On October 19, 1860, Mary Putnam Jacobi was twenty years old, working as a teacher in New York, and studying pharmacy at the New York College of Pharmacy — one of the few institutions in the United States that would admit a woman to a science program. She had been refused admission to several medical schools. She was determined to become a physician.

Putnam Jacobi was born in London in 1842, the eldest daughter of the publisher George Palmer Putnam. The family returned to New York when she was two. She published her first article at seventeen. She applied to the Female Medical College of Pennsylvania, which admitted her, and obtained her MD in 1864. Unsatisfied with the quality of her training, she applied to the École de Médecine in Paris — the first woman admitted to the institution. She studied there for five years, graduated with honors in 1871, and returned to New York.

She practiced medicine and taught at the Woman's Medical College of the New York Infirmary, eventually becoming professor of materia medica. She challenged the received medical wisdom of her era: her 1876 essay on rest during menstruation, which won the Boylston Prize at Harvard, directly refuted the prevailing theory that women needed bed rest during their periods. She submitted evidence, including her own physiological measurements. The essay won the prize under a pseudonym; when the identity was revealed, the Harvard judges expressed surprise.

She died in 1906 of a brain tumor she had diagnosed herself. Her last scientific paper described her own symptoms.