • We are bad at abstract logical reasoning, but when problems are presented as costs and benefits in social exchanges, we are good at solving them
  • People naturally pay close attention to potential cheaters
  • People are reasonably accurate at predicting who will cheat and who is a genuine altruist and cooperator
  • People are more generous when others are watching (the benefit of “indirect reciprocity” and building a reputation as collaborator)
  • Altruists seem good at spotting each other and preferentially hanging out with each other
  • Emotions evolved to support the social exchange system, including gratitude, anger towards non-reciprocators, guilt,

More research is needed in this area, and you can also read “The Origins of Virtue” for more information.


Buss also gets into coalitions and the free-rider problem, and says there is mounting evidence that we evolved psychological adaptation to punish free-riders.

The studies are still in their infancy, but some possible adaptations include:

  • gossip as a means of social bonding and controlling free-riders (Dunbar, 2004; Kniffin & Wilson, 2005),
  • in-group favoritism bias (Schiller, Baumgartner, & Knoch, 2014),
  • prejudice against and punishment of out-group members (Schiller et al., 2014)
  • xenophobia 
  • adaptations to enforce group norms
  • ostracizing those who violate social norms (van Vugt & van Lange, 2006)
  • enforcing rules and norms of fairness
  • status and reputational benefits to those who contribute heavily to group goals
  • providing rewards to those who contribute (Kiyonari & Barclay, 2008).

The Four Classes of Evolutionary Problems

David Buss says that humans had to tackle four major classes of problems, and he structures his work along them:

  1. Survival and growth: reaching the stage at which the organism is capable of reproduction
  2. Mating: selecting, attracting, and reproducing
  3. Parenting: support the offspring until they can also reach reproduction stage
  4. Aiding genetic relatives: supporting those around us who carry our genes

My Note: Why “Problems”?
This might feel like nitpicking, but I have an immediate gut reaction to the use of the word “problems”.
Buss quotes Darwin, who in turn talks about the “hostile forces of nature”, but that nature is what allowed life in the first place, and it’s what allowing all life forms to thrive
Nature empowers life, does not do its very best to thwart it.

Problems of Survival

  • Folk biology: all humans have an innate grasp of nature because we all needed to learn what was edible and what was poisonous
  • We dislike bitter and sour food because it’s likely to contain toxins
  • Neophobia: we have an innate dislike for new food because new food is potentially dangerous
  • Disgust is an evolved defense against disease: that’s why we find more disgusting what’s also more likely to carry diseases. Women, at higher risk of catching STDs, have a heightened sense of disgust
    • Mothers rate their children’s feces less disgusting, signaling an adaptation to tend for their offspring
    • In dire necessity, humans can override disgust (see cannibalism)
  • Adapted fears of life threats: snakes, spiders, heights, strangers, public rejection of courtship attempts, etc.
  • Auditory bias: approaching sounds are perceived as louder than receding ones because of the greater danger of approaching threats
  • Threat-saliency: people, as well as children, are faster at spotting dangerous animals such as snakes and lions among random objects
  • Darwinian medicine: fever, cough, sneezes, they probably shouldn’t be treated because they evolved to help us tackle diseases

The Hunting Hypothesis (& Gathering Hypothesis)

The hunting hypothesis suggests that hunting has been instrumental in developing many of our adapted mechanisms, including:

The gathering hypothesis suggests instead that women provided the impetus for human evolution via gathering, but it falls short in many areas.

In any case, the specialization of gender-specific division of labor has resulted in measurable differences between men and women.
Men have better navigational abilities, map reading, and mental rotation of objects -for hurling spears maybe?-.
Women have better spatial location memory. 

Challenges of Sex & Mating

For more on this section, please read:

David Buss also wrote a book fully focused on sex and mating, called “The Evolution of Desire“.

Patterns of Inheritance & Spousal Diverging Interests

This was fantastic.

The data on inheritances analyzed from an evolutionary point of view was eye-opening.

Here is the data from the analysis of 1.000 probated wills (Smith, Kish, and Crawford, 1987):

  • Women distributed their estates to a larger number of people (2.8 VS 2.0)

This might be because women have a stronger tendency towards building and maintaining networks of support.

