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Sex, Murder and the Meaning of Life by Douglas T. Kenrick

Good and very interesting book that I learned a lot from.

The author is a professor of psychology at Arizona St. University where he studied under the famous psychologist known for his best-selling book Influence, Robert Cialdini.

Douglas' work integrates evolutionary psychology and cognitive science which he incorporates a lot in this book. This book also got some nice blurbs on the back from some very well-known authors and psychologists including Dan Ariely, Steven Pinker, and Daniel Gilbert.

This book is mostly about mating and how our minds - from a female and male perspective - choose our partners. It incorporates a lot of evolutionary psychology and the thought process that our minds go through in choosing our partners.

There are big differences in how a male and a female choose a partner that relate to risk and reward. A male obviously doesn't bear nearly as high a cost as a female does from pregnancy, so this puts a lot higher cost on women who are promiscuous, and this shows up in how females and males attract mates.

One major difference that reflects this cost is that the woman carries the baby in her body if a sperm fertilizes her egg. This demonstrates one of a couple big reasons why women are much choosier than men in choosing mates and sleeping around, meanwhile, males are a lot less choosy in who they sleep with and select as a mate.

A lot of these costs vs. reward tradeoffs and how our bodies function had a large reflection on how humans decide who to mate with.

Douglas goes into a lot more detail on this and other factors in this book.


Work from my lab reveals that we are all multiple personalities; that is, each one of us can shift among several different subselves, each capable of adaptively changing the way we think and behave, to negotiate the qualitatively different threats and opportunities that pop up in seven key domains of social life. I have dubbed those subselves the team player (concerned with the goal of making friends), the go-getter (concerned with getting ahead), the night watchman (concerned with protecting us from the bad guys), the compulsive (concerned with protecting us from disease), the singing single (concerned with finding mates), the good spouse (concerned with the very different problem of keeping those mates), and the parent (concerned with taking care of our kin, especially any children we might have).

Amazingly, all the complexities of human society – religious and political movements, economic markets, and more – emerge out of the dynamic interaction of the simple rules operating inside individual people’s heads.

We have considered questions such as: Why are old men attracted to much younger women? Why are older women not drawn to young men in the same way? Why does a woman’s commitment to her partner drop after seeing a powerful executive, regardless of whether he is good-looking or not, whereas a man’s commitment is shaken by good-looking women regardless of their social status?

Men looking at our simulated crowds lingered almost twice as long on beautiful women as on average-looking women. When we showed them groups of photos later, the men were especially accurate at saying whether they did or did not se a particular pretty woman. When it comes to crowds of men, on the other hand, men did not gaze any longer at the George Clooney types than at the Joe Schmoes. And later on, guys were not especially good at picking handsome men out of a lineup. These findings all fit well with a traditional assumption about attention and memory: The more you attend to someone or something, the more likely you are to remember that person or thing later. But women violated that assumption in an interesting way. The female subjects in our study, like the male ones, spent more time looking at beautiful women, and they were also good at remembering whether or not they had seen a particular female beauty before. Unlike men, though, they looked selectively at the handsome George Clooney types when presented with a crowd of men. That part was not too surprising, but what happened later was: Women were unable to remember those good-looking guys they had been staring at. This was unexpected, given that there is usually a simple linear connection between attention and memory – the more you look at someone, the more you remember them.

The whole body of findings points to a simple conclusion about [the effect] of a beautiful woman [on men]: They capture everyone’s attention and monopolize down-stream cognitive processes. The conclusion about handsome men is different: they grab women’s eyes but do not hold their minds; good-looking guys quickly get washed out of the stream of mental processing. This discrepancy is consistent with men’s and women’s different mating strategies; women are more selective and less interested in casual affairs with strangers.

Exposure to extremes of physical appearance affected people’s judgement of what was average. As we had predicted, an average-looking woman was judged significantly uglier than normal if the subjects had just been gazing at a series of beauties.

[Men’s] exposure to beautiful women changes people’s adaption level for what they consider beautiful. The harmful side effect for guys like my neighbor Dave is this: Real women, the kind he could have dated, do not look as attractive once the mind has been calibrated to assume that centerfolds are normal. And for guys in relationships, exposure to beautiful photos undermines their feelings about the real flesh-and-blood women with whom their lives are actually intertwined.

Men who had been bombarded with socially dominant men felt that they themselves were less desirable as marriage partners; women who had been bombarded with physically attractive women downgraded their own marriage prospects.

