George Wald
George Wald (
November 18,
1906 –
April 12,
1997) was an
American scientist who is best known for his work with pigments in the
retina. He won a share of the
1967 Nobel Prize in Physiology or Medicine with
Haldan Keffer Hartline and
Ragnar Granit.
 |
Wald plotted the absorbance of rod pigment (black curve), then later the absorbance of cone pigments (red, green, and blue curves) |
As a postdoctoral researcher, Wald discovered that
vitamin A was a component of the retina. His further experiments showed that when the pigment
rhodopsin was exposed to light, it yielded the protein opsin and a compound containing vitamin A. This suggested that vitamin A was essential in retinal function.
In the 1950s, Wald and his colleagues used chemical methods to extract pigments from the retina. Then, using a
spectrophotometer, they were able to measure the light absorbance of the pigments. Since the absorbance of
light by retina pigments corresponds to the
wavelengths that best activate
photoreceptor cells, this experiment showed the wavelengths that the eye could best detect. However, since
rod cells make up most of the retina, what Wald and his colleagues were specifically measuring was the absorbance of rhodopsin, the main photopigment in rods. Later, with a technique called microspectrophotometry, he was able to measure the absorbance directly from cells, rather than from an extract of the pigments. This allowed Wald to determine the absorbance of pigments in the
cone cells (Goldstein, 2001).
Wald was born in
New York City to Isaac Wald and Ernestine Rosenmann,
Jewish immigrant parents. He was a member of the first graduating class of the
Brooklyn Technical High School in New York in 1922. He received his Bachelor of Science degree from
New York University in 1927 and his PhD in
zoology from
Columbia University in 1932. After graduating, he received a travel grant from the US National Research Council. Wald used this grant to work in Germany with
Otto Heinrich Warburg where he identified vitamin A in the retina. Wald then went on to work in
Zurich,
Switzerland with the discoverer of vitamin A,
Paul Karrer. Wald then worked briefly with
Otto Fritz Meyerhof in
Heidelberg, Germany, but left Europe for the
University of Chicago in 1933 when
Adolf Hitler came to power and life in Europe became more dangerous for Jews. In 1934, Wald went to
Harvard University where he became an instructor, then a professor. He was elected to the
National Academy of Sciences in 1950 and in 1967 was awarded the
Nobel Prize for Physiology or Medicine for his discoveries in vision.
Wald spoke out on many political and social issues and his fame as a Nobel laureate brought national and international attention to his views. He was a vocal opponent of the
Vietnam War and the
nuclear arms race.
In
1980, Wald served as part of
Ramsey Clark's delegation to
Iran during the
Iran hostage crisis.
With a small number of other Nobel laureates, he was invited in 1986 to fly to Moscow to advise
Mikhail Gorbachev on a number of environmental questions. While there, he questioned Gorbachev about the arrest, detention and exile to
Gorki of
Yelena Bonner and her husband, fellow Nobel laureate
Andrei Sakharov, (Peace, 1975). Wald reported that Gorbachev said he knew nothing about it. Bonner and Sakharov were released shortly thereafter, in December, 1986.
Wald died in
Cambridge, Massachusetts.
Goldstein, B. 2001.
Sensation and Perception, 6th ed. London: Wadsworth.
*
Nobel Prize Biography*
A remembrance by fellow biologist John Dowling*
A remembrance by his son ElijahTwo of George Wald's speeches can be read on-line:
*
A Generation in Search of a Future*
The Origin of Death
