A In the 1830s, sending a letter in Britain was an expensive and frequently exasperating business. Charges were calculated according to the distance an item travelled and the number of sheets of paper it contained, so that a single sheet carried from London to Edinburgh cost more than a shilling — a considerable part of a labourer's daily wage. Moreover, it was normally the recipient rather than the sender who paid, and many poorer households simply turned away letters they could not afford. Members of Parliament, meanwhile, enjoyed the privilege of "franking", which allowed them to send mail without charge. The privilege was widely abused: signed covers were handed to friends and acquaintances, and some were even sold.
B The man who proposed a solution had no background in the postal service. Rowland Hill, born in Kidderminster in 1795, had spent much of his early career running a progressive school near Birmingham with his brothers. In 1837 he published a pamphlet entitled Post Office Reform: Its Importance and Practicability, in which he set out to discover what it actually cost to deliver a letter. His approach was essentially statistical. Working from the Post Office's own published figures rather than from any survey of his own, he estimated that the expense of physically conveying a letter between London and Edinburgh amounted to only about one thirty-sixth of a penny. The far greater cost, he argued, lay in the elaborate procedures required to calculate and collect the fee for each item. Clerks had to count sheets, check distances and record the sums owed, while letter carriers were obliged to wait at each door until the money was found.
C From this analysis Hill drew a radical conclusion. If charges were based on weight rather than distance, and paid in advance by the sender, most of the administrative burden would disappear. A single low rate — one penny for a letter weighing up to half an ounce — could then be applied anywhere in the country. Hill predicted that the fall in price would cause the volume of correspondence to grow so sharply that the Post Office's income would eventually recover. To show that payment had been made, he suggested "a bit of paper just large enough to bear the stamp, and covered at the back with a glutinous wash" — generally regarded as the earliest description of the adhesive postage stamp.
D The proposals met with hostility from senior figures in the Post Office, among them its Secretary, Colonel William Maberly, who dismissed them as impractical. Public support, however, grew rapidly, encouraged by merchants and campaigning groups, and in 1839 Parliament approved the scheme. After a brief transitional period during which a uniform rate of fourpence applied, the penny rate came into force on 10 January 1840. The stamps themselves took longer to prepare. The Treasury organised a competition for ideas that attracted some 2,600 entries, but none was judged suitable, and the final design was developed by Hill himself in collaboration with engravers and printers. Based on a profile of the young Queen Victoria taken from a medal by William Wyon, the black one-penny stamp went on sale on 1 May 1840 and became valid for use on 6 May.
E In terms of traffic, Hill's forecast proved broadly accurate. The number of letters handled in the United Kingdom rose from around 76 million in 1839 to roughly 169 million in 1840. Financially, the outcome was less impressive: net revenue fell steeply and did not regain its pre-reform level for more than twenty years. Critics took this as proof that the reform had failed, although its defenders pointed out that the social benefits — cheaper communication for families separated by migration to the industrial towns, and for small traders — did not appear in any balance sheet.
F The new stamp also needed adjustment. The red ink used to cancel the Penny Black was difficult to see against the dark background and could be cleaned off, allowing stamps to be used a second time. In 1841 the colours were therefore reversed: the stamp was printed in red, and cancellations were made in black. A further inconvenience was that sheets had to be cut apart with scissors, a slow task that often left ragged edges. After trials with perforating machines developed by the inventor Henry Archer, the Post Office began issuing perforated stamps in 1854.
G Hill's ideas spread beyond Britain with remarkable speed. The Swiss cantons of Zurich and Geneva and the Empire of Brazil issued stamps in 1843, and the United States followed in 1847. Within a few decades prepayment by adhesive stamp had become the norm almost everywhere, and in 1874 the General Postal Union — soon renamed the Universal Postal Union — was founded to coordinate mail between nations. Hill himself was eventually appointed to senior posts within the very institution he had once criticised, and was knighted in 1860. When he died in 1879 he was buried in Westminster Abbey, an honour that reflected how thoroughly his once controversial scheme had come to be accepted.
1Lawmakers had a right to post items at no cost, known as ______, which was often misused
2Hill's earlier work: managing a ______ with members of his family
3The 1837 pamphlet: Hill's method was largely ______
4Main expense was administration, e.g. delivery staff delayed at every ______ while payment was located
5Proposal: price to depend on ______, not on how far the item went
6Official contest for stamp ideas: roughly ______ submissions, all rejected
7Before the reform, the addressee was usually expected to cover the cost of postage.
8Hill's calculations relied on information that he had gathered independently.
9Those in charge of the mail system were quick to welcome Hill's ideas.
10Within twelve months of the new rate, the quantity of mail had more than doubled.
11The majority of the additional correspondence was generated by commercial users.
12Henry Archer was rewarded financially by the authorities for his invention.
13Hill later held high office in the organisation whose leaders had once opposed him.
