Effects of Respiratory Outbreaks During Early Life on Lifespan and Survival Probabilities in Wild Eastern Chimpanzees (Pan troglodytes) in Gombe National Park, Tanzania Open Access
Cayless, Grace (Spring 2025)
Abstract
Early life adversity (ELA) has been linked to poor health and behavioral outcomes in many long-lived social mammals, including humans. Currently, the long-term effects of cumulative adversity have only been studied in two primate species, with conflicting results – in female baboons, cumulative ELA predicted a shortened lifespan, while the experience of 3+ sources of ELA was correlated with a 70% reduction in later-life mortality risk for mountain gorillas. Chimpanzees, like humans, exhibit lengthy, defined stages of development, during which they face various sources and magnitudes of adversity while forming complex relationships with conspecifics. This makes them quality models for investigating how ELA influences health and survival outcomes. Health adversity has not been addressed in previous primate studies of ELA, but respiratory outbreaks are known to create severe energetic stress in wild chimpanzees. Therefore, exposure to respiratory outbreaks during development is a potentially significant source of early life adversity. Here, ‘exposure’ refers to being present in a community during a respiratory outbreak, rather than confirmed infection with a specific pathogen. To explore this further, I utilized long-term field data collected on wild chimpanzees living in Gombe National Park, Tanzania to evaluate the impact of exposure to respiratory outbreak during critical developmental windows on lifespan and survival probabilities. I found that experiencing fatal outbreaks in-utero significantly reduced the likelihood of surviving to age 10. However, post-birth exposure to fatal outbreaks in the first five and 10 years of life decreases the risk of death with age, seemingly creating a protective effect. Furthermore, I found that the highest counts of cumulative exposures in the first 10 years of life are associated with a decreased risk of death with age. Overall, my findings suggest that different mechanisms mediate the consequences of in-utero and post-birth respiratory outbreak exposures, such that in-utero exposures have a detrimental impact, while post-birth exposures may bolster immune development. Future research should focus on evaluating the impact of specific pathogens, maternal health, and the timing of exposure during these developmental windows.
Table of Contents
Table of Contents
Overview 1
Respiratory Disease as a Potential Source of Adversity 2
Critical Periods for Exposure 5
In-utero 5
Infancy and Juvenility/Adolescence 6
Purpose and Objectives 8
Methods 8
Demographic Data and Study Subjects 9
Outbreak Periods 10
Analyses 12
In-utero 12
Birth to age five 12
Birth to age 10 13
Results 13
Outbreak Periods 13
In-utero 16
Birth to Age Five 18
Birth to Age 10 20
Discussion 24
Outbreak Periods 24
In-utero Exposure 25
Exposures Throughout Infancy 26
Exposures from Birth Through Juvenility/Adolescence 27
References 32
Supplementary Figures 39
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Effects of Respiratory Outbreaks During Early Life on Lifespan and Survival Probabilities in Wild Eastern Chimpanzees (Pan troglodytes) in Gombe National Park, Tanzania () | 2025-04-08 21:00:56 -0400 |
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