Rosalyn Yalow

The Bronx physicist who revolutionized medicine by making the invisible measurable

Most people think of Rosalyn Yalow as the woman who won the Nobel Prize for developing radioimmunoassay, but few know she almost never became a scientist at all—her high school physics teacher told her she wasn't smart enough for the subject. Even fewer know that when she finally did win the Nobel in 1977, she was so stunned that she hung up on the caller from Stockholm, thinking it was a prank.

Timeline of Key Moments

• 1921: Born Rosalyn Sussman in the South Bronx to immigrant parents who never finished elementary school
• 1941: Graduates magna cum laude from Hunter College with physics degree; rejected from graduate programs due to gender discrimination
• 1943: Earns PhD in nuclear physics from University of Illinois, one of only two women in a class of 400
• 1947: Begins work at Bronx Veterans Administration Hospital, initially as part-time consultant
• 1950: Partners with physician Solomon Berson to begin groundbreaking research on insulin metabolism
• 1959: Develops radioimmunoassay (RIA) technique with Berson, revolutionizing medical diagnostics
• 1968: Berson dies suddenly; Yalow continues their work alone despite devastating personal loss
• 1976: Becomes first woman to win Albert Lasker Award for Basic Medical Research
• 1977: Wins Nobel Prize in Physiology or Medicine, second woman ever in the category
• 1986: Receives National Medal of Science from President Reagan
• 2011: Dies at age 89, having transformed modern medicine and opened doors for women in science

The Human Story

Rosalyn Sussman grew up in a tenement in the South Bronx, where her father sold paper and twine from a pushcart and her mother cleaned houses. Neither parent had finished elementary school, but they possessed an immigrant's fierce belief in education as the path to a better life. When young Rosalyn announced she wanted to be a scientist, they didn't understand what that meant, but they supported her anyway. Her mother would say years later, "I knew she was smart, but I never knew she was that smart."

The path wasn't easy. Despite graduating magna cum laude from Hunter College in 1941, graduate schools rejected her applications—not because of her grades, but because she was a woman. The few programs that might have accepted her required her to take stenography courses, assuming she'd end up as a secretary to male scientists. It was only when World War II created a shortage of male graduate students that the University of Illinois finally offered her a spot, along with a teaching assistantship that paid $75 a month.

At Illinois, she was one of only two women among 400 graduate students in physics. The isolation was crushing, but it also forged her legendary determination. She threw herself into her studies with an intensity that would characterize her entire career, often working 16-hour days. Her professors were skeptical—one told her she might make a decent high school teacher if she was lucky. She proved them wrong by completing her PhD in nuclear physics in just four years, writing a dissertation on the interaction of neutrons with matter.

After graduation, she faced the same gender barriers that had plagued her undergraduate years. Academic positions were virtually closed to women, and industrial labs weren't much better. She took a job teaching physics at Hunter College, but the work felt limiting. Then, in 1947, she heard about a part-time consulting position at the Bronx Veterans Administration Hospital. The pay was modest, but it offered something precious: the chance to do real research.

At the VA, she met Solomon Berson, a brilliant physician who would become her closest collaborator and dearest friend. Their partnership began almost by accident—Berson needed someone who understood radioactive isotopes, and Yalow needed a research project. What started as a practical arrangement blossomed into one of the most productive scientific collaborations of the 20th century. They were an unlikely pair: she was the meticulous physicist who could spend hours perfecting a measurement technique, while he was the intuitive clinician who could see the bigger picture. Together, they were unstoppable.

Their breakthrough came from studying diabetes. In the 1950s, doctors knew that diabetics needed insulin injections, but they had no way to measure how much insulin was actually in a patient's blood. The amounts were too tiny for conventional chemical analysis—like trying to find a few drops of water in an Olympic swimming pool. Yalow and Berson realized they could use radioactive isotopes as incredibly sensitive detectors, creating what they called radioimmunoassay, or RIA.

The technique was elegantly simple in concept but fiendishly difficult to execute. They would inject a patient with a tiny amount of radioactive insulin, then use the body's own immune system as a measuring device. Antibodies would bind to both radioactive and non-radioactive insulin in predictable ratios, allowing them to calculate exactly how much natural insulin was present. It was like using the immune system as a biological scale that could weigh individual molecules.

The medical establishment initially rejected their work. When they submitted their first paper on RIA to the prestigious journal Science, it was rejected. The reviewers couldn't believe that such tiny amounts of substances could be measured accurately. One critic dismissed their technique as "too sensitive to be useful." Yalow kept that rejection letter framed on her wall for the rest of her career, a reminder of how revolutionary ideas often face skepticism.

But RIA worked, and it worked spectacularly. Within a few years, doctors could measure not just insulin, but hundreds of other hormones, drugs, and biological substances that had previously been invisible. The technique transformed endocrinology, making it possible to diagnose thyroid disorders, monitor cancer treatments, and understand how hormones regulate everything from growth to reproduction. Today, RIA and its descendants are used in millions of medical tests every year.

