Causes of death in the Kasekela chimpanzees of Gombe National Park, Tanzania

Abstract

Understanding the rates and causes of mortality in wild chimpanzee populations has important implications for a variety of fields, including wildlife conservation and human evolution. Because chimpanzees are long-lived, accurate mortality data requires very long-term studies. Here, we analyze 47 years of data on the Kasekela community in Gombe National Park. Community size fluctuated between 38 and 60, containing 60 individuals in 2006. From records on 220 chimpanzees and 130 deaths, we found that the most important cause of mortality in the Kasekela community was illness (58% of deaths with known cause), followed by intraspecific aggression (20% of deaths with known cause). Previous studies at other sites also found that illness was the primary cause of mortality and that some epidemic disease could be traced to humans. As at other study sites, most deaths due to illness occurred during epidemics, and the most common category of disease was respiratory. Intraspecific lethal aggression occurred within the community, including the killing of infants by both males and females, and among adult males during the course of dominance-related aggression. Aggression between communities resulted in the deaths of at least five adult males and two adult females in the Kasekela and Kahama communities. The frequency of intercommunity violence appears to vary considerably among sites and over time. Intercommunity lethal aggression involving the Kasekela community was observed most frequently during two periods. Other less common causes of death included injury, loss of mother, maternal disability, and poaching.

Evolution of the human lifespan and diseases of aging: Roles of infection, inflammation, and nutrition

“…The main cause of mortality throughout human evolution until the 20th century must have been infections, as observed in wild chimpanzees and 20th-century hunter-foragers. Longitudinal studies of the Gombe chimpanzees (Tanzania) since 1960 by Goodall and colleagues identified infections in the majority of deaths (67%) for all ages (Table 2) (15). The oldest individuals frequently had prolonged diarrhea (16, p 104).…”

“…Remarkably, no spontaneous mammary carcinoma has been reported in the great apes. In males 25 years and older, benign prostatic hyperplasia is common, and associated with clinical-grade blood prostate-specific (15,16). This table excludes deaths from poaching and predation; deaths of dependent offspring from maternal death or disability; and from unknown causes.…”

“…Wasting is described as "a conglomerate of enteric diseases, parasitic infections, or perhaps cancer or AIDS-like disease"; some were positive for streptococci and nematode parasites. The life history of the oldest individuals is known in detail (15,16). Two elderly males aged 41 (Evered and Huxley) died of infected wounds, which I represented as infections.…”

How grandmother effects plus individual variation in frailty shape fertility and mortality: Guidance from human–chimpanzee comparisons

“…In captivity it is 29 years (66). This doubling of chimpanzee life expectancy is associated with reductions in rates of infection and nutritional stress (38,116). In both chimpanzees and humans, improvements in nutrition and hygiene combined with medical interventions can double life expectancy.…”

Vaccinating captive chimpanzees to save wild chimpanzees

“…These assays tell us that wild apes are regularly infected by a variety of virulent pathogens, including simian immunodeficiency virus (SIV) (1), anthrax (2), and malaria (3). The ethical finger has been pointed squarely and quantitatively at researchers and conservationists with the discovery that "spillover" of human respiratory viruses cause about half of deaths among chimpanzees (4,5) and gorillas (6) habituated to human approach for research or tourism. Even more widely recognized have been massive Ebola virus (EBOV) outbreaks in gorillas and chimpanzees (7,8), which have killed roughly one-third of the world gorilla population and led to the 2007 upgrading of western gorillas to Critically Endangered status on the World Conservation Union's Red List of Threatened Species (9).…”