IELTS CAM Inspired 15 - Reading Test 2 with Practice Test, Answers And Explanation
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IELTS Mock Test 15 - Reading Test 2 With Practice Test, Answers And Explanation
Passage
❓ Câu hỏi passage 1
Question 1 - 6
Which paragraph contains the following information?
Write the correct letter, A-G.
1
a claim that the design assumptions engineers still rely on produced today's energy-hungry transport
2
a description of how rehearsing an outcome with the body produces insights unreachable by reasoning alone
3
a remark on the way present-day design methods keep their user removed from real-world conditions
4
an account of barriers that lengthen the felt distance of crossing a road
5
a reference to an expert who blames unsuccessful city-making on the divorce of thought from bodily experience
6
a statement that dance and engineering pursue one common aim: organising bodily motion within the confines of available space
Question 7 - 13
Complete the summary below.
Choose ONE WORD ONLY from the passage for each answer.
Kessler Court
Constructed along the modernist lines fashionable in the 1970s, Kessler Court was set out as a of streets and and was meant to hand the town a new to be crossed on foot. Those responsible, however, leaned too heavily on what their design software forecast about the way it would perform. They did not anticipate that the open-air cafes would be unbearable under the fierce unless fitted with the sort of that shielded the older structures nearby, and so would come to depend on air that swallowed huge quantities of energy. They also misjudged how bleak the huge parking area would feel to drivers. What seems entirely reliable on a , in the end, can behave very differently once it has been built.
Passage
❓ Câu hỏi passage 2
Question 14 - 17
Which paragraph contains the following information?
Write the correct letter, A-F.
14
the reason it is impossible to recreate a species exactly as it once was
15
a comparison of how densely two related bird species build their nests
16
a suggestion that the technology could keep large numbers of species from disappearing in future
17
a statement giving the exact day on which a species finally disappeared
Question 18 - 22
Complete the summary below.
Choose NO MORE THAN TWO WORDS from the passage for each answer.
The tundra elephant revival project
Professor Mateo Silva and his team are trying to establish the that allowed tundra elephants to survive on the frozen tundra. What they discover could support attempts to protect the animal's endangered relative, the lowland elephant.
According to Silva, relocating lowland elephants to the tundra would demand a number of physical changes intended to limit . To withstand the cold, the animals would need several features seen in the tundra elephant: smaller ears, a denser covering of , and an increased amount of body .
Returning elephants to the tundra would also alter the surrounding environment in ways that could bring temperatures down and reduce .
Question 23 - 26
Match each statement with the correct person, A, B or C.
List of Findings
A
Ravi Anand
B
Lena Haas
C
Karl Vogel
23
Returning a lost species to the place it came from could make an animal that lives there healthier.
24
The focus should be on understanding what caused a species to die out.
25
A revived species could greatly benefit the plant life of the area it inhabits.
26
The measures currently being taken to protect wildlife are not enough.
Passage
❓ Câu hỏi passage 3
Question 27 - 31
Choose the correct letter, A, B, C or D.
27
In the first paragraph, the writer highlights laughter's
A
importance across different cultures.
B
usefulness as a subject of study.
C
occurrence in non-human species.
D
connection to spoken language.
28
What does the writer imply about Marvin Prewitt?
A
He regarded live comedy as superior to television.
B
He assumed viewers at home needed to be told when to laugh.
C
He recognised that laughter comes more easily in the company of others.
D
He found live audiences simpler to work with than his own recordings.
29
Why does the writer regard the Fernwood study as especially important?
A
It drew on researchers from many academic fields.
B
A great variety of individuals had their laughter recorded.
C
It looked at several distinct forms of laughter.
D
People from many different societies responded in much the same way.
30
Which of the following happened in the Halvorsen study?
A
Participants took turns to occupy different roles.
B
A number of participants found the experience upsetting.
C
Some participants proved unable to laugh when asked.
D
Participants who had earlier been strangers ended up as friends.
