Australian physicist Sir Robert May has won a prize of 500,000 Swiss francs (Pounds 214,000) from the Italo-Swiss International Balzan Foundation. Sir Robert, chief scientific advisor to the British government, was given the award for his contributions to the mathematical analysis of biodiversity, in particular his pioneering work on chaos theory and ecological systems, and the development of methods for estimating the total number of species alive on earth today and their rates of extinction. Similar prizes went to Andrzej Walicki (United States) for his work on the cultural and social history of the Slavonic world from the reign of Catherine the Great to the Russian revolutions of 1917 and to Harmon Craig (US) for geochemistry.