Matthew Stanley Meselson (born May 24, 1930) is a notable geneticist and molecular biologist currently at Harvard University, known for his discovery of messenger RNA as well as semi-conservative DNA replication. After completing his Ph.D under Linus Pauling at the California Institute of Technology, Meselson became a Professor at Harvard University in 1960, where he has remained, today, as Thomas Dudley Cabot Professor of the Natural Sciences.