31
In the fifth paragraph, what did the results of the Halvorsen study suggest?
A
It is obvious whether a dominant laugh comes from a senior or a junior member.
B
Someone of junior rank who is in charge will still laugh submissively.
C
People of high standing are seen as such however they laugh.
D
The submissive laughs of junior and senior members are much alike.
Question 32 - 36
Complete the summary using the list of words, A-H, below.
The benefits of humour
In a study at Alderwood University, groups of participants chosen at random each watched one of three film clips, every clip intended to bring about a particular . All of them were then set a task that had deliberately been made impossible to finish, and those who had first seen the clip carried on with it for longer, and worked harder at it, than the participants in the other two groups. A follow-up study, in which volunteers had to complete an especially task by hand, produced much the same outcome. According to Priya Nadkarni and Tomas Berg, these results indicate that, besides lowering and helping people form connections with one another, humour may in fact have an effect on both body and mind.
A
dull
B
soothing
C
mood
D
comic
E
tension
F
invigorating
G
pleasure
H
practical
Question 37 - 40
Do the following statements agree with the information given in the Reading Passage?
TRUE if the statement agrees with the information
FALSE if the statement contradicts the information
NOT GIVEN if there is no information on this
37
In the Fernwood study, listeners did no better than pure guesswork at telling whether laughers were friends or strangers.
38
The senior members in the Halvorsen study behaved as the researchers had expected them to.
39
Participants in the Alderwood study earned more money if they did the tasks well.
40
The conclusion reached by Nadkarni and Berg fits with the traditional view of how tasks are best performed.
DOL IELTS Đình Lực
21/10/2026
📖 Bài đọc passage 1
Could urban engineers learn from dance?
A
A. Whether a city can sustain itself is bound up with how its inhabitants get from place to place. Roughly 30% of the energy burned in the richer nations of the world goes, by most estimates, on transport, and so any real reduction in mobility's environmental toll depends on our leaning less heavily on energy-guzzling vehicles. Movement of other sustainable kinds matters too, all the more as ever-greater numbers crowd into urban centres. Our health of body and mind, the friendships we keep, the work and culture we can reach, even the air we breathe, all of it is coloured by how we make our journeys. Reshaping that journey through urban design falls to engineers, yet their profession keeps building on the same premises behind the energy-thirsty networks already around us, worshipping speed, efficiency and the hard number above all else. Nothing short of a thorough overhaul will do, one that leaves city travel kinder to health, to pleasure and to the environment alike.
B
Some of those answers may lie in dance. The point is not that we should all pirouette our way to the office, cheering though that might be, but that the methods choreographers use to explore and shape movement could hand engineers fresh ways of thinking about how cities are made. Aldo Verekker, a prominent urbanist and sociologist whose work has reshaped how we understand the making of cities, contends that ever since the architectural blueprint arrived, urban design has been split between the mind and the body.
C
Where the builders of medieval times worked by improvising and adjusting as they went, drawing on a close feel for their materials and first-hand knowledge of a site's conditions, the plans for a building are today conceived and kept inside media technologies that hold the designer apart from the physical and social realities being brought into being. Indispensable as these newer practices are for handling the sheer technical intricacy of the modern city, they carry a cost: reality gets flattened along the way.
D
Verekker illustrates the point with Kessler Court, a scheme in the city of Rendholm and a textbook case of the modernist planning so much in vogue in the 1970s. Laid out as a grid of streets and towers, it was meant to furnish the city with a fresh centre in which people might move about on foot. Its undoing, as Verekker tells it, was the excessive trust its makers reposed in computer-aided design to predict how the whole would function. What escaped them was that the cafes built along the streets could not endure the fierce sun without the awnings that keep older buildings shaded, relying therefore on air conditioning that devoured energy; nor that the vast car park would prove so cheerless as to leave people unwilling to step from their cars. Whatever appears wholly foreseeable, wholly governable, on a screen turns out otherwise the moment it becomes brick and pavement.