  • A majority of men left their entire estates to their wives, often with expressed confidence that the wife would pass along the resources to their children

Men tend to trust women more.
This is because women have higher parental investment than men, so it is indeed more likely that women will take care of his own children.

And, of course, it’s because older women are more unlikely to remarry and even more unlikely to have additional children, so the husband can be more confident that his widow will allocate the resources toward their mutual children.

  • Women never expressed trust that the man will take care of her children

Women tended to trust men less.
And they might not be wrong: older men are far more likely than older women to remarry, and they might use their previous wife’s resources to attract a new mate and perhaps even start a new family.
That’s risky for her: resources will be diverted from the original wife’s children to unrelated individuals.

  • But if their wives were young, men were more likely to leave their estate directly to their children

Which makes sense, since younger women are more likely to remarry and, possibly, have more children fathered by another man.
And they might use their late husband’s money to dote on children that are not his.

The evidence of psychological adaptations for short-term mating in men

The psychological evidence for an inborn bias toward male short term mating are:

  • Desire for sexual variety
    • Porn consumption trends
    • Number of desired partners (men mention far higher numbers than women)
  • Nature and frequency fantasies: women more likely to emphasize feelings, but there are large individual differences and some women also fantasize of sex with strangers
  • The amount of time elapsing before a person seeks sex
  • Lowering of standards in short-term mating
    • De-prioritization of face in favor of body (women don’t show the same)
    • Closing time phenomenon: men find women more attractive as the venue-time approaches
  • Search for “exploitability cues”: men like women who look simple-minded and exploitable, while women don’t like men who look exploitable
  • Attraction reduction shif: men tend to be less attracted to women right after sex (especially true for men with a short-term bias)
  • Tactics to avoid short-term mating from becoming committed 
    • Keeping the conversation sexual in nature
    • Maintain multiple sex partners
    • Having sex with someone else
  • Extramarital affairs: men in most cultures pursue extramarital affairs more than women do

Women also sometimes use tactics to prevent casual sex from becoming more, but it’s usually more about “giving the wrong phone number”.

Overall, male more and more deeply rooted psychological adaptations for short-term mating show that casual sex is a strategy more significant for men, than for women.

The evidence for female short-term mating strategy

Here is an overview of the current evidence for an evolved female strategy for short-term sex:

  • Desire for sexual variety
    • Porn consumption trends
    • Number of desired partners (men mention far higher numbers than women)
  • Nature and frequency fantasies: women more likely to emphasize feelings, but there are large individual differences and some women also fantasize of sex with strangers
  • The amount of time elapsing before a person seeks sex again
  • Lowering of standards in short-term mating
  • De-prioritization of face in favor of body (women don’t show the same)
  • Closing time phenomenon: men find women more attractive as the venue-time approaches
  • Search for “exploitability cues”: men like women who look simple-minded and exploitable, while women don’t like men who look exploitable
  • Attraction reduction shift: men tend to be less attracted to women right after sex (especially true for men with a short-term bias)
  • The existence of common tactics to avoid short-term mating from becoming committed 
    • Keeping the conversation sexual in nature
    • Maintain multiple sex partners
    • Having sex with someone else
    • Preference for loose women
    • Not minding too much if a woman is in a committed relationship

Overall, male more and more deeply rooted psychological adaptations for short-term mating show that casual sex is a strategy more significant for men, than for women.

Benefits of Short-Term Mating for Women

Several theories have been put forward to account for female evolved short-term sexual strategy:

  • Resources
    • Investment via paternity confusion
    • Immediate economic resources: short-term biased women prefer men with an extravagant lifestyle (conspicuous consumption), and who spend money on them early on.
    • Protection through “special friendships”
    • Status elevation
  • Genes
    • Sexy son hypothesis: women who engage in short-term mating place a premium on the man’s physical attractiveness, but replication failure suggests caution
    • Genetic diversity:
  • Mate switching
    • Mate expulsion
    • Mate replacement: women who have affairs are significantly less happy with their partners, and they find “promiscuity” and existing relationships mildly undesirable in an affair partner, supporting this hypothesis)
    • Mate insurance:
  • Short-term for long-term mating goals: women themselves rated the possibility of switching casual sex for a relationship as the second most important reason for casual sex
    • Sex to evaluate long–term mate potential: young women might go through a period of casual sex as a way to assess their own SMV
    • Clarifying mate preferences:
    • Honing skills of mate attraction:
  • Mate manipulation
    • Increasing commitment of long–term mate:
    • Revenge as deterrence

