Jane Goodall, the intellectual, soft-spoken conservationist renowned for her groundbreaking, immersive chimpanzee field research in which she documented the primates’ distinct personalities and use of tools, has died. She was 91.

The environmental advocate became a beloved household name who transcended generations through her appearances in documentaries and on television, as well as her travels to address packed auditoriums around the world.

The Jane Goodall Institute announced the primatologist’s death Wednesday in an Instagram post. According to the Washington, D.C.-based institute, Goodall died of natural causes while in California on a U.S. speaking tour.

Her discoveries “revolutionized science, and she was a tireless advocate for the protection and restoration of our natural world,” it said.

While living among chimpanzees in Africa decades ago, Goodall documented them doing activities previously believed to be exclusive to humans. Her observations and subsequent magazine and documentary appearances in the 1960s transformed how the world perceived not only humans’ closest living biological relatives but also the emotional and social complexity of all animals, while propelling her into the public consciousness.

“Out there in nature by myself, when you’re alone, you can become part of nature and your humanity doesn’t get in the way,” she told The Associated Press in 2021. “It’s almost like an out-of-body experience when suddenly you hear different sounds and you smell different smells and you’re actually part of this amazing tapestry of life.”

She had been scheduled to meet with students and teachers on Wednesday to launch the planting of 5,000 trees around wildfire burn zones in the Los Angeles area. Organizers learned of her death as the event was to begin at EF Academy in Pasadena, said spokesperson Shawna Marino. The first tree was planted in Goodall’s name after a moment of silence.

“I don’t think there’s any better way to honor her legacy than having a thousand children gathered for her,” Marino said.