You should spend about 20 minutes on Questions 1–14, which are based on Reading Passage 1.
Space travel AND health
A Space biomedicine is a relatively new area of research both in the USA and in Europe. Its main objectives are to study the effects of space travel on the human body, identifying the most critical medical problems and finding solutions to those problems. Space biomedicine centres are receiving increasing direct support from NASA and/or the European Space Agency (ESA).
B This involvement of NASA and the ESA reflects growing concern that the feasibility of travel to other planets, and beyond, is no longer limited by engineering constraints but by what the human body can actually withstand. The discovery of ice on Mars, for instance, means that there is now no necessity to design and develop a spacecraft large and powerful enough to transport the vast amounts of water needed to sustain the crew throughout journeys that may last many years. Without the necessary protection and medical treatment, however, their bodies would be devastated by the unremittingly hostile environment of space.
C The most obvious physical changes undergone by people in zero gravity are essentially harmless; in some cases they are even amusing. The blood and other fluids are no longer dragged down towards the feet by the gravity of Earth, so they accumulate higher up in the body, creating what is sometimes called 'fat face', together with the contrasting 'chicken legs' syndrome as the lower limbs become thinner.
D Much more serious are the unseen consequences after months or years in space. With no gravity, there is less need for a sturdy skeleton to support the body, with the result that the bones weaken, releasing calcium into the bloodstream. This extra calcium can overload the kidneys, leading ultimately to renal failure. Muscles too lose strength through lack of use. The heart becomes smaller, losing the power to pump oxygenated blood to all parts of the body, while the lungs lose the capacity to breathe fully. The digestive system becomes less efficient, a weakened immune system is increasingly unable to prevent diseases and the high levels of solar and cosmic radiation can cause various forms of cancer.
E To make matters worse, a wide range of medical difficulties can arise in the case of an accident or serious illness when the patient is millions of kilometres from Earth. There is simply not enough room available inside a space vehicle to include all the equipment from a hospital's casualty unit, some of which would not work properly in space anyway. Even basic things such as a drip depend on gravity to function, while standard resuscitation techniques become ineffective if sufficient weight cannot be applied. The only solution seems to be to create extremely small medical tools and 'smart' devices that can, for example, diagnose and treat internal injuries using ultrasound. The cost of designing and producing this kind of equipment is bound to be, well, astronomical.
F Such considerations have led some to question the ethics of investing huge sums of money to help a handful of people who, after all, are willingly risking their own health in outer space, when so much needs to be done a lot closer to home. It is now clear, however, that every problem of space travel has a parallel problem on Earth that will benefit from the knowledge gained and the skills developed from space biomedical research. For instance, the very difficulty of treating astronauts in space has led to rapid progress in the field of telemedicine, which in turn has brought about developments that enable surgeons to communicate with patients in inaccessible parts of the world. To take another example, systems invented to sterilize waste water on board spacecraft could be used by emergency teams to filter contaminated water at the scene of natural disasters such as floods and earthquakes. In the same way, miniature monitoring equipment, developed to save weight in space capsules, will eventually become tiny monitors that patients on Earth can wear without discomfort wherever they go.
G Nevertheless, there is still one major obstacle to carrying out studies into the effects of space travel: how to do so without going to the enormous expense of actually working in space. To simulate conditions in zero gravity, one tried and tested method is to work under water, but the space biomedicine centres are also looking at other ideas. In one experiment, researchers study the weakening of bones that results from prolonged inactivity. This would involve volunteers staying in bed for three months, but the centre concerned is confident there should be no great difficulty in finding people willing to spend twelve weeks lying down. All in the name of science, of course.
You should spend about 20 minutes on Questions 15–27, which are based on Reading Passage 2.
VANISHED Who pulled the plug on the Mediterranean? And could it happen again?