Parenting and Kinship

Parenting dispositions and behavior can be predicted, at the most general level, through the following three contexts:

  • Paternity uncertainty (ie.: are children really mine?)
    • This is one of the reasons why men generally invest less in children
    • Step-parents more likely to beat, abuse and ignore children who are not theirs
    • Women “remind” men the children look like them
    • Paternal grandparents invest less than maternal ones
    • Men who perceive their wives as faithful and trustworthy also invest more in the children
  • Alternative uses of the resources: where can I get the biggest bang for the buck? My children’s or my sister’s? Nurturing or looking for another mate? 
    • Young women are more likely to kill their infants because they can produce more later on, under better conditions
    • Young women without a providing man kill their infants more often, except when they’re old because they won’t have another chance at procreation
    • Men high in status offer less parental care and ramp up their matings efforts
  • Children’s ability to survive and reproduce: parents invest more in children most able to convert their effort into fitness (does not mean they always invest more in the healthiest child, sometimes curing a sick one can make more sense, but they tend to allocate investment strategically)
    • Ill and deformed children receive less help and are killed more often

Interestingly, resources can change the pattern of parental investment. Mothers with little resources followed the predictable pattern of investing less in prematurely born babies (high risk), while mothers with lots of resources invested more in high-risk infants than low-risk ones.
Who said that money is the root of all evils?

Women, as the primary caregiver, have evolved more psychological adaptations for nurturing, including:

  • Better at decoding facial expressions, particularly negative ones
  • General reduction in risk-taking
  • Reduction in risk-taking when paired with babies

Parent-Child Conflicts

Parents and children share 50% of genes.
But that also means they are 50% different, and that leads to potential conflict.

A child always gains in seeking more investment, while a parent might gain more by sharing their support among several children -or looking outside of the relationship-.

The theory of parent-offpsring and, more in general, genetical self-interest and different interests within families predicts that:

  • Children will want more of their parent’s resources
    • The mother-child conflicts starts in the uterus, with children trying to get as much as possible even if gets unhealthy for the mother 
    • Children want to be breastfed for longer than mothers want
    • Children seek to get more resources than their siblings
  • Parents will want to give less than the child requests
    • Parents want to wean children sooner
    • Parents punish conflict between siblings
    • Parents encourage more cooperation among siblings than they really want

Parent/offspring conflict also increases in the presence of new offspring as that means more competition, and in the presence of half-siblings, since that means competing with someone who has even less genetic relatedness. 

Parents/Child Conflict Over Mates

Parents and offspring’s interests also diverge when it comes to the choice of mates.

Children will gain more from selecting a genetically superior partner because their offspring will inherit 50% of their genes. But parents only have 25% of their genes in common with their grandchildren, so they will gain more if their children select a partner that promotes their interest independently of genetic quality. Say, for example, a mate that will further their status and economic well-being.

This is especially true for fathers, since they retain fertility for long, and they have more interest in securing new possible future mates.

The evidence indeed proves that:

  • Offspring prioritize physical attractiveness more than their parents
  • Parents prioritize family background 
  • Parents and offspring are in conflict over the pursuit of a short-term mating strategy (it’s hypotesized that a short-term mating strategy can compromise the status and reputation of the family)

Parents indeed find a short-term mating strategy far more acceptable for themselves than for their sons and, especially, daughters.

My Note: This Was Eye-Opening
This conflict on mate selection was truly a novel and genius revelation for me.
Even after tens of books on evolutionary psychology, I had never thought about it.
I am still not 100% bought into it as offspring might simply want an attractive partner because they will have sex with them. Parents don’t care since they don’t have to live and have sex with them, but it’s still an interesting new point of view.

Conflict Changes Over Time

Manipulation of course goes both ways, with both parents and children trying to manipulate each other in what’s in their own best interests.

