Nobel Prize in Physiology or Medicine · 1967
George Wald
He found vitamin A at the heart of the eye's light sensor and helped show how light straightens it, the first step of seeing.
The Nobel citation: “for their discoveries concerning the primary physiological and chemical visual processes in the eye”
- Born
- November 18, 1906, New York, NY, USA
- Died
- April 12, 1997, Cambridge, MA, USA
- Shared with
- Ragnar Granit, Keffer Hartline
- Affiliation at the time
- Harvard University, USA
Medicine prize
1967
Shared with 2 other laureates.
Age that year
61years
Born in 1906.
Sources cited
31
Fact-checked September 24, 2026.
- He discovered retinal, the light-catching core of the eye's pigment, in 300 frogs that arrived while his Heidelberg lab was on holiday. An assistant was about to set them free.
- During World War II he and Donald Griffin showed that people can see very intense infrared light. Near 1,000 nanometers, a red glow appears just as the skin feels warm.
- In 1966 Time magazine named him one of the ten best teachers in the United States, for an introductory biology course he taught until 1977.
- His 1969 antiwar speech at MIT was translated into more than 40 languages and was even released as a record album.
- He was on a 1972 White House list of McGovern supporters given to the IRS, one of Nixon's so-called enemies lists. His family said he was proud of it.
The breakthrough
Vitamin A in the eye and the single light reaction that starts vision
At the back of the eye, the retina is lined with light-catching cells: rods for dim light and cones for color. Each is packed with pigment molecules built from two parts. One is a protein called an opsin. The other is a small molecule made from vitamin A, now called retinal. Working in Berlin, Zurich and Heidelberg in 1932 and 1933, Wald found vitamin A in the retina and then retinal itself. He proposed a visual cycle: light breaks the pigment apart, and the eye rebuilds it from vitamin A. It was the first known job in the body for a fat-soluble vitamin, and it explained why a lack of vitamin A causes night blindness. Back at Harvard, he, Ruth Hubbard and Paul Brown found that the eye's pigments use one bent, twisted shape of retinal, called 11-cis. Hubbard and Allen Kropf then showed that the only thing light does in vision is straighten that bend. Think of a bent key jammed in a lock: one particle of light snaps it straight, the lock springs open, and everything after that, including the nerve signal, is chemistry in the dark. The straightened retinal must be bent back before the pigment can work again. In the 1960s Wald and Brown measured three kinds of cone pigment in the human eye, tuned to blue, green and red light. All three use the same retinal with different proteins. In color-blind volunteers, Wald could detect only two of the three.[2],[3],[4],[6],[7]
“A scientist lives with all reality. There is nothing better. To know reality is to accept it, and eventually to love it.”
What it meant for humanity
Wald's work changed how scientists and doctors understand sight. By tying vitamin A directly to the eye's light-catching pigment, it explained why a shortage of the vitamin causes night blindness. The remedy, vitamin A from sources such as cod-liver oil, was known before him; what he supplied was the reason it works. The symptom still matters. The World Health Organization uses night blindness to track vitamin A deficiency, and estimated that it affected about 5.2 million young children and 9.8 million pregnant women in at-risk populations between 1995 and 2005. His measurements of the three human cone pigments, made with Paul Brown at the same time as a Johns Hopkins team, directly confirmed an idea dating back to Thomas Young: that color vision rests on three kinds of receptor, and his tests on color-blind volunteers showed that each lacked one of the three. In 1965 he proposed that a single activated pigment molecule sets off an amplifying chain of reactions, like blood clotting; laboratories confirmed this in the 1980s. Rhodopsin, the rod pigment he studied for decades, became a model for a huge family of cell receptors. In the 1980s a hormone receptor's resemblance to rhodopsin revealed that family, which about a third of approved drugs now target. The recycling step his laboratory showed was essential, bending retinal back into shape, is done by an enzyme called RPE65. In 2017 a treatment that supplies a working RPE65 gene became the first gene therapy for a genetic disease approved in the United States, sharply raising light sensitivity in people with an inherited blindness that starts in early childhood. Wald also taught thousands of Harvard students and used his fame to campaign against war and nuclear weapons.
