Why we buy what we buy—and how evolutionary psychology explains modern consumerism
In Spent (Penguin, 2010), evolutionary psychologist Geoffrey Miller offers one of the most ambitious—and unsettling—interpretations of modern consumer behavior. He argues that we don’t buy things primarily for comfort, pleasure, or practicality. Rather, we spend money to signal traits—like intelligence, kindness, creativity, or status—that helped our ancestors succeed in mating and social life.
Miller, best known for his earlier work The Mating Mind, applies the logic of sexual selection to shopping malls, lifestyle brands, and online dating profiles. The result is a bold reframing of capitalism: consumerism is not a cultural glitch but a continuation of ancient mating displays, now played out through credit cards and curated wardrobes.
While Spent hasn’t won mainstream literary awards, it has had considerable impact among marketers, psychologists, and behavioral economists. Thinkers like Dan Ariely and Douglas Kenrick have praised it as essential reading for anyone trying to understand modern desires. The book has also been cited in university courses on branding, human behavior, and product design.
Of course, Miller’s thesis is not without criticism. Some argue that he leans too heavily on speculative evolutionary narratives—offering “just-so stories” without enough empirical support. Others note that reducing identity to a bundle of mating signals risks flattening cultural and psychological complexity. Still, few deny that Miller’s framework is thought-provoking and uncomfortably plausible.
Chapter 1 – Darwin Goes to the Mall
Miller opens with a striking thought experiment: what would a Martian anthropologist learn by observing Earth’s shopping malls? Likely, they would be baffled. So many goods—luxury watches, cologne, high heels—seem unrelated to basic survival. But through the lens of sexual selection, it makes perfect sense. These goods are not for survival, but for display. Humans are “signalers,” he explains, and modern products function as status messages embedded in material form.
Miller notes that much of consumer behavior is driven by the need to advertise personal traits to others. As he puts it,
“most consumer behavior is signaling behavior.”
Much like a peacock’s tail, our fashion choices or car brands are costly, visible, and often functionally unnecessary—but evolutionarily useful when it comes to attracting mates and allies.
Chapter 2 – The Genius of Marketing
According to Miller, marketers—though rarely trained in evolutionary science—are some of the most intuitively accurate psychologists in society. They understand what really drives us: the desire to appear sexy, smart, funny, interesting, or virtuous. Rather than inventing new desires, marketing amplifies traits we already value. It packages intelligence in minimalist design, creativity in limited editions, and conscientiousness in sustainable packaging.
Products, he writes, are “symbols we use to explain ourselves to others.”
And marketers are the craftsmen of those symbols, helping us shape narratives about who we are and what we’re worth.
Miller also criticizes academic psychology for ignoring the role of branding in shaping behavior, noting that consumer goods are the most common, vivid, and revealing signals we transmit—but also the least studied by social scientists.
Chapter 3 – Why Marketing Is Central to Culture
Miller extends his argument by asserting that modern consumer culture has replaced traditional systems of identity. Where religion, ethnicity, and social role once gave us meaning, we now rely on brands, hobbies, and media preferences. This is not a glitch in the system—it’s an evolutionary rerouting.
He explains that
“we use consumer products to explain ourselves to each other, just as our ancestors used rituals and body ornaments.”
Brand loyalty functions like tribal affiliation. Ads no longer just sell things—they sell archetypes. The rugged man with the Ford truck. The ironic creative with the MacBook. These aren’t just demographics—they’re curated personas designed for audience approval and mating potential.
Chapter 4 – This Is Your Brain on Money
In this chapter, Miller pivots to behavioral economics and neuroscience, arguing that humans are irrational when it comes to money. We’re wired to respond to emotion, not arithmetic. We suffer from predictable cognitive distortions: we discount the future, segment our spending in illogical ways, and adapt quickly to new comforts.
Using neuroscience research, he shows how shopping lights up the brain’s reward system—particularly the dopamine-driven circuits also involved in food, sex, and addictive substances. It’s not the having, but the act of buying that delivers the psychological high.
As Miller puts it, money is “not just a medium of exchange—it’s a medium of display.”
In other words, we spend less to solve problems than to perform identities.
Chapter 5 – The Fundamental Consumerist Delusion
One of the central myths of consumerism is that buying things makes us happier. Yet, as Miller explains, research in positive psychology shows that material goods produce only short-lived pleasure. What brings long-term well-being are experiences, relationships, and purpose—none of which can be bought directly.
And yet, we keep buying. Why? Because even when goods fail to satisfy us emotionally, they may still succeed socially. They help us appear attractive, interesting, or competent in the eyes of others. That’s the real function.
