Jane Goodall, the conservationist renowned for her groundbreaking chimpanzee field research and globe-spanning environmental advocacy, has died. She was 91.

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 the animals using tools and doing other activities previously believed to be exclusive to humans, and also noted their distinct personalities.

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.

In her later years, Goodall devoted decades to education and advocacy on humanitarian causes and protecting the natural world. In her usual soft-spoken British accent, she was known for balancing the grim realities of the climate crisis with a sincere message of hope for the future.