E
Transport engineering stumbles over the very same difficulty, for it too leans on models to anticipate and channel the movement of people through a city. No one doubts that such models earn their keep, yet each is founded on a particular outlook, one that admits some version of efficiency and safety while quietly discarding other ways of experiencing the streets. A design that reads as logical on the model can strike its everyday user as downright contrary. Take the metal railings that greet anyone attempting to cross a busy urban road: conceived as an engineer's remedy for pedestrian safety, they sprang from models in which the unbroken flow of traffic came first. Where roads run wide, the railings herd walkers toward chosen crossing spots and drag out their journey across by splitting it into two staggered stages, a carriageway apiece. A crossing thus made to feel longer raises psychological obstacles that press hardest on the least mobile, while goading others into hazardous dashes around the rails. More than nuisances at the kerb, these barriers slice through communities and shrink the room for healthier travel, which is why so many are now being ripped out, at no little upheaval, expense and waste.
F
Give the designers of those rails the means to reason through the body, as a dancer does, and to feel in advance how the barriers would sit with a pedestrian, and a wiser answer might have surfaced. If we are to overhaul how our cities are lived in, engineering must cultivate a deeper grasp of what draws people to move in the ways they do and of what such movement does to them. An unlikely ally, choreography, turns out to chase the very thing engineering chases: the shaping of movement within the bounds that space imposes. Almost its whole method is to rehearse an idea in the flesh and register at once how the result feels. A dancemaker knows, from the inside, the mental, aesthetic and bodily consequences of favouring one way of moving over the next.
G
When the cognitive scientist Tomas Reell watched the choreographer Lena Sørby, he spoke of someone who thinks with the body. Pressing her own body into the work of trying outcomes out, he maintains, lets Sørby light on answers that abstract thought, however rigorous, would never yield. Expertise of many stripes holds such bodily knowing in high regard, and yet the formal machinery of engineering design leaves no room for it. Reell suggests that transport engineers, too, might rough out answers on the spot and judge them by the felt experience of trying them, or stage a design at full scale as a choreographer puts a company of dancers through its paces. Beyond everything else, they may learn to design as much for what is felt as for what merely functions.
Should we try to bring extinct species back to life?
A
A. Few birds have entered legend as the ashen plains-dove did. Across the grasslands of southern Argentina it once travelled in flocks so enormous — millions of birds, on occasion, moving as one — that its seasonal passage ranked among the natural world's most extraordinary sights. That spectacle ended on 19 April 1921, the day the very last of the species died in the zoological gardens at Rosario. Reviving it is now the aim of a bold undertaking led by the geneticist Dr Karl Vogel, who is pursuing what has come to be called 'de-extinction'. In essence, the method takes DNA recovered from a vanished animal, converts it into a fertilised embryo, and places that embryo inside the closest surviving relation — here, the still-plentiful widespread scrub-dove — which then carries and delivers a living creature. The plains-dove was among the first species to which the approach was applied, though far from the last, since the same advanced techniques are now being tried on many other animals.
B
A comparable effort is under way for the Kestran wolf, a predator that once roamed the island of Kestra and disappeared roughly a century ago. 'Since the wolf was lost, no meat-eater on Kestra has taken over the role it used to play,' notes Professor Ravi Anand of the University of Otago. In the years after the animal vanished, he explains, a severe and disfiguring facial-tumour disease has spread through the population of Kestran quolls — the small marsupial for which the island is otherwise best known — and now endangers their survival. Had the wolves remained, Anand argues, they would have killed enough quolls to keep the sickness in check. 'A contagious cancer of that sort, arising in earlier times, would simply have died out wherever it first appeared. Bringing the wolf back to Kestra might guarantee that the quolls are never exposed to such a danger again.'
