IELTSwithJurabek

Read the text and answer questions 14-26

Jellyfish – The Dominant Species

A Jellyfish have become the curse of beach holidays, permeating every ocean on the globe, thriving in the Arctic and the tropics. In an ever-changing world where other species struggle to endure, jellyfish populations are on the rise.

To the untrained eye, these creatures drift aimlessly on the oceans' currents and appear benign. In addition, they lack sharp claws, piercing teeth or even a brain. Despite this, they are armed with an amazing arsenal of weapons, especially the stinging power of their tentacles. As a result, jellyfish are among the most-feared, least-understood creatures in the seas.

B According to Dr Monty Graham, a jellyfish scientist at the University of South Alabama, US, 'Jellyfish are a pretty good group of animals to track coastal ecosystems. When you start to see jellyfish numbers grow, that usually indicates a stressed system.' While populations appear to be down this year, Dr Graham sees 'a statistically solid increase' over the longer term.

This increase first gained attention in the 1980s when a huge number of jellyfish, Atlantic Ocean natives named Mnemiopsis leidyi, devastated the Black Sea, an ecosystem already weakened by overfishing of anchovies. Scientists believe that this species of jellyfish came in on the bottom of a ship and then rapidly multiplied, feeding on anchovy eggs and the plankton that young fish rely on.

C Dense jellyfish aggregations can be a natural feature of healthy ocean ecosystems, but a clear picture is now emerging of more severe and frequent jellyfish outbreaks worldwide. Dr Anthony Richardson, from the University of Queensland, Australia, explains that once jellyfish gain a foothold, if conditions are right they can establish a massive population at the expense of other ocean life. The problem is that parts of the ocean might switch from being dominated by fish to being dominated by jellyfish.

D A study done by Richardson and his colleagues explores the causes behind jellyfish infestation, and the need for swift, decisive action to stem jellyfish takeover. Jellyfish outbreaks are linked directly to human actions, including overfishing, the input of fertilizer and sewage into the ocean, and climate change.

Overfishing has removed fish from marine ecosystems at astounding rates. According to Richardson, this has made it possible for jellyfish to take their place. 'This is because small fish appear to keep jellyfish in check by predation (on jellyfish when they are very small) and competition (when feeding). So, once we remove fish, jellyfish can proliferate.'

Eutrophication is another human-caused change in the ocean that has likely contributed to jellyfish explosions. Eutrophication is an increase of nitrogen and phosphorus in the ocean, largely caused by fertilizer and waste run-off. This leads to algae blooms, which lower oxygen in the marine ecosystem, creating so-called 'dead zones', which have been increasing dramatically around the world. According to Richardson, these low-oxygen waters give jellyfish the advantage. 'Fish avoid low-oxygen waters but jellyfish, having lower oxygen demands, not only survive but can thrive in these conditions as there is less predation and competition from fish.'

E Furthermore, Richardson and his colleagues speculate that climate change may expand the traditional geographical range of jellyfish. 'As water warms, tropical species are moving towards the poles. Many venomous jellyfish species are tropical and could move into more densely populated subtropical and temperate regions.'

F Once jellyfish appear en masse in an ecosystem they can make it very difficult for fish to stage a comeback. By feeding on fish eggs the jellyfish successfully prevent fish from returning to their normal population numbers, says Richardson. 'One can thus think of two alternate states with each being stable: one dominated by fish and the other by jellyfish. Unfortunately, where there is a jellyfish-dominated state then this does not support the nutritional needs of other fish, marine mammals, and seabirds.' In other words an ecosystem that loses fish also loses the species that depend on fish for survival.

This state has been defined as a 'monoculture of jellyfish', an apt analogy since the situation shares similarities with other monocultures. When the rich biodiversity of tropical forests is replaced by plantations growing a single species of tree, an area of rich variety becomes a desert in terms of biodiversity, as do ocean ecosystems when jellyfish become the dominant species.

One result of large jellyfish populations is the economic effect it has had on the fishing industry. In the Gulf of Mexico, shrimp fishermen are struggling with a jellyfish boom that fills nets, causing them to break and resulting in millions of dollars in losses.

G Experts say that a greater understanding of jellyfish, including their ideal water temperature and feeding habits, is necessary to determine with certainty what is causing the recent massive invasion, and to come up with ways to combat it.

Due to the difficulty of turning ecosystems around once jellyfish have become dominant, Richardson and his colleagues propose focusing on 'prevention rather than cure'. They recommend a halt to overfishing small fish that are vital to keeping jellyfish in check, reducing the amount of fertilizer and sewage running off into the oceans, and finally, if possible, confronting climate change.

