Chuck Bednar for redOrbit.com – @BednarChuck
Conventional wisdom indicates that larger species live longer than smaller ones, but lemurs are on notable exception to that rule, and researchers from Duke University believe that the secrets of their longevity could lead to new insights into the aging process.
In January, the world’s oldest known dwarf lemur, Jonas, passed away, and inspired Sarah Zehr and Marina Blanco of the Duke Lemur Center in Durham, North Carolina to analyze over 50 years worth of medical records pertaining to his species and three other types of lemurs.
Suspended animation, suspended life
Dwarf lemurs live two to three times longer than similar-sized animals, they explained, and the duo was searching for clues to help explain their longevity. They found that these hamster-sized creatures are actually capable of placing their bodies in suspended animation to prevent aging.
How long the animals live and how quickly they age directly correlates with the amount of time they spend in this state, which is known as torpor and is comparable to the standby or sleep mode feature found in many modern electronic devices. Lemurs that enter this state and put their body functions on hold can outlive those that don’t by up to 10 years, the data revealed.
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Jonas was one of the most extreme examples found in the study, the researchers said. While in the wild, he spent up to half the year in this state of deep hibernation. Most dwarf lemurs go into a semi-hibernation state for no more than three months in captivity, Zehr said, but that was still enough to give them added longevity.
Hibernating dwarf lemurs can reduce their heart rate from 200 to eight beats per minute, she added. Their breathing slows and their internal thermostat shuts down, meaning that instead of maintaining a steady body temperature, they warm and cool along with their environment.
Ahhhh, torpor
In many primates, this could be life threatening, but the researchers found that lemurs use this trait to conserve energy during times when food and water are scarce. In addition to helping them live longer, torpor allows them to remain healthier and able to reproduce for more than twice as long as normal (six years post-maturity for non-hibernators, up to 14 for hibernators).
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While the species they examined suffered from cataracts and other age-related eye diseases as they got older, the hibernators were able to fight off symptoms until they were far older. Some experts have suggested that hibernating allows lemurs to live longer and remain healthy because it allows them to avoid predators, but the Duke team believes there is more to it than that.
“The fact that we see the same pattern in captivity, where they’re protected from predators, suggests that other factors are at work,” said Zehr, whose research was supported by the Rufford Foundation, MMBF/Conservation International Primate Action Fund, Primate Conservation, Inc. and the Margot Marsh Biodiversity Foundation.
Blanco noted that torpor could also be increasing longevity by protecting cells against oxidative damage, a regular side-effect of breathing and metabolism. “If your body is not ‘working full time’ metabolically-speaking, you will age more slowly and live longer,” she explained.
Since lemurs are more closely related to humans than mice are, the findings could ultimately help scientists identify genes that can help prevent aging in humans as well. The findings have been published online in the Journal of Zoology.
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