IELTS Academic Reading Practice Test 8

A The settlement of the Pacific by Polynesian navigators stands as one of the most extraordinary feats of pre-modern exploration, and is regarded as the human discovery and colonisation of a quarter of the planet. Beginning around 1500 BCE, voyaging peoples ancestral to today's Polynesians spread eastward across an ocean covering one-third of the planet, establishing populations on islands as widely separated as Hawaii, Easter Island, and Aotearoa New Zealand. By approximately 1300 CE — well before European sailors had ventured far beyond coastal waters — virtually every habitable Pacific island had been reached, and many had been settled. The European explorers who arrived from the sixteenth century onwards, often equipped with sophisticated instruments and centuries of accumulated astronomical theory, were astonished to find the islands already inhabited. Their journals broadly attest to a recurring puzzlement: how a people without writing, maps, or metal could have completed voyages that European maritime science still considered marginal.

B The European reaction to this discovery was, for centuries, one of confusion and condescension. Some explorers refused to believe that the dispersed populations could share a common origin, attributing the colonisation instead to drift voyages by accidental castaways. The Norwegian adventurer Thor Heyerdahl's 1947 Kon-Tiki expedition was undertaken in part to prove that the Pacific had been colonised from South America, riding westward on the currents and trade winds. Although the voyage demonstrated that such a journey was possible, accumulated linguistic, botanical, and archaeological evidence has since established beyond reasonable doubt that the Polynesian dispersal was an east-bound migration originating from Southeast Asia, deliberately undertaken using sailing canoes capable of making considerable progress against the prevailing winds.

C Traditional Polynesian navigation techniques, partially eclipsed during centuries of European cultural dominance, have been substantially reconstructed over the past sixty years. The Polynesian Voyaging Society, founded in 1973, has conducted reconstructed long-distance voyages aboard traditional double-hulled canoes including the Hokule'a, demonstrating practical feasibility for techniques recorded only fragmentarily in oral tradition. Among the most important figures has been Mau Piailug, a traditional navigator from the Micronesian island of Satawal, who taught the navigation systems still partially used in his community to a new generation of Polynesian voyagers. His role bridges what scholars typically describe as an interrupted transmission of practical knowledge, with his apprenticeship of younger sailors credited with re-establishing skills that would otherwise have been lost within a generation.

D At the heart of traditional navigation is what practitioners call the star compass. The navigator memorises the rising and setting points of dozens of named stars and constellations on the horizon. By holding a known course relative to a rising or setting star, the navigator maintains a heading even out of sight of land. As one star rises too high, the navigator switches to another rising or setting star with the same azimuth. The system requires extensive memorisation but provides direction-keeping accuracy comparable to a magnetic compass under clear-sky conditions. Apprentice navigators have spent years memorising the heading points of perhaps two hundred named stars, enabling them to maintain orientation in conditions where Western navigators have been required to wait for sextant observations.

E Beyond stars, navigators read sea swells, wind patterns, cloud formations, and the behaviour of seabirds. Wave systems generated by distant storms persist as predictable swells that the navigator feels through the hull of the canoe, providing a reliable directional reference even when the sky is overcast. Reef herons and noddies, which roost on land at night and forage at sea by day, return to land at characteristic distances from shore, offering early evidence of nearby islands. Cloud formations over land take characteristic shapes — towering cumulus over high islands, lower cloud streaks over low atolls — visible far before the islands themselves come into view. The combination of indicators allows experienced navigators to detect land hundreds of kilometres before it becomes visible.

F Most distinctive is the absence of a literal map. Polynesian navigators did not record positions on paper or chart. Instead, they used an embodied mental model in which the canoe remains stationary and islands move past on either side. This conceptual framework, sometimes called the etak system in some Caroline Island traditions, allows the navigator to track progress and adjust heading without needing absolute coordinates. To Western navigators reliant on charts, this approach seemed mystifying; to those who learned the system from masters, it has proved fully functional across thousands of kilometres of open ocean. Modern researchers studying these traditions have come to regard etak as a different but fully adequate spatial framework rather than a primitive substitute for cartography.

