IELTS Academic Reading Practice Test 16

A The invention of writing is widely regarded as one of the most consequential transitions in human history, allowing language to be stored across time and transmitted across distance with a fidelity that purely oral systems cannot match. For most of human existence, communication was confined to face-to-face speech and a limited repertoire of pictures and tallies. Tallying notches on bone, stone, or wood is widely said to have provided a partial substitute for memory, but its expressive range was severely restricted. The development of true writing — systems capable of representing the full range of speech — is widely said to have occurred independently in only a small number of places, with each origin shedding light on what conditions favour the emergence of literacy. B The earliest known true writing system is identified as the cuneiform script of southern Mesopotamia, developed by the Sumerians around 3,200 BCE. Cuneiform is widely said to have begun as an accounting system: small clay tokens of standardised shapes represented standard quantities of agricultural goods, and over time these tokens were replaced by impressions made on flat clay tablets with a wedge-shaped stylus. The earliest tablets generally record nothing more than the inventories of temple storehouses — sacks of grain, jars of oil, head of sheep. Only later did the system reportedly expand to record names, then verbs, then complete sentences. Once cuneiform could represent grammar, it was rapidly adopted by Akkadian, Babylonian, Elamite, and Hittite administrations, eventually becoming a diplomatic lingua franca of the ancient Near East and surviving for nearly three thousand years.

C Egyptian hieroglyphic writing emerged independently around 3,150 BCE. Unlike the inventory-derived cuneiform, hieroglyphs are widely said to have originated as inscriptions on ceremonial palettes and tomb walls, used principally for naming royalty and recording religious propositions rather than tracking grain. Hieroglyphs combined pictographic, syllabic, and alphabetic principles in a complex but stable system that persisted with only modest change for more than 3,000 years. A cursive form, the hieratic script, was used by priests and scribes for everyday administrative and literary documents on papyrus, with hieroglyphs themselves reserved largely for monumental and sacred contexts. The Rosetta Stone, recovered by French soldiers near Alexandria in 1799 and deciphered by Jean-François Champollion in 1822, finally allowed Western scholars to read hieroglyphs after a gap of more than a millennium.

D Chinese writing is regarded as a third independent invention. The earliest substantial examples are oracle bone inscriptions from approximately 1,250 BCE, used by Shang dynasty diviners to record questions put to ancestral spirits and the resulting prognostications. Chinese characters never moved fully to phonetic representation; they remained primarily logographic, with each character representing a morpheme rather than a sound. This is widely said to have made the system unusually conservative — the same characters could be read across mutually unintelligible spoken dialects — but also made literacy enormously demanding, with educated readers required to memorise several thousand characters. The conservatism of the script has, in some scholars' view, played a substantial role in the political unity of the Chinese cultural sphere over long historical periods.

E Mesoamerican writing systems, including the Maya glyphs that flourished between roughly 250 and 900 CE, developed in isolation from the Old World traditions. The Maya script was, in researchers' view, an elaborate hybrid of logograms and syllabic signs, used for religious texts, astronomical records, and dynastic histories. Most Maya texts are said to have been destroyed during the sixteenth-century Spanish conquest, and the script was widely considered substantially undeciphered until the late twentieth century, with major breakthroughs coming from Russian and Soviet scholars working largely separately from Western academia. The painstaking decipherment of Maya glyphs is widely cited as a model of how cumulative epigraphic work can eventually crack a system that initially appears opaque.

F The geographic distribution of writing origins is widely described as revealing. All four primary independent origins — Mesopotamia, Egypt, China, Mesoamerica — coincided with the rise of large agricultural societies organised around centralised political and religious institutions. Smaller-scale societies generally did not develop writing, even where contact made the idea available. The dominant explanation, advanced by archaeologists from Childe in the 1930s onwards, is widely said to be that writing addresses specific needs that arise principally in stratified societies with substantial economic surplus, public works, and bureaucratic administration. Where these conditions are absent, the considerable investment required to invent and propagate writing reportedly rarely produces compensating benefits. Subsequent diffusion is, however, widely said to be a different matter: once writing existed somewhere, neighbouring peoples borrowed the idea and reshaped it, producing the great variety of scripts found across the historical record.

