by Elissa Foss
It’s cold outside and you can’t find anything to eat, so you might as well just sleep the day away, right? Well, that could be your best answer if you were a mouse lemur!
A pair of mouse lemurs eating persimmons. Photo credit: David Haring from the Duke Lemur Center Website.
Mouse lemurs are the world’s smallest primates! They are nocturnal, roughly the size of a baseball, and, like their name suggests, they are pretty mouse-like. They are incredibly fast and scurry along tree canopies at night looking for food. Mouse lemurs have large round eyes specialized for seeing in the dark, and their ears are very sensitive to even the smallest sounds in the forest. Mouse lemurs only live on the island of Madagascar, which is a very large island off the coast of Africa. Not only are mouse lemurs one of the few nocturnal primates, but they are also one of the few mammals to survive in all regions of the island. There are 7 distinct ecological habitats across the island, ranging from tropical wet forests to dry highland plateaus and spiny desert forests. Interestingly, mouse lemurs have adapted to survive in all of these different climates and habitats!
One of the reasons they can live almost anywhere is because they have a very special ability to slow down their metabolic rate and enter a deep sleep-like state for 24 hours called “torpor.” You can think of torporing like daily hibernation. When there is not enough food around to survive off, the mouse lemurs will save up their precious energy and spend the day in this resting state, where their heart rates and body temperatures are decreased. After 24 hours or so, they will rewarm their bodies and begin to wake up again. If it’s still very dry and food isn’t easily found nearby, then the mouse lemurs can tuck back into their hiding hole and go back into their torpor state. They can choose to torpor for multiple days back to back, until conditions become more favorable and they have a better chance of finding food. Like bears who get fat in the summer to sleep through the winter, mouse lemurs rapidly gain weight when food is abundant to use as an energy store during long stretches of torpor bouts. The extra fat protects the mouse lemurs from experiencing metabolic distress or starvation while torporing.
A mouse lemur finding nectar from a flower. Photo credit: David Haring from the Duke Lemur Center Website, under “Behavior.”
Scientists are still trying to understand how the mouse lemurs are able to slow down their metabolic systems by looking at the changes in gene expression that happen when the mouse lemurs enter torpor. Since mouse lemurs are primates like us, there is a chance we share a similar gene regulatory system with the mouse lemurs that allows them to be able to enter this deep sleep-like state. If we could understand how the mouse lemurs change their metabolism to enter the torpor state, we could potentially figure out how to make humans torpor. This could be incredibly useful for humans to figure out as we are starting to explore outer space where it takes 10s or even 100s of years to travel to our nearby planets and solar systems. All the sci-fi films rely on using some human cryopreservation method to survive the journey into deep space, though we still don’t have this technology yet. But by studying the mouse lemurs, we could get one step closer to making these sci-fi dreams a reality.
Photo of humans in a cryopreservation pod from “Passengers.” Photo credit: Jamie Trueblood, Columbia Pictures
However, we must act fast to help keep these incredible animals from going extinct. Currently, lemurs are the most endangered mammals in the world. Almost every single species is listed as critically endangered by the IUCN, a worldwide organization dedicated to assessing which species are at risk of going extinct. The lemurs of Madagascar face many challenges in today’s world with deforestation, introduction of invasive species, and more frequent natural disasters such as typhoons and forest fires. But YOU can help protect the lemurs of Madagascar. Donate to the Duke Lemur Center by “adopting a lemur,” donate to Malagasy conservation organizations, and reduce your own carbon footprint. Visit the website https://www.lemurconservationnetwork.org/how-to-help/ to find even more ways you can help protect and preserve these incredible primates. Together we can do our part to bring lemurs back from the edge of extinction and learn how to sleep our way to deep space!
