Life at the Extremes

Frances Ashcroft

• Publisher: Flamingo
• Year: 2010
• ISBN:
  9780007381111
• Topic: Biowissenschaften
• Subtopic: Wissenschaft Allgemein

The debut of a female Steve Jones – likeable, literate, lucid and laconic. A sprightly, lavishly illustrated book on the science of human survival.

1

LIFE AT THE TOP

‘Great things are done when men and mountains meet;’

WILLIAM BLAKE, Gnomic Verses, I

Mount Everest

AT 8848 METRES (29,029 FEET), Mount Everest is the highest mountain on Earth. If it were possible to be transported instantaneously from sea-level to the summit of Everest, you would lose consciousness and lapse into a coma within seconds because of lack of oxygen. Yet in 1978, the Austrian climbers Peter Habeler and Reinhold Messner reached the top of Everest without the aid of supplementary oxygen; and ten years later, more than twenty-five others had also done so. What is the explanation for their apparently impossible feat? The scientific detective story of how the answer to this question was unravelled, the twists and turns along the way, the excitements, extraordinary feats of endurance and colourful characters involved are the subject of this chapter.

Mountains have fascinated and challenged people for centuries. Beautiful but forbidding, they were initially believed to be the home of the gods. The Greek Pantheon lived on the summit of Mount Olympus, the highest mountain in Greece; the Indians considered the Himalayas the abode of the gods; and evidence of ancient human sacrifice, probably to mountain gods, has been found in the Andes. Even today, many cultures hold sacred mountains in reverence – Tenzing Norgay buried chocolate and biscuits on the summit of Everest during the first successful ascent, as a gift to the gods that live there. Mountains lie shrouded in myth and legends, their peaks and crags imaginatively populated not only with gods, but also by mysterious monsters like the Himalayan Yeti and the trauco of southern Chile (that feeds on human blood). Even their names cause enchantment: ‘Chimborazo, Cotopaxi, They had stolen my soul away!’¹ Yet despite, or perhaps because of, these stories, people have always been attracted to mountains, whether for spiritual refreshment, the promise of hidden treasure, a means of escaping oppressive regimes, the thrill of exploring new terrain or, more mundanely, to find a way through to the other side: or simply, in George Mallory’s memorable phrase, ‘Because it’s there’.²

As a consequence, mountain sickness has been known for centuries. Its cause remained a mystery to the ancients who considered it due to the presence of the gods (which drove men mad), or the result of poisonous emanations from plants, and led to the early European view of mountains as dangerous and mysterious. Some time around the latter half of the nineteenth century, however, mountain climbing emerged as a sport and men vied with the elements and with each other to be the first to reach the highest peaks. Physiologists became increasingly interested in the effects of altitude on the body, and increasingly knowledgeable about their causes, and their studies contributed greatly to the success of the first expedition to reach the summit of Everest. Yet they have been repeatedly astonished by the ability of mountaineers to ascend higher than their predictions.

High altitude is defined, somewhat arbitrarily, as more than 3000 metres (10,000 feet) above sea level. Many people, probably around 15 million, live above this height in the mountainous areas of the world, with the greatest numbers in the Andes, the Himalayas and the Ethiopian Highlands. Many more people visit altitudes of over 3000 metres each year for skiing, backpacking and tourism. The highest permanent human habitations are mining settlements on Mount Aucanquilcha in the Andes, at an altitude of 5340 metres. Although the sulphur mines are located at 5800 metres, the miners prefer to climb the additional 460 metres to work each day rather than sleep higher up. The Indian army is also reputed to have kept troops at 5490 metres for many months, to guard their border with China, but this is probably the limit at which it is possible for humans to live for an extended period, for life at such altitudes is fraught with difficulties. Chief among these is the reduction in the oxygen concentration of the air, but cold, dehydration and the intense solar radiation are also significant problems.

The decrease in the density of the air at altitude means that it contains less oxygen, which poses a considerable problem for most organisms, including humans, who need to supply oxygen constantly to all their cells. Within each cell, oxygen is burned, together with foods such as carbohydrates, to produce energy. Cells that do large amounts of work, such as muscle cells, need proportionately more oxygen, and exercise further increases their demands. Oxygen was ‘discovered’ in 1775, as recounted in Chapter Seven, and its beneficial effects were immediately understood. But it was almost another hundred years before it was recognized, by the Frenchman Paul Bert, that it was a lack of oxygen (hypoxia) that was the main cause of mountain sickness. It took even longer for his idea to become widely accepted.

