inputs: hypothesis: Rita Levi-Montalcini has never gotten married. premise: Most centenarians attribute their great age to some magic elixir or other. The longevity of the Italian scientist Rita Levi-Montalcini, who this week became the first Nobel Prize-winner to reach the age of 100, might be the result of a potion that is a little out of the ordinary: Professor Levi-Montalcini, it is said, puts her undiminished mental vigour down to regular doses of nerve growth factor (NGF) - the discovery that made her famous. She was awarded the 1986 Nobel Prize for Medicine jointly with an American, Stanley Cohen, for her research into NGF: the proteins and amino-acids which enable the cells of the nervous system to grow and take on specialised tasks. Despite her age, Dr Levi-Montalcini, a neurologist and development biologist, still works every day at the European Brain Research Institute, which she founded in Rome.