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The Vatican will include discussion of intelligent design in a conference marking the 150th anniversary of Charles Darwin's "On the Origin of Species," officials said Tuesday.

The announcement reverses a decision to exclude such discussion but officials said intelligent design would be treated only as a cultural phenomenon — not as science or theology.

Organizers of the March 3-7 conference did not explain at a news conference Tuesday why they had decided to include discussion of the view that life is too complex to have developed through evolution alone, and that a higher power has had a hand in changes among species over time.

"The committee agreed to consider ID as a phenomenon of an ideological and cultural nature, thus worthy of a historic examination, but certainly not to be discussed on scientific, philosophical or theological grounds," said Saverio Forestiero, a conference organizer and professor of zoology at the University of Rome.

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The Vatican under Benedict has been trying to stress its belief that there is no incompatibility between faith and reason, and the evolution conference is supposed to be a key demonstration of that.

Church teaching holds that Catholicism and evolutionary theory are not necessarily at odds. But the Vatican's position became somewhat confused in recent years, in part because of a 2005 New York Times op-ed piece penned by a close collaborator of Pope Benedict XVI, Austrian Cardinal Christoph Schoenborn.

In the piece, Schoenborn seemed to back intelligent design and dismissed a 1996 statement by Pope John Paul II that evolution was "more than just a hypothesis." Schoenborn said the late pope's statement was "rather vague and unimportant."

Vatican officials later made clear they didn't believe intelligent design was science and that teaching it alongside evolutionary theory in school classrooms only created confusion.

The conference is being hosted by Rome's Pontifical Gregorian University, along with the Vatican's Pontifical Council for Culture and the University of Notre Dame in the U.S. state of Indiana.