Matthew Stanley Meselson (born May 24, 1930) is a geneticist and molecular biologist currently at Harvard University, known for his demonstration, with Franklin Stahl, of semi-conservative DNA replication.

Many of his past students are notable biologists, including Nobel Laureate Sidney Altman, as well as Mark Ptashne, Susan Lindquist, Stephen F. Heinemann, and Richard I. Morimoto.

After searching for options, he enrolled at the University of Chicago at the age of 16 in 1946 intending to study chemistry, since it did not require a high school diploma to attend.

As a graduate student of Linus Pauling in chemistry at the California Institute of Technology (1953-1957), Meselson's doctoral dissertation was on equilibrium density gradient centrifugation and on x-ray crystallography.

[5] In order to test hypotheses for how DNA replicates, Meselson and Stahl, together with Jerome Vinograd, invented a method that separates macromolecules according to their buoyant density.

Meselson and his colleagues have recently demonstrated that Bdelloid rotifers do, in fact, engage in sexual reproduction employing meiosis of an atypical sort.

[18] In 1963 Meselson served as a resident consultant in the US Arms Control and Disarmament Agency, where he became interested in chemical and biological weapons programs and policies.

Concluding that biological weapons served no substantial military purpose for the US and that their proliferation would pose a serious threat and that, in years ahead, the exploitation of advanced biology for hostile purposes would be inimical to society generally, he worked to persuade members of the Executive Branch, the Congress and the public that the US had no need for such weapons and that there would be benefits in renouncing them and working for worldwide prohibition.

During August and September 1970, on behalf of the American Association for the Advancement of Science, Meselson led a team in the Republic of Vietnam in a pilot study of the ecological and health effects of the military use of herbicides.

[19][20][21] Upon returning to Harvard, he and Robert Baughman developed an advanced mass-spectrometric method for analysis of the toxic herbicide contaminant dioxin and applied it to environmental and biomedical samples from the Vietnam and the US.

[23][24][25][26] In April 1980 Meselson served as a resident consultant to the CIA investigating a major outbreak of anthrax among people in the Soviet city of Sverdlovsk.

He concluded that on the basis of available evidence the official Soviet explanation that the outbreak was caused by consumption of meat from infected cattle was plausible but that there should be an independent on-site investigation.

Their reports conclusively showed that the official Soviet explanation was wrong and that the outbreak was caused by the release of an anthrax aerosol at a military biological facility in the city.