- He established the first known biochemical role for a fat-soluble vitamin: vitamin A, as retinal, is the light-catching part of every visual pigment. This explained the long-known link between vitamin A deficiency and night blindness.[3],[6],[7]
- Night blindness is still a key warning sign of vitamin A deficiency. WHO estimated it affected about 5.2 million preschool children and 9.8 million pregnant women in at-risk populations in 1995-2005.[19]
- With Paul Brown he measured blue-, green- and red-sensitive pigments in single human cones in 1964, and found that people with the main forms of color blindness lack one of the three.[3],[6],[7]
- His 1965 idea that light sets off an amplifying chemical cascade was confirmed in the 1980s. A hormone receptor's likeness to rhodopsin then revealed the G-protein-coupled receptor family, which about 35% of approved drugs target.[6],[21],[30]
- The enzyme RPE65 performs the re-bending step of his visual cycle. Luxturna, which supplies a working RPE65 gene, became the first US-approved gene therapy for a genetic disease in 2017, raising patients' light sensitivity 100- to 45,000-fold.[6],[20]
- From 1960 until he retired in 1977 he taught Natural Sciences 5, an introductory biology course that drew thousands of undergraduates. Time magazine named him one of the country's ten best teachers in 1966.[6],[7],[9],[11]
Impact in numbers
Wald's legacy is knowledge rather than a product, so we make no numerical claim. With his co-workers he explained, molecule by molecule, the first step of vision in every animal eye they studied: light straightening a bent form of vitamin A. That explanation underlies the modern understanding of night blindness, color blindness and some inherited retinal diseases, and it helped make rhodopsin arguably the best-understood member of a receptor family now central to drug discovery. But the treatments that followed, from vitamin A programs to RPE65 gene therapy, depended on many later scientists, doctors and public health workers, and no published source estimates how many people his work helped. His other legacies are human. For 17 years he taught an introductory biology course that drew thousands of students, and he used a Nobel laureate's platform to press scientists and the public to weigh how science is used, from nuclear weapons to genetic engineering.
Fundamental scienceHealthEducationPeace
No number is given here on purpose. Some contributions cannot be counted honestly, and we would rather describe them than invent a figure.
The double edge
No harm is documented from Wald's vision research itself. The controversies come from his activism. In June 1980, during the Iran hostage crisis, he joined former Attorney General Ramsey Clark's delegation to a 'Crimes of America' conference in Tehran, defying a US ban on travel to Iran. In 1976 he fought plans for a recombinant DNA lab at Harvard, and his protests before the Cambridge city council helped bring a temporary ban. A citizens' board then let the research go ahead under safety rules, and later tests suggested the risks were small. The local oversight that the debate produced became accepted practice in the biotech industry. Around the first Earth Day in 1970, he warned that civilization could end within 15 or 30 years without urgent action, a forecast critics cite as failed doom-saying. A 1977 student newspaper profile quoted a Harvard colleague who said some faculty found his DNA campaign self-righteous and who called him too much of a showman.
- Moderate
Defying a travel ban during the Iran hostage crisis
From 2 to 5 June 1980, while American hostages were held in Tehran, Wald was one of ten Americans in Ramsey Clark's delegation to a 'Crimes of America' conference in Iran. A State Department history says they broke a government travel ban carrying up to 10 years in prison and a $50,000 fine; the Attorney General favored civil charges and fines instead.[11],[15]
- Minor
Opposing recombinant DNA research
In 1976 Wald told a crowd of 500 that a planned gene-splicing lab should be built in a thinly populated area, and called the city's extended moratorium important but mostly symbolic. A citizens' review board let the work go ahead under safety rules adapted from federal guidelines; later tests suggested the risks were small, and the lab was never built. A colleague said some faculty found his campaign self-righteous.[12],[16],[17],[28]
- Minor
A doomsday forecast that did not come true
Around the first Earth Day in 1970, Wald estimated that civilization would end within 15 or 30 years unless action was taken at once. Critics, such as Reason magazine's science correspondent in 2000, cite it as an example of failed apocalyptic predictions.[18]
Against the odds
The antisemitism Wald met was mostly background rather than direct attack. His father, a tailor, came from a village near Przemyśl in Austrian Poland, and his mother came from Bavaria. They met working in New York's garment trade. He was born on the Lower East Side, grew up in a run-down part of Brooklyn, and was the first in his family to go to college. In the early 1920s Columbia, Harvard and Yale all began limiting how many Jewish students they admitted. Wald went to New York University's Washington Square College, the first college on the subway line from Brooklyn. His sharpest brush with persecution came in 1933. Hitler took power that January, while Wald was on a research fellowship in Berlin and Zurich, and Wald then went back to Germany to work in Heidelberg. That June the local Nazi party began agitating to remove his Heidelberg host, Otto Meyerhof, because he was Jewish. Wald's funder, the National Research Council, insisted that Wald, also Jewish, return to the United States, and he finished his fellowship in Chicago. His second wife and closest co-worker, Ruth Hubbard, reached America as a teenager in 1938, after her family left Vienna when Nazi Germany annexed Austria.
