PDF Summary:The Moral Animal, by Robert Wright

In The Moral Animal, journalist Robert Wright uses evolutionary psychology to explain the hidden forces driving human behavior. Drawing from research in biology, anthropology, and psychology, Wright argues that our minds and social instincts were shaped by natural selection to maximize reproductive success in our ancestral environments—and these ancient programming patterns continue to influence everything from our romantic relationships to our moral judgments today. This evolutionary lens helps explain why people treat others differently based on their social status, why parents invest more in some children than others, and why monogamy is so difficult to stick to.

Wright argues that by understanding the role of instinct in our daily lives, we can become more aware of our motivations and more understanding of others. Our guide will explore how evolution shaped human instincts for finding mates, raising families, and navigating social environments. Finally, we’ll take a look at Wright’s arguments for how an evolutionary perspective should change our understanding of morality.

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In contrast with this view, some feminist scholars say monogamy undermines equality between the sexes because it has historically made women the property of men. They argue that monogamous marriage began as a way to ensure that a man’s resources and property would go to his biological heirs; restricting women to one partner ensured that a man didn’t accidentally bequeath an inheritance to another man’s biological children.

However, men weren’t under the same cultural pressures to be faithful, and women were often forced to take on a disproportionate amount of domestic labor, leading to an unequal position between men and women. Some have argued that non-monogamy could present an alternative to this historically unequal tradition of monogamous marriage.

2) Polygyny

Polygyny is the practice of one man marrying multiple wives. Wright explains that throughout history, societies with a highly uneven distribution of resources have favored polygyny, as elite men are able to support multiple wives, and, as we’ve discussed, have a reproductive incentive to mate with multiple partners. Historically, this arrangement has been found in feudal, aristocratic, and monarchist societies with an extreme disparity between the social classes.

Polygyny provides a reproductive advantage to high-status men, who can then father far more children than if they had limited themselves to one wife. Wright argues that women may also have a reproductive advantage in polygynous societies, because if a society is stratified enough, the women may have more resources for their offspring by sharing a high-status man with other women than by having all the resources of a low-status man to themselves. However, Wright explains that this arrangement puts low-status men at a reproductive disadvantage, as they’ll end up with no partners at all.

Polygyny’s Decline

According to some experts, polygyny was common in the ancient world, practiced by as many as 75% of the world’s societies. However, the practice has dramatically declined over the centuries. Today, the only countries where a substantial portion of the population lives in polygamous homes are found in Western Subsaharan Africa, with Burkina Faso (36% of the population) and Mali (34%) leading the pack.

Some scholars attribute this to changing cultural practices. Christianity places a heavy emphasis on monogamous marriage, and during the era of European colonialism, colonial laws forced monogamous marriage on previously polygynous cultures. Those cultures became Christianized over time, and most retained monogamous marriage even once colonial powers withdrew from those regions.

Furthermore, some scholars argue that as women’s rights and access to income and education have increased, they’ve gained the economic freedom to opt out of polygynous marriages and express a preference for monogamy. Many now view polygyny as an affront to gender equality that forces women into subservient roles. The UN Human Rights Committee has stated that polygyny “violates the dignity of women” and should be “abolished wherever it continues to exist.” These changing norms have also likely contributed to its scarcity in modern times.

3) Polyandry

Wright explains that polyandry is the practice of one woman taking multiple husbands. Though rare, this marriage practice tends to emerge in societies where resources are extremely scarce. This is because if the resources a man provides are inadequate to raise a child, the woman has an incentive to take on additional partners and pool their contributions.

Fraternal Polyandry and Alternatives to the Scarcity Explanation

Some scholars have disputed the “scarcity” explanation for polyandry put forward by Wright. However, to understand some of the alternative explanations, it’s important to note that one of the most commonly practiced forms of polyandry is “fraternal polyandry,” in which one woman marries several brothers. These are typically arranged marriages worked out by the spouses’ parents, and children in these arrangements are usually seen as either all belonging to the eldest brother or belonging to all the brothers equally.

Some argue that this practice largely serves to prevent a family’s estate from being divided between multiple heirs. By allowing all brothers to inherit the family property, its land and resources remain intact from generation to generation. Still other scholars argue that fraternal polyandry gives a household more laborers by increasing the number of young, able-bodied men around.

Both of these would confer an advantage on a household regardless of the scarcity or abundance of resources, by increasing its wealth relative to other households. A large, unbroken estate will have more land to farm, while a household with more workers will be more productive. This additional wealth could give a household an advantage by increasing its social status and resources.

