Grizzly Bears, Dreaming and the Frontier of Wonder
For all the research that has been done on bears and other mammals, much remains unknown about hibernation. Wild animals will always exceed the compass of the human intellect – and that is as it should be.
There are a few things that we do know about hibernation: bears don’t eat or drink or excrete waste for between 100 and 180 days. If it were you or me, we would be long dead. But they crawl out of their dens in the spring, and they are basically fine. They don’t lose much bone strength or muscle mass (maybe 30% at most) (link). Their kidneys, liver and hearts don’t fail.
By late November to mid-December, grizzly bears slow and den for the winter. A few may stay up for a few more weeks or even a month, pursuing the dangerous practice of feeding on gut piles during the late season elk hunts in places such as Jackson Hole.
Bears are not unconscious like “deep hibernators”, and their temperatures don’t plummet to freezing like ground squirrels do. That is why mother bears are able to give birth in the dead of winter to a cub or two, each the size of a teacup. The whole hibernation enterprise is nothing short of a miracle.
Of course none of this is lost on medical researchers. They have long suspected that bears could benefit people with heart disease, diabetes, osteoporosis, as well as traumatic injuries. (If you could induce hibernation in someone with a stroke or undergoing cardiac arrest, you could buy doctors precious treatment time).
So have the researchers gotten closer to solving the mystery? Yes and no. Regarding osteoporosis, bears produce a parathyroid hormone (link) which maintains bone density and strength, and offsets deterioration that would occur while snoozing for so long. But it will be a while before doctors will know enough to be able to use this hormone to treat humans suffering from osteoporosis.
The means by which hibernating bears avoid diabetes represents a similar mystery. Each year, bears get obese, so as to survive their many months of winter famine. But they do not get Type 2 diabetes. Diabetes occurs when cells lose their ability to take up sugar in response to infusions of insulin. When humans who are starving or who have uncontrolled diabetes rely on fat for energy, the body cannot handle the toxic byproducts of fat catabolism. Not so for bears. They are able to recycle these byproducts into making more fat (link). Cool or what?
Kidney function in bears is similarly weird and wonderful. If our kidneys did not excrete wastes such as uric acid, we would soon die. But get this: bears have microbes in their guts that, during the winter months, convert urea to nitrogen to make new amino acids, which are the building blocks of protein (link). With that, they are able to maintain lean body tissue in the comfort of their own dens without eating or eliminating waste. If that is not a miracle, what is? It is no accident that researchers are looking to bears for some answers for how to feed malnourished populations in developing countries with limited access to protein-rich foods (link).
For years, scientists have dreamed of putting people who have experienced traumatic injury into the kind of suspended animation that characterizes hibernation. So far, the closest they have come is to apply cold fluids, internally and externally, to temporarily slow metabolic processes, with positive results (link).
Hibernating bears blow researchers’ minds for yet more reasons. For example, when they implanted a defibrillator in a bear’s heart to measure heartrate during hibernation, the bear’s body forcibly ejected it (link). Same with implants in its gut. The bear’s basic response to implants of foreign objects is to powerfully reject them. Maybe that is why bears rarely get infections. Researchers wonder if this response could somehow be bottled to deal with human injuries (link).
And here is another surprise: bears actually stop breathing during hibernation, for maybe 25-30 seconds at a time (link). With lower oxygen requirements as they sleep, they don’t have to breathe as much. When oxygen levels get low enough, the brain sends a signal take another breath. And get this: when a bear inhales, its heart rate can increase 800-fold, while a human’s increases only by one-fortieth as much (link). What athlete doesn’t want to borrow that skill?
What a miracle is the bear…
Ancient cultures understood this well, of course. The bear, with its ability to seemingly die in winter and remerge in spring with new life, has long symbolized transformation. Seeking the bear’s gifts, we have looked to this creature as teacher, guide and healer. These basic connections, defined by respect and reverence, are true for ancient cultures around the world – anywhere people and bears co-existed.
In modern ecology, you hear that the grizzly bear is an “umbrella species.” The health of grizzly bear populations engenders health for entire ecosystems. The ancients had a different way of orienting to the same issue. For example, there is an old story of a bear that goes into her den to dream the world into being during the winter. She dreams of antelope, and whitebark pine, and buffalo. She creates each being, and entire ecosystems, during the course of each winter. When she emerges in the spring, trailed by a young cub, she is celebrated by all the creatures of the earth.
The only story about grizzly bears that truly baffles me is the modern one that utterly lacks wonder. It is the story that demands killing bears as trophies and resolving conflicts with bears by killing them when nonlethal approaches are available. This story is not about respect, reverence, or wonder, but about domination and use, as codified in current systems of state wildlife management (link).
This is the narrative that drives the proposed removal of Endangered Species protections for Yellowstone grizzly bears (link). This is a story that would erase wonder from our lives and relegate all living things to the status of objects.
There is much to wonder about as grizzly bears disappear into high-country dens to undertake the annual miracle of hibernation. What kind of world will we dream for grizzly bears and the world that we share with them? What kind of world will grizzly bears wake up to next spring? Will it be a world in which wonder is diminished, or one in which wonder is renewed?