A Anyone who has counted the rings on a tree stump knows the basic principle: in climates with a distinct growing season, a tree adds one layer of wood each year, pale and open in spring, darker and denser towards autumn. What is less widely appreciated is how much more than age these layers record. Because a ring tends to be wider in a favourable year and narrower in a harsh one, the sequence of rings in a trunk forms a kind of barcode of local conditions. Trees of the same species growing in the same region share broadly the same barcode, and it is this shared pattern, rather than the simple tally, that has made dendrochronology — the dating of events by means of tree rings — one of the most exact tools available to anyone studying the past.
B The discipline owes its foundations to an unlikely figure. Andrew Ellicott Douglass was an astronomer, not a botanist, and when he began examining pine trunks in Arizona in the early twentieth century, he hoped to find evidence that cycles of sunspot activity influenced the Earth's climate. That link was never convincingly established, but in pursuing it Douglass developed the technique of cross-dating: matching distinctive runs of wide and narrow rings between living trees and older timbers, so that a chronology could be extended back beyond the lifespan of any single tree. In 1929 a charred beam recovered from a ruin at Show Low, Arizona, enabled him to join a "floating" sequence, built from the timbers of ancient settlements, to his absolute chronology, assigning calendar dates to dozens of Ancestral Puebloan sites at a stroke. In 1937 he founded the Laboratory of Tree-Ring Research at the University of Arizona, which remains one of the leading centres in the field.
C The most celebrated contribution of tree rings, however, has been to a quite different dating method. In the 1950s Edmund Schulman established that some bristlecone pines in the White Mountains of California were more than 4,000 years old, and these remarkably long-lived trees, combined with dead wood that had survived for millennia on the arid slopes, yielded a chronology reaching back thousands of years further. When radiocarbon measurements taken from rings of known age were compared with their true calendar ages, the two did not always agree, revealing that the proportion of carbon-14 in the atmosphere had fluctuated over time. The chemist Hans Suess was among the first to plot these discrepancies. Tree-ring sequences — later extended in Europe by oak and pine chronologies covering more than 12,000 years — now form the backbone of the curves used to calibrate radiocarbon dates worldwide.
D Individual rings can also preserve the signature of sudden events. The palaeoecologist Mike Baillie, working with Irish oak chronologies at Queen's University Belfast, drew attention to clusters of exceptionally narrow rings, notably around AD 536, which he linked to episodes of severe cooling and a darkened sky; later studies of polar ice cores have traced the downturn of 536 mainly to volcanic eruptions that filled the atmosphere with dust. In 2012 a team led by the physicist Fusa Miyake, analysing Japanese cedars, detected an abrupt jump in carbon-14 in the ring for AD 774–775, now generally attributed to an intense burst of radiation from the Sun. Because such spikes appear in the same year in trees across the globe, they serve as fixed reference points. In 2021 researchers used a similar spike from AD 993 to show that wood at the Norse site of L'Anse aux Meadows in Newfoundland had been cut in precisely AD 1021 — the earliest securely dated European presence in the Americas.
E The method nevertheless has clear limits. It works best for trees growing near the edge of their tolerance — at high altitudes or latitudes, or in dry regions — whose growth is strongly controlled by a single factor such as temperature or rainfall; trees in comfortable conditions produce rings too uniform to cross-date. Many tropical species lack clear annual rings altogether because they grow throughout the year. Even in suitable trees, an extremely poor year can leave a ring absent from part of the trunk, while a drought in mid-season can produce a "false" ring, so careful comparison of many samples is needed to avoid errors. Climate reconstructions face a subtler difficulty: since roughly the middle of the twentieth century, some trees in northern forests have not tracked rising temperatures as closely as they once did, a puzzle that the climatologist Keith Briffa and colleagues highlighted in 1998 and that became known as the "divergence problem".
F Outside the laboratory, tree rings increasingly settle questions in history and the arts. Oak panels used by Flemish and Dutch painters can be dated to establish the earliest year in which a picture could have been painted, occasionally exposing works once credited to famous masters as later copies. Similar analysis has been applied to the spruce fronts of violins attributed to Antonio Stradivari, including the "Messiah" violin in Oxford, whose authenticity was disputed for years. Such work cannot reveal who made an object, only when its wood was felled; but by ruling out what is impossible, it has become an indispensable witness.
14Paragraph A
15Paragraph B
16Paragraph C
17Paragraph D
18Paragraph E
19Paragraph F
20What was Douglass's original purpose in studying tree trunks?
21The burnt timber found in 1929 was significant because it
22According to the writer, carbon-14 spikes are especially useful because they
23The 'divergence problem' refers to the fact that
Tree rings and radiocarbon
In the American West, ancient pines still standing and the remnants of trees that perished centuries ago, kept intact by the (24)______ conditions of the mountainside, gave researchers an exceptionally long record. Checks on wood of established age showed that the atmosphere's share of this radioactive isotope had not remained (25)______ over the centuries. Today, long series of rings from several continents supply the (26)______ for adjusting radiocarbon results.
