Dollars and Sex

Have you ever wondered why you fall for certain people, why some marriages succeed while others crumble, or why dating feels so transactional these days? In Dollars and Sex, economist Marina Adshade argues that love, lust, and relationships can’t be fully understood without considering the invisible hand of economics. She contends that every romantic decision—who we sleep with, when we marry, whether we stay faithful—is ultimately driven by costs, benefits, and opportunity costs shaped by education, income, and technology.

Adshade’s bold claim is that sexual behavior obeys economic laws as much as commerce does. Economic conditions, from industrialization to student debt to gender wage gaps, have transformed how we approach love. If economics can explain why people buy houses or negotiate salaries, it can also explain why women marry older men, why men send flirtatious messages online, and why birth control changed not just sex but society. The book integrates personal stories, historical examples, and an impressive body of research to show how markets for sex and love evolve alongside broader macroeconomic shifts.

The Core Economic Argument

At the heart of Adshade’s argument lies a simple economic framework: individuals make rational choices about love and sex based on expected costs and benefits. These include the chances of pregnancy, STD infections, social stigma, and lost education or career opportunities—each of which changes as societies grow wealthier or more educated. When the cost of premarital sex dropped thanks to safe contraceptives in the mid-twentieth century, the public’s behavior adjusted accordingly. Likewise, when education became critical for earning power, young people delayed marriage and sex became less about reproduction and more about recreational connection.

From Markets to Marriage

Adshade treats love as a market, complete with supply, demand, and price. On this market, attractive, smart, or high-earning individuals command higher value. Online dating platforms make this market visible and, by reducing search costs, create thicker markets—meaning more participants and better matches. She expands this logic to marriage, arguing that couples specialize based on comparative advantage just like trading nations. Historically, men specialized in market labor while women undertook domestic production; economic shifts and technology eroded those divisions, forcing households to renegotiate power and roles.

How Macroeconomic Variables Shape Intimacy

Adshade’s blend of macroeconomics and micro behavior is what makes her perspective unique. Industrialization encouraged monogamy by changing women’s economic value, while urbanization fostered single living and casual sex through denser markets. Education widened gender imbalances on university campuses and altered dating dynamics—creating intense competition among well-educated women and influencing men’s behavior. Even recessions and booms affect marriages by shifting financial stress and bargaining within households.

Why This Matters

Understanding sex through economics isn’t cold or mechanical—it’s empowering. When you realize that love operates under market conditions, you can consciously change how you negotiate relationships. You can identify economic biases that affect your choices, such as how income inequality fosters divorce or why education makes some women delay childbearing. This lens clarifies that sexual freedom and romantic happiness are not random—they respond to prices, incentives, and expectations in predictable ways.

Across nine chapters, Adshade builds a compelling mosaic: from the economics of contraception and student hooking up, to online dating markets, household bargaining, teenage sexuality, and late-life love. Ultimately, she shows that romance isn’t irrational at all—it’s economics in action, influenced by technology, wealth, and policy. Whether we’re sexting, marrying, divorcing, or staying single, our hearts often follow the money, even when we don’t realize it.

Adshade begins with what seems a simple question: “Should I have sex tonight?” It’s the same cost-benefit analysis people perform for any decision. The answer depends on risk—pregnancy, disease, or reputation—against the reward of pleasure and intimacy. As contraceptive technology evolved, those risks declined and global behavior changed. In 1900, only 6% of unmarried 19-year-old women were sexually active; a century later, 75% were. The pill made sex safer but also reshaped culture, because when costs fall, demand rises.

The Price of Promiscuity

Sex, Adshade insists, is never free. Economically, its "price" includes both tangible and intangible costs—reputation, health, missed education, and future income. A poor woman facing low marriage prospects, for example, faces little opportunity cost from an unplanned pregnancy. A wealthier or educated woman, on the other hand, risks career losses, social stigma, or reduced earning power. Thus, promiscuity is rational among the economically marginal, because they have less to lose.

Why Birth Control Didn’t Lower Out-of-Wedlock Births

The paradox of rising illegitimacy despite better contraception makes sense through economics. When more people have premarital sex, even small failure rates lead to more pregnancies. Adshade’s insight echoes economist Jeremy Greenwood’s work: technology lowered pregnancy risk and reduced stigma, encouraging more sex. Over time, cultural norms followed, erasing taboos and increasing single motherhood. In purely numerical terms, the spread of contraceptives inevitably raised total births outside marriage simply by expanding the population of sexually active women.