Part 3: Family Ties

In addition to shaping human reproductive behaviors, Wright explains, evolution has shaped human behavior toward members of their families. In this section, we’ll explore why humans make sacrifices for family members, why siblings compete, and why parents may prioritize one child over another.

Sacrificing for Immediate Family

Wright explains that evolution has created a powerful instinct to make sacrifices for family members, like sharing food or spending time helping or instructing others. This includes not just sacrifices parents make for children, but also sacrifices made for parents, siblings, cousins, or even distant relatives. However, this poses a slight paradox: If evolution rewards those who maximize their own self-interest, what benefit is gained by helping a sibling, cousin, or aunt?

To understand this tendency, Wright argues that we must turn our attention from the reproductive success of the individual to the reproductive success of the gene. A gene that encourages someone to make sacrifices for members of their immediate family would still have a strong chance of spreading, simply because families share the same genes. Therefore, those who benefit from others’ self-sacrificing behavior will also be carrying the gene.

Wright explains that self-sacrificing behaviors change in direct proportion to the amount of shared genes. Someone will be more likely to make sacrifices for a member of their immediate family than a member of their extended family, such as a cousin or uncle. However, they’re still more likely to sacrifice for extended family members than for complete strangers.

(Shortform note: While prioritizing your own family sounds like an unmitigated positive, it can be a double-edged sword. According to some researchers, nepotism—the practice of using power and influence to benefit family members—is a nearly universal problem found across the world. This takes the form of hiring family members for jobs or contracts even when there are more qualified options available. Nepotism has a range of detrimental effects: It deprives an organization of talent, lowers employee trust and morale, and puts incompetent people in positions of responsibility.)

Competition Between Siblings

Wright argues that evolution hasn’t shaped human families to be completely altruistic. Siblings have a strong evolutionary incentive to compete with each other for their parents’ attention. A child’s survival depends on attentive parents, so those who succeeded at monopolizing this resource survived at a higher rate and went on to spread their competitive genes as adults.

Wright explains that this also pits children’s interests against their parents’. Because all children will be equal carriers of their parents’ genes, parents have a strong incentive to get their children to share resources equally rather than compete with each other. Thus, parents the world over try to teach their kids to share—while children compete with their siblings instead.

(Shortform note: Nonhuman species take sibling competition to grim extremes. Some birds will push their siblings out of the nest when food is scarce (facultative siblicide). A small number of species, such as blue-footed boobies, practice “obligate siblicide,” in which siblings will kill each other regardless of the environmental conditions. For sand tiger sharks, this practice begins even before birth, as fetal sharks will cannibalize their siblings in the womb, ensuring that only the strongest among them gets to be born. When humans kill their siblings, it’s called fratricide—it’s not common today, but has been legal or commonplace in some historical contexts, like the medieval Ottoman empire.)

Prioritizing One Child Over Another

Though all children equally carry their parents’ genes, Wright explains that parents may still have an incentive to prioritize one child over another. This is because a parent can maximize the chance of passing on their genes through their children by investing more resources in the child that has the greatest chance of successfully reproducing. Wright argues that this varies by gender, social status, and age.

High-status parents tend to invest more in their sons than their daughters, since as high-status men, they’ll be more likely to attract many partners and pass on their genes. However, low-status families tend to invest more into their daughters, as they have a higher chance of “marrying up” and passing along their parents’ genes with greater resource security.

(Shortform note: Even if it’s “natural” for parents to prefer one child over another, psychologists have found that parental favoritism can have a lifelong detrimental impact on a person’s psychological well-being. One study found that people who perceived that their mother preferred one child over another had higher rates of depression as adults. Surprisingly, this effect was found in both those who felt that their sibling was the favorite and in those who felt that they were the favorite. Those who felt their sibling was the favorite had a lower sense of self-worth. Meanwhile, those who felt they were the favorite often feel distant from their siblings and pressured to live up to high parental expectations.)

Part 4: Social Instincts

In addition to reproducing and caring for family, humans have evolved strong instincts that govern how they behave in society. In this section, we’ll explore friendship, social status, reputation, social norms, and self-deception.

Friendships and Exchange

Wright argues that evolution explains why people form close friendships and help those who are not their immediate relatives. Humans were more likely to pass on their genes if they cultivated alliances that shared resources. This is because sharing resources can be more than a zero sum trade. If one person has a surplus of grapes, then for them, the relative value of each extra grape is low because they already have so many. By exchanging their grapes with someone who has a surplus of meat, both parties gain more value than they lose, providing a powerful survival advantage to both.

In addition to exchanging goods, Wright explains that friends also exchange information. By passing on knowledge about where to find valuable things, or who’s been fighting or sleeping with whom, friendships enable people to mutually improve their chances of survival and reproduction.

