Aging bonobos in the wild could use reading glasses too

https://www.eurekalert.org/pub_releases/2016-11/cp-abi102816.php

Public Release: 7-Nov-2016
Aging bonobos in the wild could use reading glasses too
Cell Press

As people age, they often find that it's more difficult to see things up close. Reading a newspaper suddenly requires a good pair of reading glasses or bifocals. Now, researchers reporting in the Cell Press journal Current Biology on November 7 find that the same goes for bonobos, one of human's closest primate relatives along with chimpanzees, even though they obviously don't read.

This long-sightedness in bonobos is most evident as older animals engage in grooming their peers, the researchers say. The older they get, the longer they stretch their arms from the rest of their bodies as they groom.

"We found that wild bonobos showed the symptoms of long-sightedness around 40 years old," says Heungjin Ryu of the Primate Research Institute of Kyoto University. "We were surprised that the pattern found in bonobos is strikingly similar to the pattern of modern humans. This suggests that senescence of the eyes has not changed much from the Pan-Homo common ancestor, even though the longevity of modern humans is far longer than that of chimpanzees and bonobos."

Ryu says that researchers had already noticed this trend of bonobos needing longer distances for grooming before. There had also been anecdotal reports in chimpanzees. It's just that no one paid much attention to it.

"One day, I was with another researcher and observed the oldest male bonobo Ten (TN) grooming Jeudi (JD)," Ryu recalls. "TN had to stretch his arm to groom JD, and only when he found something on JD's body would he come close to remove it using his mouth. It was funny to see how he groomed."

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