Income and Opportunity Costs

A person’s income, education level, and realistic chance of marriage define their opportunity costs of sex. Low-skilled individuals, destined for stagnant wages, have little to lose; their decision calculus favors short-term pleasure. For educated people aiming for professional success, those opportunity costs are high, leading to delayed sexual involvement or careful contraception use. This logic also explains persistent differences in teen pregnancy rates between the U.S. and Europe—American college costs are higher, creating pessimism among low-income teens and encouraging risky sex.

In Adshade’s world, moral behavior isn’t moralistic—it’s adaptive. When circumstances make careful behavior valuable, people adjust. Economies that educate women and raise wages for skilled labor, therefore, indirectly change sexual norms. Sexual freedom expands when technology and wealth make risk less costly; restraint grows when investment in education raises opportunity costs. Sex, like any transaction, follows the economics of incentives.

College campuses, Adshade argues, are perfect mini-economies. They show how sexual markets react to gender ratios, opportunity costs, and alcohol prices. Her story of Sarah—a freshman who gets pregnant after drunken sex—illustrates what happens when too many women chase too few men. On campuses where women outnumber men, the price of sex falls and casual hookups replace traditional dating. Men face less competition and acquire market power, while women lose bargaining leverage.

Supply, Demand, and Sex Ratios

Universities with high female-to-male ratios flip mating norms upside down. Women on these campuses report less happiness with dating, more casual sex, and lower rates of virginity. Sociologists Jeremy Uecker and Mark Regnerus found that every percentage point increase in female representation raises the odds of hooking up. In a competitive market, scarcity favors the buyer. Men can demand sex sooner and commit less often, because women fear losing scarce partners.

The Cost of a Jägerbomb

Adshade’s economic lens extends even to the price of booze. Lower drink prices increase both binge drinking and risky sex, while campus prohibitions ironically intensify danger by pushing underage students to drink privately. Experiments show that higher liquor taxes correlate with fewer STDs and unwanted pregnancies. In essence, the cost of alcohol moderates sexual decision making. Yet in student economies, delayed gratification is rare—students consume time and money as if borrowing against future income. That impatience makes them less responsive to price signals.

Why Women Feel Obliged After Dates

Studies cited by Adshade show an uncomfortable truth: both genders subconsciously equate monetary spending with sexual obligation. Male students believe expensive dates merit sex; women reject that claim but admit the expectation rises with cost. This implicit contract reveals the commodification of intimacy—even when money isn’t exchanged directly. Adshade’s classroom experiment shows that men ask, “How expensive were the drinks?” before deciding if sex counts as transactional. Economics infiltrates morality; perceived investment converts into entitlement.

Universities demonstrate how economic imbalance—excess supply of women, cheap alcohol, and shifting incentives—reshapes culture. It creates a buyer’s market for men, undermines negotiation, and transforms sex into a transaction where emotional satisfaction declines. The hook-up culture, through Adshade’s lens, isn’t moral decay. It’s simple market logic.

If you’ve ever swiped left too quickly, you’ve felt what economist Marina Adshade calls the “choice overload” problem. Online dating creates vast, thick markets—so thick that people simplify decisions by filtering potential mates into narrow categories. The result? People eliminate promising partners before ever meeting them. Searching for love online is like browsing a pastry shop: you can’t taste everything, so you use categories to simplify—age, income, height, race. In doing so, you often miss the treat you’d truly enjoy.

How Markets Sort Lovers

Online dating is a textbook example of a market seeking equilibrium. Attractive, wealthy, or educated individuals command a high “price” and match with similar partners—what economists call assortative mating. Studies from Columbia University’s speed-dating experiments show that women strongly prefer same-race, well-educated men; men are less selective about race but value beauty heavily. On websites, men send many first-contact messages (“shotgun” approach), while women send far fewer but aim higher. The outcome is predictable: people mostly date within their league.

Signaling and Value

Economic signaling theory explains how daters communicate quality. Attaching a virtual rose to a message—an option some platforms test—raises acceptance rates by 20%. Costly signals, like personalized messages or paid memberships, mimic market credibility; they show commitment. Among thousands of exchanges studied, daters who signal genuinely—through thoughtful notes or limited gifts—enhance perceived value, just like firms with strong brands.

Beauty Inflation and Market Distortion

Everyone posts their best photo. That creates “beauty inflation,” where the average appearance online exceeds reality. When users meet offline, disappointment follows because the perceived distribution of attractiveness was skewed. Psychologists call this a contrast effect: after seeing endless flawless pictures, average faces look worse. Adshade warns that inflated self-assessments delay market clearing—people overestimate their own value, aiming too high and staying single longer.

