Did life begin virtually simultaneously on Earth and Mars some 3.5 billion years ago? That hypothesis, first aired at a press conference held by the National Aeronautics and Space Administration (NASA) in the USA in August 1996, served as the main point of discussion at a public lecture by J. William Schopf, professor of paleobiology at the University of California, Los Angeles, USA, at the ICTP on 20 September. Schopf's lecture, presented before a packed house in the Kastler Lecture Hall at the Adriatico Guesthouse, was one of the highlights of the Sixth Trieste Conference on Chemical Evolution. The conference received extensive coverage in the Italian press, including feature articles in the Corriere della sera, la Repubblica, La Stampa and il Giornale.