A Plastic recycling has been promoted for decades as a virtuous response to one of the era's most visible environmental problems. The reality has, in many analysts' view, proved consistently more complicated than the marketing implies. Of the approximately 460 million tonnes of plastic produced globally each year, only around 9 percent is reported to be recycled and reused as a new product, with another 19 percent incinerated and the remaining 72 percent landfilled or released into the environment. The headline figures mask substantial variation between countries and between plastic types: bottle-grade polyethylene terephthalate is often recycled at far higher rates than mixed films or coloured plastics, which are lumped into general waste because the cost of sorting exceeds the value of the recovered material.

B The technical challenges of recycling plastic are widely regarded as substantial. Different plastic types — polyethylene, polypropylene, polyethylene terephthalate, polystyrene and many others — typically have different melting points, different chemical structures, and generally cannot be melted together without losing useful properties. Sorting incoming plastic by type is therefore widely said to be essential, and even with modern optical sorting equipment, contamination by food residues, multi-material packaging, or even differently-coloured plastic can disqualify entire batches from recycling. Recycled plastic typically has shorter polymer chains than virgin material, making it weaker and less suitable for high-quality applications. The result is widely described as a slow downgrade through successive uses: a plastic bottle may, for instance, be recycled into fibre or low-grade construction material rather than back into a bottle, with each pass making subsequent recycling progressively harder.

C The economics of plastic recycling have, according to many analysts, always been precarious. Recycled plastic competes directly with new plastic produced from cheap petroleum feedstocks. When oil prices are low, virgin plastic is cheaper than recycled plastic, making the recycling industry economically unviable without subsidy or regulation. The collapse of Chinese imports of foreign plastic waste in 2018, formerly the destination of much of the developed world's collected plastic, is widely said to have thrown the global recycling industry into crisis and exposed the dependence of supposedly responsible waste management on what was effectively long-distance dumping. Domestic processing capacity in the developed world has lagged behind what is needed to absorb the volumes formerly exported, and stockpiles of unprocessed plastic have built up in several European and North American jurisdictions as municipalities scramble to find new buyers.

D Mechanical recycling — melting and reshaping plastic — has been the dominant approach for decades. Newer chemical recycling technologies, including pyrolysis (heating plastic in the absence of oxygen to break it into hydrocarbon products) and solvolysis (using solvents to break polymers into monomers), generally promise to recover plastic from streams that mechanical recycling cannot handle. Commercial-scale chemical recycling plants have begun operating in several countries, although critics argue that current chemical-recycling output is largely converted to fuel rather than new plastic, and that the energy and carbon costs of the process may negate environmental benefits. The framing of chemical recycling as a renewable solution is, in many analysts' view, accordingly disputed, with industry advocates emphasising its potential to handle mixed streams and critics emphasising its current performance against rigorous lifecycle analyses.

E Policy responses have, in researchers' view, multiplied. The European Union's Single-Use Plastics Directive of 2019 banned a list of disposable items including straws, cutlery, and certain cotton-bud sticks, and required minimum recycled content in plastic bottles from 2025. Extended producer responsibility schemes, which transfer the cost of waste management to the manufacturers of plastic products, have been adopted in over 60 countries. The United Nations Environment Programme is in the process of finalising a Global Plastics Treaty, with negotiations between member states continuing through the mid-2020s. The treaty negotiations are widely described as the most ambitious attempt yet to coordinate a global response to plastic pollution, broadly comparable in intent to the ozone-layer agreements of the late twentieth century, although progress is said to have been slowed by predictable disagreement between petroleum-producing and waste-receiving states.

F Beyond recycling itself, reduction in primary plastic production has, in many environmental analysts' view, emerged as the central goal of many environmental groups. The argument is said to be that even an ideal recycling system would still leak substantial quantities of plastic into the environment, and that reducing input is the only solution adequate to the scale of the problem. Single-use packaging bans, refillable container schemes, and consumer behaviour change campaigns all reportedly push in this direction, with mixed results. The combined direction of policy is, increasingly, widely described as moving away from a recycling-centred response toward one that prioritises preventing plastic from being made unnecessarily in the first place.