Cannes. Monte Carlo. St Tropez. Magic names all. And much of the enchantment comes from the deep blue water that laps their shores. But what if somebody pulled the plug? Suppose the Mediterranean Sea were to vanish, leaving behind an expanse of salt desert the size of India. Hard to imagine? It happened.
'It would have looked like Death Valley,' says Bill Ryan, from the Lamont-Doherty Earth Observatory in New York, one of the leaders of the team that discovered the Mediterranean had once dried up, then refilled in a deluge of Biblical proportions. Between five and six million years ago, the great desiccation touched off what scientists call the Messinian Salinity Crisis – a global chemical imbalance that triggered a wrenching series of extinctions and plunged the Earth into an ice age.
The first indications of some extraordinary past events came in the 1960s, when geologists discovered that major rivers flowing into the Mediterranean had eroded deep canyons in the rock at the bottom of the sea. River erosion of bedrock cannot occur below sea level, yet somehow the River Rhone in the South of France had managed to create a channel 1000 metres deep in the sea floor, while the Nile had cut nearly 1500 metres into the rock off the North African coast. There was more: despite the fact that the formation of caves can only take place above water, scientists discovered a whole network beneath the island of Malta that reached an astonishing depth of 2000 metres below sea level.
Further evidence came to light in 1970, when an international team chugged across the Mediterranean in a drilling ship to study the sea floor near the Spanish island of Majorca. Strange things started turning up in core samples: layers of microscopic plants and soil sandwiched between beds of salt more than two kilometres below today's sea level. The plants had grown in sunlight. Also discovered inside the rock were fossilized shallow-water shellfish, together with salt and silt: particles of sand and mud that had once been carried by river water. Could the sea floor once have been near a shoreline?
That question led Ryan and his fellow team leader, Kenneth Hsü, to piece together a staggering chain of events. About 5.8 million years ago, they concluded, the Mediterranean was gradually cut off from the Atlantic Ocean when continental drift pinned Morocco against Spain. As the opening became both narrower and shallower, the deep outward flow from sea to ocean was progressively cut off, leaving only the shallow inward flow of ocean water into the Mediterranean. As this water evaporated, the sea became more saline and creatures that couldn't handle the rising salt content perished. 'The sea's interior was dead as a door nail, except for bacteria,' says Ryan. When the shallow opening at Gibraltar finally closed completely, the Mediterranean, with only rivers to feed it, dried up and died.
Meanwhile, the evaporated water was falling back to Earth as rain. When the fresh water reached the oceans, it made them less saline. With less salt in it to act as an antifreeze, parts of the ocean that would not normally freeze began to turn to ice. 'The ice reflects sunlight into space,' says Ryan. 'The planet cools. You drive yourself into an ice age.'
Eventually, a small breach in the Gibraltar dam sent the process into reverse. Ocean water cut a tiny channel to the Mediterranean. As the gap enlarged, the water flowed faster and faster, until the torrent ripped through the emerging Straits of Gibraltar at more than 100 knots. 'The Gibraltar Falls were 100 times bigger than Victoria Falls and a thousand times grander than Niagara,' Hsü wrote in his book The Mediterranean was a Desert (Princeton University Press, 1983).
In the end the rising waters of the vast inland sea drowned the falls and warm water began to escape to the Atlantic, reheating the oceans and the planet. The salinity crisis ended about 5.4 million years ago. It had lasted roughly 400,000 years.
Subsequent drilling expeditions have added a few wrinkles to Ryan and Hsü's scenario. For example, researchers have found salt deposits more than two kilometres thick – so thick, some believe, that the Mediterranean must have dried up and refilled many times. But those are just geological details. For tourists the crucial question is, could it happen again? Should Malaga start stockpiling dynamite?
Not yet, says Ryan. If continental drift does reseal the Mediterranean, it won't be for several million years. 'Some future creatures may face the issue of how to respond to nature's closure. It's not something our species has to worry about.'
You should spend about 20 minutes on Questions 28–40, which are based on Reading Passage 3.
