IELTSwithJurabek

PASSAGE 2

Read the text and answer questions 14-26

The fascinating world of attine ants

Nicholas Wade examines leaf-cutter ants and their amazing agriculture

A. Leaf-cutting ants and their fungus farms are a marvel of nature and perhaps the best-known example of symbiosis - the mutual dependence of two species. The ants cultivate a mushroom-like fungus in farms. Both the ants and their so-called agriculture have been extensively studied over the years, but recent research has uncovered intriguing new findings. Ants invented agriculture 50 million years before people did, and the leaf-cutters, members of the large attine ant family, practice the most sophisticated example of it. They grow their fungus in underground chambers that can reach the size of a football. A single leaf-cutter nest may contain a thousand such chambers, embedded in an underground metropolis up to 18 feet deep, and support a society of more than a million ants.

B. These ant communities are the dominant plant-eaters of the Neotropics, the region comprising South and Central America, Mexico and the Caribbean. Biologists believe 15 per cent of the leaf production of tropical forests disappears down the nests of leaf-cutter ants. In the nest, the leaves are shredded and added to the fungus, which digests the leaves and is in turn eaten by the ants. The attine ants' achievement is remarkable because it allows them to consume, courtesy of their mushroom's digestive powers, the harvest of tropical forests whose leaves are laden with poisonous chemicals.

C. There are more than 200 known species of attine ant, divided into 12 groups. The leaf-cutters use fresh vegetation while the other groups, known as the lower attines because their nests are smaller and their techniques more primitive, feed their gardens with similar leaves which have fallen on the ground and insects that lie on the forest floor. Lower attine ants are all a similar size. However, leaf-cutter worker ants come in made-to-fit sizes: large ants to saw off leaves, medium ones to shred them and miniature workers to seed them with fungus and clean off alien growths.

D. In 1994, biologists from the United States Department of Agriculture analyzed the DNA of ant funguses. They found that the leaf-cutters' fungus was descended from a single pure strain, propagated for at least 23 million years. However, the funguses grown by lower attine ants fell into four different groups, as if the ants had domesticated wild funguses at least four times in evolutionary history. What could be driving these two patterns of fungus gardening, the pure clone cultivation of the leaf-cutters and multiple varieties of the lower attines?

E. The answer has been suggested by Cameron Currie of the University of Toronto. The pure strain of fungus grown by the leaf-cutters, it seemed to him, resembled the single crops grown by humans to the exclusion of all others, such as potato growing. These monocultures are very productive for a while but can succumb to disease. Monocultures, which lack the genetic diversity to respond to changing environmental threats, are particularly vulnerable to parasites, organisms which live and feed on their host, often causing harm. Currie felt there had to be a parasite in the ant-fungus system. But a century of ant research did not provide any evidence for his idea. Textbooks describe how leaf-cutter ants scrupulously weed their gardens of all foreign organisms. "People kept telling me, the ants keep their gardens free of parasites," said Currie. Nevertheless, after three years of sifting through attine ant gardens, Currie discovered several alien organisms, particularly a family of parasitic molds called Escovopsis.

F. Escovopsis is a deadly disease that can devastate a fungus garden in a couple of days. It blooms like a white cloud which envelops the whole garden. Other ants will not go near it and the ants associated with the garden just starve to death. Evidently, the ants usually manage to keep Escovopsis and other parasites under control. Nevertheless, with any lapse in control Escovopsis will quickly burst forth. Although new leaf-cutter gardens start off free of Escovopsis, within two years some 60 per cent become infected.

G. The discovery of Escovopsis's role brings a new level of understanding to the evolution of the attine ants. In the last decade, evolutionary biologists have become increasingly aware of the role of parasites as driving forces in evolution. With Currie's work, there is now a possible reason for the different varieties of fungus in the lower attine mushroom gardens - to stay one step ahead of the relentless Escovopsis. Interestingly, the leaf-cutters had fewer alien molds in their gardens than the lower attines, yet more Escovopsis infections. Clearly, the price they pay for cultivating a pure variety of fungus is a higher risk from Escovopsis.

H. So how do attine ants keep this parasite under control? People have known for a hundred years that ants have a whitish growth on their body surface. It was thought to be a wax but, after examining it under a microscope, Currie discovered a specialized patch on the ants' bodies that harbors a particular kind of bacterium, one well known to the pharmaceutical industry and the source of many antibiotics used in medicine. This bacterium is a potent poisoner of Escovopsis, inhibiting its growth and suppressing spore formation. Astoundingly, the leaf-cutter ants are accomplishing feats beyond the power of humans: they are growing a monocultural crop year after year without disaster, and they are using an antibiotic apparently so wisely that, unlike people, they are not provoking antibiotic resistance in the target disease-producing organism.

