Jane Goodall's cause of death has been revealed.
Weeks after the primatologist's death at 91, reports have emerged that she died of "cardiopulmonary arrest," or cardiac arrest, according to TMZ, who cited her death certificate.
The certificate, which was issued by the County of Los Angeles Department of Public Health, also stated that the conservationist also had epilepsy, although it is not clear whether that was a factor in her death.
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Goodall passed away on Oct. 1 in California during a U.S. speaking tour, as Fox News Digital previously reported.
The Jane Goodall Institute (JGI) initially reported that she died "due to natural causes." Fox News Digital reached out to JGI requesting comment.
Cardiac arrest occurs when an electrical issue causes the heart to stop beating, health experts confirm.
When the heart is no longer pumping blood, it causes the person to become unconscious and can lead to death within minutes.
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Before losing consciousness, someone experiencing cardiac arrest may have symptoms including heart palpitations, chest pain, nausea, vomiting, shortness of breath, dizziness, lightheadedness and weakness, per Cleveland Clinic.
This is different from a heart attack (myocardial infarction), which occurs when a coronary artery is blocked, cutting off blood supply and causing injury to the heart muscle, according to the American Heart Association.
Certain groups face a higher risk of cardiopulmonary arrest - including older people, males, and people who have other cardiovascular risk factors, such as high cholesterol, blood pressure and diabetes.
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Those who are obese, are inactive or have a smoking habit are also at a higher risk, according to Mayo Clinic.
Other higher-risk groups include those with congenital heart defects or disorders, structural heart problems, or a history of coronary artery disease or heart failure.
After Jane Goodall's death, JGI issued a statement saying, "Dr. Goodall's discoveries as an ethologist revolutionized science, and she was a tireless advocate for the protection and restoration of our natural world."
Goodall's fascination with primates began at an early age. She earned a PhD in ethology from the University of Cambridge in the mid-1960s, one of few students admitted without holding a prior bachelor's degree.
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In 1960, she discovered that chimpanzees can use and make tools, which the JGI called "one of the greatest achievements of twentieth-century scholarship." She founded her institute, which has become a prominent conservation NGO, in 1977.
"She took an unorthodox approach in her field research, immersing herself in their habitat and their lives to experience their complex society as a neighbor rather than a distant observer and coming to understand them not only as a species, but also as individuals with emotions and long-term bonds," the JGI's site notes.
In 1991, she founded the Roots & Shoots program, a youth movement focused on conservation and humanitarianism.
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Most recently, Goodall was given the Presidential Medal of Freedom by former President Joe Biden at the beginning of 2025.
Fox News Digital's Brooke Curto contributed reporting.