Since parents and children share 50% of their genes, sometimes there is an overlap in their common interest.
But as time goes by, so does the interests overlap.
As both parents and children age, parents become less useful to children, both in terms of producing new offspring with a 50% relatedness, and in terms of direct help to the self.

To learn more on both manipulation and sexual manipulation, read:

Conflict, Organized Conflict & Recalibration Theory

David Buss discusses conflict among humans, the only species together with chimp which is on record for organizing squads of alliances to attack other individuals of the same species.

How could war even become widespread?
Tooby and Cosmides list four conditions that must be met for war to become part of the human repertoire:

  • The average long-term gain in reproductive resources must outweigh the reproductive costs of engaging in warfare over evolutionary time
    • An increase in sexual access to females is the most likely candidate, since it’s the resource that imposes the greatest limit on male reproduction
  • Men must believe that their group will emerge victorious
  • The risk and the importance of each member’s contribution must translate into a corresponding share of the benefits
  • Men who go into battle must be cloaked in a “veil of ignorance” about who will live or die.

Recalibration Theory

The recalibration theory proposes that anger serves to increase -recalibrate- the value that the target of your anger places on your well-being.

Individuals with a superior ability to inflict costs and confer benefits should be more prone to anger because they can be more effective with it.
And indeed a man’s upper body strength and a woman’s physical attractiveness both predict the propensity towards anger and showed a history of fighting, more success in prior social conflicts, a greater perceived utility of aggression, and a greater sense of entitlement.

Status, Prestige, and Social Dominance

Human mechanisms to be effective social animals are inherently complex.

Contrary to many other animals, our social hierarchies transcend mere physical brawn to include social skills, leadership, and the ability to enlist powerful friends and form coalitions.

Since the payoff for men are higher, men also tend to seek status and prestige more than women do.

There are many traits that correlate with dominance, including some that you might not always expect:

  • domain expertise 
  • size / athleticism
  • testosterone and serotonin levels 
  • intelligence
  • physical attractiveness
  • humorousness
  • good grooming

Service-for-prestige theory

Leaders provide key survival resources to followers by leading the group in more effective ways than anyone else could.
In exchange, he receives social status and more mating opportunities.

Elevated status and dominance improved male mating success in three ways:

  1. Women prefer high-status men
  2. It proves men with more resources to support women and their children
  3. More powerful men might simply take the mate of subordinate men

Social Dominance Orientation

Men are higher than women in social dominance orientation (SDO).

Individuals high in SDO endorse the legitimacy of one group’s domination over another, the deservingness of discrimination and subordination of one group by another, and the allocation of more perks to one group than another.

Gender Differences in Dominance

Dominant men have more egoistic dominance acts, while dominant women have a higher incidence of prosocial dominance acts.
Female dominance is more group-oriented.

Dominance Theory

Deontic reasoning, such as thinking in terms of which actions one may or must not perform with respect to a social rule, emerges early in life.

People have a tendency to spontaneously check for other people’s social violations, and especially so when those violators are lower in status. 

Also read:

Social Attention-Holding Theory

Paul Gilbert emphasizes the emotional components of dominance (also see “social rank theory“).

Animals naturally assess each other’s “resources-holding potential” (RHP), and based on that information they might attack if they are superior, or flee or submit if they believe they are inferior.

Gilbert says that humans also use RHP, but made it part of a “higher level socialization” in what he calls “attention-holding potential”.
Humans compete with each other to be attended and valued by their social group. High-status members command lots of attention, and when they bestow their attention on another peer, that individual rises in status. Ignored individuals instead lose status.

Going up the ranks results in elatedness, more helpful and prosocial behavior, and happier mood.
Loss of status results in anxiety, shame, envy, depression, and anger.

Presumably, social anxiety should help the anxious individual to avoid any risk that would likely result in a loss of social status.
Shame is similar, kicking in when the individual will be devalued by others.
Envy instead might function to make us pursue the same path as those who have the resources we want. Hero worship and the idealization of others is nothing but a positive form of envy.

Again stressing the differences between men and women, men tend to be envious of men who have more sexual experience and have more mates, while women are envious of more physically attractive women.

Friends’ Benefits & Frenemies Dangers

Men tend to prefer a larger number of less intimate friends, and tend to spend less time nurturing their friendships.

