Dr. Jane Goodall Dead at 91

Jane Goodall, the world-renowned primatologist and chimpanzee expert, has died ... according to a statement posted to her official Instagram account.

According to a statement released by the Jane Goodall Institute ... Jane passed away Wednesday morning in California while on a speaking tour of the United States.

The institute states she died of natural causes but does not specify beyond that.

Dr. Goodall spoke at The Plaza Hotel in New York City one week ago ... and, she was set to speak at a nearly sold-out event in Los Angeles this upcoming Friday.

Jane was one of the world's first female experts on primates, beginning her career by making a trip to Kenya to visit a friend in 1957 and connecting with palaeoanthropologist and archaeologist Louis Leakey.

Leakey helped Jane secure funding to study at Cambridge during the 1960s ... and, she became a preeminent expert on chimpanzees by studying them in the forest at Gombe in Tanzania -- pointing out how similar their personalities were to that of humans.

She was the first researcher to publish that primates used tools ... when it was previously believed only humans did so. Goodall says she received tremendous backlash for her views because she gave human characteristics to animals.

Jane wrote numerous books -- both for adult researchers and children -- through the years ... and, her work was the subject of a series of documentaries, including the critically-acclaimed "Jane" which was drawn from 100 hours of previously unseen footage.

She founded the Jane Goodall Institute in 1977 ... which has poured tons of resources into conservation and development in Africa since its founding.

Goodall made her mark on pop culture as well ... with Stevie Nicks writing the song "Jane" about her. Joe Biden awarded her the Presidential Medal of Freedom just before he left office in January of this year.

We last caught up with Jane Goodall in 2016 ... and, she advocated for more movies to use CGI animals instead of real ones like the 2016 'Jungle Book' film.

Jane was married twice ... to wildlife photographer Hugo van Lawick from 1964 until they divorced in 1974 and to farmer Derek Bryceson from 1975 until he died in 1980.

She was 91.