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Written by: Nancy Moncrief
Tuesday February 3, 2015

What would happen to you if you only took a breath once every five or six minutes?  Did you know that, right now, there are groundhogs hibernating in most of eastern North America (including Virginia) who are only taking about 11 breaths per hour?  Hibernation is a kind of sleep that allows an animal to live for months without eating or drinking.  During hibernation, an animal’s metabolic rate is greatly reduced, its breathing and heart rate are much slower, and its body temperature is dramatically lower.  So, a hibernating groundhog’s heart contracts only about three times a minute (compared to the normal 80-95 beats per minute).  And its body temperature drops from 90oF (32oC) to only 38oF (3oC).  By hibernating, a groundhog (also called woodchucks or whistle pigs) avoids low temperatures and food shortages that often occur during winter.  In Virginia, most groundhogs enter hibernation by early November and don’t arouse from hibernation until late February.

Groundhogs are large squirrels that hibernate. Punxsutawney Phil is perhaps the most famous of them all.  Photo by Victor Loewen.

Entering hibernation and arousing from it are accompanied by a complex set of changes in metabolic rate.  These changes are regulated by a series of genes that are activated and de-activated seasonally.  Scientists are studying these genes in hibernating animals in order to identify which genes are active at what time of year and to determine exactly how those genes regulate metabolic rate.  If these hibernation genes are present in humans, and if they can be activated and de-activated at appropriate times, this technology has several potential applications.  For example, induced hibernation would reduce the amount of food and water a human would need during long trips through outer space.  Also, studying the genetics of hibernation and the genes that regulate metabolism may allow us to identify (and selectively activate) genes that cause animals, including humans, to lose body fat without losing muscle mass.  These applications will probably require decades of research, however, so don’t look for hibernation pills on your store shelves anytime soon.

Tags: Biology, Dr. Nancy Moncrief, Mammal of the Month, Research and Collections