(Shortform note: Medical research supports the view that friendship enhances survival, even in environments where resources are abundant. One study found that people with a strong network of friends are 50% less likely to die at any stage of life compared to someone who is socially isolated. Researchers believe that this is not just because of the material advantages of friendship (food and information), but because of the impact friends have on our mental and physical well-being. Spending time with close friends releases oxytocin, a chemical that reduces stress. Chronic stress increases blood pressure and is associated with a wide range of negative health impacts, including heart disease, so by keeping stress levels lower, friendship not only feels good, it extends your life.)

Sensitivity to Unfair Treatment

According to Wright, humans have evolved a keen sensitivity to unfair treatment. This is because people sometimes take advantage of each other in relationships, and there’s an evolutionary benefit to doing so. If one person consistently gives food to another while the other fails to reciprocate, the recipient has a survival advantage over the giver because they have more to eat. Because of this, humans instinctually evaluate contributions to relationships to make sure they’re fair.

That being said, Wright argues that a person’s sense of fairness is heavily biased in their own favor. In other words, our awareness of “fair” and “unfair” relates to how we’re being treated, not our treatment of others—so it’s not as accurate as we might hope.

(Shortform note: Research shows that a sense of fairness develops in early childhood and may be a universal trait. However, what’s considered fair or unfair varies from one culture to the next. For example, fairness could be based on equality (everyone gets the same thing), equity (those with the highest need to get the most), or merit (people are rewarded in proportion to their efforts, talents, or other metrics). Furthermore, while research supports Wright’s view that our sense of fairness is biased in our own favor, this can also change depending on the situation. In one study, this bias was reduced when participants were prompted to be more self-aware by doing a task in front of a mirror.)

Pity and Gratitude

Wright explains that helping others seems altruistic, but it’s motivated by a feeling connected to evolutionary advantage: pity. When someone pities another person who’s in an unfortunate situation, they’re driven to help. The person they help then feels gratitude, which incentivizes them to “pay back” the help in some way. In other words, doing a favor for someone you pity puts them in your debt—helping others isn’t an altruistic act, but rather a long-term investment in a future reward.

(Shortform note: The indebtedness created by gift-giving has historically played an important role in creating social power structures. For example, the Roman Empire used a system called clientship, in which wealthy patrons provided their “clients” with financial support, food, and protection. In return, clients provided their patrons with labor, services, and political support. Clients also greeted their patrons every morning at dawn with a salute. This system was written into law, and clients were allowed to have their own clients too, creating complex chains of hierarchy. According to some historians, Roman clientship laid the foundations for European feudalism in the Middle Ages.)

Social Status

Wright argues that evolution has created a strong tendency to form hierarchies of social status, which are found across cultures and species. Status hierarchies emerge because of two fundamental drives, both of which provide a reproductive advantage.

The first is ambition, a drive for status within one’s group. This presents a reproductive advantage, as people with higher social status have more potential mates and reproduce at higher rates. In most societies, they also have more access to food and other resources useful in raising children. Wright explains that while both men and women have this drive, it’s stronger in men. This is because men have more to gain reproductively by increasing their social status, since their biology places fewer limitations on the number of children they can have.

(Shortform note: While Wright maintains that men are naturally more ambitious than women, some scholars argue that this has more to do with how boys and girls are socialized than with innate biological differences. They argue that young people internalize gender roles from the culture around them, and this shapes their expectations and goals in life. So if young people perceive that politics is a “man’s domain,” then young men will be more likely to cultivate political ambitions growing up than young women, which results in more men than women holding political offices.)

The second drive is deference, the tendency to submit to those with higher status. Wright explains that deference may have provided a reproductive advantage to the submissive individual—it helped them avoid expending energy or sustaining injuries in unwinnable fights.

(Shortform note: While deference can help someone avoid unwinnable fights, it can also lead groups to make poorer decisions. According to communication experts, groupthink takes place when people conceal disagreement to avoid conflicts. This results in leaders making poorer decisions because if everyone defers to their opinion rather than challenging them, they’ll lack important information and perspectives that might have otherwise swayed their judgment.)

According to Wright, all human societies have some form of status hierarchy. However, what determines status varies dramatically between cultures—it could be hunting skill, artistic talent, wealth, or even humility and wisdom. The underlying psychological machinery remains the same: To gain respect, people pursue excellence in the domains their culture values.

(Shortform note: Even if status hierarchies are universal, they can still cause unexpected problems when scaled up to modern societies. In early societies, when hierarchies were small and local, individuals had a much better shot at raising their own status. Now, people live in societies with enormous economic class disparities, and social media allows us to compare ourselves to countless strangers online. This has led many people into a sense of chronic status anxiety: they feel less than others, but raising their own status seems impossible. This chronic status anxiety increases stress and depression, eroding mental health for reasons our ancestors never had to deal with.)