The partnership with Berson lasted 22 years, until his sudden death from a heart attack in 1968. Yalow was devastated—she had lost not just a collaborator but her closest friend. Many expected her to retire or fade into obscurity, but she refused to let their work die with him. She continued their research alone, driven by a fierce loyalty to their shared vision and an unshakeable belief in the importance of their discoveries.

When the Nobel Committee called her in October 1977, she was so shocked that she hung up, convinced someone was playing a prank. Only when they called back did she realize it was real. She was the second woman ever to win the Nobel Prize in Physiology or Medicine, and the first American woman to win a Nobel in any scientific field. The recognition was bittersweet—Berson had died nine years earlier and couldn't share the honor, since Nobel Prizes aren't awarded posthumously.

Her Nobel acceptance speech was characteristically direct and passionate. She spoke not just about RIA, but about the barriers facing women in science. "We must believe in ourselves or no one else will believe in us," she declared. "We must match our aspirations with the competence, courage, and determination to succeed." She used her platform to advocate for women in science, mentoring young researchers and speaking out against discrimination.

The Nobel Prize changed her life in ways both wonderful and challenging. She was suddenly in demand as a speaker and consultant, traveling the world to share her expertise. The attention was gratifying but also overwhelming—she had always been most comfortable in the laboratory, not on the lecture circuit. She worried that fame might distract from her real work, telling reporters, "I'm a scientist, not a celebrity."

Despite the pressures of fame, she continued working well into her 80s, driven by the same curiosity that had sustained her since childhood. She never lost her edge or her impatience with mediocrity. Colleagues remember her as demanding but fair, someone who expected excellence from herself and others. She could be intimidating in scientific discussions, but she was also generous with her time and knowledge, especially with young women entering science.

Her personal life was more complex than her public image suggested. She married Aaron Yalow, a fellow physicist, in 1943, and they had two children together. Balancing career and family was a constant struggle in an era when working mothers faced intense social pressure. She often brought her children to the lab on weekends and holidays, teaching them to see science as a family adventure rather than a burden. Her son Benjamin became a systems analyst, while her daughter Elanna became a child psychologist—both inherited her analytical mind, if not her specific passion for physics.

Yalow was also shaped by her Jewish identity and her immigrant background. She never forgot where she came from or the barriers she had overcome. When anti-Semitism limited her opportunities early in her career, she responded not with bitterness but with determination to prove herself through excellence. She often spoke about the responsibility that came with success, the obligation to open doors for others who faced similar obstacles.

Revealing Quotes

On persistence and self-belief: "We must believe in ourselves or no one else will believe in us; we must match our aspirations with the competence, courage and determination to succeed." (From her Nobel acceptance speech, reflecting her philosophy about overcoming barriers)

On the nature of scientific discovery: "The failure to think positively about a problem may prevent its solution. We must learn to think the unthinkable." (Explaining how breakthrough discoveries often require abandoning conventional assumptions)

On her partnership with Berson: "Sol was my closest friend, my colleague, my critic. We could fight about science and never hurt each other's feelings because we both knew we were fighting for the truth." (Describing their legendary collaboration and the trust that made it possible)

On being underestimated: "Initially, our work was not accepted by the medical community. The concept was too new, too different. But we knew we were right, and we kept working." (Reflecting on the early rejection of RIA and the importance of perseverance)

On her legacy: "I want to be remembered as a good scientist who happened to be a woman, not as a woman who happened to be a scientist." (Expressing her complex relationship with being a pioneering woman in science)

Lessons from a Revolutionary Life

Rosalyn Yalow's story teaches us that revolutionary breakthroughs often come from the intersection of different fields—in her case, physics and medicine. Her willingness to work at the boundaries, to apply nuclear physics techniques to biological problems, created possibilities that neither field could have achieved alone. This reminds us that innovation often requires crossing traditional boundaries and thinking beyond the silos of our training.

Her journey also illuminates the power of partnership in scientific discovery. The collaboration with Berson wasn't just about dividing labor—it was about creating something neither could have achieved alone. Their different perspectives and skills complemented each other perfectly, showing us that the best collaborations aren't between similar people, but between people whose differences create synergy.

Perhaps most importantly, Yalow's life demonstrates that persistence in the face of rejection isn't just about stubbornness—it's about maintaining faith in the value of your work when others can't see it yet. Her technique was "too sensitive to be useful" until it became indispensable. Her story reminds us that truly innovative ideas often face skepticism precisely because they challenge existing assumptions about what's possible.

Her Nobel journey also reveals something profound about recognition and legacy. The fact that Berson couldn't share the prize because of his death highlights both the arbitrary nature of timing in recognition and the importance of continuing work that matters, regardless of whether we live to see it honored. Yalow's determination to continue their research alone, driven by loyalty to their shared vision rather than personal ambition, shows us what it means to serve something larger than ourselves.