The geneticist and microbiologist Joshua Lederberg was without doubt one of the leading scientists of the 20th century. He was a pioneer of modern microbiology and immunology, one of the founders of molecular biology, and a leader in the development of biotechnology. He helped to lay the foundations for genetic engineering and the genetic approaches to medicine. The benefits to mankind of his work have been enormous and they increase each year. He was awarded the Nobel Prize for Physiology or Medicine in 1958 at the extraordinarily young age of 33.

Lederberg’s inventiveness was not confined to genetics and microbiology. He recognised and gave warning about the potential danger to space science of space vehicles carrying bacteria to the moon or Mars and became a pioneer of space biology, helping to design equipment used by Nasa on space missions. His main concern was that other planets on which there might be life could be contaminated by micro-organisms (pathogens) carried from Earth on spacecraft, and that, conversely, Earth could be contaminated by some unknown disease-producing pathogen brought back from another planet, a pathogen to which Earth’s inhabitants had no immunity; he called this a potential “cosmic catastrophe”.

Lederberg was very excited about space exploration because of its promise of the discovery of new secrets about the nature of the universe and the origins of life. In 1958 the US National Academy of Sciences set up the Space Science board and Lederberg was one of its founding members. The purpose of the Board was to examine the scientific aspects of space exploration, manned spaceflight, and space stations, and to devise scientific experiments to search for life in space.

In 1976 Lederberg and his colleagues at the Instrumentation Research Laboratory at Stanford University designed instruments for soil analysis used on the US Viking I and Viking II spacecraft when they explored Mars. A device designed by Lederberg and a colleague, Elliott Levinthal, consisted of a conveyer belt that scooped up samples of the soil on Mars and deposited them in a computer-controlled mass spectrometer. Readings from the spectrometer were transmitted back to Earth, where scientists looked for evidence of organic compounds and micro-organisms. But no signs of life were found.

Lederberg was a very competent applied mathematician and, with a colleague, he created some of the first computers. Lederberg was one of the first to realise the potential of computers and artificial intelligence to further biomedical research and molecular biology. He established a new field of scientific research — the acquisition, systematisation, and dissemination of biomedical knowledge using computers. Computer scientists and biologists have drawn on each other’s disciplines. Today’s neuroscientists use computers to evolve models of the human brain and computer engineers use biology, for example, to devise neural networks.

Lederberg was an effective communicator of science, keen on furthering its public understanding and anxious to close the gap between scientists and the public. Between 1966 and 1971, he wrote a weekly column on science, society and public policy in The Washington Post, called Science and Man; it was syndicated to newspapers throughout the US. He firmly believed that governments, with the help of the scientific community, could improve social welfare, control armaments, bring about a just and lasting peace and protect the environment.

Joshua Lederberg was born in Montclair, New Jersey, in 1925. His father, Zvi Lederberg, was an Orthodox rabbi and his mother, Esther Schulman, descended from a long line of rabbinical scholars. His parents immigrated to America from Palestine in 1924 and the family moved to New York when he was 6 months old. Joshua Lederberg was attracted to science at an early age. When he was 7 his ambition was to be like Einstein and “discover a few theories in science”.

Between 1938 and 1940 he attended the Stuyvesant High School, Manhattan, a selective science and technology school. He completed his schooling at the age of 15 but continued experimenting at the American Institute Science Laboratory, an offspring of the 1939 New York World’s Fair. He learnt to prepare and stain tissue samples, to preserve and make visible the details of cell structure, for study under the microscope.

In 1941 he went to Columbia University to study zoology, graduating in 1944. He did his military service between 1943 and 1945 in the US Naval Reserve by doing a compressed medical course at St Albans Naval Hospital, Long Island. Between 1944 and 1946, he studied Medicine at Columbia University College of Physicians and Surgeons. In 1946 he obtained a two-year research fellowship at Yale. He received his PhD from Yale in 1947 for research in genetics.

Just before he was due to return to medical school at Columbia in 1947, Lederberg was offered the post of assistant professor in genetics at the University of Wisconsin, Madison, allowing him to pursue basic genetic research full-time.

In the next few years, he published a number of original research papers. The most important described his discovery of viral transduction — the ability of viruses that infect bacteria to transfer bits of DNA from one infected bacterium to another and insert them into the latter’s genome (the genome of an organism is the organism’s whole hereditary information encoded in its DNA). Transduction has important applications in bacterial genetics and biotechnology, and the use of viruses to manipulate bacterial genomes became the basis of genetic engineering in the 1970s.

Lederberg was appointed Professor of Genetics at the University of Wisconsin, Madison, a post he held until 1959. He then became the first chairman of the newly established Department of Genetics at Stanford University School of Medicine. Then came news that he had been awarded a share of the 1958 Nobel Prize in Physiology or Medicine, “for his discoveries concerning genetic recombination and the organization of the genetic material of bacteria”.