The Pope has picked a Protestant to head the Vatican's sciences academy.
Benedict XVI chose Werner Arber, a Swiss molecular biologist who shared the Nobel Prize for Medicine in 1978, as president of the Pontifical Academy of Sciences.
A Vatican spokesman, Father Ciro Benedettini, said it is the first time a non-Roman Catholic has led the academy in its four centuries of history.
The academy help pontiffs understand scientific advances in fields ranging from genetics to nuclear physics.
Mr Arber became a member in 1981.
Other non-Catholics who have been prominent academy members, but not president, include Rita Levi Montalcini, an Italian Jew and 1986 Nobel winner for medicine.