Says Buss:

In contrast to the psychological closeness and intimacy of women’s friendships, men tend to use friendships to achieve some common goal, such as cooperative hunting, cooperative defense, or coalitional warfare.

Friends can bring lots of benefits, but they’re also competitors and rivals, and that’s often always in the air.
Men tend to perceive more sexual competition from their friends than women do, but women also compete with their female friends.
For example, the less female attractive member of the friendship pair perceived more mating rivalry than the more attractive member (see: “frenemies” and “how to spot a frenemy“).

Towards a Unified (Evolutionary) Psychology

In the last chapter of “Evolutionary Psychology,” David Buss talks about the many overlapping fields of psychology and the lack of a unifying force.

He says that evolutionary psychology should be that discipline that ties all the different branches of psychology together.

And I couldn’t agree more.

He also partially -and tactfully- criticizes the effort of cognitive psychology to hunt for “cognitive biases”, saying that they are not really biases, but simply evolved shortcuts that work well for most our evolution and most of our problems (for cognitive biases see “Thinking Fast and Slow” by Daniel Kahnemann).

Finally, Buss introduces a few more interesting theories, including attachment theory.
For more on attachment theory see:

Buss of course puts attachment theory within the wider lenses of evolutionary psychology.
He says for example that variations from a secure attachment represent children’s adaptation to non-optimal familial environments.
Avoidant attachment adapts to parents unwilling to invest, while anxious attachment adapts to a parent who is unable to invest -and which leads to more short-term mating strategies.

More Wisdom

  • Dark triad predicts deception: dark triad traits predict deception and sexual harassment (see: best dark triad books)
  • Psychopathy as a strategy: psychopaths pursue a “cheating” strategy that can be rewarding, as long as there are enough cooperators in the system. Psychopaths pursue a cheating strategy mostly with especially with interaction partners who are less attractive and those who they don’t expect to interact with in the future (also see: why psychopaths get laid more)
  • Sexual selection has two modes: Sexual selection operates on two levels: intrasexual competition for access to mates, and intersexual selection or mate choice (which can also be conflictual at times, see: intersexual conflict
  • Evolution hasn’t stopped: there has been an acceleration of human evolution in the last 40.000 and 10.000 years, and not a slow down as some had thought
  • Offspring’s niches: first borns tend to be more conservative and close to their parents. Later brons enter into an already existing child/parent bond and, mathematically, might receive less support even if the parents seek to be equal, so they seek their own way in life and reject the status quo. Last borns, who receive all the family’s support, tend again to be closer to their parents
  • Female beauty allows for upward mobility: Buss says that beautiful women “marry up”, also referred to as “female hypergamy“.
    To learn more about the science of female hypergamy see:

Best Quotes

The quote, in this case, is not necessarily “inspirational”, but it’s a good wake-up call:

These homicide data are preliminary, of course, but they suggest that there are risks of being the less valued party in the parent–child relationship.

evolutionary psychology book cover


“Evolutionary Psychology” is a monumental work.
These are the small notes I took on the side that left me wondering sometimes:

Does Not Always Entertain Alternatives or “Problems” of The Presented Theories

Some theories are presented as if they were perfectly proven and accepted.

But not all of them are. Or, at least, some of them do present some issues. For example, when it comes to the differences between male and female jealousies, David Buller correctly points out that most German men report emotional infidelity to be more worrying than sexual infidelity. 

Why’s that so?
Could it be that culture, especially when it comes to openness towards sex, is far more important than Buss acknowledges (at least on this one issue)?

Or consider the theory that we evolved a dual mating system for short and long-term mating.
Couldn’t be instead that we always had the short term drive, and then only added the long-term one, thus being two different systems that evolved independently instead of inter-dependently?

These “problems” with Buss’ presented theories don’t necessarily undermine his argument. As a matter of fact, I am still convinced of the general validity of his arguments.
But I wished he had mentioned the problems, too, and that would have given him even more authority and credibility.

Over-explanations of what might just be randomness?

Evolutionary psychology has been criticized for being an “after the events” exercise of nice-sounding narratives with little science.

I think people who say that don’t really understand evolutionary psychology or human nature, but that doesn’t mean that, at times, evolutionary psychologists don’t tend to over-explain things.

