Marshall D. Sahlins, a brilliant and witty anthropologist who, starting in the 1970s, explored how individuals shape and are shaped by their cultures — a point he had already put in practice a decade earlier as the inventor of the “teach-in” against the Vietnam War — died on April 5 at his home in Chicago. He was 90.

His son, Peter Sahlins, a historian at the University of California, Berkeley, confirmed the death.

Professor Sahlins had not fully developed his ideas about culture when, in March 1965, he and several colleagues from the University of Michigan gathered in his living room to discuss what they could do to oppose President Lyndon B. Johnson’s escalation of the war.

Some wanted to go on strike, a move that threatened to shut down the university and, Professor Sahlins worried, harm the students they were there to instruct. Instead, he said, taking a page from the sit-in protests of the civil rights movement, what if they set aside their syllabuses and gave lectures about America’s foreign policy, politics and history?

Professor Sahlins called friends at Columbia, where he had received his Ph.D., and other schools, and within weeks faculty at dozens of campuses were holding teach-ins. In May 1965, Professor Sahlins led a national teach-in in Washington that received worldwide news media coverage.

His activism didn’t stop the war, of course. But the teach-in created an intellectual bridge between older leftists like Professor Sahlins and the budding activists of the baby boom generation. And as one of the earliest high-profile protests against America’s intervention in Vietnam, it set a template for future antiwar activism.

It also signaled something of an intellectual turn for Professor Sahlins. Until then he had been a committed materialist, convinced that cultures evolved along with technological development. His undergraduate mentor at Michigan, Leslie A. White, was a leading figure in the effort to turn anthropology into something of a science; he even devised equations purporting to measure cultural evolution as a function of a society’s ability to produce energy.

But as the 1960s progressed, Professor Sahlins grew disenchanted with elements of his mentor’s view, in part because it valorized America’s technologically advanced culture at a time when he was fiercely opposed to its military aggression in Vietnam.