Zhores A. Medvedev, the Soviet biologist, writer and dissident who was declared insane, confined to a mental institution and stripped of his citizenship in the 1970s after attacking a Stalinist pseudoscience, died on Thursday at his home in London, where he had lived for decades. He had turned 93 the day before.
Dr. Medvedev’s twin brother, the historian Roy Medvedev, told the Russian news media that the cause was a heart attack. He said his family had celebrated Dr. Medvedev’s birthday on Wednesday.
“He had never complained about his heart,” he told RBC, a Russian news agency. “Three ambulances came, but they weren’t able to save him.”
With Roy Medvedev, the physicist Andrei D. Sakharov, the author Aleksandr I. Solzhenitsyn and others, Dr. Medvedev was a central figure in the seething intellectual dissidence that exposed, largely through underground literature known as samizdat, the repression of ideas, science and human rights in the Soviet Union.
Dr. Medvedev played a large role in discrediting the doctrines of Stalin’s director of biology, Trofim D. Lysenko, who was behind a pseudoscience known as Lysenkoism. He also gave the world shocking accounts of the Soviet practice of committing political dissenters to mental institutions, campaigned for greater freedoms for Soviet scientists and writers to study and travel abroad, and exposed a 1957 nuclear disaster in the Urals, one of the worst of the nuclear age.
Dr. Medvedev was an authority on biochemistry, gerontology and molecular evolution and wrote many scientific papers as well as biographies of Soviet leaders and dissidents, and books on the hazards of nuclear power.
A son of a Leningrad State University Marxist philosopher who was arrested in Stalin’s purges in the 1930s and died in Siberia, Dr. Medvedev remained loyal to his country and to the Communist Party. But he fell into disfavor with the Soviet authorities in the 1960s by openly opposing Lysenko in the last years of his reign of power.
For decades, that reign had corrupted Soviet agricultural sciences, contributed to disastrous crop failures and famines after the forced collectivization of farms, and led to the imprisonment, expulsion and deaths of hundreds of his academic and political opponents.