Martin D. Kamen was responsible, with Samuel Ruben, for the discovery of carbon 14. His discovery of the long-lived radioactive isotope made possible much further research on photosynthesis, so this was of particular importance to biologists. Carbon 14 was also subsequently found to be extremely useful in dating fossils, so Kamen's work had broad implications for scientists in varied fields such as geology, paleontology, and archaeology.
Kamen was born August 27, 1913, the first-born son of Russian Jewish immigrant parents. The Kamens ran a photographic portrait studio in the Hyde Park area of Chicago. Kamen was a child prodigy on the violin, and through his high school years it was assumed that he would have a career in music. But balking at family pressure to perform, Kamen stopped studying music seriously, and entered the University of Chicago in 1930 intending to major in English. However, his family's fortune had slid considerably in the Great Depression, and Kamen's parents urged him to switch his major to chemistry. Though Kamen had felt no previous interest in science, he began the chemistry courses, because this was one of the few fields that offered any hope of future employment. Kamen finished his bachelor of science degree in three years, and then continued at the University of Chicago for his Ph.D., which he received in another three years.
In 1936, he set out for Berkeley, California to visit Edward O. Lawrence's famed Radiation Laboratory, home of the cyclotron. After working for six months for no pay, Kamen was hired on at the lab. He used the cyclotron to isolate a radioactive carbon isotope that could be used as a tracer to study the still mysterious process of photosynthesis. Kamen and his colleague Samuel Ruben first worked with Carbon 11, which had a half-life of only 21 minutes. The team worked furiously to perform plant and animal experiments with Carbon 11 before it decayed. Logistical problems sometimes led the team to use carrier pigeons to fly samples between labs. Because of its short life, the usefulness of Carbon 11 was limited. Apparently Edward Lawrence, head of the Radiation Laboratory, feared that he would lose grant funding if the lab could not come up with a better product. So Lawrence ordered Kamen to find something better: a long-lived carbon isotope. The scientists had an idea that such a thing existed, and Kamen s team worked practically around the clock for months to come up with it. Finally they found Carbon 14, which proved to have a half-life of 5,730 years.
Carbon 14 was one of the most important radioactive substances ever discovered. It is present in all living tissues, but it begins to decay once an organism dies. Because it decays at a uniform rate, it can be used to determine when something died, and thus how old it is. This process, called carbon dating, was invented by William Libby in 1946. Kamen's discovery also led to experiments that finally mapped the process of photosynthesis.
After his momentous discovery, Kamen worked on the Manhattan Project, developing equipment for the separation of uranium isotopes. But in July 1944, Kamen was ordered off the project. He had been tracked by the Federal Bureau of Investigation (FBI), and apparently was considered a security risk because of left-wing leanings and because he was outgoing and talkative. After this blow, Kamen for a time worked in a shipyard, the only job he could get. He later found employment at Washington University in St. Louis, where he did significant biomedical research. But he was still shadowed by the FBI, and in 1948 the House Un-American Activities Committee (HUAC) declared him a spy. Kamen battled the allegation for years. He eventually won a libel suit and forced the State Department to grant him a passport.
Kamen s later research covered photosynthesis, biological oxidation, protein structure, and several other areas. He made a lasting contribution to many branches of science with his discovery of Carbon 14. He carried out eminent scientific work under the cloud of political persecution, and finally succeeded in clearing his name.
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