Cute Lemur a Boon for Long-Duration Spaceflight?

Could one of the world's smallest primates hold the secret to sleep, hibernation and making long-duration space flight a little more bearable? Continue reading →

The next giant leap for mankind will be when we send humans, not robots, on deep space sojourns. But our biology is a huge limiting factor. Using current propulsion techniques, a trip to Mars will take a minimum of six months, whereas a voyage to the outermost reaches of the solar system will take years. Even assuming some propulsion tech breakthrough, traveling to our nearest star will take a generation or two. Health problems, age-related brain degeneracy, death and life-sucking boredom will undoubtedly ensue. Not to mention feuds between spaceship crew members that could last decades.

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To conveniently side-step the human condition in deep space, many science fiction ideas have been thrown around - such as an extended cryo-sleep so space explorers can enter a kind of suspended animation for the journey. But the effect of cryogenics on human physiology is poorly understood and there is much debate surrounding the "freeze away the light-years" idea.

However, genetic help may be at hand in the form of the tiny primate, Cheirogaleus medius - the fat-tailed dwarf lemur.

This little Madagascar resident is one of the world's smallest primates and it has a surprising talent: it is the only known primate that can hibernate. It is therefore the closest genetic cousin to humans that hibernates. Strangely, it hibernates during warm periods when its habitat is at its driest - normally, hibernating mammals enter dormancy during freezing, winter periods; C. medius does just the opposite.

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In a study published in PLOS One on Wednesday, researchers of Duke University investigated the hibernation talents of C. medius to reach a fascinating - and possibly groundbreaking - conclusion. Studying the lethargic state of these cute little primates may aid the treatment of heart attack, stroke and head trauma victims. It might also provide a tantalizing clue to the long-duration human space exploration problem.

"It is the closest genetic relative to humans that hibernates and is therefore the most likely to be providing useful information to understanding things like what is the capacity to induce hibernation-like states in humans," said psychiatrist Andrew D. Krystal, director of Duke's medical school's sleep laboratory, in an interview with Los Angeles Times.

"If we wanted to travel to some point in outer space that took 100 years, how could we possibly do it?" said Krystal. "We would have to induce a period of hibernation that would allow a person not to need to function for a period of time in order to get there and survive and return."

By studying the temperature and metabolism relationship of hibernating fat-tailed dwarf lemurs, the researchers found that the animal readily enters REM (rapid eye movement) sleep when hibernating, something that other hibernating mammals do not do, like the much-studied Arctic ground squirrel. During the hibernation of the ground squirrel, studies have shown that they occasionally speed up their metabolism to enter a non-REM sleep. It seems that, like in humans, sleep is extremely important to the ground squirrel that they will expend precious energy to ensure their brains experience sleep during hibernation.

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Sleep appears "so important to these animals that they arouse out of their torpor, and it's a metabolically expensive thing to do," Krystal said. "There's got to be a good reason for it, and it may not be the sleep, but sleep seems to be linked to the process."

C. medius, on the other hand, hibernates in high temperatures and readily drops into an REM sleep throughout.

If we can understand this genetic trait, we may be able to find a way to augment it for our own purposes. Imagine if we could, through gene therapy, modify our physiology to switch into a hibernation state, while being able to maintain an REM sleep. Long-duration spaceflight for the crew could be seriously curtailed, while harnessing all the health benefits of sleep, potentially making journeys through interplanetary and interstellar space a little more bearable.

"There are all kinds of interesting possibilities that open up that sound a bit like science fiction," Krystal said. "But I think fundamentally we're motivated by the medical applications. This is the long-term view of why we're doing this."

Source: LA Times

Image credit: Getty

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