Read the text and answer questions 27-40

The Pirahã people of Brazil

The Pirahä language has stirred up debate among experts

The Pirahã tribe live deep in Brazil's Amazon forest, and their language is hotly debated by linguists. Since 1977, the ethnologist Daniel Everett has spent a total of seven years living with the Pirahã and has committed his career to studying their puzzling speech. Indeed, he was uncertain for so long about what he was actually hearing while living among the Pirahä that he waited nearly three decades before publishing his findings.

The debate over the Pirahā language goes right to the core of the riddle regarding how Homo sapiens managed to develop vocal communication. Although bees dance, birds sing and whales even sing with syntax*, human language is unique, if only for the reason that it enables humans to piece together never-before- constructed thoughts, and be infinitely imaginative - think of Shakespeare's plays or Einstein's theory of relativity.

Linguistics generally focuses on what features all human languages have in common, but the Pirahã language departs from what some academics have long maintained are essential and inalienable features of all human languages. Most of all, it may be unique for not employing subordinate clauses. Instead of saying, 'When I have finished eating, I will speak to you,' the Pirahã say, 'I finish eating, I speak with you.' Equally perplexing, the Pirahã appear not to use numbers. During the time he spent with them, Everett never heard words like 'all', 'every' and 'more'. There is one word, 'hoi', that comes close to the numeral 1, but it can also mean 'small'. And they were never observed to count without language,on their fingers for example, in order to determine important tasks in village life like how many pieces of meat to grill.

Everett's findings among the Pirahã have brought new life to a controversial theory by the linguist Benjamin Whorf, who suggested that people are only capable of constructing thoughts for which they possess actual words. Or to put it another way, because they have no words for numbers, they cannot even begin to understand the concept of numbers or arithmetic.

The Warlpiri language - spoken by a group of Australian Aborigines-like that of the Pirahã, features only the most rudimentary system of counting. However, the Warlpiri people had no difficulty counting farther than three in a foreign language, in this case English, but when Everett attempted to teach the Pirahã how to count in Portuguese like other Brazilians, not a single person could count to 10.

Everett is at pains to point out that the Pirahã are not unintelligent, for their thinking is not any slower than that of the average university student. And although they reside in a remote part of the forest, they do not live in complete genetic isolation, but mix with people from the surrounding populations and share similar intellectual capacities with their neighbours whose languages do contain numbers.

Eventually, after some 30 years of research, Everett has come up with a surprising explanation for the peculiarities of the Pirahã language. Language, he believes, is created by a people's way of life, their belief system and values. In this way, variety in human language is almost limitless, a function of the human capacity to live in different ways, such as in the forest. What Everett's research has revealed is that the central tenet of the Pirahã culture is to live in the here and now. The only thing of importance that is worth communicating to others is what is being experienced at that very moment, though this can often be described with great care and detail. In consequence, the language has no means to conjugate verbs in order to describe 'yesterday' or 'last week' or 'when I was a child'. Their very literal view of the world curtails abstract thought, and many features taken for granted among other peoples are absent among the Pirahã, such as a creation myth, story telling and painting. One manifestation of their beliefs is that by tradition the names they give their children are not particularly imaginative. Often they are named after other members of the tribe with whom they share similar character traits. Standing out or being different is not encouraged by the Pirahã, and this is reflected in their perhaps colourless choice of names.

Everett anticipated that these findings would be controversial and the reaction came as expected. Until this point, many linguists had defended the theories of Noam Chomsky, according to which all human languages have a universal grammar. What exactly makes up this universal grammar is the subject of debate, but at its heart is the concept of 'recursion', which is defined as replication of a structure within its single parts. Without it, humans would not be able to view separate thoughts as subordinate parts of a complex whole. And, most pertinent to Everett's work, there would not be subordinate clauses, which are responsible for translating the concept of recursion into grammar. But if the Pirahã do not form subordinate clauses, then recursion cannot explain the uniqueness of human language, and this would negate Chomsky's theories.

The logical way forward now would be to try to prove that the Pirahã can think in a recursive fashion. The only problem is, nobody can confirm or deny Everett's observations since no other researcher can speak Pirahã as well as he does. Despite this, several researchers - including two of Chomsky's colleagues - will soon travel to Brazil to check his claims. My concern is that soon the Pirahã will simply become one more scientific oddity with every aspect of their lives being exploited and analysed.