The link between a man’s status and his value on the mating market connects to two of the most important principles in evolutionary biology: sexual selection and differential parental investment. According to the principle of differential parental investment, when one sex (usually the female) invests more in the offspring, members of that sex will be more careful about mating. As a consequence, members of the other sex (usually the male) will need to compete to be chosen.

The process through which males are chosen is known as sexual selection. To win the attentions of selective females, male animals can do one of several things. They can display positive characteristics, as when a peacock displays his extravagant tail. They can find and control a resource-rich territory. Or they can beat out the competition directly – by fighting their way to the top of the local dominance hierarchy. Whether the game is defending a territory or winning a place at the top of the hierarchy, it helps to be larger and more aggressive.

So the bottom line of this series of studies is this: Either status or mating motives can lead men tow ant to be directly aggressive. But men seem to realize that violence itself is not sexy to women. Hence, a man in a mating frame of mind is inclined to behave himself in front of women but to be especially prone to show off his aggressive reactions if the audience is made up of other men. To the question about why men fight in bars even when there are no women to impress, the answer is that the show is in fact for the other guys – it is a gambit to hold onto one’s position in the male dominance hierarchy, not to win love directly. Indeed, in many other species, the males arrive at the mating area several weeks before the females and do all their headbanging before the females arrive. The females do not need to see the fight. They merely want to know who won.

Our brains allocate cognitive resources functionally – the mind frees up space to pay special attention to other people who might be especially pertinent to our survival or reproductive process.

Defense mechanisms – tools we use to protect ourselves from anxiety. If some unpleasant memory is upsetting to you for example, you can defend your ego by repressing it from consciousness or by denying that the unpleasant even ever happened.

The question is not what sound good to us but what actually causes humans to do the things they do.

To the extent men tend to accumulate social status and resources with age, women would be expected to prefer old men.

Women were looking for somewhat older men and this general pattern persisted throughout their lives. We were actually surprised to find that the preference for slightly older men even persisted among women in their sixties, when there are a lot fewer older men to choose form.

Because women contribute their own bodily resources to the offspring, men are seeking cues linked to fertility and health. Because men contribute indirect resources to the offspring, women are seeing cues linked to the ability to acquire those resources. Men’s resource acquisition and women’s fertility are correlated with age, but age itself is not the driving force.

Despite the abundant cultural differences apparent in these Indian marital ads, we nevertheless found the same pattern of sex differences we had found in North American and European samples. When an Indian woman’s relatives advertised to find her a husband, they asked for a slightly older man regardless of her age. As Indian men aged, their relatives sought women who, relative to the men, were progressively younger and younger.

The human brain does not use the same set of rules to make decisions about different people in our lives. Indeed, it may even be a mistake to talk about “the brain” as if it were one organ, somehow encompassing our tightly unified self. Instead, it makes more sense to imagine that each of us has a loose confederacy of subselves inside our head, each controlled by a different combination of neural hardware and software.

There is another very influential domain-general theory of human relationships. Social psychologists call it economic-exchange theory, and it is a simple extension of what economists call utility theory, or as the theory of rational man. According to this approach, we are more calculating and rational in approaching our relationships. On this model, all human beings think about relationships in the same way that stockbrokers think about financial transactions – we buy in when it looks as if we will make a profit and sell if it looks as if we will take a loss. Whether we are thinking about friends, relative, lovers, coworkers, or strangers, the general assumption is that we seek to optimize the ratio of costs to benefits.

When you are under the influence of a different fundamental motive, such as mating or self-protection, you are a different person – you notice different things and you remember different things, and that leads you to respond differently to the same situation.

Here is a list of separate characters that I think you and I have running around inside our heads, and what set of problems or opportunities each of those subselves is in charge of managing: the team player, the go-getter, the night watchman, the compulsive, the swinging single, the good spouse and the parent. At any given moment of consciousness, only one of the subselves is running the show.

Maslow’s hierarchy of human motives (Highest need to lowest need): Immediate physiological needs, safety, love, esteem, self actualization.

Probably the biggest problem with Maslow’s pyramid is this: He did not understand the central importance of reproduction to human life.

Maslow pyramid also had another basic problem in its blueprint. He believes that the motives at the top of the hierarchy are somehow disconnected from biology. I face, he later called the lower needs “deficiency needs” – linking them to basic biological processes that keep us alive by avoiding starvation, bodily harm, and being cast out of our social groups.