24Answer 24
25Answer 25
26Answer 26
A In 2012 the biochemists Jennifer Doudna and Emmanuelle Charpentier published a paper showing that a bacterial defence system known as CRISPR-Cas9 could be programmed to cut DNA at a chosen location. The discovery, which earned them the Nobel Prize in Chemistry in 2020, transformed molecular biology, and plant breeders were among the first to exploit it. Within two years a team co-led by Caixia Gao at the Chinese Academy of Sciences had used gene-editing tools to disable all three copies of a particular gene in bread wheat at once, producing plants resistant to the fungal disease powdery mildew. Since then edited crops have begun to reach the market: in 2021 a tomato edited to contain higher levels of GABA, a compound promoted as helping to lower blood pressure, went on sale in Japan.
B Supporters argue that gene editing differs fundamentally from the genetic modification that provoked such hostility in the 1990s. Earlier GM crops typically contained genes transferred from unrelated organisms, such as bacteria; many edited crops, by contrast, carry only small alterations of a kind that could in principle arise through natural mutation or conventional breeding, only faster and more precisely. On this view, it makes little sense to regulate an edited plant more strictly than an identical one obtained by exposing seeds to radiation — a technique in widespread use since the mid-twentieth century, which scatters random mutations through the genome without attracting comparable public concern.
C Regulators have not agreed. In 2018 the Court of Justice of the European Union ruled that organisms produced by the new techniques fall within the scope of the EU's existing legislation on genetically modified organisms, subjecting them to the same lengthy approval process. Argentina had taken the opposite approach in 2015, assessing products case by case and exempting those that contain no foreign DNA, and several other countries have since followed its lead. England passed the Genetic Technology (Precision Breeding) Act in 2023, and in the same year the European Commission proposed that most edited plants be treated like conventionally bred ones. The result is a patchwork in which the same crop may be grown freely in one country and be effectively prohibited across the border.
D For some scientists, the cost of caution is measured in human lives, and they point to the fate of an earlier crop to make the case. Golden Rice is not a product of gene editing at all but a conventional GM variety, made by inserting genes from other species so that the grain produces beta-carotene, which the body converts into vitamin A. One of its developers, Ingo Potrykus, has argued for years that excessive regulation held back a crop that could have reduced deficiency-related blindness and death among children in poor countries. First described in 2000, Golden Rice was not approved for cultivation anywhere until the Philippines did so in 2021, and even that approval was suspended by a Philippine court in 2024. Norman Borlaug, the plant scientist whose contribution to the Green Revolution earned him the Nobel Peace Prize in 1970, was blunter still, suggesting that many affluent campaigners in the West had never known what it is to go hungry.
E Critics respond that the debate is not, or not only, about safety. The Indian scholar and activist Vandana Shiva has long maintained that patents on seeds transfer control of agriculture from farmers to a handful of corporations, eroding the ancient practice of saving and exchanging seed from one harvest to the next. Gene editing, she and others contend, does nothing to alter this; if anything, by making it cheaper to create proprietary varieties, it may hasten the process. Such critics also question whether high-technology solutions address the real causes of hunger, which frequently lie in poverty, conflict and unequal access to land rather than in any shortage of improved crops.
F Much of this criticism seems to me well founded, but it is aimed at the wrong target. The concentration of ownership in the seed industry is a genuine problem. It was, however, well advanced long before CRISPR appeared, and it is a matter for competition law and patent policy rather than for rules about how a DNA sequence was altered. Indeed, because gene editing is relatively inexpensive, it could open breeding to public institutions and small firms that could never afford the decade of testing demanded of conventional GM crops — provided that regulation does not make it as costly as the older technology.
G For that reason I believe that regulation should focus on the characteristics of a new variety, not on the method used to produce it. A plant designed to tolerate heavy doses of a weedkiller deserves careful scrutiny, whether it was created by editing, by transferring genes or by traditional crossing, because of the farming practices it may encourage; a tomato with a slightly altered nutrient content poses no obvious risk at all. Assessing traits rather than techniques would also be more honest, since it would no longer imply that conventional methods are harmless simply because they are familiar.
H None of this means that the public's concerns can be brushed aside. People are entitled to know what they are eating, and the industry's resistance to openness has done more than any scientific finding to breed distrust. A clear public register of edited varieties would cost little and could do much to restore confidence. The technology itself is neither saviour nor menace; what matters is who controls it, and to what end.
27Official restrictions stopped a nutritionally improved food from helping vulnerable young people.
28Many wealthy opponents of new crops have no personal experience of a lack of food.
29All the duplicates of one gene in a plant species can be changed in a single step.
30Legal ownership of plant varieties undermines a long-established custom among growers.
31A lower-cost technology may speed up the trend towards privately owned crops.
32The objections raised by Shiva and her supporters are largely without foundation.
33A few large firms already dominated the seed business before the new editing tools existed.
34Crops that withstand large amounts of weedkiller ought to be banned.
35Traditional breeding methods are wrongly presumed to be safe because people are used to them.
36Most shoppers would avoid food made from edited crops if it were clearly identified.
37Advocates of the new tools mention the irradiation of seeds because this method
38Because national authorities disagree, an identical edited variety
39Some critics suspect that technically advanced responses to food shortages
40In the writer's opinion, the relatively low cost of the new technique could