Paul Bert (1833–86) is widely acclaimed as the father of altitude physiology and aviation medicine. A pupil of the famous French physiologist Claude Bernard, he built a decompression chamber large enough for a man to sit comfortably inside in his laboratory at the Sorbonne in Paris, to simulate the effects of altitude. His famous work, La Pression Barométrique, presents evidence to support his idea that the deleterious effects of high altitude are due to the lack of oxygen. He was also the first to show that decompression sickness (the bends) is due to the formation of bubbles in the blood (see Chapter Two).

Early Accounts of Mountain Sickness

The Chinese were the first to document the effects of altitude, in a classic text, the Ch’ien Han Shu, that describes the route between China and what is probably Afghanistan around 37–32 BC: ‘Again on passing the Great Headache Mountain, the Little Headache Mountain, the Red Land and the Fever Slope, men’s bodies become feverish, they lose colour and are attacked with headache and vomiting; the asses and the cattle all being in like condition.’ The eminent Chinese scholar Joseph Needham has suggested that such experiences convinced the Chinese that they were meant to stay within the natural borders of their country. Likewise, the Greeks, who found they became breathless on the top of Mount Olympus (around 2900 metres), assumed that the summit was reserved for the gods and was out of bounds to mere mortals.

One of the first clear descriptions of the effect of acute mountain sickness was published in 1590 by Father Jose de Acosta, a Spanish Jesuit missionary who crossed the Andes and spent some time on the high plateau known as the Altiplano. Many of his party became sick when crossing the high pass at Pariacaca (4800 metres). He himself was ‘suddenly surprized with so mortall and strange a pang, that I was ready to fall’ and considered that ‘the aire is there so subtle and delicate, as it is not proportionable with the breathing of man.’ He also wrote that at this pass and all along the ridge of the mountains were to be found ‘strange intemperatures, yet more in some partes than in others and rather to those which mount from the sea, than from the plaines.’ This passage has been taken to indicate that Father Acosta was aware that people who had become acclimatized to high altitude by spending time on the high plains, such as the Altiplano plateau, succumbed less readily to mountain sickness than those who ascended directly from sea-level. Scholars now suggest that this is probably not the case, as the original Spanish text appears to have been incorrectly translated.

The local Inca population, however, were very well aware of the effects of altitude and of how acclimatization took time. They knew that lowlanders died in great numbers if transported to high altitudes to work in the mines and they maintained two armies, one that was kept permanently at high altitude to ensure they were acclimatized, and a second which was used for fighting on the coastal plains. To escape the ravages of the Conquistadores, the Incas retreated higher and higher into the mountains, where the Spanish invaders found it difficult to follow. Although the Spanish eventually established a city at Potosí (4000 metres), it was very much a frontier town and both women and livestock had to return to sea-level to give birth and bring up their offspring for the first year. The fertility and fecundity of the native women was unaffected but Spanish children born at altitude died at birth or within the first two weeks of life. The first child of Spanish descent to survive was not born until fifty-three years after the city was founded, on Christmas Eve 1598, an event that was hailed as the miracle of St Nicholas Tolentino. Sadly, none of the ‘miracle’s’ six children survived to maturity. Nevertheless, the problem resolved itself after two to three generations, probably because of interbreeding with the indigenous Indian population. The cattle and horses remained relatively infertile, however, and as a consequence, the Spanish eventually moved the capital to Lima. Infantile mountain sickness is not simply a problem of the past, for it afflicts the lowland Han Chinese colonists of Tibet today.

As the Incas appreciated, mountain sickness is less severe in people who become accustomed to altitude gradually. The dramatic and often fatal consequences of very rapid ascent to high altitude were first encountered by the early balloonists. The first flight in a hot air balloon was made in 1783 by Jean-François Pilâtre de Rozier and the Marquis d’Arlandes in a balloon made by the Montgolfier brothers, Etienne and Joseph. Later the same year another Frenchman, Jacques Charles, invented the hydrogen balloon and reached 1800 metres on his initial ascent, with no apparent ill effects. Balloons are capable of reaching even greater heights, however, which can have serious consequences.

