Joshua Lederberg

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Montclair, New Jersey
Birth Sign
Montclair, New Jersey

Joshua Lederberg was an American geneticist who shared the 1958 Nobel Prize in Medicine with George W. Beadle and Edward Tatum for discovering how genetic recombination happens in bacteria. He was born in New Jersey and at first wanted to become a doctor. But he was always good at research, even as a child. While he was getting his medical degree at Columbia University, he started experimenting with the bread mold Neurospora crassa with the help of Francis Ryan. Soon, he decided that experimenting was more interesting than studying medicine. After two years in medical school, he left to work with Edward L. Tatum at the University of Stanford on bacterial conjugation. Soon, he found out that E-coli bacteria can also reproduce sexually. At the age of 33, he won the Nobel Prize for this discovery. He later found that genetic material could be moved from one strain of the bacterium Salmonella typhimurium to another by using bacteriophage as a middle step. His work in this area made it clear that bacteria could be used to study genes. Lederberg also did a lot of research on artificial intelligence and helped make Dendral, which was one of the first projects in artificial intelligence, a reality.

Early years and childhood

Joshua Lederberg was born in Montclair, NJ, on May 23, 1925. His father was a Rabbi. His name was Zwi H. Lederberg. Esther Goldenbaum, his mother, moved to the United States from Palestine just two years before he was born. He was the oldest of the three sons that his parents had.

When Joshua was six months old, his family moved to New York City and settled in Washington Heights, a neighborhood in the borough of Manhattan. He first went to Public School 46, but then he moved to Junior High School 164.

In 1941, he finally finished high school at Stuyvesant. Through the American Institute Science Laboratory program, Lederberg was able to do research in cytochemistry after school hours while he was in school. He was also influenced by the works of H.G. Wells, Bernard Jaffe, and Paul De Kruif.

Joshua got a scholarship from Hayden Trust to pay for college after he graduated. So, he went to the University of Columbia as a pre-med student majoring in zoology. He was given a lab to work on the cytophysiology of plant mitosis and the uses of genetic analysis in cell biology.

In 1942, he met Francis Ryan, who was interested in biochemical genetics and sparked his interest. Slowly, he started to think that science was more difficult than medicine.
Lederberg joined the military in 1943, and as part of his service, he worked in the clinical pathology lab at St. Albans Naval Hospital. Here, he was told to look at blood and stool samples from sailors to see if they had malaria.

After that, he got his bachelor’s degree in 1944 and went on to get his medical degree at Columbia College of Physicians and Surgeons. He kept going with his experiments at the same time. But after Oswald Avery published his paper about DNA, Lederberg’s goal in life changed.

Joshua Lederberg’s Career

Lederberg thought that bacteria passed down exact copies of their genetic information so that every cell in the lineage was a clone of the original. He started working on it again at Columbia University. His work caught the eye of his teacher, Francis Ryan, who told Edward L. Tatum about him.

Tatum worked on bacteria at Yale University at the time. He asked Lederberg to come work in his lab. Then, Lederberg took a year off from Columbia University and went to Yale to work with Tatum in March 1946. In this case, he got help from the Jane Coffin Childs Fund.

Lederberg and Tatum did a lot of research on an Escherichia coli bacterium and found that it went through a sexual phase during which it could share genetic information with other bacteria. In the same year, they wrote a paper called “Gene Recombination in Escherichia coli” about what they had found.

When Lederberg’s one-year leave from Columbia University ended, he decided not to go back. He decided instead to stay at Yale and get his Ph.D., which he did in 1948.
In 1947, he was given a job at the University of Wisconsin as an assistant professor of genetics. In 1950, he was made an Associate Professor. In 1954, he was made a full Professor.

Lederberg kept studying bacteria at the same time and, with the help of his graduate student Norton D. Zinder, made another amazing discovery in 1952. In a paper called “Genetic Exchange in Salmonella,” they wrote about a second way that bacteria share genes.

