Complex sentence: He taught at Carleton University between 1972 and 1984, and has been a Professor of Political Science at York University since 1984, serving as the Chair of the Department of Political Science from 1988-1994.
Split into simpler sentences: He taught at Carleton University between 1972 and 1984. He has been a Professor of Political Science at York University since 1984, during which time he served as the Chair of the Department of Political Science from 1988-1994.