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Clues to the origin of the virus that causes AIDS continue to emerge from studies of African viruses. But African countries have more pressing concerns.
Between April and June 1946, Joshua Lederberg and Edward L. Tatum carried out a series of experiments that proved that bacteria can exchange their genes by sexual crossings. The experiments were reported in Nature just 40 years ago1. In the following pair of articles, Joshua Lederberg first provides a personal reminiscence of the circumstances of the discovery and then, together with Harriet Zuckerman, considers it as a possible case of ‘postmature’ scientific discovery.