They showed that a virus that infects bacteria and is called a “bacteriophage” could act as a “carrier” to move a gene from one bacterium to another. It starts by infecting one bacterial cell. Once inside, it uses the bacteria’s cell machinery to make copies of itself.

They called this process “transduction.” In 1956, Joshua Lederberg, Laurance Morse, and Esther Lederberg found “specialized transduction.” Later, he came up with a way to make copies of bacteria. It made it possible to make copies of bacterial colonies to study them more.

In 1957, Lederberg was asked by the University of Wisconsin to set up the Department of Medical Genetics. He was the group’s first Chairman, a job he held until 1958.

In 1959, he left the University of Wisconsin and became the first Chairman of the Department of Genetics at the Stanford University School of Medicine. Later in 1962, he became the Director of the Kennedy Laboratories for Molecular Medicine in the same institute, a job he held until 1978.

During this time, he worked with Frank Macfarlane Burnet, an Australian virologist, to study antibodies made by viruses. From the middle of the 1960s on, he also became very interested in artificial intelligence. Together with Edward Feigenbaum, Bruce G. Buchanan, and Carl Djerassi, he worked on Dendral, which was one of the first AI projects.

Lederberg left Stanford in 1978 to become President of Rockefeller University. He stayed in that job until 1990 when he decided to leave. After that, he got a job at Rockefeller University as a Professor Emeritus of Molecular Genetics and Informatics.

Works of note

Lederberg is best known for the work he did on the bacterium Escherichia coli. Scientists used to think that bacteria could only reproduce asexually, which means that they could only do so by splitting in half. Lederberg and Edward Tatum worked together to show that E. coli could also make babies in a sexual way.

In a 1946 paper called “Gene Recombination in Escherichia coli,” they showed that when two different strains of the same bacterium were mixed together, genetic recombination happened, which caused a new bacterium to form. They also found that the systems of genes in bacteria were very similar to those in higher organisms.

Lederberg is also known for his research on what is now called “transduction.” In 1952, he and Norton D. Zinder showed that a virus called bacteriophage could move a bacterial gene from one bacterium to another.

His work in the field of astrobiology is also very important. Lederberg was the one who warned that extraterrestrial microbes might get into the earth’s atmosphere when Sputnik was launched in 1957. He said that when astronauts and spacecraft come back to Earth, they should be put in quarantine and checked for these kinds of microbes.

Awards & Achievements

The Society of Illinois Bacteriologists gave Joshua and Esther Lederberg the Pasteur Medal in 1956 for “their outstanding contributions to the fields of microbiology and genetics.”

Joshua Lederberg was awarded the Nobel Prize in Physiology and Medicine in 1958 “for his discoveries about genetic recombination and the way bacteria’s DNA is organized.” He was only 33 years old at the time.

Personal History and Legacies

Lederberg married fellow scientist Esther Miriam Zimmer on December 13, 1946. Esther Miriam Zimmer went on to become a famous microbiologist and a leader in the field of bacterial genetics. They worked on different projects together for twenty years. But personal competition slowly drove them apart, and by 1966, they were no longer together.

In 1968, Lederberg married psychiatrist Marguerite Stein Kirsch. Anne Lederberg was the name of their daughter. Lederberg also had a stepson from Marguerite’s first marriage, David Kirsch. The couple stayed together until he died.

Joshua Lederberg died in New York on February 2, 2008. His wife and two children lived on after he died.
In 2012, Lederberg’s name was given to a large impact crater on the surface of Mars. It is in Xanthe Terra and is 87 km across.

Estimated Net worth

Joshua is one of the most popular and wealthiest biologists. Based on what we found on Wikipedia, Forbes, and Business Insider, Joshua Lederberg is worth about $1.5 million.


Joshua Lederberg was a student of Edward L. Tatum when his first wife, Esther, went to Stanford to get an advanced degree from George W. Beadles.