A Life on Earth has been interrupted by five major mass extinction events over the past 540 million years, each erasing more than three-quarters of contemporary species in geologically rapid intervals. Each event has its own pattern, causes, and consequences, but together they reveal a planet whose biological history is far less continuous than nineteenth-century geologists assumed. The current period of biological loss, sometimes called the sixth extinction by analogy with these earlier events, is unique in being driven by a single species — human beings — rather than by physical perturbations of the planet itself. Geologists generally regard the recognition of the five-plus-one pattern as one of the most consequential conceptual shifts in modern earth science, with implications that extend from biological conservation to assessments of long-term planetary habitability.

B The end-Ordovician extinction, occurring around 444 million years ago, was the first of the great mass extinctions and the second-most severe in terms of species loss. Its likely cause was a sudden cooling of the climate driven by tectonic processes that locked up carbon dioxide, followed by a rapid warming as glaciers melted and sea levels rose. Marine invertebrates, which dominated the biota of the time, suffered catastrophic losses. The recovery, which took several million years, produced a substantially different marine ecosystem with new dominant groups. Subsequent evidence from chemical proxies preserved in marine sediments has reinforced the climate-driven interpretation while leaving the exact tectonic trigger a subject of continuing debate.

C The Late Devonian extinction, peaking around 372 million years ago, was a more drawn-out crisis lasting some 20 million years. Multiple pulses of extinction targeted especially the reef-building organisms of the time, including the great Devonian coral-stromatoporoid reef systems. The causes remain debated but appear to involve the expansion of land plants whose roots accelerated weathering of rocks, lowering atmospheric carbon dioxide and cooling the climate while simultaneously polluting oceans with nutrients that created widespread anoxic conditions. The Devonian crisis has been described as an early case study in how the colonisation of one terrestrial niche can drive cascading consequences for entirely unrelated marine ecosystems.

D The end-Permian extinction, around 252 million years ago, is the most severe biological catastrophe in the fossil record. Approximately 96 percent of marine species and 70 percent of terrestrial vertebrate species disappeared in what palaeontologists sometimes call the Great Dying. The most widely accepted cause is the eruption of the Siberian Traps, an enormous volcanic province that released vast quantities of carbon dioxide and sulphur dioxide over a period of perhaps two million years. The resulting global warming, ocean acidification, and oxygen depletion killed most life on the planet, and the recovery took some 10 million years — longer than any other extinction event in the geological record. Many palaeontologists have regarded the end-Permian as the closest the Earth has come to a complete biological reset.

E The end-Triassic extinction, around 201 million years ago, was less severe in total species loss but reshaped the dominant land animals: it eliminated most of the large reptile groups that had survived the end-Permian event, leaving the way clear for the dinosaurs to expand into the ecological vacuum. The cause is thought to be another large igneous province, the Central Atlantic Magmatic Province, whose eruptions accompanied the breakup of the supercontinent Pangaea. The pattern illustrates how a substantial extinction can reshape the dominant clade even where total species loss is moderate by comparison with other events.

F The end-Cretaceous extinction, around 66 million years ago, is the most famous of the mass extinctions because it ended the long age of non-avian dinosaurs and cleared the way for mammals to diversify. The dominant cause was the impact of a large asteroid in what is now the Yucatán Peninsula of Mexico, leaving the Chicxulub crater that was identified in the early 1990s. The impact triggered global wildfires, blocked sunlight with debris for months or years, and disrupted photosynthesis across the planet. Volcanic activity in the Indian Deccan Traps contributed to the stress, but the asteroid impact is now widely regarded as the proximate trigger. Subsequent recovery saw mammals diversify into ecological roles previously occupied by dinosaurs, a transition that produced the lineages from which all modern mammalian orders, including primates and ultimately humans, would descend.

G Modern biological loss is driven by very different causes: habitat destruction, species introduction, hunting, pollution, and increasingly climate change. The rate of loss, while debated, is widely estimated to be 100 to 1,000 times the background rate inferred from the fossil record. Whether the current pulse will reach the magnitude of the earlier five events depends largely on policy responses in the coming decades. What is clear is that biological recovery from major extinction events takes millions of years — far longer than any human institution has ever endured.