Treating Others Based on Social Status

In addition to seeking social status for themselves, Wright explains that a sense of social hierarchy informs how people treat others and cultivate relationships. Humans are naturally programmed to seek out alliances with higher status individuals, due to their better access to resources and connections. An alliance with a higher status individual, then, can yield better rewards than an alliance with a person of low status.

(Shortform note: Wright’s assertions about humans’ tendency to seek high-status allies are complicated by research into how people choose potential friends. One study found that flashy displays of wealth, such as expensive watches, made someone appear less desirable as a friend than those with more modest brands instead. This may be due to humans’ documented tendency to seek friendships with people who are similar to themselves, including similarity in social status.)

Reputation

Wright explains that humans have evolved a keen concern for their reputation. Broadly defined, reputation is simply what other people think about someone. Having a positive reputation improves someone’s social status in a hierarchy and provides them with more opportunities for friendships, alliances, and romantic partners. As a result, humans devote substantial time and energy to maintaining and improving their reputations. In this section, we’ll explore how concern for reputation encourages people to adopt social norms and maintain a positive perception of themselves, even if it’s based on deceit.

(Shortform note: Researchers have found that reputation awareness may develop in children as young as three. One experiment found that even interacting with an image of watchful eyes was enough to change children’s behavior. Those who saw the image of eyes were found to be more likely to share erasers with a hypothetical “next child to play the game” compared to those who were presented with an image of flowers instead.)

Social Norms

According to Wright, the concern for reputation encourages humans to adapt to their society’s norms. Every group has shared expectations for appropriate behavior, beliefs, and dress. Those who meet those expectations are held in higher regard than those who fall short. So, humans have a strong reputational interest to learn their group’s norms and carefully act in alignment with them.

For example, consider someone who grows up in a strict religious community where people wear plain and modest clothing. To maintain their reputation in the group, they adopt this norm as well, placing greater emphasis on group membership than on wearing flashy or stylish clothes. Wright notes that these norms can vary widely from culture to culture, but the desire to follow norms and remain in good standing is universal.

(Shortform note: Even though conforming to social norms may have provided an evolutionary advantage, it can also leave you deeply unhappy. According to Michael Gervais and Kevin Lake in The First Rule of Mastery, when we conform to others’ expectations, we often fail to pursue our own goals and ambitions. This prevents us from achieving what we truly want in life. Furthermore, by maintaining inauthentic facades to protect our reputations, we can become isolated, because no one will understand us if we don’t show them our true selves. Therefore, by living for others’ expectations instead of living for ourselves, we can end up unfulfilled and lonely.)

Self-Perception

Wright asserts that humans strive not only to enhance their reputation among others, but to maintain a positive perception of themselves, even if it’s embellished or self-deceptive. This is because confidence provides value: Humans who believe in their usefulness advocate more vigorously for their social status and alliances, improving their reproductive potential. Thus, humans are not only hardwired to embellish their positive qualities and disguise their faults, but to believe their own deceptions and act accordingly.

(Shortform note: Psychologists refer to this embellishment as “self-enhancement bias.” This trait commonly manifests in people’s willingness to take full credit for the successes in their lives, while highlighting factors outside of their control when explaining their failures. Furthermore, people are likely to over-estimate their abilities: In one study, 80% of people reported being “above average” drivers, when by definition, only half of them could be.)

Part 5: Implications

Wright argues that an evolutionary understanding of human behavior can transform how we think about ourselves and our world. He highlights two domains that stand to be impacted by this awareness: psychology and ethics.

Psychological Implications

Wright argues that an evolutionary understanding of the human mind will change how we understand psychology. Traditional psychology, influenced by Freud, maintains that problems like insecurity and low-self esteem can be solved by looking inward and reflecting on our childhoods. On the other hand, Wright says these negative emotional states were designed by evolution to spur people into action. Your brain isn’t meant to make you happy, but to make you seek group belonging, social status, survival, and reproductive opportunities. Instead of trying to “solve” insecurity and low self-esteem, Wright argues that you should treat these as drives impelling you toward behaviors that will bring social belonging and personal fulfillment.

Evolution and Mental Health

While Wright argues that insecurity and depression should compel us toward action, some evolutionary psychiatrists argue that the picture is a little more complicated. They explain that these drives were shaped by evolution to handle very specific situations, and that the world we live in is very different today. So, for example, you could spend your life pursuing an unattainable goal if you simply took these drives as a spur to action without also reflecting on the broader situation of your life.