PASSAGE 3

Read the text and answer questions 27-40

Decisions, decisions!

Research explores when we can make a vital decision quickly and when we need to proceed more deliberately

A widely recognised legend tells us that in Gordium, in what is now Turkey, in the fourth century BC an oxcart was roped to a pole with a complex knot. It was said that the first person to untie it would become the king of Asia. Unfortunately, the knot proved impossible to untie. The story continues that when confronted with this problem, rather than deliberating on how to untie the Gordian knot, Alexander, the famous ruler of the Greeks in the ancient world, simply took out his sword and cut it in two - then went on to conquer Asia. Ever since, the notion of a Gordian solution has referred to the attractiveness of a simple answer to an otherwise intractable problem.

Among researchers in the psychology of decision making, however, such solutions have traditionally held little appeal. In particular, the conflict model of decision making proposed by psychologists Irving Janis and Leon Mann in their 1977 book Decision Making argued that a complex decision making process is essential for guarding individuals and groups from the peril of group-think. Decisions made without thorough canvassing, surveying, weighing, examining and reexamining relevant information and options would be suboptimal and often disastrous. One foreign affairs decision made by a well-known US political leader in the 1960s is typically held up as an example of the perils of inadequate thought, whereas his successful handling of a later crisis is cited as an example of the advantages of careful deliberation. However, examination of these historical events by Peter Suedfield, a psychologist at the University of British Columbia, and Roderick Kramer, a psychologist at the Stanford Graduate School of Business, found little difference in the two decision-making processes; both crises required and received complex consideration by the political administration, but later only the second one was deemed to be effective.

In general, however, organizational and political science offer little evidence that complex decisions are better than simpler ones. In fact, a growing body of work suggests that in many situations simple snap decisions will be routinely superior to more complex ones - an idea that gained widespread public appeal with Malcolm Gladwell's best-selling book Blink.

An article by Ap Dijksterhuis of the University of Amsterdam and his colleagues, On Making the Right Choice: the Deliberation-without-attention Effect, runs very much in the spirit of Gladwell's influential text. Its core argument is that to be effective, conscious, deliberative decision making requires cognitive resources. Because increasingly complex decisions place increasing strain on those resources, the quality of our decisions declines as their complexity increases. In short, complex decisions overrun our cognitive powers. On the other hand, unconscious decision making, what the authors refer to as deliberation without attention, requires no cognitive resources, so task complexity does not degrade effectiveness. The seemingly counterintuitive conclusion is that although conscious thought enhances simple decisions, the opposite holds true for more complex decisions.

Dijksterhuis reports four simple but elegant studies supporting this argument. In one, participants assessed the quality of four hypothetical cars by considering either four attributes, a simple task, or 12 attributes, a complex task. Among participants who considered four attributes, those who were allowed to engage in undistracted deliberative thought did better at discriminating between the best and worst cars. Those who were distracted and thus unable to deliberate had to rely on their unconscious thinking and did less well. The opposite pattern emerged when people considered 12 criteria. In this case, conscious deliberation led to inferior discrimination and poor decisions.

In another study, Dijksterhuis surveyed people shopping for clothes, simple products, and furniture, complex products. Compared with those who said they had deliberated long and hard, shoppers who bought with little conscious deliberation felt less happy with their simple clothing purchase but happier with the complex furniture purchases. Deliberation without attention actually produced better results as the decisions became more complex.

From there, however, the researchers take a big leap. They write: There is no reason to assume that the deliberation-without-attention effect does not generalize to other types of choices - political, managerial or otherwise. In such cases, it should benefit the individual to think consciously about simple matters and to delegate thinking about more complicated matters to the unconscious.

This radical inference contradicts standard political and managerial theory but doubtless comforts those in politics and management who always find the simple solution to the complex problem an attractive proposition. Indeed, one suspects many of our political leaders already embrace this wisdom.

Still it is there, in the realms of society and its governance, that the more problematic implications of deliberation without attention begin to surface. Variables that can be neatly circumscribed in decisions about shopping lose clarity in a world of group dynamics, social interaction, history and politics. Two pertinent questions arise. First, what counts as a complex decision? And second, what counts as a good outcome?

As social psychologist Kurt Lewin noted, a good decision that nobody respects is actually bad. His classic studies of decision making showed that participating in deliberative processes makes people more likely to abide by the results. The issue here is that when political decision makers make mistakes, it is their politics, or the relation between their politics and our own, rather than psychology which is at fault.

Gladwell's book and Dijksterhuis's paper are invaluable in pointing out the limitations of the conventional wisdom that decision quality rises with decision-making complexity. But this work still tempts us to believe that decision making is simply a matter of psychology, rather than also a question of politics, ideology and group membership. Avoiding social considerations in a search for general appeal can take us away from enlightenment rather than towards it.