C
Supposing lost species really can be revived, might our kind at last begin to undo the harm done to nature over the last few thousand years? 'What de-extinction promises is a reversal — a way of restoring creatures that have ceased to exist,' says Dr Lena Haas, of the Genomics Centre at the University of Leiden. 'My own view is that this cannot truly be achieved. Something that vanished in the distant past can never be reproduced so as to be one hundred per cent the same.' For species gone a very long time, she suggests, the more workable route is to treat a living species' DNA as a foundation and splice into it fragments of the extinct animal's genetic material. What emerges is not the old animal but a new one — a hybrid based on the living species, yet resembling the lost creature in look or behaviour.
D
Given how intricate the procedure is, and how uncertain its result, one might reasonably ask what the technology is really for. 'Our aim, from the start, has been to put a fitting stand-in where the extinct species used to be,' Vogel says. 'Scrub-doves nest apart from one another — perhaps a nest or two to a hectare — but plains-doves were intensely sociable birds that would pack ten thousand nests or more into that same hectare.' Once this pivotal bird was gone, the woodlands of the Argentine interior began to decline: with no thousands of plains-doves breaking branches and battering the trees, little disturbance occurred, and so little regrowth was ever called for. The forests grew static, and thus inhospitable to the very plants and creatures that had evolved to restore woodland after such disturbance. Vogel believes a scrub-dove crossed with the nesting behaviour of a plains-dove might, at least in principle, bring that disturbance back, and by doing so recreate the conditions on which a great many other native species depend.
E
The tundra elephant is another favourite candidate for such work. Professor Mateo Silva — who teaches at the Ashcroft Institute of Molecular Biology and heads the Tundra Elephant Revival Project — has concentrated on cold tolerance, the chief respect in which the vanished tundra elephant and its closest living cousin, the endangered lowland elephant, part company. By identifying the genetic traits that once let these animals endure the tundra's freezing climate, the team hopes to return them, or some near equivalent, to that landscape. 'Safeguarding the endangered lowland elephant is what I would put first,' Silva remarks, 'along with pushing its range out into the immense expanse of the tundra. That would call for a few adjustments — ears of a smaller size, a thicker coat of hair, added layers of insulating fat — each a means of curbing heat loss in the cold, and each present in the tundra elephant that is now gone.' Restoring large mammals to the tundra and northern Eurasia's forests might also help hold down carbon emissions: such elephants drive holes through the snow and topple trees, which favours the spread of grass, and the grass, by cooling the ground, restrains the emissions released as frozen soil thaws.
F
Reviving extinct animals may fire the imagination, yet rescuing a living species that is merely at risk of dying out is, naturally, a far simpler matter. 'A good deal of the technology people picture when de-extinction comes up can equally serve as a kind of "genetic rescue",' Haas points out. What she would rather the discussion centred on is how these new methods might reveal precisely why particular species were lost to begin with — and, from that, how the same tools could be used to make the genetic changes that would head off large-scale extinctions in years to come. 'There is, I'd add, a tremendous moral hazard in doing nothing whatsoever,' she goes on. 'What we manage today plainly falls short, and we must be prepared to take a few carefully weighed risks.'
What psychologists have discovered shows how much humour matters
By the time they are only a month or two old, infants already begin to smile and laugh at the things around them - the first signs of a developing sense of humour. No human culture lacks laughter, and something resembling it can even be observed in chimpanzees, bonobos and rats. For psychologists, laughter and the humour behind it open a window onto an unusually wide range of questions, from how children acquire language to what happens in the brain when we read other people socially.
Among the explanations for how laughter evolved, one influential idea treats it as a tool that helped early humans communicate with one another. Consider the canned laughter familiar from television comedies. The unpredictable reactions of a live studio audience frustrated the American sound technician Marvin Prewitt, and so, in 1952, he began assembling recordings of laughter of his own. The point of these tracks was to give viewers sitting alone at home the sensation of being among others, as though seated in a packed theatre. Prewitt taped laughter of many kinds - from men, from women, from children, and in various blends - and in doing so he noticed something that intrigues researchers today: even a plain 'haha' carries a surprising quantity of socially useful information.