For example, I found the explanation of humans drinking alcohol as a by-product of our taste for ripe fruits to be quite an unsubstantiated stretch.

At least, I would have liked a note saying that some of these correlations were more speculative.

Too little room left for personal variations?

Buss says that “there is nothing arbitrary nor culture-bound about the standard of beauty”.

But that’s not true.
First of all, some standards of beauty are quite arbitrary in the way they develop, arising from random mutations in tastes that might or might not correlate too well with fitness.

Second, there is quite a bit of cultural variance in at least a few traits, as Buss himself found out.
For example, the amount of fat on a woman.

Also see:

An overly-competitive view of nature

I’ve already mentioned about Buss talking about “hostile forces of nature”.

And I believe that is only one side of the coin.
If nature was so “hostile”, there would be no life. Instead, the earth is covered with life, so nature can’t be that hostile, after all.

The same approach extends to competition.
It seems to me that the author focuses too much on competition at the detriment of cooperation.
For example, he writes:

Natural selection is intrinsically competitive, a feedback process in which one organism’s design features out-reproduce those of others in an existing population.

Of course nature is “intrinsically competitive”.
But it’s also “intrinsically cooperative”. Sometimes you could call it “competitive cooperation”, or “codependency”, like in humans’ gut microbe, but it’s still a form of cooperation.

Naive view on men not joining forces against women?

OK, Buss is no naive author.

However, just in this one instance, I felt it was a “too rosy view” of mankind.

The author says it’s not true, and not possible, that men might unite to exclude women from resources and power.

He writes:

Feminist writers sometimes portray all men as united for the common goal of oppressing all women (Dworkin, 1987; Faludi, 1991). Evolutionary psychological analyses suggest that this cannot be true because men and women compete mainly against members of their own gender. Men strive to control resources at the expense of and to the exclusion of other men.

I think the author is missing out here on the power dynamics involved

Men compete against themselves the same way that most organisms compete but, as we’ve mentioned already, many organisms also collaborate while they compete.

Very high quality men would not mind if women get more power, resources, and freedom to have sex as they please.
They’d still win and find mates. As a matter of fact, they would win even more (albeit disempowered women also make it easier for high-quality men to keep attraction and power in their relationships).

But the majority of men are not very high in SMV.
So the vast majority of men do have an interest in keeping women away from sources of income and sexual freedoms.
The poorer women are, and the more forced they are to pair with a man, any man, the better off most average men are.
This is a case where a win for the group can be a win for the majority of individuals in that group.

Indeed, Buss says it right a little later:

Evolutionary psychology points to a different conclusion: each individual is united in interests with some members of each sex and is in conflict with some members of each sex.

And when each individual is united with a large number of members of his own sex, then an effective, silent coalition to restrict the power and freedom for women can naturally form -and it probably did form-.
There is some truth in the patriarchy.

Also read:

Also read “how men keep women down at work“.

Sometimes research was based on too small samples

Writes Buss, talking about the link between attractiveness and number of offspring:

A smaller study of 47 modern Polish women failed to find a link between female attractiveness and reproductive output.
It is possible that modern birth control technology may sever the historical link between female beauty and offspring production.

Yes, it’s certainly possible.
But I would not generalize from such a small sample and I would avoid drawing any conclusion based on it.

Sometimes does not account for possible confounding factors in the research

Sometimes I felt that confounding factors were not properly accounted for and the authors might have been too quick in jumping to conclusions.

For example:

  • Men ejaculate more when the partner isn’t there, but masturbation can’t be the same as sex?

The author mentions an experiment whereby 35 couples agreed to provide ejaculates resulting from sexual intercourse from condoms.

He says that the longer the couple was apart, the more the man ejaculated. Since the research took into account masturbation as well, that’s proof that the quantity of ejaculate depended on time apart only.

However, that means that the researchers put masturbation and sex on the same level.
Who says that masturbation is equivalent to having with the partner? Maybe those men always ejaculated less when masturbating as compared to having sex. That should have been taken into account.

  • Teenagers killed more often, but teenagers also annoy people more

The author says that teenagers are not killed by parents because they are the best age to secure future offspring. 
The proof that it’s not about the ability of the child to defend himself lays in non-relatives, who kill teenager more often than any other age category.