—
Other
He grew up in a working-class Jewish immigrant family in Brooklyn. His father was a tailor, his parents had met in the garment trade, and he was the first member of his family to attend college.[6],[7],[11],[31]
—
Quota
In the early 1920s Columbia, Harvard and Yale began restricting the number of Jewish students they admitted. Wald studied at NYU's Washington Square College instead; our sources do not say whether the quotas shaped his choice.[11],[23]
1933
Persecution
He was working in Otto Meyerhof's Heidelberg institute in 1933 as local Nazis began agitating against Meyerhof as a Jew. His American funder insisted that Wald, who was Jewish, leave Germany by the end of the summer, cutting short his European research.[6],[7],[22],[25]
Jewish background
Wald was born in New York to Jewish immigrant parents: Isaac Wald, a tailor from a village near Przemyśl in Austrian Poland, and Ernestine Rosenmann, from a village near Munich. His National Academy of Sciences biographer and the Dictionary of Scientific Biography both describe him as Jewish, and the Encyclopaedia Judaica includes him. As a teenager he performed a vaudeville act at Jewish community centers, and his son recalls Jewish-dialect comic recitations as a family ritual. He was not religious: in 1969 he told the New York Times Magazine that nature was his religion. In retirement he studied early Jewish and Christian history.[2],[6],[7],[8],[10],[11],[13],[26],[31]
Key dates
November 18, 1906
Born on Manhattan's Lower East Side, the youngest of three children of Jewish immigrants Isaac Wald, a tailor, and Ernestine Rosenmann.[1],[7],[11]
1927
Earns a bachelor of science at NYU's Washington Square College, then starts graduate work in zoology at Columbia under vision researcher Selig Hecht.[2],[6]
1932
Receives his PhD from Columbia and begins a National Research Council fellowship in Otto Warburg's Berlin lab, where he finds vitamin A in the retina.[2],[3],[6]
1933
In Meyerhof's Heidelberg lab he discovers retinal (then called retinene) and proposes the visual cycle. With Hitler in power, his funder orders him home.[3],[6],[7]
1934
Joins Harvard as a tutor in biochemical sciences, beginning a 43-year career there. He becomes a full professor in 1948.[2],[6],[7]
1955
With Ruth Hubbard, Paul Brown and organic chemists, completes the proof that the bent 11-cis form of retinal is the building block of the visual pigments.[6],[7]
1958
Marries Ruth Hubbard, his co-worker. By that year Hubbard and Allen Kropf have shown that light's only action in vision is to straighten 11-cis retinal.[3],[6],[7],[24]
1964
With Paul Brown, measures blue-, green- and red-sensitive pigments in single human cones.[3],[6],[7]
1965
Signs an open letter in The New York Times protesting the Vietnam War, and proposes in Science that light triggers an amplifying chemical cascade, like blood clotting.[6],[7]
December 10, 1967
Receives the Nobel Prize in Physiology or Medicine with Ragnar Granit and Keffer Hartline for discoveries about the primary visual processes in the eye.[1],[4],[5]
March 4, 1969
Gives 'A Generation in Search of a Future' at an MIT antiwar teach-in. The speech is reprinted worldwide, and politics becomes his main interest.[6],[7],[27]
December 20, 1973
A list of McGovern staff and supporters, given to the IRS by the White House in 1972 and later called a Nixon enemies list, is made public. Wald's name is on it.[11],[14],[29]
1977
Retires from Harvard as Higgins Professor of Biology and devotes himself mainly to political causes, including a 1980 trip to Tehran that defied a US travel ban.[6],[7],[12],[15]
April 12, 1997
Dies at his home in Cambridge, Massachusetts, aged 90, after two years of declining health.[1],[11],[25]
Sources
- 1.George Wald – Facts · NobelPrize.org (Nobel Prize Outreach)