A The Earth's magnetic field, generated by convection in the planet's liquid outer core, points roughly along the rotational axis at any given time — but only roughly, and not always in the same direction. Periodically through geological history, the field has reversed: the magnetic North and South Poles have swapped, in a process that takes between a few hundred and a few thousand years to complete. The fact that this happens at all was, in researchers' view, startling when first established in the early twentieth century; the consequences for life on Earth and for the technologies that depend on the magnetic field remain a subject of active research. Early observations of reversal behaviour are widely said to have come from comparison of magnetised rocks of different ages, in which the alignment of iron-oxide grains pointed to a field that had reversed repeatedly.

B The evidence for geomagnetic reversals comes principally from ancient rocks. Molten lava and slowly-cooling intrusive rocks both generally record the direction of the prevailing magnetic field at the moment they solidify, locked in by the alignment of microscopic iron-oxide grains. By measuring these directions in rocks of known age — from sea-floor basalts adjacent to mid-ocean ridges, lava flows on land, and lake-bed sediments — geophysicists are widely said to have constructed a detailed chronology of reversals over the past 200 million years. The chronology shows reversal events occurring at irregular intervals averaging around 200,000 to 300,000 years, although individual intervals have ranged from less than 50,000 to nearly 40 million years. The mid-ocean ridge record is widely considered a particularly clean archive because new ocean crust forms continuously and carries a clear magnetic stripe pattern outward, allowing reversal sequences to be read off the seafloor like a barcode.

C The most recent full reversal — known as the Brunhes-Matuyama transition — occurred approximately 780,000 years ago, well before the appearance of anatomically modern humans. The next-most-recent, the Jaramillo subchron, is said to have ended about 990,000 years ago. The longest documented period of stable polarity is regarded as the Cretaceous Normal Superchron, during which the field did not reverse for nearly 40 million years between approximately 121 and 84 million years ago. The reasons for such variability remain widely described as incompletely understood, although they are thought to involve long-term changes in core-mantle heat exchange. The contrast between the Cretaceous Superchron and shorter, more frequent reversal sequences in the past ten million years is widely treated as a central puzzle of geodynamo behaviour.

D Reversals themselves are, according to most geophysicists, not instantaneous. During a reversal, the field weakens to perhaps 10 percent of its normal strength, becomes complex and multipolar, and then re-establishes a strong dipole in the opposite orientation. The duration of the transition has been variously estimated at between several hundred and several thousand years, although a 2019 study using detailed records from Chinese stalagmites argued that the most recent reversal may have taken more than 20,000 years. The geological record suggests that reversal frequency has varied substantially over hundreds of millions of years, with the past 80 million years showing far more frequent reversals than the preceding 50 million years.

E The implications of an ongoing reversal for modern civilisation have attracted increased attention. The Earth's geomagnetic field has, in researchers' view, been weakening at a rate of approximately 5 percent per century, and the south-Atlantic region in particular has developed a substantial anomaly of low field strength. Some commentators have argued that this signals an imminent reversal; geophysicists, while taking the weakening seriously, generally caution against this interpretation, noting that field strength has fluctuated significantly over historical times without subsequent reversals. The most plausible immediate effects of a substantial field weakening would, in many researchers' view, be increased radiation reaching the upper atmosphere — disrupting satellite electronics and possibly power grids — rather than the catastrophic outcomes sometimes depicted in popular accounts. Several space agencies have, in recent years, begun explicitly to plan for higher background radiation in low-Earth orbit when designing future satellites.

F The biological consequences of reversals are, according to many palaeontologists, similarly debated. The principal extant record — comparison of fossil assemblages across reversal boundaries — shows no clear evidence of mass extinctions linked to reversal events. Various smaller effects, including disorientation of migratory species that navigate magnetically, are plausible but difficult to document in the rock record. Some researchers have suggested that the increased high-energy radiation reaching ground level during a long, weak transition could have effects on mutation rates, but again the magnitude of any such effect is widely said to be small relative to other selection pressures.

G The deeper scientific interest in reversals is widely described as lying in what they reveal about the dynamics of the Earth's core. Computer simulations of magnetohydrodynamic flow in a conducting fluid, when run for long enough simulated time, reportedly do spontaneously produce reversal behaviour resembling the geological record. Linking such simulations to the specific patterns recorded in rocks remains a major frontier of geophysics, with the hope of eventually predicting future reversals from current core conditions — although whether this can ever be done with practical accuracy is, in researchers' view, contested.