The symptoms of altitude sickness associated with ballooning were described in a famous report by James Glaischer, a meteorologist who accompanied the balloonist Henry Coxwell on a flight from Wolverhampton in 1862. Within an hour they had ascended to a height at which his barometer read 247 millimetres of mercury – around 8850 metres. They continued to rise, but the precise altitude they reached is unclear because above this height Glaischer was no longer able to see the barometer clearly, nor is it certain his barometer was correct; but it is likely to be less than the 11,000 metres he reported. He described vividly how he found his arms and legs were paralysed, he was unable to read his watch or see his companion clearly, he tried to speak but found he could not, and he then became temporarily blind. Finally, he lost consciousness. Fortunately, Coxwell was not completely incapacitated and was able to bring the balloon down, although with great difficulty, by venting hydrogen. Because his arms were paralysed, he had to pull the rope that released the vent valve with his teeth. On the way down, Glaischer recovered consciousness and was able to take notes again at an altitude he calculated as around 8000 metres, which illustrates the rapid recovery that can occur following severe acute hypoxia.

The first fatalities occurred a few years later, in 1875, when three French scientists, Sivel, Tissandier and Croce-Spinelli, ascended to over 8000 metres in the balloon Zenith. Although they had primitive oxygen equipment, the amount of oxygen they carried was small and they agreed not to use it until they felt it was really necessary.³ Unfortunately, the over-confidence and feeling of well-being characteristic of acute oxygen starvation meant they never used it and they all lost consciousness. Only Tissandier survived. He later related that he tried to use the oxygen equipment but was unable to move his arms. However, far from feeling concerned, he wrote: ‘one does not suffer in any way; on the contrary. One feels an inner joy, as if filled with a radiant flood of light. One becomes indifferent and thinks no more of the perilous situation or of the danger.’

The famous balloon flight from Wolverhampton of James Glaisher and Henry Coxwell. The lithograph depicts them at the peak of their ascent – an estimated altitude of around 11,000 metres (seven miles high). Glaisher is insensible, collapsed in the basket. Coxwell, who has lost the use of his hands from a combination of hypoxia and cold, is struggling to release the gas valve by pulling the release cord with his teeth. In contrast, the pigeons (in the basket suspended from the ring) seem unaffected by the altitude.

Lithograph of H.T. Sivel, Gaston Tissandier and J.E. Croce-Spinelli in the balloon Zenith. Sivel (left) is about to cut the strings holding the bags of ballast in order to ascend higher. Tissandier (centre) is reading the barometer. Croce-Spinelli has the mouthpiece of the oxygen equipment in his hands; this is connected to the striped balloon, which contains a mixture of 72 per cent oxygen in air.
The balloon took off on 15 April 1875 from a gas factory at Villette, outside Paris, and ascended to a height of 7500 metres. At this point, pictured right, Sivel asked his companions if they should go higher and, on receiving their assent, released the ballast. The balloon then rose rapidly to 8600 metres. All three men became paralysed and passed out before they felt the need to breathe oxygen. Both Tissandier and Croce-Spinelli briefly regained consciousness at separate times but, confused by hypoxia, they each let go more ballast, which only exacerbated their situation for it caused the balloon to rise further. When Tissandier finally awoke, the balloon was at 6000 metres and falling rapidly, but both his companions were dead.

The Ascent of Everest

With the advent of mountaineering, the effects of mountain sickness became more widely known and better understood. By the mid-1920s it was appreciated that people could climb as high as 8000 metres and remain there safely for a few days, providing they had spent many weeks at an intermediate altitude gradually acclimatizing. In contrast, when exposed to a similar barometric pressure in a decompression chamber, consciousness was lost within a few minutes.

The 1953 British expedition to Mount Everest, led by Sir John (later Lord) Hunt, was well aware of the importance of acclimatization. The long march from Kathmandu to Khumbu, at the foot of the mountain, took several weeks and imposed an obligatory period of acclimatization because most of the trek is at 1800 metres, rising only occasionally to 3600 metres. A further four weeks was then devoted to acclimatizati...