As Miller puts it, “we are signaling creatures trapped in a hedonic loop.”
We consume not to fulfill our needs, but to advertise our desirability—whether we admit it or not.
Chapter 6 – Flaunting Fitness
Here, Miller revisits Darwin’s theory of sexual selection to explain the kinds of traits we signal. We flaunt signs of youth (via fashion and cosmetics), health (via fitness gear and organic food), and energy (via adventurous travel and lifestyle choices). Even risk-taking itself—driving fast cars or spending lavishly—can signal biological strength and psychological boldness.
Every consumer good, he argues, becomes a channel for evolutionary display.
“Every visible purchase is an ad campaign for your genes,” he writes.
What’s being communicated isn’t always conscious—but it’s legible to others who have evolved to read the signals.
Chapter 7 – Conspicuous Waste, Precision, and Reputation
Building on Thorstein Veblen’s theory of conspicuous consumption, Miller discusses how extravagance and inefficiency become powerful signals. A $200 T-shirt that does nothing more than a $10 one signals abundance. But it also signals discretionary aesthetic taste, brand literacy, and insider knowledge.
Miller also introduces a second form of signaling: precision. When someone buys a handcrafted watch, a tailored suit, or artisan coffee, they’re not just showing wealth—they’re displaying attention to detail, conscientiousness, and taste. He explains that “the more inefficient the signal, the more honest it appears,” because such signals are harder to fake. Waste, in this view, becomes evidence of authenticity.
Chapter 8 – Self-Branding Bodies, Self-Marketing Minds
In the final chapter of Part I, Miller explores how consumer logic has colonized the self. Today, we don’t just buy brands—we become brands. From social media bios to dating profiles to résumé bullet points, we are constantly crafting our own narrative and curating our public image.
As he puts it bluntly, “we are all self-marketing now.” The problem, Miller suggests, isn’t that self-presentation is new—humans have always done it. The issue is the scale, intensity, and artificiality of it. We now perform for vast, anonymous audiences, rather than small, mutual social groups. That leads to insecurity, comparison, and a loss of authentic self-connection.
Miller stops short of offering moral condemnation. Instead, he paints a picture of a species struggling to adapt to a radically new context—with brains built for mating and minds overwhelmed by algorithms.
Chapter 9 – The Central Six
Miller begins by asking a critical question: what traits do people most want to know about one another, especially in mating and friendship contexts? His answer draws from personality psychology and evolutionary theory. The six traits that matter most—because they’re heritable, visible, and socially predictive—are:
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General intelligence
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Openness to experience
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Conscientiousness
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Agreeableness
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Emotional stability
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Extraversion
These traits are attractive because they offer useful information. They predict how someone will behave in relationships, parenting, work, and social life. As Miller puts it, “these are the traits that advertisers should care about—but often ignore.”
Marketers tend to target superficial demographics (age, gender, income), rather than the psychological traits that actually drive preference, signaling, and loyalty. The rest of Part II examines each of these traits in depth.
Chapter 10 – Traits That Consumers Flaunt and Marketers Ignore
Here, Miller makes a surprising claim: consumers do try to signal these six traits—but often through roundabout means. We choose brands and experiences not just because they reflect who we are, but because they project a version of who we want to appear to be.
Yet marketers rarely understand these signals in depth. Instead of engaging with consumers’ desire to display intelligence or agreeableness, most branding efforts focus on aspirational fantasy or lifestyle archetypes.
Miller sees this as a missed opportunity. He suggests that the future of marketing lies in designing products that authentically reflect underlying personality traits—not just class status or trendiness.
Chapter 11 – General Intelligence
Intelligence, or “g,” is perhaps the most central human trait when it comes to signaling value. It predicts educational attainment, job success, social fluency, and creative problem-solving. In ancestral terms, it was a reliable indicator of fitness, adaptability, and parenting ability.
According to Miller, we use a wide range of cultural consumption to broadcast intelligence:
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Reading literary novels
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Listening to complex music
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Attending lectures or buying science-branded media
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Preferring minimalist, tech-savvy design
He notes that many brands—like Apple, NPR, or Tesla—subtly frame themselves as intelligence enhancers or intelligence indicators. A MacBook is not just a laptop; it’s a claim about the user’s cognitive style.
“The most prestigious brands,” he explains, “often serve as IQ tests in disguise.”
