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Now, I am not suggesting that surviving a fall from the sky is something that anyone can count on, but it has happened more often than you might expect. In 1972, a flight attendant named Vesna Vulović survived a fall of 33,000 feet when the Yugoslav Airlines DC-9 on which she was flying broke up in midair over Czechoslovakia. And in 2007, an Ecuadorean-born window cleaner in Manhattan, Alcides Moreno, fell 472 feet when scaffolding he was standing on collapsed. His brother, working alongside, was killed instantly on impact, but Moreno miraculously survived. The human body, in short, can be a wonderfully resilient thing.
Indeed there is seemingly no challenge to human endurance that hasn’t been overcome. Consider the case of little Erika Nordby, a toddler in Edmonton, Alberta, who woke up one night in the dead of winter and, wearing only diapers and a light top, walked out of her house through a back door that hadn’t closed properly. When she was found, hours later, her heart had been stopped for at least two hours, but she was carefully warmed up at a local hospital and miraculously restored to life. She made a full recovery and became known, not surprisingly, as the Miracle Baby. Remarkably, just a couple of weeks later, a two-year-old boy on a farm in Wisconsin did almost exactly the same thing and was successfully revived and made a full recovery. Dying is, to coin a phrase, the last thing your body wants to do.
Children do much better with extreme cold than with extreme heat. Because their sweat glands aren’t fully developed, they don’t sweat freely as adults do. That is in large part why so many of them die so swiftly when left in cars in warm weather. In a sealed car with the temperature outside in the 80s, the inside can reach 130, and no child can cope with that for long. Between 1998 and August 2018, almost eight hundred children in the United States died when left unattended in hot cars. Half were under two years of age. Remarkably—indeed, I would say shockingly—more U.S. states have laws making it illegal to leave an animal unattended in a car than to leave a child unattended. The margin of difference is twenty-nine to twenty-one.
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Because of our frailties, much of our own planet is off-limits to us. Earth may feel like a generally benign and kindly place, but a very large part of it is too cold or hot or arid or lofty for us to live successfully on it. Even with the advantage of clothing, shelter, and boundless ingenuity, humans can manage to live on only about 12 percent of Earth’s land area and just 4 percent of the total surface area if you include the seas. It is a sobering thought that 96 percent of our planet is off-limits to us.
The thinness of the atmosphere puts a limit on how high we can live. The highest permanent settlements in the world are in the Andes in northern Chile on Mount Aucanquilcha, where miners live at 17,500 feet, but that appears to be absolutely at the limits of human tolerance. The miners themselves choose to trudge an additional 1,500 feet up the slopes to their workplace each day rather than sleep at 19,000 feet. For purposes of comparison, Mount Everest is about 29,000 feet.
At very high altitudes, any exertion becomes difficult and exhausting. Around 40 percent of people experience altitude sickness above thirteen thousand feet, and it is impossible to predict who the victims will be because it is not related to fitness. At extreme heights everyone struggles. Frances Ashcroft in Life at the Extremes notes how Tenzing Norgay and Raymond Lambert, on a climb of the South Col of Mount Everest in 1952, took five and a half hours to climb just 650 feet.
At sea level, about 40 percent of your blood volume is occupied by red blood cells, but that can increase by about half as much again with acclimatization to higher altitudes, though there is a price to be paid. The increase in red cells makes the blood thicker and more sluggish and puts extra pressure on the heart when pumping, and that can apply even to those who have lived their whole lives at great heights. Residents of lofty cities, such as La Paz in Bolivia (11,500 feet), sometimes suffer an illness called Monge’s disease, which produces blue lips and clubbed fingers because their perpetually thickened blood is not flowing well. The problem goes away if they move to a lower altitude. Many sufferers are thus permanently exiled to the valleys, far from friends and families.
For reasons of economy, airlines normally keep cabins pressurized to an altitude equivalent of forty-nine hundred feet to seventy-nine hundred feet, which is why alcohol is more likely to go to your head while flying. It also accounts for why your ears pop during descent because the pressure changes as you reduce elevation. On an airliner flying at a normal cruising altitude of thirty-five thousand feet, if the cabin suddenly depressurized, passengers and crew could become confused and incompetent in as little as eight or ten seconds. Ashcroft notes the case of a pilot who passed out because he paused to put on his eyeglasses before his oxygen mask. Fortunately, the co-pilot was not incapacitated and took control of the plane.
One of the more infamous examples of oxygen deprivation—or hypoxia, as it is more formally known—was in October 1999 when the American professional golfer Payne Stewart, along with three business associates and two pilots, was on a chartered Learjet en route from Orlando to Dallas when the plane lost pressurization and all aboard blacked out. The plane’s last contact was at 9:27 a.m., when the pilot acknowledged clearance to climb to thirty-nine thousand feet. Six minutes later, when a controller contacted the plane again, there was no response. Instead of turning west for Texas, the jet continued on a northwesterly track, on automatic pilot, across the central United States before eventually running out of fuel and crashing in a field in South Dakota. All six aboard were killed.
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A disturbingly large amount of what we know about human survival abilities comes from experiments carried out on military prisoners, concentration camp inmates, and civilians during World War II. In Nazi Germany, healthy prisoners were subjected to amputations or experimental limb transplants and bone grafts in the hopes of finding better treatments for German casualties. Russian prisoners of war were plunged into ice water to determine how long a German pilot could survive a downing at sea. Others were kept outdoors naked in freezing weather for up to fourteen hours for similar purposes. Some experiments seem to have been driven by nothing more than morbid curiosity. In one, the subjects’ eyes were injected with dyes to see if their eye color could be permanently changed. Many others were subjected to poisons and nerve gases of all types or infected with malaria, yellow fever, typhus, and smallpox. “Contrary to postwar apologies,” write George J. Annas and Michael A. Grodin in The Nazi Doctors and the Nuremberg Code, “doctors were never forced to perform such experiments.” They volunteered.*
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Horrifying as the German experiments were, they were outdone, in scale if not cruelty, by the Japanese. Under a doctor named Shiro Ishii, the Japanese built an enormous complex of more than 150 buildings spread over almost 1,500 acres at Harbin in Manchuria with the avowed purpose of determining human physiological limitations through any means necessary. The facility was known as Unit 731.