Ultimately, the digital love market operates by traditional economics: lower search costs mean more efficient matches, but filtering and inflated expectations create inefficiency. Recognizing that dating apps are marketplaces—full of prices, preferences, and trade-offs—helps you use them wisely. Love online isn’t random; it’s economics with emojis.

Marriage, Adshade insists, is a productive institution—a factory for household goods, emotional services, and financial insurance. Like nations trading based on comparative advantage, spouses specialize where they’re most efficient. Before industrialization, men had a comparative advantage in labor and women in home management. As technology reduced domestic drudgery and women entered paid work, marriages had to reinvent specialization—turning from production units to partnerships of negotiation.

Marriage as Efficient Production

Sex, children, and household tasks are “goods” produced more efficiently by couples. Sex within marriage carries lower risks and costs than casual markets, while childcare guarantees genetic investments. Adshade’s example of Jordan and Alex—the couple dividing chores based on comparative advantage—illustrates how rational allocation yields happiness. Each specializes not by absolute skill but by relative efficiency, just like trading nations. This simple math turns love into collaboration rather than sacrifice.

Economic Shocks and Power Shifts

When women gained education and wage parity, marital bargaining shifted. Power moved from husbands to dual-earner wives. Studies show educated couples divorce less frequently because shared decision-making stabilizes households. Yet inequality between classes widens as richer couples merge high incomes and poorer couples splinter under stress. Adshade cites data showing upper-income women enjoy more leisure but also more housework—a reminder that equality at work doesn’t erase domestic imbalance.

Through this lens, marriage evolves as economies evolve. Industrialization birthed monogamy; the service economy fostered partnership; digital technology and urban mobility now challenge it again. What keeps the institution alive is its efficiency—it still provides insurance and synergy unmatched by single life.

Why do rich nations practice monogamy when economic theory suggests polygamy benefits wealthy men? Adshade examines this paradox historically and mathematically. Early agricultural societies used polygyny, allowing powerful men to hoard wives. Industrialization reversed this pattern: as education determined income rather than land, skilled women became expensive, and men could afford only one educated partner. Monogamy, she argues, persists because educated wives raise high-quality children—a better investment than many uneducated ones.

Pareto Efficiency and Tradeoffs

Through simple “Monogamy Math,” Adshade shows that in a polygamous society, poor men lose access to wives altogether. Monogamy ensures no man is left without a partner, creating social stability. Economist Nils-Petter Lagerlöf calls this “pacifying monogamy”—a way for rulers to avoid rebellion by enforcing one-wife laws. Thus, even if wealthy men sacrifice potential mates, they gain peace, productivity, and legitimacy.

Religion, Economics, and Female Education

Spiritual morality codified what economics already required: fewer wives, more educated households. Once women gained property rights and jobs, they no longer needed marriage for survival, and men needed educated wives to ensure capable children. As comparative advantage between genders narrowed, monogamy became self-reinforcing. Even those with power, like Bill Gates in Adshade’s thought experiment, would choose quality over quantity because intelligent wives maximize long-term returns for their offspring.

What looks like sentiment—loving one person forever—is, under Adshade’s lens, rational equilibrium. Monogamy survives not from virtue but from efficiency. It equalizes opportunities, reduces conflict, and optimizes the next generation’s productivity.

Adshade’s analysis of teenagers reveals how inequality, cost of education, and policy shape young sexuality more deeply than moral teaching ever could. She tells the story of Sarah and Troy: two teens from different socioeconomic backgrounds whose sexual decisions mirror their expectations about the future. Sarah delayed sex because she believed college would change her life; Troy’s family did not expect him to attend school, making early fatherhood seem inevitable. Their choices weren’t moral—they were economic forecasts.

Economic Hope Reduces Risky Behavior

Teen pregnancy rates fall where education is affordable and future income prospects high. Economist Benjamin Cowan found that reducing college tuition by $1,000 decreased teen sexual partners by 26%. Optimism about future opportunity discourages immediate risk. The reverse holds true in unequal societies, where low-income teens internalize hopelessness—a “culture of despair.” In such cultures, unprotected sex and early childbirth become rational responses to bleak futures.