That richness was explored in a study carried out in 2015, in which recordings of laughter from pairs of English-speaking students were gathered at Fernwood University in the western United States. A research team of more than thirty psychologists, anthropologists and biologists then presented the clips to listeners drawn from twenty-two very different communities, ranging from remote Amazonian groups to urban populations in Japan and across Europe. Each listener had to say whether the two people laughing were friends or had never met before. What emerged was strikingly uniform from one society to the next: wherever they lived, listeners judged correctly a little under sixty per cent of the time.
Laughter, other researchers have shown, also encodes the intricate rankings that structure human groups. Working at Halvorsen University, a team headed by Renata Salkind established that the laughs of high-ranking people differ from those of low-ranking ones, and that outsiders' impressions of someone's standing are swayed by how dominant or submissive that person's laugh sounds. For the study, forty-four male undergraduates were divided at random into groups of four, each with two newcomers recently admitted to a campus rowing club and two long-standing senior members. In turn, every participant was subjected to good-natured teasing by the others, who addressed him by mildly mocking nicknames. As the researchers had predicted, the senior members generated a greater proportion of dominant laughs and fewer submissive ones than the newcomers did. The newcomers, for their part, adjusted their laughter according to where the power lay, producing more dominant laughs once it was their turn to do the teasing. Compared with submissive laughter, dominant laughter was louder, higher in pitch and more varied in tone.
A separate set of volunteers was then played a balanced selection of dominant and submissive laughs, taken from both the senior and the junior members, and asked to judge each laugher's rank. Just as the team had anticipated, those producing dominant laughs were taken to be considerably higher in standing than those producing submissive ones. 'The effect was strongest for the low-status people, who were judged much higher in rank when they laughed dominantly rather than submissively,' Salkind's group reports. 'By putting on a more dominant laugh whenever the situation permits, then, someone of low standing can raise how others rate them.' Senior members, by contrast, were seen as high-ranking regardless of whether they laughed in their usual dominant manner or attempted a submissive one.
A different line of enquiry, pursued by Priya Nadkarni and Tomas Berg of Alderwood University, began from the idea that some humour might relieve dreary stretches of work, and that such a mental pause could help restore depleted mental energy. To examine this, they brought in sixty-eight business students, told misleadingly that the exercise concerned perception. The students first worked through a monotonous task, striking out every occurrence of a particular letter across two pages of writing. Each was then assigned at random to one of three video clips, meant to stir up amusement, contentment or nothing in particular: a scene from the comedy series The Copper Kettle, footage of geese gliding across a still lake, and a matter-of-fact film about warehouse logistics.
Next came a task designed to test persistence: judging, from a set of profiles, how well various employees were likely to perform, with the promise that ten right answers in a row would count as a win. The program, though, had been rigged so that reaching ten correct in succession was all but impossible, and anyone could abandon the exercise whenever they liked. Those who had seen the clip from The Copper Kettle stuck with it markedly longer, making twice as many judgements as either of the other groups.
Nadkarni and Berg obtained the same pattern again in a follow-up experiment, this time asking their volunteers to work through lengthy multiplication problems by hand. Once more, those who had watched the amusing clip laboured at this tiresome chore far longer, and got more answers right, than those in the two comparison groups.
'Humour is known to ease stress and to smooth the way for social bonds, yet the conventional understanding of task performance holds that people ought to steer clear of anything - humour included - that might pull their attention away from the job in hand,' the two researchers conclude. 'Our findings suggest that humour is not merely pleasurable; more importantly, it recharges us.'
B. Some of those answers may lie in dance. The point is not that we should all pirouette our way to the office, cheering though that might be, but that the methods choreographers use to explore and shape movement could hand engineers fresh ways of thinking about how cities are made. Aldo Verekker, a prominent urbanist and sociologist whose work has reshaped how we understand the making of cities, contends that ever since the architectural blueprint arrived, urban design has been split between the mind and the body.
