Lysenkoism (Russian: Лысе́нковщина, romanized: Lysenkovshchina) was a political campaign conducted by Trofim Lysenko, his followers and Soviet authorities against genetics and science-based agriculture. Lysenko served as the director of the Soviet Union's Lenin All-Union Academy of Agricultural Sciences. Lysenkoism began in the late 1920s and formally ended in 1964.
The pseudoscientific ideas of Lysenkoism assumed the heritability of acquired characteristics (Lamarckism). Lysenko's theory rejected Mendelian inheritance and the concept of the "gene"; it departed from Darwinian evolutionary theory by rejecting natural selection. Proponents falsely claimed to have discovered, among many other things, that rye could transform into wheat and wheat into barley, that weeds could spontaneously transmute into food grains, and that "natural cooperation" was observed in nature as opposed to "natural selection". Lysenkoism promised extraordinary advances in breeding and in agriculture that never came about.
Joseph Stalin supported the campaign. More than 3,000 mainstream biologists were fired or even sent to prison, and numerous scientists were executed as part of a campaign instigated by Lysenko to suppress his scientific opponents. The president of the Agriculture Academy, Nikolai Vavilov, was sent to prison and died there, while scientific research in the field of genetics was effectively destroyed until the death of Stalin in 1953. Research and teaching in the fields of neurophysiology, cell biology, and many other biological disciplines was also negatively affected or banned.
In modern usage, the term lysenkoism has become distinct from normal pseudoscience. Where pseudoscience pretends to be science, lysenkoism aims at attacking the legitimacy of science itself, usually for political reasons. It is the rejection of the universality of scientific truth, and the deliberate defamation of the scientific method to the level of politics.