Legendary chimpanzee researcher Jane Goodall, 91, has died of natural causes while on a speaking tour in California, the Jane Goodall Institute announced.

Goodall revolutionized ethology by observing chimpanzees using tools in Tanzania’s Gombe Stream National Park, challenging the belief that only humans could make and use tools.

Despite having no formal scientific training, she gained global recognition through a National Geographic documentary and used her fame to advance conservation efforts for chimpanzees and other endangered species.

Born in London in 1934, she began her career under paleoanthropologist Louis Leakey, later marrying cameraman Hugo van Lawick, who documented her groundbreaking work, USA Today has reported.

Goodall’s lifelong dedication to animals and the environment made her one of the most influential conservationists of the 20th century.