The authors updated hierarchy of fundamental human motives (from highest need to lowest): Immediate physiological needs, self-protection, affiliation, status/esteem, mate acquisition, mate retention, and parenting.

The three important differences between our new hierarchy and the old one. First, self actualization is displaced from its hallowed position at the top of the pyramid Second, there are now three new motives at the top of the hierarchy, all linked to reproduction, and three, rather than stacking the goals on top of one another, the goals in the new hierarchy are overlapping. This graphic twist is meant to capture another important point: The high needs develop later, but they do not replace the lower ones.

So why do we need love, esteem, pizza, and personal fulfillment? Let us first try to answer that question in terms of evolutionary function. At one level, everything any animal does is the product of mechanisms that enhanced what biologist call inclusive fitness (as I described earlier, that term refers to success at assisting one’s genes on their trip into the future).

Research by Arne Ohman and his colleagues has shown that the fear system, designed to rapidly respond to threats, comes preequipped with some of its own adaptively tuned wiring, just as the hunger system does. For example, it is difficult to condition a fear response to flowers or abstract paintings, but it is very easy to learn to fear a dog or a snake.

There is one point on which Maslow, Freud, and Skinner agreed: that people are usually unaware of the underlying causes of their behavior. O this point, I will join the chorus. Remember the birds that migrate when the days start getting shorter; they have no idea of the connection between their urge for going and how it links up to finding food, nesting sites, and their ultimate reproductive success. Likewise, although people are good at making up explanations for their behaviors, we certainly do not consciously experience the links between those behaviors and their ultimate functional goals. At the functional level, though, everything we do is intimately linked together. Eating, drinking, and staying out of dangerous neighborhoods at night serve the higher goal of surviving long enough to make. Playing nice with others and striving for their respect serve the higher goal of finding mates, and trying to stay together with those mates serve the higher goal of having children. Taking care of the children serves the higher goal of increasing our inclusive fitness. Those connections are not conscious and they do not need to be, any more than the connections among day length, migration, and inclusive fitness are conscious in a scarlet tanager.

[The details that] we notice and remember and which ones we distort depends on what is most functionally relevant to the subself currently in control. Although we have only one motivational subself in the cockpit of consciousness at any moment, the others have their radar systems running in the background.

Women – although they will spend time looking at good-looking men – do not remember them very well later, whereas men looking at attractive women do remember them. We think that sex difference in memory is linked to men’s and women’s different mating strategies: A man can in theory reap more reproductive profits and pay lower costs from having a relationship with an attractive stranger; a woman needs to make an informed decision. Perhaps staring at a handsome stranger increases the odds he will introduce himself. But if he does not, a woman is not likely to chase after him or even to waste cognitive resources thinking about him.

Our brains seem to allocate resources in ways designed to best promote survival and reproduction.

“Is there something you wish you had done differently?” When it came to their parents and to their school careers, both men and women had about twice as many regrets over inactions, things that they should have done but did not, than over actions, things they actually did but wished they had not. When it came to romantic relationships, though, men and women were very different. Women were much more likely than men to have regrets over things they had done (getting involved with that self-centered bastard despite Mom’s warnings, for example). The vast majority of men’s regrets over relationships, on the other hand, were about actions they did not take (a time they did not get more intimately involved with some desire damsel). From an evolutionary perspective, this makes a lot of sense: Men incline a bit more toward promiscuity, and women to careful choice. When women make a bad romantic choice, they remember. And perhaps by remember, they will do a better job of avoiding those mistakes in the future.

We have seen that what is in [our minds] is not a blank slate and not a blueprint but a coloring book, with some guidelines drawn before birth and some spaces awaiting the artistic inputs of life experience. And we have seen that there is not just one executive self inside our heads but sets of sometimes segregated subselves, each designed to perform different essential tasks, such as watching out for bad guys from other neighborhoods, getting along with our neighbors, and taking care of our families. Those different subselves come on line at different phases of our life’s journey, and they take turns in the driver’s seat, depending on the threats and opportunities in the current landscape.​

Although evolution is often mistakenly dubbed “survival of the fittest,” the name of the game in evolution is not survival but reproduction. To be fit in an evolutionary sense, an animal needs to survive long enough to reproduce. But survival without reproduction does not enhance fitness. A celibate life, no matter how long, does not contribute genes to future generations. On the other hand, an animal that lives fast, attracts mates, and has offspring is an evolutionary success story even if it dies young. Sexual selection comes in two flavors. Some traits (such as a peacock’s tail) enhance an animal’s fitness by attracting members of the opposite sex. Other traits (like antlers or horns) may enhance fitness via an indirect route: by helping the animal compete with members of its own sex.

