Science at the Extreme: Scientists on the Cutting Edge of Discovery

Natural History, Oct, 2000 by Steven N. Austad

Science at the Extreme: Scientists on the Cutting Edge of Discovery, by Peter Lane Taylor (McGraw-Hill; $29.95)

Scientist who study environmental extremes are looking at how organisms--including humans--adapt to such conditions.

People tell me that after my first (and definitely last) bungee jump into the gorge just below Victoria Falls, I appeared to be intoxicated by the experience. Not only was I giddier than usual (with relief), but for days my eyes were as bloodshot as if I had just survived the mother of all New Year's Eve parties. Thanks to Oxford University physiologist Frances Ashcroft's fascinating new book, Life at the Extremes, I now know that the small hemorrhages commonly precipitated in the eyes of bungee jumpers are caused by the great g- (for "gravitational") forces exerted on the head as the bungee cord snaps taut during free fall. What's more, sky divers, who are relatively more sensible than bungee jumpers, do not suffer such injuries: parachutes cause falling bodies to decelerate less abruptly, and sky divers don't open their parachutes when their heads are below their feet.

Ashcroft describes the physiological effects of positive (toward the feet) and negative (toward the head) g-forces by outlining the complex and destructive bodily impact of orbiting Earth: after a few weeks in a space capsule, most astronauts are incapable of standing up without fainting when they first return to terra firma. The experience also induces muscle loss, anemia, cardiac irregularities, and bone thinning. After reading Ashcroft's book, I now have little doubt that the White House had a backup speech ready in case John Glenn's inspiring space flight at the age of seventy-seven ended less happily than it did.

Besides detailing the rigors of athletic feats and space flight, the book explores me physiological impact--on whales, birds, and bacteria as well as on us--of such extremes as plunging into oceanic depths and experiencing very high and very low temperatures. In so doing, Ashcroft explains a lot about how the human body operates under normal conditions. She also points out the engineering logic of the artificial environments we have created to preserve us as we journey to places our bodies are normally unequipped to handle.

She discusses at length, for example, the mechanics of what happens to people at high elevations, especially to mountaineers and lifelong residents of the high Andes and the Himalaya, and describes reactions that can lead to the lungs fatally filling with fluid. Equally interesting are the specific physiological changes--chiefly a fivefold to sevenfold increase in breathing rate--that allow the body to gradually acclimatize to high altitudes, thus enabling particularly hardy mountaineers to ascend Mount Everest without supplemental oxygen. She also imparts potentially useful, if not exactly reassuring, tips on what to do when your plane depressurizes: you have slightly less than thirty seconds to put on that dangling oxygen mask before you lose consciousness. In the Concorde, however, it's probably not worth bothering with, because at the cruising altitude of that aircraft, you couldn't survive even breathing pure oxygen. "The low barometric pressure at these altitudes," writes Ashcroft, "means there is simply not enough room in the lungs for the necessary amount of oxygen."

Having amassed a wealth of historical information on each topic, Ashcroft provides an endless resource for cocktail party conversationalists--and for teachers of biology such as myself. For instance, John and Charles Deane rescued some horses from a burning barn in the early nineteenth century by improvising a breathing device out of the helmet on a suit of armor "supplied with air via a hose and a hand pump." They later patented the device for fire fighting. In 1828 the brothers came up with a diving suit, an apparatus that allowed them to open the first marine salvage business in England. Equally intriguing, the physiologist father of the great English biologist J. B. S. Haldane invented the method of staged ascent, which allows today's scuba divers to avoid the bends. Ashcroft cites 236 feet as the world record free dive (on a single breath and without a diving suit) and 436 feet with a rock and a rocket (for rapid descent and ascent).

Of course, human physical feats achieved in extreme environments pale in comparison with the achievements of animals specialized for living there. Elephant seals can dive to depths of almost a mile without getting the bends. The bar-headed goose does not need to acclimatize to flying over the Himalaya, even though it may have taken off from sea level earlier the same day. What differences in body design allow seals and birds to do what no unaided human can do? This book provides the answers.

But one topic it doesn't discuss is what drives people to purposely seek out these extreme environments in the first place. In 1911, in an age when exploration was the road to fame and fortune, Roald Amundsen wanted to be (and succeeded in becoming) the first person to reach the South Pole. Yet even he concocted some scientific cover for his quest, declaring that "the main object is a scientific study of the Polar Sea itself."