- 2.George Wald – Biographical (from Nobel Lectures, Physiology or Medicine 1963-1970) · NobelPrize.org (Nobel Prize Outreach), 1967
- 3.The Molecular Basis of Visual Excitation (Nobel Lecture, 12 December 1967) · NobelPrize.org (Nobel Prize Outreach), 1967
- 4.The Nobel Prize in Physiology or Medicine 1967 – Award ceremony speech (C.G. Bernhard) · NobelPrize.org (Nobel Prize Outreach), 1967
- 5.George Wald – Banquet speech (10 December 1967) · NobelPrize.org (Nobel Prize Outreach), 1967
- 6.George Wald, 1906–1997: A Biographical Memoir (John E. Dowling), Biographical Memoirs vol. 78 · National Academy of Sciences, 2000
- 7.Wald, George (Complete Dictionary of Scientific Biography, by Diana E. Kenney) · Encyclopedia.com / Charles Scribner's Sons
- 8.George Wald (Encyclopedia of World Biography) · Encyclopedia.com / Gale
- 9.Wald, George (Scribner Encyclopedia of American Lives, Thematic Series: The 1960s, by Maura C. Flannery) · Encyclopedia.com / Charles Scribner's Sons
- 10.Wald, George (Encyclopaedia Judaica, by George H. Fried) · Encyclopedia.com / Encyclopaedia Judaica (Gale), 2007
- 11.Nobel Winner, Peace Activist Wald Dies · The Harvard Crimson, 1997
- 12.For Wald, Science Sets the Stage (Michael Kendall) · The Harvard Crimson, 1977
- 13.George Wald - Biologist from Brooklyn (Elijah Wald) · elijahwald.com
- 14.Nixon Enemies List entry for Dr. George Wald (Second List, #539) · EnemiesList.info (Daniel G. Axtell)
- 15.Foreign Relations of the United States, 1977–1980, Volume XI, Part 1, Iran: Hostage Crisis, Document 291: Summary of Conclusions of a Special Coordination Committee Meeting · US Department of State, Office of the Historian, 1980
- 16.Council Extends DNA Experiment Ban; Wald, Meselson Debate Gene Research · The Harvard Crimson, 1976
- 17.The People vs. Recombinant DNA (Distillations podcast) · Science History Institute
- 18.Earth Day, Then and Now (Ronald Bailey) · Reason, 2000
- 19.Global prevalence of vitamin A deficiency in populations at risk 1995–2005: WHO Global Database on Vitamin A Deficiency · World Health Organization, 2009
- 20.Clinical Perspective: Treating RPE65-Associated Retinal Dystrophy (Maguire AM, Bennett J, Aleman EM, Leroy BP, Aleman TS), Molecular Therapy · Molecular Therapy (via PubMed Central), 2021
- 21.The Nobel Prize in Chemistry 2012 – Popular information: Smart receptors on cell surfaces · NobelPrize.org (The Royal Swedish Academy of Sciences), 2012
- 22.Personal and National Tragedy Undermine Krehl's Dream · NobelPrize.org (Nobel Prize Outreach)
- 23.How the Ivy League's Jewish quotas shaped higher education (interview with Mark Oppenheimer) · Inside Higher Ed, 2022
- 24.Ruth Hubbard Wald, Harvard Biologist, Dies at 92 · Harvard University, Department of Molecular and Cellular Biology, 2016
- 25.Nobel Winner Wald Dies; Biologist Won for His Work on Vision (Associated Press) · The Roanoke Times (via Virginia Tech digital archive), 1997
- 26.George Wald · Wikipedia
- 27.George Wald: A Generation in Search of a Future (speech of 4 March 1969, with introduction by Elijah Wald) · elijahwald.com, 1969
- 28.Fifty years since recombination debate ushered in biotech in Cambridge · Cambridge Day, 2026
- 29.The Second Enemies List, or 'List of McGovern Staff Members and Campaign Contributors' · EnemiesList.info (Daniel G. Axtell)
- 30.G Protein-Coupled Receptors as Targets for Approved Drugs: How Many Targets and How Many Drugs? (Sriram K, Insel PA), Molecular Pharmacology 93:251-258 · Molecular Pharmacology (via PubMed Central), 2018
- 31.George Wald: Scientist and Activist (Lawrence Bush) · Jewish Currents, 2017
Fact-checked on September 24, 2026 by a separate AI fact-checking pass that re-opened the sources, with 8 corrections made. How we check
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