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Male chimps in Japan live longer than females; the oldest died at 68


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Male chimpanzees outlive female ones, with the oldest living until 68 years old, according to a study of primates reared in Japan over the past 100 years.

A Kyoto University team found that the 821 chimps lived an average of 28 years, saying its analysis was the world’s first large-scale study of its kind.

The findings were published in the international journal Primates on Oct. 4.

By comparison, an earlier report released overseas had shown that the average life span for such primates under rearing conditions was 23 years.

A total of 1,017 chimpanzees in Japan were listed on breeding records from 1921 to March 2019, the oldest that of a chimp raised in a circus.

The team analyzed the life spans of 821 primates whose birthplace, such as Africa or Japan, as well as the birth and death year were available.

It found that the creatures lived an average of 28.3 years, with males at 30.3 years outliving females at 26.3 years.

As one-fifth of chimpanzees die within a year, the average life span of those that survived 1 year or more was 34.6 years, with males at 35.7 and females at 33.4.

Five male and 10 female chimps lived 50 years or more, with the longest lives recorded at 68 years for a male and 59 years for a female.

Based on a month-by-month analysis of when they died, January proved to be the most deadly, followed by February and December.

As chimps are native to the tropical zone, Japan’s cold and dry winters may affect their health, and the team recommends that they be carefully reared in winter months.

According to team member Satoshi Hirata, who specializes in primatology, the previous report on the life spans of chimpanzees leaves many questions unanswered.

There is also a wide range for the life span of chimps in the wild between 12.9 to 32.8 years, depending on the living environment and the group it belonged to.

“I want to study the rearing environment, life histories and causes of death (of chimps), and compare the results with those for humans,” Hirata said.

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