the first-in may have to wait a very long time.”
Make that a very, very long time, like … never. Unfortunately for Williams and the other sixty-six superchilled cadavers at Alcor, human tissue doesn’t react well to freezing. When water is frozen, it expands into sharp little crystals. When humans are frozen, the water in our blood freezes, and the ice shards cut blood cells and cause capillaries to burst. It’s not dissimilar to the way a pipe bursts when the water’s left on in an unheated house – except no repairman can fix it.
Of course, just because we can’t survive a true deep freeze doesn’t mean our bodies haven’t evolved many ways to manage the cold. They have. Not only is your body keenly aware of the danger cold poses, it’s got a whole arsenal of natural defenses. Think back to some time when you were absolutely freezing – standing still for hours on a frigid winter morning watching a parade, riding a ski lift with the wind whipping across the mountain. You start to shiver. That’s your body’s first move. When you shiver, the increased muscle activity burns the sugar stored in your muscles and creates heat. What happens next is less obvious, but you’ve felt the effect. Remember the uncomfortable combination of tingling and numbness in your fingers and toes? That’s your body’s next move.
As soon as the body senses cold, it constricts the thin web of capillaries in your extremities, first your fingers and toes, then farther up your arms and legs. As your capillary walls close in, blood is squeezed out and driven toward your torso, where it essentially provides a warm bath for your vital organs, keeping them at a safe temperature, even if it means the risk of frostbite for your extremities. It’s natural triage – lose the finger, spare the liver.
In people whose ancestors lived in particularly cold climates – like Norwegian fishermen or Inuit hunters – this autonomic response to cold has evolved with a further refinement. After some time in the cold, the constricted capillaries in your hands will dilate briefly, sending a rush of warm blood into your numbed fingers and toes before constricting again to drive the blood back into your core. This intermittent cycle of constriction and release is called the Lewis wave or “hunter’s response,” and it can provide enough warmth to protect your extremities from real injury, while still ensuring that your vital organs are safe and warm. Inuit hunters can raise the temperature in the skin of their hands from near freezing to fifty degrees in a mater of minutes; for most people it takes much longer. On the other hand, people descended from warm-weather populations don’t seem to have this natural ability to protect their limbs and their core at the same time. During the frigid cold of the Korean War, African American soldiers were much more prone to frostbite than other soldiers.
Shivering and blood vessel constriction aren’t the only ways the body generates and preserves heat. A portion of the fat in newborns and some adults is specialized heat-generating tissue called brown fat, which is activated when the body is exposed to cold. When blood sugar is delivered to a brown fat cell, instead of being stored for future energy as it is in a regular fat cell, the brown fat cell converts it to heat on the spot. (For someone acclimated to very cold temperatures, brown fat can burn up to 70 percent more fat.) Scientists call the brown fat process nonshivering thermogenesis, because it’s heat creation without muscle movement. Shivering, of course, is only good for a few hours; once you exhaust the blood sugar stores in your muscles and fatigue sets in, it doesn’t work anymore. Brown fat, on the other hand, can go on generating heat for as long as it’s fed, and unlike most other tissues, it doesn’t need insulin to bring sugar into cells.
Nobody’s written the Brown Fat Diet Book yet because it requires more than your usual lifestyle change. Adults who don’t live in extreme cold don’t really have much, if any, brown fat. To accumulate brown fat and get it really working, you need to live in extreme cold for a few weeks. We’re talking North Pole cold. And that’s not all – you’ve got to stay there. Once you stop sleeping in your igloo, your brown fat stops working.
The body has one more response to the cold that’s not completely understood – but you’ve probably experienced it. When most people are exposed to cold for a while, they need to pee. This response has puzzled medical researchers for hundreds of years. It was first noted by one Dr. Sutherland, in 1764, who was trying to document the benefits of submersing patients in the supposedly healing – but cold – waters of Bath and Bristol, England. After immersing a patient who suffered from “dropsy, jaundice, palsy, rheumatism and inveterate pain in his back,” Sutherland noted that the patient was “pissing more than he drank.” Sutherland chalked the reaction up to external water pressure, figuring (quite wrongly) that fluid was simply being squeezed out of his patient, and it wasn’t until 1909 that researchers connected increased urine flow, or diuresis, to cold exposure.
The leading explanation for cold diuresis – the need to pee when it’s cold – is still pressure; but not external pressure, internal pressure. The theory is that as blood pressure climbs in the body’s core because of constriction in the extremities, the body signals the kidneys to offload some of the extra fluid. But that theory doesn’t fully explain the phenomenon, especially in light of recent studies.
The U.S. Army Research Institute of Environmental Medicine has conducted more than twenty years of study into human response to extreme heat, cold, depth, and altitude. Their research conclusively demonstrates that even highly cold-acclimated individuals still experience cold diuresis when the temperature dips toward freezing. So the question persists: Why do we need to pee when we’re cold? This certainly isn’t the most pressing question facing medical researchers today – but as you’ll soon discover, the possibilities are intriguing. And the answers may shed light on much bigger issues – like a disease that currently affects 171 million people.
Let’s put aside the delicate subject of cold diuresis and turn to one much more suitable for the dinner table – ice wine: delicious, prized, and – supposedly – created by accident. Four hundred years ago, a German vintner was hoping to squeak just a few more growing days out of the late autumn when his fields were hit by a sudden frost, or so the story goes. The grapes were curiously shrunken, but, not wanting to let his entire harvest go to waste, he decided to pick the frozen grapes anyway and see what would come of it, hoping for the best. He let the grapes defrost and then pressed the crop as he usually did but was disappointed when it yielded just one-eighth of the juice he was expecting. Since he had nothing to lose, he put his meager yield through the fermentation process.
And discovered that he had a hit on his hands. The finished wine was insanely sweet. Since its first, semilegendary, certainly accidental harvest, some winemakers have specialized in ice wine, waiting every year for the first frost so they can harvest crops of frozen grapes. Among the many ways wine is rated, graded, and weighted today, it is measured on a “sugar scale.” Typical table wine runs from 0 to 3 on the sugar scale. Ice wine runs from 18 to 28.
The shrunken nature of the grapes is due to water loss. Chemically speaking, it’s not difficult to guess why grapes might have evolved to offload water at the onset of a freeze – the less water in the grape, the fewer ice crystals there are to damage the delicate membranes of the fruit.
How about the sharp increase in sugar concentration? That makes sense too. Ice crystals are only made of pure water – but the temperature at which they start to form depends on what else is suspended in the fluid where the water is found. Anything dissolved in water interferes with its ability to form the hexagonal latticework of solid ice crystals. Average seawater, for example, full of salt, freezes at around 28 degrees Fahrenheit instead of the 32 degrees we think of as water’s freezing point. Think about the bottle of vodka some people keep in their freezer. Usually, alcohol is about 40 percent of the liquid volume in the bottle; it does a great job of interfering with the creation of ice – vodka doesn’t freeze until you cool it down to around minus 20 degrees Fahrenheit. Even most water in nature doesn’t freeze at exactly 32 degrees, because it usually contains trace minerals or other impurities that lower the freezing point.
Like alcohol, sugar is a natural antifreeze. The higher the sugar content in a liquid, the lower the freezing point. (Nobody knows more about sugar and freezing than the food service chemists at 7-Eleven who were in charge of developing a sugar-free Slurpee beverage. In regular Slurpees, the sugar is what helps to keep the frozen treat slurpable – it prevents