Nav: Home

Aging bonobos in the wild could use reading glasses too

November 07, 2016

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."

While it might have looked amusing, the researchers began to appreciate that this long-sightedness, caused by a decline in the refractive power of the crystalline lens with age, might also have serious consequences for the survival and social lives of those older animals.

To learn more, the researchers used digital photographs to measure the grooming distance of 14 wild bonobos of various ages, ranging from 11 to 45 years old. They also examined how grooming distance varied in relation to age and sex in bonobos and compared it with the nearest focus distance in humans.

The measurements showed that the grooming distance increased exponentially with age. In one case, an old video of one of the bonobos, named Ki, enabled them to show that his eyesight had worsened over time.

"The results we found were very surprising even for us," Ryu says. "When I started to collect data, I did not expect that age could be such a strong predictor of long-sightedness."

Ryu says that long-sightedness might hinder the social lives of older individuals, explaining why older individuals aren't favored when it comes to selecting grooming partners. People who grow long-sighted with age also have particular trouble seeing in the dark, he adds. That could be a big challenge for the bonobos, living as they do in the shade of the rainforest canopy.

As for us humans, the findings in our bonobo relatives suggest that long-sightedness isn't a consequence of the modern lives we lead and all that time spent reading or staring at a screen. Rather, it's a natural process of aging rooted deep in our past. Ryu says that they plan to continue studying aspects of aging in bonobos to learn more about them and us.
-end-
This study was supported by the Japan Society for the Promotion of Science, the Grants-in-aid for Scientific Research, and the JSPS Core-to-Core, and admitted by the Ministry of Scientific and Technological Research of the D.R. Congo.

Current Biology, Ryu et al.: "Long-sightedness in old wild bonobos during grooming" http://www.cell.com/current-biology/fulltext/S0960-9822(16)31068-5

Current Biology (@CurrentBiology), published by Cell Press, is a bimonthly journal that features papers across all areas of biology. Current Biology strives to foster communication across fields of biology, both by publishing important findings of general interest and through highly accessible front matter for non-specialists. Visit: http://www.cell.com/current-biology. To receive Cell Press media alerts, contact press@cell.com.

Cell Press

Related Aging Articles:

Brain development and aging
The brain is a complex organ -- a network of nerve cells, or neurons, producing thought, memory, action, and feeling.
Aging gracefully in the rainforest
In an article that appears in the current issue of Evolutionary Anthropology, researchers synthesize over 15 years of theoretical and empirical findings from long-term study of the Tsimane forager-farmers.
Reversing aging now possible!
DGIST's research team identified the mechanism of reversible recovery of aging cells by inducing lysosomal activation.
Brain-aging gene discovered
Researchers at Columbia University Medical Center have discovered a common genetic variant that greatly affects normal brain aging in older adults.
Aging can be good for you (if you're a yeast)
It's a cheering thought for anyone heading towards their golden years.
More Aging News and Aging Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Teaching For Better Humans
More than test scores or good grades — what do kids need to prepare them for the future? This hour, guest host Manoush Zomorodi and TED speakers explore how to help children grow into better humans, in and out of the classroom. Guests include educators Olympia Della Flora and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#534 Bacteria are Coming for Your OJ
What makes breakfast, breakfast? Well, according to every movie and TV show we've ever seen, a big glass of orange juice is basically required. But our morning grapefruit might be in danger. Why? Citrus greening, a bacteria carried by a bug, has infected 90% of the citrus groves in Florida. It's coming for your OJ. We'll talk with University of Maryland plant virologist Anne Simon about ways to stop the citrus killer, and with science writer and journalist Maryn McKenna about why throwing antibiotics at the problem is probably not the solution. Related links: A Review of the Citrus Greening...