Perez introduces the 'default male' — the assumption that the male body and experience represent all of humanity.

Sweden's snow-clearing schedule is revealed to prioritize roads over walkways, inadvertently benefiting male drivers over female pedestrians and transit users.

Brazil's public housing scheme places residential zones far from jobs and transport, pushing many women permanently out of paid work.

Ninety percent of Icelandic women refuse all paid and unpaid work for one day, forcing a national reckoning with the scale of women's labor.

Data reveals that women in the UK make up 61% of workers earning below a living wage, largely due to care responsibilities.

When the New York Philharmonic implements blind auditions, the number of female musicians hired increases dramatically.

Occupational health research is revealed to focus almost exclusively on male-dominated industries, leaving the risks of female-dominated jobs largely unstudied.

A female British police officer is stabbed and killed after removing her ill-fitting body armor to operate a door ram.

Perez reveals that BPA's serious health dangers could have been identified sooner if researchers had monitored the health of female factory workers.

A major university study finds medical textbooks depict male bodies three times more often than female ones.

Pharmaceutical companies refuse to fund further trials of a drug shown to completely relieve severe period pain, fearing damage to male sales.

Perez identifies the exclusion of women's unpaid labor from GDP calculations as the single greatest gender data gap.

Research shows female legislators are significantly more likely than male counterparts to increase social spending and address family policy needs.

Approximately 60,000 women are raped as a deliberate weapon of war during the Bosnian conflict.

Mathematician Daina Taimina solves a century-old problem about hyperbolic space by crocheting a physical model that had eluded experts for generations.

Perez opens by establishing that the 'default male' — treating men as the universal human standard — pervades every aspect of modern life, from language to product design. Moving through urban planning, workplace conditions, and occupational safety, she shows how this default creates real harm: women die in poorly fitting body armor, and public housing schemes fail because planners never consulted women. The medical system compounds these failures, with textbooks dominated by male bodies and clinical trials that routinely exclude women. Perez's economic argument reaches its peak when she names the exclusion of women's unpaid labor from GDP as the greatest gender data gap of all. In government, female legislators are shown to produce better social outcomes, yet women in conflict zones remain catastrophically unprotected from violence. The book closes with an optimistic example: when one woman brings a fresh perspective to a century-old problem, she solves it.

The core case for closing the gender data gap.

19th-century composer Felix Mendelssohn publishes six of his sister Fanny's musical compositions under his own name.

The Bank of England's name-recognition requirement for appearing on banknotes is shown to systematically exclude women from consideration.

Barcelona redesigns its bus network with flexible routes to accommodate the trip-chaining travel patterns more common among women.

Equal-space allocation for men's and women's restrooms is shown to create longer queues for women because urinals take far less space.

Researchers estimate that inadequate public toilet access in one South African township causes 635 assaults and costs approximately 40 million dollars annually.

Swedish towns redesign parks with subdivisions and multiple entrances, successfully increasing women's participation in outdoor recreational activities.

American universities are shown to grant tenure at far lower rates to female professors with children compared to their male counterparts.

Japan's culture of measuring workplace effectiveness by hours in the office is revealed to systematically disadvantage women with care responsibilities.

Piano keyboards, designed for average male hand size, are shown to cause significantly higher rates of pain and injury among female pianists.

Voice recognition software is shown to fail disproportionately for female users because its training data is overwhelmingly composed of male voices.

Apple's health-tracking app is revealed to monitor many health metrics while initially omitting any tracking of women's menstrual cycles.

Automobile safety testing using only male crash-test dummies is shown to leave women significantly more likely to be seriously injured in crashes.

A 2013 study finds that Viagra completely relieves severe period pain for four hours with no side effects, but receives no follow-up funding.

Perez argues that universal childcare would be the single most effective job-creation program any government could implement.

Women avoid the Louisiana Superdome as a Hurricane Katrina shelter after reports of rape and beatings inside the designated refuge.

Perez traces the gender data gap through a series of specific, concrete cases that collectively reveal how thoroughly women's needs have been overlooked. From the historical erasure of women's creative contributions to the design of restrooms and bus networks, women face friction and risk at every turn. The workplace penalizes women in subtle but damaging ways — through tenure clocks that ignore care responsibilities, long-hours cultures that assume no domestic burden, and physical tools calibrated to male bodies. Technology adds new layers of disadvantage, with voice recognition software, fitness trackers, and car safety systems all designed around men. Medical research offers the starkest examples, from a drug that relieves period pain going unfunded to crash dummies that don't reflect the female body. Perez concludes that only deliberate structural changes — from universal childcare to safety reforms in disaster shelters — can begin to close these gaps.

Hidden patterns of exclusion across everyday life.

The World Economic Forum finds that languages with grammatical gender embedded in words correlate with significantly higher levels of gender inequality.

Austria successfully builds public housing near schools, medical facilities, and public transport after incorporating women's needs into planning data.

A Swedish study finds that while moderate overtime benefits men's health, the same amount of overtime increases women's hospitalization and mortality rates.

When Google discovers women are not self-nominating for promotions, the company tries to change women's behavior rather than fix the biased policy.

Teaching evaluations are shown to routinely describe female professors as 'mean' and 'annoying' while describing male professors as 'brilliant' and 'genius.'

Perez introduces the 'Henry Higgins Effect' to describe the tendency to fix women to fit male systems rather than redesign the systems themselves.

Clean cooking stove programs repeatedly fail because designers don't consult women, but succeed once women are asked about their actual needs.

Venture capitalists, 93% of whom are male, dismiss proposals for a better breast pump despite a lucrative and obviously underserved market.

Research reveals that pelvic-floor disorders affecting half of all women over 50 have received almost no medical study or research investment.

Animal studies reveal that male and female mice show completely opposite results for the timing and survival rates of heart attacks.

Doctors are shown to prescribe antidepressants to women and painkillers to men when both present with similar pain complaints.

Research reveals that joint tax filing actively disincentivizes married women from entering or remaining in paid employment altogether.

After the Labour Party uses all-women shortlists in internal elections, female representation in the UK Parliament increases dramatically.

Women in Bangladesh, prohibited from learning to swim, die at significantly higher rates than men when floods strike.

The COVID-19 pandemic reveals a continued failure to systematically collect and publish sex-disaggregated data on infection rates, symptoms, and deaths.

This pool follows the moments of discovery and decision that reveal how thoroughly male bias is embedded in systems — and how often the instinctive response is to fix women rather than redesign the system. From research linking gendered language to inequality, to a public housing project that works precisely because planners asked women what they needed, each event illuminates both the problem and the potential solution. The workplace and academia produce some of the sharpest turning points: evaluation language that consistently marks women as difficult and men as brilliant, and algorithms that reward male online habits while penalizing female ones. Medical research reveals dangerous blind spots, including animal studies that show male and female subjects respond in completely opposite ways. In politics, structural tools like all-women shortlists prove their effectiveness, while tax systems and disaster planning continue to render women invisible. The epilogue confirms that even a global pandemic could not prompt consistent collection of sex-disaggregated health data.