(NEXSTAR) – Conservationist and preeminent chimpanzee expert Jane Goodall died at the age of 91, the Washington D.C.-based Jane Goodall Institute announced on Wednesday.

Goodall was in California as part of her speaking tour and was scheduled to speak in Los Angeles Friday.

The research organization said they learned Wednesday that "Dr. Jane Goodall DBE, UN Messenger of Peace and Founder of the Jane Goodall Institute, has passed away due to natural causes." It's not yet clear when she died. • Jane Goodall, British ethologist, kisses Pola, a 14-months-old chimpanzee baby of the Budapest Zoo, that she symbolically adopted in Budapest, Hungary, on Monday, Dec. 20, 2004. (AP Photo / Bela Szandelszky) • Anthropologist Jane Goodall goes through slides before making presentation in Chicago

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