The development of the first successful polio vaccine was not without controversy, one of the pioneers of that effort recalled yesterday as he warned that science and controversy will always be inextricably linked.

	John Heller, Post-Gazette University of Pittsburgh Chancellor Mark A. Nordenberg, right, applauds Julius S. Youngner, 84, as he receives an honorary degree in public service during the 2005 Honors Convocation yesterday at Soldiers & Sailors Memorial Hall in Oakland. Click photo for larger image.

But while the vaccine debate was largely a scientific dispute, far more vexing controversies occur when scientific theories conflict with articles of faith, such as with evolution and creationism, said Julius S. Youngner, former chairman of microbiology at the University of Pittsburgh School of Medicine.

"Faith has to be unquestioning; it is belief that does not demand proof and that is not based on proof," Youngner said yesterday as he accepted Pitt's highest honor, an honorary degree in public service, at the university's annual Honors Convocation in Oakland.

"Science, on the other hand, depends on evidence and demands proof. It is inevitable that with many fundamental issues, evolution being only one, the two systems of thought ... are difficult to reconcile."

Youngner, who at age 84 remains an active researcher, joined Pitt in 1949 and became a key member of Dr. Jonas Salk's polio vaccine team. Their vaccine proved to be "one of the greatest victories in the history of medicine," said Pitt Chancellor Mark A. Nordenberg, as he conferred the honorary degree on Youngner before hundreds of people gathered in Soldiers & Sailors Memorial Hall.

A half-century ago, many prominent researchers believed a polio vaccine would have to include a live, but weakened form of the poliovirus to be effective. The Pitt team ultimately proved that their killed-virus vaccine would indeed work.

"Time has proved that both sides of this debate were correct," Youngner said yesterday, noting the killed-virus vaccine and the later oral vaccine that used a live, attenuated virus both helped largely to eradicate polio from the globe.

The debate over evolution is not so easily put to rest. Charles Darwin may not have gotten everything correct when he published his theory of evolution in 1859, Youngner said, but the mass of evidence accumulated since then has convinced most scientists that evolution is the determining factor in the development of the biological world.

"In spite of all this evidence, a large portion of our population clings to an unyielding denial of the validity of evolution," he said.

Youngner compared this denial of evidence to astronomer Galileo being convicted of heresy in 1633 because he had concluded that Earth and the planets orbited the sun.

"This evidence was in direct contradiction to the church ruling that the Bible stated clearly that the sun traveled around the Earth," he noted.

Controversy will always be part of science, whether the subject is evolution, or embryonic stem cells or global warming, Youngner said.

"I urge you, whatever the arguments, pro or con, presented to you, that you always try to demand proof before making judgments," he said.