A short history of nearly everything - Bill Bryson [116]
I thought about this the next morning as I made a brief call, on my way out of the park, at a place called Emerald Pool, in the Upper Geyser Basin. Doss hadn't had time to take me there the day before, but I thought I ought at least to have a look at it, for Emerald Pool is a historic site.
In 1965, a husband-and-wife team of biologists named Thomas and Louise Brock, while on a summer study trip, had done a crazy thing. They had scooped up some of the yellowy-brown scum that rimmed the pool and examined it for life. To their, and eventually the wider world's, deep surprise, it was full of living microbes. They had found the world's first extremophiles—organisms that could live in water that had previously been assumed to be much too hot or acid or choked with sulfur to bear life. Emerald Pool, remarkably, was all these things, yet at least two types of living things, Sulpholobus acidocaldarius and Thermophilus aquaticus as they became known, found it congenial. It had always been supposed that nothing could survive above temperatures of 50°C (122°F), but here were organisms basking in rank, acidic waters nearly twice that hot.
For almost twenty years, one of the Brocks' two new bacteria, Thermophilus aquaticus, remained a laboratory curiosity until a scientist in California named Kary B. Mullis realized that heat-resistant enzymes within it could be used to create a bit of chemical wizardry known as a polymerase chain reaction, which allows scientists to generate lots of DNA from very small amounts—as little as a single molecule in ideal conditions. It's a kind of genetic photocopying, and it became the basis for all subsequent genetic science, from academic studies to police forensic work. It won Mullis the Nobel Prize in chemistry in 1993.
Meanwhile, scientists were finding even hardier microbes, now known as hyperthermophiles, which demand temperatures of 80°C (176°F) or more. The warmest organism found so far, according to Frances Ashcroft in Life at the Extremes, is Pyrolobus fumarii, which dwells in the walls of ocean vents where the temperature can reach 113°C (235.4°F). The upper limit for life is thought to be about 120°C (248°F), though no one actually knows. At all events, the Brocks' findings completely changed our perception of the living world. As NASA scientist Jay Bergstralh has put it: “Wherever we go on Earth—even into what's seemed like the most hostile possible environments for life—as long as there is liquid water and some source of chemical energy we find life.”
Life, it turns out, is infinitely more clever and adaptable than anyone had ever supposed. This is a very good thing, for as we are about to see, we live in a world that doesn't altogether seem to want us here.
PART V LIFE ITSELF
16 LONELY PLANET
IT ISN'T EASY being an organism. In the whole universe, as far as we yet know, there is only one place, an inconspicuous outpost of the Milky Way called Earth, that will sustain you, and even it can be pretty grudging.
From the bottom of the deepest ocean trench to the top of the highest mountain, the zone that covers nearly the whole of known life, is only something over a dozen miles—not much when set against the roominess of the cosmos at large.
For humans it is even worse because we happen to belong to the portion of living things that took the rash but venturesome decision 400 million years ago to crawl out of the seas and become land based and oxygen breathing. In consequence, no less than 99.5 percent of the world's habitable space by volume, according to one estimate, is fundamentally—in practical terms completely—off-limits to us.
It isn't simply that we can't breathe in water, but that we couldn't bear the pressures. Because water is about 1,300 times heavier than air, pressures rise swiftly as you descend—by the equivalent of one atmosphere for every ten meters (thirty-three feet) of depth. On land, if you rose to the top of a five-hundred-foot eminence—Cologne Cathedral or the Washington Monument, say—the change in pressure would