Inequality and Infection

Income inequality doesn’t just increase teen pregnancy; it increases STDs. When risk-averse teens opt out of sex, the remaining sexual market consists of more risk-tolerant partners. Infection rates rise even as total activity falls—a perverse unintended consequence. Gender imbalances amplify this, giving teen boys greater bargaining power over safe-sex decisions. The economics of scarcity—fewer male partners, more female competition—explains why girls, especially Black teens facing high male incarceration rates, suffer disproportionately from infections.

Policy Lessons from Kenya

Abstinence-only education fails because it ignores cost-benefit thinking. When Kenyan students learned the age-based HIV risk—that older men posed greater infection danger—teen pregnancies dropped by 28%. Offering relevant information, not moral lectures, allows rational teens to make healthful choices. Economics predicts this outcome: when the price of unsafe sex rises visibly (as with knowledge of risk), behavior changes more effectively than when obedience is preached.

Adshade reframes youth sexual behavior from moral panic to rational adaptation. Teens respond to the economic environment—opportunity, inequality, and education costs—not hormones alone. Better incentives, not moralizing, foster smarter choices.

Adshade compares cheating in marriage to any risky investment. A spouse weighs expected benefits—pleasure, novelty, emotional validation—against costs—loss of reputation, divorce, financial hardship. When the probability of being caught or penalized drops, cheating becomes more appealing. She uses real-world cases, like Leonard, whose craving for novelty led him from swinging to quiet dissatisfaction, showing that even infidelity follows rational patterns of incentives.

Dynamic Inconsistency

Promises of monogamy illustrate the “time inconsistency” problem economists describe in policy: a husband may vow to leave if betrayed, but when cheating occurs, he finds staying more convenient. Without credible penalties, threats lack enforcement. Historically, religion and moral stigma filled this gap. Contracts like prenuptial agreements replicate that function today by raising the cost of infidelity.

Why Power Equals Opportunity

Powerful individuals cheat more, not because wealth guarantees desire but because it lowers risk and increases opportunity. Research shows managers and CEOs with high authority confess infidelity rates above 25%. Confidence and mobility act as market advantages: they can find lovers easily and hide affairs better. Interestingly, powerful women are just as likely as powerful men to cheat—a reminder that equality produces equal temptation.

Economic Predictors of Fidelity

Poor women cheat more than rich women because they face smaller costs if discovered. Wealthy men, contrary to stereotype, cheat less because financial penalties or social backlash are high. Studies show that only 2% of children in wealthy households are fathered by other men, compared with 30% in poor ones. Cheating isn’t about moral character; it’s about risk exposure and potential loss.

In Adshade’s calculus, adultery becomes a rational, if tragic, economic act—the pursuit of marginal gains until costs outweigh benefits. Whether faithful or not, we respond to incentives. When risk rises—through transparent laws or emotional costs—markets for infidelity contract.

Adshade ends where many love stories do: the later-in-life market for companionship. Contrary to media myths, older adults are thriving in romance, aided by longevity, online dating, and changing gender norms. The infamous 1986 Newsweek article claiming educated women over forty were doomed to die single is debunked—68% later married. Economics explains why: longer life expectancy increases the return on investing in relationships after midlife.

A Thicker Market for Seniors

Older singles now enjoy dense dating markets thanks to technology and social acceptance of cohabitation. Falling stigma around late marriage, fewer children, and higher education create freedom to choose love again. Men seek younger women; women increasingly seek younger men—a phenomenon economists Coles and Francesconi call the “toy-boy equilibrium,” driven by female education and earning power. Economic parity makes older women competitive buyers in a once male-dominated market.

Risk, Health, and Bargaining Power

As life expectancy gaps shrink, older women’s bargaining power improves. They can choose independence rather than caregiving. Adshade shares anecdotes of women demanding doctor’s notes before dating—literal due diligence against “depreciating assets.” Emotional satisfaction and physical health, not social necessity, now guide senior relationships. Late-life sexual behavior also reflects risk calculus; low infection probability raises participation, but gender imbalances still influence condom use and negotiation.

Romance as Investment

Adshade likens an older partner to an annuity: an investment yielding love and affection with uncertain duration. Rational women, more risk-averse, set higher reservation values—they demand high-quality matches. Men may feel overconfident in their market power, but equilibrium requires humility; when both sides misprice themselves, mismatched expectations leave both single. Longevity means there’s more time to find that balance.

Late-life love proves that markets for affection persist across age. As economic independence grows, love survives—not as necessity but as choice. Even in the sunset years, romance remains subject to supply, demand, and the enduring price of desire.