I thought that was a smart way of looking for trends. 
Yet, teenagers are also more likely to rebel and annoy people, which is why non-relative might get into violent altercations more often.

  • People leave more heredity to children than siblings only because they’re younger and thus more valuable?

The author says that people leave more inheritance to children than to siblings because they’re younger and thus have more future mating potential.

That didn’t make sense to me.
People leave more inheritance to children because they are responsible for their children, but they’re not equally as responsible for their siblings, who in turn are responsible for their own children.

This is a case of overthinking through genetic payoffs without considering other factors, such as “unwritten human contracts”. In this case: “I care about my children, you care about yours”.

Contradictory information on altruism & value

The author says that parents kill infants more than teenagers because they invested more in teenagers, and in teenagers are getting close to reproductive age.

Yet, he also says that helping in the life-or-death situation declines steadily as the recipient’s age increased.
That might be the case because younger people need more help, yet it’s a potential discord one should investigate further.

Mother / child uterus conflict: is it a case of arms race?

The author says that mothers want to abort unhealthy fetuses while fetuses, having only one shot at life, produce chemicals to prevent spontaneous abortions.

The author says it’s an arms’ race, and seems to imply that unhealthy children produce hCG to “trick” the mother’s system into keeping the fetus implanted.
The mother’s body appears to interpret high levels of hCG as a sign that a fetus is healthy and viable and so does not spontaneously abort

But there is no proof whatsoever that unhealthy children produce more hCG, so I didn’t see it as an arms race as the author implies.

Sometimes implies causation where there is only correlation

There were a few instances where I felt causation was implied without there being the basis for.

For example: 

  • The author says that homicide statistics are the proof that poor and unmarried people kill more as a “strategy of last resort”. However, that does not necessarily imply causation and it could be that killers are also more likely to be poor and unmarried.
  • The author says that males victimized by aggression during middle and high school lose status and have significantly fewer sex partners by the time they reach college, but who says it wasn’t the low status they had to begin with that caused victimization?
  • The author says that being in a gang results in more mating success because a study showed that gang members had more sexual partners than non-gang members. Again, this is just correlation. And then he says that gang leaders had the most, but that says nothing because leaders are always more attractive and he should have compared it with non-gang members who were leaders of something -say, a fraternity-

Does not give enough weight to sexual selection?

I am biased here because I’m a big fan of Miller’s “sexual-selection centered” view of evolution and, especially, the development of intelligence.

So I naturally found that this wonderful manual under-represents the role of sexual selection in general and, specifically, of sexual selection in the development of the human intellectual faculties.

The Deadly Innovation Silliness

That was all the more striking when the author spent a lot of time discussing the theory of “deadly innovations hypothesis“.

The theory says that as our weapons and tools became more formidable, their mishandling also caused more deaths and, thus, more selection pressure against dumb people.
Frankly, that made no sense to me. 

The number of deaths should have been so high to make an impact that I just can’t believe there are enough people who accidentally shoot themselves or, in our ancestral time, who accidentally fell on their spears.
Plus, that can happen to anyone, and I can’t see it being highly correlated with IQ.

Baker & sperm wars? Chagnon?

The author mentions a couple of times Bakers and in his research, both for sperm warms and the likelihood of women experiencing orgasms more often outside of their relationships.

Baker is controversial for his unscientific claims that have either not yet been proven, or that have been proven wrong -see his book “Sperm Wars“-.

The author also mentions Chagnon.
Chagnon’s data on increasing mating success among murderers has been criticized -and, it seems to me, for good reasons, see Sapolsky for an overview and Fry for the original paper-.

I wish Buss had done a note on the side just to make sure the Ts were crossed and Is dotted. Or at least quickly mentioned the debate raging on and why he still believed the data was good.


“Evolutionary Psychology” is a monumental work.

“Evolutionary Psychology” is to evolutionary psychology what “The Social Animal” is to social psychology, such as: the best overview available on the whole discipline.

If you had to read one book about evolutionary psychology, then pick this one.

Beyond this book, David Buss is a titan of evolutionary psychology and I am grateful and indebted to his work and to his massive body of research.

Also see:

Or get the book on Amazon

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