Dogs: a love story
A Genetic studies show that dogs evolved from wolves and remain as similar to the creatures from which they came as humans with different physical characteristics are to each other, which is to say not much different at all. 'Even in the most changeable mitochondrial DNA markers – DNA handed down on the mother's side – dogs and wolves differ by not much more than one per cent,' says Robert Wayne, a geneticist at the University of California at Los Angeles.
B Wolf-like species go back one to two million years, says Wayne, whose genetic work suggests dogs of some sort began breaking away about 100,000 years ago. Wolf and early human fossils have been found close together from as far back as 400,000 years ago, but dog and human fossils date back only about 14,000 years, all of which puts wolves and/or dogs in the company of man or his progenitors before the development of farming and permanent human settlements, at a time when both species survived on what they could scratch out hunting or scavenging.
C Why would these competitors cooperate? The answer probably lies in the similar social structure and size of wolf packs and early human clans, the compatibility of their hunting objectives and range, and the willingness of humans to accept into camp the most suppliant wolves, the young or less threatening ones.
D Certain wolves or protodogs may have worked their way close to the fire ring after smelling something good to eat, then into early human gatherings by proving helpful or unthreatening. As wandering packs of twenty-five or thirty wolves and clans of like-numbered nomadic humans roamed the landscape in tandem, hunting big game, the animals hung around campsites scavenging leftovers, and the humans might have used the wolves' superior scenting ability and speed to locate and track prospective kills. At night, wolves with their keen senses could warn humans of danger approaching.
E Times might not have been as hard back then as is commonly thought. In many instances food would have been plentiful, predators few, and the boundaries between humans and wildlife porous. Through those pores slipped smaller or less threatening wolves, which from living in packs where alpha bosses reigned would know the tricks of subservience and could adapt to humans in charge. Puppies in particular would be hard to resist, as they are today. Thus was a union born and a process of domestication begun.
F Over the millennia, admission of certain wolves and protodogs into human camps and exclusion of larger, more threatening ones led to the development of people-friendly breeds distinguishable from wolves by size, shape, coat, ears and markings. Dogs were generally smaller than wolves, their snouts proportionally reduced. They would assist in the hunt, clean up camp by eating garbage, warn of danger, keep humans warm, and serve as food. Native Americans among others ate puppies, and in some societies it remains accepted practice.
G By the fourth millennium BC Egyptian rock and pottery drawings show dogs being put to work by men. Then, as now, the relationship was not without drawbacks. Feral dogs roamed city streets, stealing food from people returning from market. Despite their penchant for misbehaviour, and sometimes because of it, dogs keep turning up at all the important junctures in human history.
H In ancient Greece, 350 years before Christ, Aristotle described three types of domesticated dogs, including speedy Laconians used by the rich to chase and kill rabbits and deer. Three hundred years later, Roman warriors trained large dogs for battle. The brutes could knock an armed man from his horse and dismember him.
I In seventeenth-century England, dogs still worked, pulling carts, sleds, and ploughs, herding livestock, or working as turn-spits, powering wheels that turned beef and venison over open fires. But working dogs were not much loved and were usually hanged or drowned when they got old. 'Unnecessary' dogs meanwhile gained status among English royalty. King James I was said to love his dogs more than his subjects. Charles II was famous for playing with his dog at Council table, and his brother James had dogs at sea in 1682 when his ship was caught in a storm. As sailors drowned, he allegedly cried out, 'Save the dogs and Colonel Churchill!'
J By the late nineteenth century the passion for breeding led to the creation of private registries to protect prized bloodlines. The Kennel Club was formed in England in 1873, and eleven years later the American Kennel Club (AKC) was formed across the Atlantic. Today the AKC registers 150 breeds, the Kennel Club lists 196, and the Europe-based Fédération Cynologique Internationale recognizes many more. Dog shows sprouted in the mid-1800s when unnecessary dogs began vastly to outnumber working ones, as they do to this day. Unless, that is, you count companionship as a job.
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