Wild chimpanzees have long life spans: Study

Chimpanzees living in the wild -- with favourable ecological factors, abundant supply of high-energy and nutritious foods and low predation levels -- can have long life spans, a study has found.

"Our findings show how ecological factors, including variation in food supplies and predation levels, drive variation in life expectancy among wild chimpanzee populations," said lead author of the study Brian Wood, Assistant Professor at Yale University.

In the study, published in the Journal of Human Evolution, the team analysed a sample of 306 chimpanzees of a community, called Ngogo, at Kibale National Park in Uganda.

They found that these chimpanzees had an average life expectancy of about 33 years, nearly twice as high as that of other chimpanzee communities and within the 27 to 37-year range of life expectancy at birth of human hunter-gatherers.

 

According to the study, favourable ecological conditions largely account for the Ngogo community's high life expectancy -- the highest on record for any group of wild chimpanzees.

The forest in Ngogo provides a relatively consistent and abundant supply of high-energy and nutritious foods, including easily digestible figs.

This rich food supply helps buffer the Ngogo chimpanzees against periods of hunger, and helps fuel their ability to stave off diseases that would otherwise lead to higher mortality, the research said.

Further, the Ngogo chimpanzees also benefit from a low risk of predation, no major disease epidemics, either introduced by humans or due to other causes, like those that have affected wild chimpanzees at several other research sites.

The study is important for understanding the evolution of chimpanzees and hominin life histories as they help us to imagine the conditions that could have changed mortality rates among our early hominin populations, Wood said.

"It has long been proposed that there are extreme differences in the life expectancies of human hunter-gatherers and chimpanzees," said David Watts, Professor at Yale University.

"In fact, the Ngogo community's pattern of survivorship more closely resembles that of human hunter-gatherers than those documented for other chimpanzee communities," he said.

--IANS

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