Sidebar: Things Known and Unknown
Heart disease in gorillas is not hardening of the arteries, a problem common among humans. Rather, it most resembles a condition in people caused by high blood pressure. The heart must work harder to pump blood, and over time, this causes the heart muscle to thicken.
Heart disease is definitely a problem for male gorillas. It can show up in animals as young as eight or ten, but most commonly manifests itself in the 20s. Some victims die quickly; others may live with the disease to a ripe old age. Scientists are still learning why.
Although the focus has been on male gorillas, female gorillas and the other great ape species (bonobos, chimpanzees, and orangutans) are also dying of heart disease. “At this point, we can’t even say it’s worst among gorillas, because we’re just at the tip of the iceberg,” says Hayley Murphy.
Obesity appears to play a role in gorillas’ heart disease. Animals that survive past the point where the disease hits hardest are not as heavy as those that succumb, Pam Dennis has found. She cautions, however, that the data may be skewed. Zoos are likely to perform cardiac exams on those animals they are most worried about, such as the overweight.
Other risk factors remain a mystery. Researchers are looking into a whole host of possibilities, including genetics, the stress of social interactions among apes, personality types (yes, there are type-A gorillas), and various dietary issues, such as calorie intake, fiber, and salt used in processing biscuits that zoos have fed to apes.
Some people have suggested that Afromomum melegueta, a ginger plant with anti-inflammatory properties that gorillas are believed to eat in the wild, protects against heart disease. But most experts think the answer is not that simple. Besides, we know little about incidence of heart disease among wild gorillas, especially the western lowland subspecies, which accounts for all the gorillas now living in U.S. zoos.
If you have a comment about Smithsonian Zoogoer magazine, please email it to us.Smithsonian Zoogoer 40(6) 2011. Copyright 2011 Friends of the National Zoo. All rights reserved.