Chapter 12 – Openness to Experience
Openness is linked to creativity, aesthetic sensitivity, and cultural curiosity. It predicts preferences for abstract art, jazz, surreal cinema, travel, and innovation. In consumer behavior, it shows up in the pursuit of novelty, authenticity, and cultural fluency.
Consumers high in openness tend to value brands that reflect uniqueness, experimentation, or identity exploration. Miller cites examples like boutique fashion, global cuisine, and niche streaming content. These aren’t random interests—they’re curated signals of intellectual depth and originality.
He also observes that openness tends to correlate with liberal politics, environmentalism, and social progressivism—which themselves become consumer identities. As he writes,
“Openness has become a lifestyle, complete with its own aesthetics, ethics, and brands.”
Chapter 13 – Conscientiousness
Conscientiousness is about reliability, orderliness, and long-term planning. It’s one of the strongest predictors of job performance, health outcomes, and relationship stability—yet it’s hard to market.
Why? Because conscientiousness is inward-facing. It’s harder to flaunt than charisma or cleverness. Miller notes that consumers signal it indirectly—through clean design, punctuality-oriented tech (like calendar apps), or personal finance tools. Hybrid cars, insurance plans, and self-help books are also conscientiousness cues, especially among older or more conservative consumers.
Yet because conscientious consumers tend to avoid waste and impulse buying, they’re less attractive to marketers—which is one reason this trait is under-represented in aspirational branding.
Chapter 14 – Agreeableness
Agreeableness reflects empathy, kindness, trustworthiness, and emotional warmth. It’s highly valued in both long-term mates and close friends. Miller explains that consumers try to signal agreeableness through ethical consumption:
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Buying fair-trade products
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Donating to visible causes
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Shopping from mission-driven brands
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Avoiding companies with unethical reputations
But he also critiques how easily agreeableness is co-opted by marketing manipulation. As he puts it,
“what began as sincere signals of conscience quickly become competitive displays.”
Greenwashing, cause branding, and performative activism dilute genuine signals of moral integrity—yet the demand to display agreeableness remains strong.
Chapter 15 – The Centrifugal Soul
In this more reflective chapter, Miller explores how the self becomes fragmented under consumer capitalism. Rather than growing inward through experiences and introspection, modern identity becomes centrifugal—thrown outward into the market for validation.
He warns that we risk becoming “a résumé of logos,” confusing branded selves with real selves.
“We mistake the surface signals for the deep traits,” he writes, “and then wonder why we feel alienated.”
What emerges is not a stable personality, but a reactive, performative identity—constantly curated, optimized, and vulnerable to the shifting norms of trend cycles and audience metrics.
Chapter 16 – The Will to Display
Here, Miller addresses a sobering truth: the desire to display is universal and inescapable. We evolved as social animals who must be seen, assessed, and chosen. Displaying traits—through speech, behavior, dress, or goods—is not a modern invention. It’s who we are.
But what matters, Miller argues, is how we display. Are our signals honest, skillful, and valuable to others? Or are they shallow, automated, and market-dependent?
He challenges readers to examine the quality of their signaling: are you displaying traits that matter to you—or those you’ve been taught to believe matter?
Chapter 17 – Legalizing Freedom
In his final chapter, Miller offers a modest proposal: to reclaim freedom of self-expression from the forces of branding. He advocates for:
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More transparent product labeling about social and psychological effects
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Stronger education in signaling literacy (especially in schools)
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And non-market spaces where people can display traits through art, service, skill, or direct interaction
He ends on a hopeful note: human beings are not doomed to hollow self-performance. We can, if we choose, build cultures that support authentic expression—and even design products that help us become who we are, rather than who others want us to seem.
Final Reflections
Taken together, Parts I and II of Spent offer a deeply original and challenging framework for understanding consumer life. Geoffrey Miller’s core claim—that we shop to signal—cuts through both economic orthodoxy and cultural critique. He neither defends capitalism nor condemns it. Instead, he tries to explain it: as the latest evolution of human display behavior, shaped by millions of years of mating psychology, social cognition, and tribal signaling.
What we buy, he argues, is never just about function. It’s about what we’re saying—to others, and to ourselves. Whether it’s a luxury car, a minimalist phone, a meditation app, or an ethically sourced T-shirt, each purchase is a story about who we are, or who we want others to believe we are.
As Miller writes, “consumer capitalism didn’t hijack our instincts—it gave them a new stage.” But that stage, for many, is not always easy to stand on. Which leads to a question for reflection and conversation:
Can you remember a time when money or consumption felt emotionally painful or identity-shaking for you? What was the situation—and how did you respond or recover?
Feel free to share your thoughts in the room—or leave a comment below.