Recall that whenever one animal makes a relatively higher investment in the offspring, that animal tends to be relatively choosy about mating. Females have an intrinsically high investment because they produce eggs and, in the case of mammals, carry the growing young inside their bodies and later nurse them. Males can, in theory and often in practice, make a very small direct investment in the offspring – the energy it takes to produce sperm. Hence, females are more likely to be choosy about mating, and males are more likely to show off.

The results were clear for women judging men: when the target acted dominant rather than submissive, our female judges rated him as more sexually attractive and desirable. How did men react when a woman acted dominant? According to one theory popular at the time, which claimed that women avoid acting dominant because they fear it will make them unattractive and masculine, acting dominant should have hurt. But whether the woman was dominant or submissive actually made no difference to her attractiveness. In three other studies, we used different methods to make the target appear dominant (being a tennis player who dominated opponents, or being rated by a team of psychologists as powerful, commanding, and masterful). In each case, we replicated the original pattern. Dominance never had an effect on a woman’s attractiveness, but it reliably made a man significantly sexier to women.

A male can stand out by being physically dominant over other males, like an alpha chimpanzee, or he can demonstrate his superior qualities to females in other ways, peacock styles…. Jill Sundie, marketing professor at the University of Texas, suspected that the pursuit of money – and the visible spending of it – has something in common with a peacock growing an elaborate tail.

One of the characteristics of great artists like Picasso is that they are constantly trying to break with tradition, striving not merely to paint or write well but to paint or write in some radically new way.

As we had predicted, fear led both men and women to conform more to the group’s opinion. (This result fits with numerous findings that animals and humans pull together under threat.) But romantic motives had different effects on men and women. Romantic mood, like fear, boosted women’s conformity. But for men, a romantic mood inspired them to stand against the group’s opinion. Furthermore, they did so in a very strategic way. Romantically motivated men only went against the group opinion when doing so could make them look good, by expressing a uniquely positive opinion when the group had been negative (Ah, but I disagree; I can see the beauty in that). And in a later study, we found that romance inspired men to go against a group only on subjective judgements, for which there is no objective right or wrong answer (Do you prefer paintings by Vincent van Gogh or Claude Monet?). When there was a clearly correct answer, and they could be proved wrong (Is it more expensive to live in New York or San Francisco?) men went along with the consensus. So again, we see that mating motives inspire men to show off in another way: By selectively demonstrating their independence from group opinion, particularly when they can do so in ways that make them look uniquely good rather than oddly different.

Women prefer to mate with men who stand out from the crowd… And for men, as for males of other species, showing off is expensive. Conspicuous consumption is literally paying money to get noticed. Dedicating years to becoming a creative artist, as Picasso and Rivera did, can involved periods without food on the table.

“Loss aversion” – the finding that people are more psychologically moved by a loss of $100 than by a gain of an identical amount. To a rational economic mind, $100 is worth exactly $100. But Kahneman won a Nobel Prize for a body of work illustrating that this seemingly simple and rational equation ain’t necessarily so. Along with Tversky, Kahneman demonstrated in various experiments that losing $100 has more psychological impact than gaining $100 and that the typical human will pay more to ensure that he or she will not lose $100 than he or she will pay for an equal chance of getting another $100.

The human mind is not a massive information-crunching computer but a multitude of miniminds, a collection of independent mental adaptions specifically designed to solve particular adaptive problems by crunching different kinds of information in very different ways. This has important implications for economic decision-making; what counts as a good decision about allocating resources to solve one problem may count as a very bad decision for solving another problem.

For example, if people are given an abundant budget of “mate dollars,” both men and women choose similar partners: They want someone who is physically attractive, funny, warm, and high status. But most of us are not like a wealthy movie actor who can “have it all”; instead, we have to prioritize. When men are put on a more limited budget of mate dollars, they spend first on physical attractiveness, indicating that that is a high priority. Women on a limited budget make different choices, placing higher priority on getting a partner with sufficient wealth or status and treating good looks as an expendable luxury.

There has been so much research on loss aversion that we can say with some certainty that people are impacted twice as much by losses as they are by gains.