C. Where the builders of medieval times worked by improvising and adjusting as they went, drawing on a close feel for their materials and first-hand knowledge of a site's conditions, the plans for a building are today conceived and kept inside media technologies that hold the designer apart from the physical and social realities being brought into being. Indispensable as these newer practices are for handling the sheer technical intricacy of the modern city, they carry a cost: reality gets flattened along the way.
D. Verekker illustrates the point with Kessler Court, a scheme in the city of Rendholm and a textbook case of the modernist planning so much in vogue in the 1970s. Laid out as a grid of streets and towers, it was meant to furnish the city with a fresh centre in which people might move about on foot. Its undoing, as Verekker tells it, was the excessive trust its makers reposed in computer-aided design to predict how the whole would function. What escaped them was that the cafes built along the streets could not endure the fierce sun without the awnings that keep older buildings shaded, relying therefore on air conditioning that devoured energy; nor that the vast car park would prove so cheerless as to leave people unwilling to step from their cars. Whatever appears wholly foreseeable, wholly governable, on a screen turns out otherwise the moment it becomes brick and pavement.
E. Transport engineering stumbles over the very same difficulty, for it too leans on models to anticipate and channel the movement of people through a city. No one doubts that such models earn their keep, yet each is founded on a particular outlook, one that admits some version of efficiency and safety while quietly discarding other ways of experiencing the streets. A design that reads as logical on the model can strike its everyday user as downright contrary. Take the metal railings that greet anyone attempting to cross a busy urban road: conceived as an engineer's remedy for pedestrian safety, they sprang from models in which the unbroken flow of traffic came first. Where roads run wide, the railings herd walkers toward chosen crossing spots and drag out their journey across by splitting it into two staggered stages, a carriageway apiece. A crossing thus made to feel longer raises psychological obstacles that press hardest on the least mobile, while goading others into hazardous dashes around the rails. More than nuisances at the kerb, these barriers slice through communities and shrink the room for healthier travel, which is why so many are now being ripped out, at no little upheaval, expense and waste.
F. Give the designers of those rails the means to reason through the body, as a dancer does, and to feel in advance how the barriers would sit with a pedestrian, and a wiser answer might have surfaced. If we are to overhaul how our cities are lived in, engineering must cultivate a deeper grasp of what draws people to move in the ways they do and of what such movement does to them. An unlikely ally, choreography, turns out to chase the very thing engineering chases: the shaping of movement within the bounds that space imposes. Almost its whole method is to rehearse an idea in the flesh and register at once how the result feels. A dancemaker knows, from the inside, the mental, aesthetic and bodily consequences of favouring one way of moving over the next.
G. When the cognitive scientist Tomas Reell watched the choreographer Lena Sørby, he spoke of someone who thinks with the body. Pressing her own body into the work of trying outcomes out, he maintains, lets Sørby light on answers that abstract thought, however rigorous, would never yield. Expertise of many stripes holds such bodily knowing in high regard, and yet the formal machinery of engineering design leaves no room for it. Reell suggests that transport engineers, too, might rough out answers on the spot and judge them by the felt experience of trying them, or stage a design at full scale as a choreographer puts a company of dancers through its paces. Beyond everything else, they may learn to design as much for what is felt as for what merely functions.
B. A comparable effort is under way for the Kestran wolf, a predator that once roamed the island of Kestra and disappeared roughly a century ago. 'Since the wolf was lost, no meat-eater on Kestra has taken over the role it used to play,' notes Professor Ravi Anand of the University of Otago. In the years after the animal vanished, he explains, a severe and disfiguring facial-tumour disease has spread through the population of Kestran quolls — the small marsupial for which the island is otherwise best known — and now endangers their survival. Had the wolves remained, Anand argues, they would have killed enough quolls to keep the sickness in check. 'A contagious cancer of that sort, arising in earlier times, would simply have died out wherever it first appeared. Bringing the wolf back to Kestra might guarantee that the quolls are never exposed to such a danger again.'
