In the wild, fat-tailed dwarf lemurs undergo hibernation anywhere between three to seven months. However, lemurs in captivity are active year-round and occasionally experience torpor, a short period of dormancy rarely lasting a day at a time, reports Ed Cara for Gizmodo.
Researchers at Duke University's Lemur Center in North Carolina feared their captive lemurs had lost the ability to hibernate after four generations stopped doing so—until now. A study published in Scientific Reports showed if captive lemurs were placed in conditions that mimicked the seasonal changes of their native habitat in Madagascar, researchers could coax them into hibernating.
In nature, fat-tailed dwarf lemurs gorge themselves on food when preparing for hibernation or during periods when food is scarce. The fat then gets stored into their tails, hence the name. A lemur’s tail can reach up to 40 percent of its body weight. Captive lemurs, however, receive an abundance of food all year, so the need to hibernate as a way to store energy is unnecessary, reports Clare Watson for Science Alert. However, Duke Lemur Center researchers wondered if captive lemurs could still hibernate after generations of captivity.
To simulate the seasonal changes in the wild, the researchers created a space that would mimic temperature and lighting changes similar to those during summer and winter in Madagascar, Gizmodo reports. Between October 2019 and February 2020, the lights and temperature in their simulated habitat were gradually lowered. In winter conditions, the lemurs would receive nine and a half hours of light on the shortest day, compared to peak summer conditions when they would receive 14.5 hours of daylight.
Simulated summer temperatures were kept at 77 degrees Fahrenheit, and then dropped between 50 to 59 degrees Fahrenheit to mimic winter temperatures, Gizmodo reports. A total of eight lemurs were fitted with equipment measures their heart rate and temperature while they hibernated in wooden artificial tree hollows built by the researchers, Science Alert reports. Food was also restricted, with more available during the summer and gradually less available as the simulated seasons changed.
For four months, the lemurs hibernated 70 percent of the time, showed no interest in food, and barely moved or breathed for 11 days at a time at peak hibernation, writes Robin A. Smith for Duke Today. After the experiment was over, the lemurs woke up and appeared healthy. Their heart rates bounced back from 8 beats per minute (bpm) to 200 bpm, and they began to eat right away, reports Science Alert.
The researchers suspect allowing the lemurs to hibernate would be better for them in the long run since not hibernating may cause the lemurs a variety of health problems, including diabetes, cataracts, and obesity. The lemurs' long lifespans compared to similar species may also be attributed to their ability to hibernate, Gizmodo reports.
The finding not only increases scientific knowledge of animal hibernation, but, as humans' closest hibernating relative, the lemur can help researchers study how hibernation can be beneficial and replicated in humans. Hibernation can make long-distance space travel easier, emergency surgery safer, and may even prevent metabolic diseases, reports Science Alert.
“If hibernators can repair DNA damage and cope with stress associated with metabolic depression, understanding those mechanisms can help revert this condition in humans,” says lead author of the study Marina Blanco, a primate biologist at Duke University, to Tara Yarlagadda for Inverse.
For future studies, the researchers plan to monitor the lemurs during hibernation closely and use non-invasive methods like metabolite analysis to further understand what goes on in the lemur’s body to prepare for hibernation and how they can bounce back quickly from the state, reports Duke Today.