The Price of Play: Self-Organized Infant Mortality Cycles in Chimpanzees

Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
PLoS ONE (Impact Factor: 3.23). 02/2008; 3(6):e2440. DOI: 10.1371/journal.pone.0002440
Source: PubMed


Chimpanzees have been used extensively as a model system for laboratory research on infectious diseases. Ironically, we know next to nothing about disease dynamics in wild chimpanzee populations. Here, we analyze long-term demographic and behavioral data from two habituated chimpanzee communities in Taï National Park, Côte d'Ivoire, where previous work has shown respiratory pathogens to be an important source of infant mortality. In this paper we trace the effect of social connectivity on infant mortality dynamics. We focus on social play which, as the primary context of contact between young chimpanzees, may serve as a key venue for pathogen transmission. Infant abundance and mortality rates at Taï cycled regularly and in a way that was not well explained in terms of environmental forcing. Rather, infant mortality cycles appeared to self-organize in response to the ontogeny of social play. Each cycle started when the death of multiple infants in an outbreak synchronized the reproductive cycles of their mothers. A pulse of births predictably arrived about twelve months later, with social connectivity increasing over the following two years as the large birth cohort approached the peak of social play. The high social connectivity at this play peak then appeared to facilitate further outbreaks. Our results provide the first evidence that social play has a strong role in determining chimpanzee disease transmission risk and the first record of chimpanzee disease cycles similar to those seen in human children. They also lend more support to the view that infectious diseases are a major threat to the survival of remaining chimpanzee populations.

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Available from: Peter D Walsh, Mar 20, 2015
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    • "We examined mortality data in nine wild non-human primate taxa across three continents to understand how seasonal variation in rainfall and resource availability may act as selection pressures by influencing mortality. Many factors contribute to primate mortality, including disease (Alexander 1974; Dunbar 1980; Milton 1996; Walsh et al. 2005; Kühl et al. 2008; Williams et al. 2008), predation (Cheney et al. 1981; Cheney and Wrangham 1987; Isbell 1994; Karpanty and Wright 2007; Teelen 2008; Irwin et al. 2009), injury during both interspecific and intraspecific interactions (van Schaik and Janson 2000; Cheney et al. 2006; Williams et al. 2008), and starvation (Dittus 1977, 1980; Dunbar 1980; Hamilton 1985). Resource availability for both primates and their predators, or other environmental variables, such as rainfall and temperature, may influence the importance of these different sources of mortality (Dunbar 1980; Richard 1985). "
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    • "With networks, researchers were able to distinguish spatial patterns of disease spillover from epidemic waves [17]. Temporal changes in contact patterns were also identified as critical for the spread of respiratory diseases in wild chimpanzees [70]. Issues of different spatial scales have been tackled with networks, specifically the relative importance of local versus long range transmission events in driving disease spread [68]. "
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