Researchers at the University of Alaska, Fairbanks have discovered a way to induce hibernation in arctic ground squirrels—by administering a substance that stimulates the brain receptors of adenosine, a molecule involved in slowing nerve cell activity. Induced hibernation could someday be used to preserve the brain functions of human stroke victims, though that’s still a ways off as the current technique only works on the arctic ground squirrels during hibernation season.
Image: Flickr/Threat to Democracy
A hibernating bear might appear to be the perfect metaphor for laziness, laying around half the year in carefree slumber. But in fact, it is a marvel of efficiency. New research in the journal Science shows that bears can drop their metabolic rate all the way down to 25 percent of normal while losing only about 10 degrees in body temperature.
Øivind Tøien and colleagues got lucky when a few black bears came a little too close to residents of Alaska for the Alaskans’ comfort. The state’s Department of Fish and Game intended to remove them as a “nuisance,” so the researchers got their hands on the bears and did a little hibernation experiment. They built artificial dens for the large mammals, complete with cameras and observational equipment including radio transmitters, allowing them to track the bears’ body temperatures and other vitals.
It was thought that, like most animals, the bears would have to drop their body temperatures to put the brakes on metabolism—each 18-degree Fahrenheit (10-degree Celsius) drop in temperature should equal a 50-percent reduction in the chemical activity. [National Geographic]
The fact that bears were so much more efficient than other hibernators came as a big surprise, Tøien says:
Yellow-bellied marmots are taking to global warming just fine—so far. A Nature study of the hibernating Rocky Mountain-dwellers found that over the last 30-plus years, the marmots have grown both in girth and in population, and the researchers think they know why.
Study author Arpat Ozgul says that the marmots have limited time to accomplish the things on their summertime agenda—namely, eating, mating, and giving birth before they crawl back into their seven- to eight-month hibernation.
But as the Colorado summers have grown longer, so too has the time the marmots have to do all of these things—and do them better. This extra preparation (and reproduction) time means that “they are more likely to succeed and survive,” said Ozgul [Scientific American].
Because of the extra time, marmots studied grew in average weight from approximately 6.8 pounds to 7.5. And since 2001 the marmot population has exploded, adding an average of 14 individuals each year; in the previous 25 years the population growth rate was only .56 per year.