C. Supposing lost species really can be revived, might our kind at last begin to undo the harm done to nature over the last few thousand years? 'What de-extinction promises is a reversal — a way of restoring creatures that have ceased to exist,' says Dr Lena Haas, of the Genomics Centre at the University of Leiden. 'My own view is that this cannot truly be achieved. Something that vanished in the distant past can never be reproduced so as to be one hundred per cent the same.' For species gone a very long time, she suggests, the more workable route is to treat a living species' DNA as a foundation and splice into it fragments of the extinct animal's genetic material. What emerges is not the old animal but a new one — a hybrid based on the living species, yet resembling the lost creature in look or behaviour.
D. Given how intricate the procedure is, and how uncertain its result, one might reasonably ask what the technology is really for. 'Our aim, from the start, has been to put a fitting stand-in where the extinct species used to be,' Vogel says. 'Scrub-doves nest apart from one another — perhaps a nest or two to a hectare — but plains-doves were intensely sociable birds that would pack ten thousand nests or more into that same hectare.' Once this pivotal bird was gone, the woodlands of the Argentine interior began to decline: with no thousands of plains-doves breaking branches and battering the trees, little disturbance occurred, and so little regrowth was ever called for. The forests grew static, and thus inhospitable to the very plants and creatures that had evolved to restore woodland after such disturbance. Vogel believes a scrub-dove crossed with the nesting behaviour of a plains-dove might, at least in principle, bring that disturbance back, and by doing so recreate the conditions on which a great many other native species depend.
E. The tundra elephant is another favourite candidate for such work. Professor Mateo Silva — who teaches at the Ashcroft Institute of Molecular Biology and heads the Tundra Elephant Revival Project — has concentrated on cold tolerance, the chief respect in which the vanished tundra elephant and its closest living cousin, the endangered lowland elephant, part company. By identifying the genetic traits that once let these animals endure the tundra's freezing climate, the team hopes to return them, or some near equivalent, to that landscape. 'Safeguarding the endangered lowland elephant is what I would put first,' Silva remarks, 'along with pushing its range out into the immense expanse of the tundra. That would call for a few adjustments — ears of a smaller size, a thicker coat of hair, added layers of insulating fat — each a means of curbing heat loss in the cold, and each present in the tundra elephant that is now gone.' Restoring large mammals to the tundra and northern Eurasia's forests might also help hold down carbon emissions: such elephants drive holes through the snow and topple trees, which favours the spread of grass, and the grass, by cooling the ground, restrains the emissions released as frozen soil thaws.
F. Reviving extinct animals may fire the imagination, yet rescuing a living species that is merely at risk of dying out is, naturally, a far simpler matter. 'A good deal of the technology people picture when de-extinction comes up can equally serve as a kind of "genetic rescue",' Haas points out. What she would rather the discussion centred on is how these new methods might reveal precisely why particular species were lost to begin with — and, from that, how the same tools could be used to make the genetic changes that would head off large-scale extinctions in years to come. 'There is, I'd add, a tremendous moral hazard in doing nothing whatsoever,' she goes on. 'What we manage today plainly falls short, and we must be prepared to take a few carefully weighed risks.'
By the time they are only a month or two old, infants already begin to smile and laugh at the things around them - the first signs of a developing sense of humour. No human culture lacks laughter, and something resembling it can even be observed in chimpanzees, bonobos and rats. For psychologists, laughter and the humour behind it open a window onto an unusually wide range of questions, from how children acquire language to what happens in the brain when we read other people socially.
