The fat-tailed dwarf lemur loves hibernating. In fact, this species is the only primate in the world that is known to hibernate for a long period of time -- a phenomenon known as torpor, which leads to decreased metabolism, heart rate, and body temperature.
These squirrel-sized primates are endemic to Madagascar, where they spend up to seven months every year mostly motionless, using the minimum energy necessary to withstand the winter. Researchers at the Duke Lemur Center in Durham, North Carolina recently tried finding answers to an interesting question: do animals in captivity, in zoos and sanctuaries, exhibit the same hibernation trends as their counterparts in the wild? The answer, it seems, is yes. By finding this result, they might have not only unlocked secrets of hibernation but could also possibly yield insights into metabolic disorders in humans.
An official university news release explains that captive dwarf lemurs are fed extra during the summer so they can bulk up like they do in the wild. They then drop into periods of torpor, but they rarely stay in this suspended state for longer than 24 hours. Research scientist Marina Blanco, who led the project along with a team at the Duke Lemur Center, located on campus of Duke University in Durham, set out to see if the lemurs in captivity could navigate seasonal changes just like they do in the wild. To do so, Blanco and the other researchers built fake tree hollows out of wooden boxes, which were placed in the dwarf lemurs’ indoor enclosures, for them to wait out the winter. “To mimic the seasonal changes the lemurs experience over the course of the year in Madagascar, the team also gradually adjusted the lights from 12 hours a day to a more ‘winter-like’ 9.5 hours, and lowered the thermostat from 77 degrees Fahrenheit to the low 50s,” the release explains.
The lemurs were offered food if they were awake and “active” and weighed every two weeks. The findings of this experiment, published in the journal Scientific Reports on 11 March, show for the first time that fat-tailed dwarf lemurs can hibernate quite well in captivity. For four months, the eight lemurs in the study spent some 70% of their time in metabolic slow-motion similar to their wild counterparts, the release adds.
With the temperature in North Carolina rising again, the lemurs are back to their active best. Their heart rates are back up from just eight beats per minute to about 200, and their appetites have returned, the release explains. “We've been able to replicate their wild conditions well enough to get them to replicate their natural patterns,” Erin Ehmke, who directs research at the center, said in the release. The study’s co-author Lydia Greene adds that the next step is to “use non-invasive research techniques such as metabolite analysis and sensors in their enclosures” to better understand what the lemurs do to prepare their bodies for this hibernation period and eventually bounce back. This could lead to new treatments for heart attacks, strokes, and other life-threatening conditions in humans, the release explains.
Since these lemus are our closest hibernating relatives, genetically speaking, this research could tell the scientists more about safely putting the human body on pause too in a variety of circumstances -- from life-saving surgery to space travel. Blanco, who has studied the lemurs from close quarters in the wild for more than a decade, says studying the lemurs at the centre would help in closer and better monitoring.