Jane Goodall Cause of Death Revealed

Dr. Jane Goodall, the world-renowned primatologist and chimpanzee expert, died earlier this month ... and TMZ has learned the cause.

According to the death certificate ... Goodall's cause of death is listed as cardiopulmonary arrest -- which is just another name for cardiac arrest, an incident where the heart simply stop beating.

Risk of cardiopulmonary arrest goes up as a person gets older ... so, this cause of death isn't totally surprising -- and, it's considered natural.

Jane also had epilepsy according to the death certificate ... unclear if that played a factor at all in her passing.

As we previously reported ... Jane passed away October 1 in California while on a speaking tour of the United States.

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 paleoanthropologist and archaeologist Louis Leakey.

Dr. Goodall famously observed chimpanzees using tools ... completely challenging the perceptions surrounding the animals.

She was 91 years old.