A For most of the twentieth century, signed languages were misunderstood as crude visual versions of spoken languages, lacking grammatical structure and depending heavily on pantomime. This view was decisively overturned, according to most contemporary linguists, by the work of William Stokoe, whose 1960 structural analysis of American Sign Language demonstrated that it possessed a complete grammatical system, largely independent of English and arguably equivalent in linguistic complexity to any spoken language. Stokoe's framework, which proposed decomposing signs into combinations of hand shape, location, movement, and orientation, was initially met with considerable pushback from members of the deaf community and from many in the linguistic establishment, but is now widely held to be a standard reference point in the field. The reframing has, in many linguists' view, transformed the discipline's understanding of what language is and what physical channels are sufficient to carry it.

B Modern linguistic research has so far documented at least 144 distinct signed languages in use across the world, and new ones are still being identified. Just as spoken languages tend to cluster into language families with common ancestors, so too do signed languages: American Sign Language and French Sign Language, for instance, appear to share a substantial common vocabulary, largely because the first deaf school in the United States was founded in 1817 by Thomas Hopkins Gallaudet, who brought across the teaching system used at the French national school. British Sign Language, by contrast, evolved independently and is considered to be mutually unintelligible with American Sign Language despite the shared spoken-language backdrop. The historical accident of who founded which deaf school explains a great deal of the modern map of signed-language relationships.

C Signed languages exhibit grammatical features that are typologically unusual, and in some cases probably impossible, in spoken languages. Spatial grammar allows signers to set up referents at different locations within the signing space, and then refer back to them by directing later signs towards those locations. Simultaneous expression of multiple grammatical components — verb, subject, manner, and aspect — appears to be far more developed than in any spoken language, taking advantage of the parallel articulatory channels offered by the two hands, facial expression, and body posture. Facial expression in particular carries grammatical rather than emotional content much of the time, marking question forms, conditionals, topics, and adverbial modification. The grammatical use of facial expression has been a recurring source of confusion for hearing learners, who tend to interpret raised eyebrows or pursed lips as emotional rather than syntactic signals.

D The acquisition of signed languages by deaf children of deaf parents tends to follow essentially the same developmental milestones as spoken language acquisition by hearing children, with one important caveat: those milestones generally occur on the same biological schedule provided the child has full early access to a complete signed language model. Deaf children of hearing parents, who lack such access, are widely reported to show significant delays in language acquisition, delays that may persist throughout life. This finding has informed strong recommendations from professional associations that deaf newborns ought to receive early signed language exposure, regardless of any future decisions about cochlear implants or other interventions. The early-exposure recommendation reflects the same critical-period considerations that govern spoken-language acquisition in hearing infants.

E Recent neuroimaging studies appear to have shown that signed languages activate broadly the same networks in the brain as spoken languages, including the classical language areas associated with the left hemisphere. The exact pattern of activation differs in detail, presumably reflecting the visual rather than auditory input channel, but the deep grammatical processing seems to be centred in regions that have traditionally been described as auditory-language regions. This finding may have important implications for theories of language evolution: it suggests that the brain regions involved are likely organised around the abstract structure of language rather than around the specific sensory modality through which it is delivered. The implication, in many neuroscientists' view, is that language has co-opted general-purpose grammatical machinery to two different sensory channels rather than evolving channel-specific systems.

F Sign languages around the world are under pressure from several directions. Globalisation has favoured the spread of a few dominant signed languages — American Sign Language in particular — apparently at the expense of smaller national and regional varieties. Cochlear implants and oralist educational philosophies that discourage signing have been linked to a declining transmission of signed languages between generations. Some smaller signed languages, including Adamorobe Sign Language used in a village in Ghana and Al-Sayyid Bedouin Sign Language in Israel's Negev region, are used by fewer than a few hundred people and arguably face the same kinds of endangerment risks that have been documented for small spoken languages. UNESCO recognised signed languages in 2017 as an essential element of linguistic diversity worthy of explicit protection.