Jane Goodall, whose lifelong work as a primatologist helped broaden the world’s understanding of animal behavior and emotions, has died, her institute said Wednesday. She was 91.

Her field studies with chimpanzees not only broke barriers for women and changed the way scientists study animals, but documented emotions and personality traits within these primates that blurred the line between humans and the animal kingdom.

She passed away due to natural causes in California during a speaking tour in the United States, according to her institute.

“Dr. Goodall’s discoveries as an ethologist revolutionized science, and she was a tireless advocate for the protection and restoration of our natural world,” the institute said in a statement on social media.

Goodall appears in the television special "Miss Goodall and the World of Chimpanzees" originally broadcast on CBS, Wednesday, December 22, 1965, in the Gombe Stream National Park, Tanzania. CBS Photo Archive/Getty Images

The United Nations, which named her a Messenger of Peace in 2002, mourned her death, said on X she “worked tirelessly for our planet and all its inhabitants, leaving an extraordinary legacy for humanity and nature.”

Goodall arrived in Tanzania’s Gombe Stream Chimpanzee Reserve in 1960 at the request of her boss, renowned anthropologist and paleontologist Dr. Louis Leakey.