Furthermore, some mental health problems may not actually be adaptive. For example, some psychiatrists argue that it’s a mistake to assume that schizophrenia serves a positive evolutionary purpose. So, there may be limitations on Wright’s advice for reshaping our understanding of psychology in light of evolutionary drives.

Ethical Implications

Wright asserts that an evolutionary perspective complicates our understanding of morality. The traditional perspective holds that moral systems are the product of divine authority, and that “goodness” entails behaving selflessly. Evolutionary psychology provides an alternate view by showing that human morals evolved through natural processes and that they developed to maximize an individual’s “selfish” survival rather than their “selfless” goodness. Therefore, it’s possible to read evolutionary psychology as a license to behave selfishly and dispense with morals altogether.

(Shortform note: We can better understand how an evolutionary perspective might undermine traditional morality by exploring the Christian response to Darwin’s theory of evolution. In The Rise and Triumph of the Modern Self, Carl Trueman explains that God created humanity to fulfill a sacred role in his creation: To live in accordance with Christian moral teachings (including selflessness) and to enact God’s plan for their lives. Therefore, Christianity grounds morality in a sense of mission: You should be good because you were created to do so. However, if humanity wasn’t created to fulfill a special role, then one could argue this fundamental “reason to be good” has been taken away, eroding the basis for morality.)

However, Wright rejects this understanding, arguing that a perspective grounded in evolutionary psychology has the potential to make us more ethical, not less. He cites two ways it can do so: by making us skeptical of our own motives and more compassionate toward others’ failings.

Be Skeptical of Your Motives

Wright argues that an evolutionary perspective can make you more moral by helping you be skeptical about your motivations. He argues that people often overlook the ways that they’re behaving selfishly when they’re convinced that they’re doing something righteous. However, evolutionary psychology teaches us that our minds are designed to trick us into maintaining a positive impression of ourselves, no matter what we do. By keeping this perspective in mind, you can think critically about your motivations and better realize when you’re acting out of selfish evolutionary instincts.

(Shortform note: As you practice being skeptical about your own motivations, keep in mind that answers to the question “Why am I doing this?” can be multiple and changing. Some philosophers argue that people often have multiple reasons for their actions and that pinning them all on one motive could mislead you into overlooking additional motives. Furthermore, neurologists have found that differing motives can still result in the same behavior or decision—so even if your motives change, your behavior might remain the same.)

Wright also cautions that just because a behavior is “instinctive” or shaped by evolution doesn’t necessarily mean that it’s “good.” Recall that our evolved psychological traits were shaped in ancestral environments very different from today’s world. This mismatch can lead to behaviors that made evolutionary sense historically but may be counterproductive now. For example, while a man’s attraction to multiple partners may have provided a reproductive advantage in hunter-gatherer societies, that doesn’t mean that it can’t have a destructive impact on family arrangements that provide stable environments for children.

Furthermore, Wright argues that even if a behavior provides a reproductive advantage, that doesn’t make it morally acceptable. For example, a fertility doctor who defrauds his patients and substitutes his own sperm for that of the intended father may produce more offspring, but that doesn’t make his deception OK.

(Shortform note: The view that your instincts and “natural” inclinations aren’t necessarily useful or good aligns with many traditional religious teachings. In Christianity, the doctrine of “original sin” holds that humans have a universal tendency toward immoral behavior that can only be overcome through instruction and reform. Furthermore, in Buddhism, any desire, if left unchecked, can trap you in a cycle of craving and suffering: You want something that you can’t actually have, and so you spend your days in mental anguish fixating on the thing that you lack. So, even a “natural” desire can cause you great harm.)

Be Compassionate Toward Others’ Failings

Finally, Wright also argues that an evolutionary perspective can make us more compassionate toward others’ failings. Since people’s behaviors are largely determined by instinct, they don’t have nearly as much control over their actions as we might assume. By recognizing that others’ moral failings are the product of widely shared instincts that they didn’t choose, you can more easily view their failings with compassion instead of blame, knowing that their misdeeds aren’t entirely their fault.

(Shortform note: Some neurologists support the view that individuals cannot be blamed for their behavior. In Incognito, David Eagleman argues that our decisions are largely guided by unconscious and automatic parts of our brains, and therefore we lack free will altogether. He asserts that whenever someone does something wrong, rather than blaming them for the harm they’ve caused, we should view them as if they were incapable of acting differently. This leads us to a different set of questions: Instead of asking “how blameworthy is this person, and how should we punish them?” we should ask “What should we do now?” and “How can we repair the harm this person caused and change their behavior?”)