Complex sentence: He attended Columbia University, where he received a B.A. in 1951, an M.A. in 1954 and a Ph.D. degree in 1959, and subsequently taught until 1971, when he became professor of sociology at McGill University.
Split into simpler sentences: He attended Columbia University, where he received a B.A. in 1951, an M.A. in 1954 and a PhD degree in 1959. He subsequently taught until 1971, when he became professor of sociology at McGill University.