Among the explanations for how laughter evolved, one influential idea treats it as a tool that helped early humans communicate with one another. Consider the canned laughter familiar from television comedies. The unpredictable reactions of a live studio audience frustrated the American sound technician Marvin Prewitt, and so, in 1952, he began assembling recordings of laughter of his own. The point of these tracks was to give viewers sitting alone at home the sensation of being among others, as though seated in a packed theatre. Prewitt taped laughter of many kinds - from men, from women, from children, and in various blends - and in doing so he noticed something that intrigues researchers today: even a plain 'haha' carries a surprising quantity of socially useful information.
That richness was explored in a study carried out in 2015, in which recordings of laughter from pairs of English-speaking students were gathered at Fernwood University in the western United States. A research team of more than thirty psychologists, anthropologists and biologists then presented the clips to listeners drawn from twenty-two very different communities, ranging from remote Amazonian groups to urban populations in Japan and across Europe. Each listener had to say whether the two people laughing were friends or had never met before. What emerged was strikingly uniform from one society to the next: wherever they lived, listeners judged correctly a little under sixty per cent of the time.
Laughter, other researchers have shown, also encodes the intricate rankings that structure human groups. Working at Halvorsen University, a team headed by Renata Salkind established that the laughs of high-ranking people differ from those of low-ranking ones, and that outsiders' impressions of someone's standing are swayed by how dominant or submissive that person's laugh sounds. For the study, forty-four male undergraduates were divided at random into groups of four, each with two newcomers recently admitted to a campus rowing club and two long-standing senior members. In turn, every participant was subjected to good-natured teasing by the others, who addressed him by mildly mocking nicknames. As the researchers had predicted, the senior members generated a greater proportion of dominant laughs and fewer submissive ones than the newcomers did. The newcomers, for their part, adjusted their laughter according to where the power lay, producing more dominant laughs once it was their turn to do the teasing. Compared with submissive laughter, dominant laughter was louder, higher in pitch and more varied in tone.
A separate set of volunteers was then played a balanced selection of dominant and submissive laughs, taken from both the senior and the junior members, and asked to judge each laugher's rank. Just as the team had anticipated, those producing dominant laughs were taken to be considerably higher in standing than those producing submissive ones. 'The effect was strongest for the low-status people, who were judged much higher in rank when they laughed dominantly rather than submissively,' Salkind's group reports. 'By putting on a more dominant laugh whenever the situation permits, then, someone of low standing can raise how others rate them.' Senior members, by contrast, were seen as high-ranking regardless of whether they laughed in their usual dominant manner or attempted a submissive one.
A different line of enquiry, pursued by Priya Nadkarni and Tomas Berg of Alderwood University, began from the idea that some humour might relieve dreary stretches of work, and that such a mental pause could help restore depleted mental energy. To examine this, they brought in sixty-eight business students, told misleadingly that the exercise concerned perception. The students first worked through a monotonous task, striking out every occurrence of a particular letter across two pages of writing. Each was then assigned at random to one of three video clips, meant to stir up amusement, contentment or nothing in particular: a scene from the comedy series The Copper Kettle, footage of geese gliding across a still lake, and a matter-of-fact film about warehouse logistics.
Next came a task designed to test persistence: judging, from a set of profiles, how well various employees were likely to perform, with the promise that ten right answers in a row would count as a win. The program, though, had been rigged so that reaching ten correct in succession was all but impossible, and anyone could abandon the exercise whenever they liked. Those who had seen the clip from The Copper Kettle stuck with it markedly longer, making twice as many judgements as either of the other groups.
Nadkarni and Berg obtained the same pattern again in a follow-up experiment, this time asking their volunteers to work through lengthy multiplication problems by hand. Once more, those who had watched the amusing clip laboured at this tiresome chore far longer, and got more answers right, than those in the two comparison groups.
'Humour is known to ease stress and to smooth the way for social bonds, yet the conventional understanding of task performance holds that people ought to steer clear of anything - humour included - that might pull their attention away from the job in hand,' the two researchers conclude. 'Our findings suggest that humour is not merely pleasurable; more importantly, it recharges us.'