Evolutionary theorists, including E.O. Wilson, have suggested a possible answer to the why [are we impacted much more by losses than gains] question: Ancestral humans would have survived better if they put a higher priority on avoiding losses than on acquiring gains because they frequently lived close to the margin of survival (extra food would be nice, but insufficient food could mean death). Consistent with this idea, loss aversion has been found not only in humans but also in other species (whose ancestors, like ours, would have suffered more from falling below the line of subsistence than they would have profited from an overabundance of resources).

As Bert Holldoebler and E.O. Wilson point out in their book Superorganism, for instance, ants have tiny brains with only a small array of simple instinctive decision rules, and yet they are able to construct complex societies with flexibly organized castes dividing up labor, solving diverse environmental challenges, and constructing architecturally brilliant living structures. And as Sean Carroll points out in his book Endless Forms Most Beautiful, genetic researchers have ben surprised to find many fewer genes than they expected and to discover that the vast majority of them are shared across species as widely separated as cockroaches and human beings. For example, the very same gene that governs the development of an insect’s six legs is the one that governs the development of our four limbs. Slight changes arising from the interaction of different genes, however, have profound and complicated consequences.

Biological anthropologists Rob Boyd, Peter Richerson, and Joe Henrich have gathered plenty of evidence that human beings are chock-full of conformity mechanisms, which usually serve us quite well (for example, you can randomly try out different leaves and roots for lunch and perhaps die experimenting, or you can eat the ones your neighbors are eating and survive). Psychologists Tanya Chartrand and John Bragh have found that our inclination to imitate other people is automatic and usually unconscious (if you are talking to someone who tends to shake her foot and scratch her eyebrow, you will start shaking your foot and scratching your eyebrow too, without even being aware of it).

If you want to understand how social complexity arises among humans, you cannot just assume we are like interchangeable ants and that the outcome will depend on random general processes that apply equally to any dynamical system. You have to realize that the outcomes will be powerfully influenced by the particular decision biases that mark our species and that those decision biases are very different depending on which social domain we are currently considering.

Individual human beings have different kinds of decision biases that we carry into each of the different domains of social life. Those biases are not only important in influencing what happens between pairs of people, but they drastically influence the larger web of social life, shaping different social geometries for our different relationships and doing so in patterned and functional ways.

It is to say that broad-scale cultural, historical, and economic patterns emerge from the decisions of individuals. Most fascinating about this worldview is that it implies there is no Big Brother, no central decision-maker running the show. The emergent aggregate is more powerful and immensely more complex than any single individual. The military-industrial complex, the world economy, public opinion, and modern society is us. The reason it does not seem like it down here is that human society is in some ways like a giant ant colony: a product of many little brains making many little decisions in response to narrow local inputs.

When I was a thirteen-year-old punk hanging around with the Forty-sixth Street Boys, my first priority was status and acceptance; when I was a long-haired college student, my first priority was finding women who would sleep with me; and now as someone approaching eligibility for Social Security, my first priority is helping my children.

Selfish genes do not necessarily produce selfish people. It is true that our minds are equipped with a host of simple selfish mechanisms that incline us to make decisions promoting our individual reproductive success. But in our ultrasocial species, the goal of reproductive success. But in our ultrasocial species, the goal of reproductive success is often achieved by being nice to others.

Whatever else has been going on in my life, my children’s needs have always trumped all other demands. As I began to think about it, I realized that all this research on people’s simple and selfish biases really did have something to say about how to live a more meaningful life. Unlike many of the other things I have done to seek pleasure, the time I’ve spent with either of my sons has never given me the slightest hangover of regret.

Human beings are ultimately designed not to seek ecstatic happiness from dawn to dusk but to be linked into a supportive web with other human beings. Indeed, two of the bedrock principles of evolutionary biology are kin selection and reciprocal altruism. The first explains why we are driven to take care of our family members; the second clarifies why we often go to such great lengths to do favors for our friends and coworkers.

But I will tell you about the worst piece of advice I heard in my life. I heard it when I was moving toward a divorce from my first wife: “You’ve got to do what’s right for you.” I heard it again and again from different people, and even at the time I wondered how doing what was right for me could also be right for my young son. Like many others before and since, I learned the hard way that the mantra should have been “You’ve got to do what’s right for those you love.”

Their research suggests that, although family members and friends can often be demanding and annoying on a moment-to-moment basis, people who spend time doing nice things for their loved ones are ultimately less depressed and more fulfilled in their own personal lives. My favorite positive psychology study is one published in Science by Li Dunn and her colleagues at UBC. They found that people who spent their salary bonuses on other people were happier than those who spent it on themselves.

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