Coastline: IELTS Academic Reading practice test

Along much of the rocky coast of the North Pacific, from northern Japan to California, lies a habitat that few people ever see: the kelp forest. Kelp is a large brown seaweed, and in cool, nutrient-rich water some species can grow by as much as half a metre in a single day, forming canopies at the surface. Beneath them, long stalks rise like the trunks of trees from a root-like anchor called a holdfast, which grips the rock of the sea floor. These forests shelter a remarkable variety of life. Yet in many places their survival depends on a single animal, and not a large one: the sea otter.

Unlike seals and whales, sea otters have no layer of blubber to protect them from the cold. Instead they keep warm in two ways: with their fur, the densest of any animal, which traps a layer of air against the skin, and by burning energy at a very high rate. To fuel this, an adult must eat between a fifth and a quarter of its own body weight every day. Otters dive for sea urchins, crabs and clams, and they are among the few mammals known to use tools: floating on its back, an otter will place a flat stone on its chest and strike hard-shelled prey against it until the shell breaks.

Its appetite links the otter to the forest, because sea urchins, which graze on kelp, are among its favourite foods. Where otters are present, the urchins that survive tend to stay hidden in cracks in the rock, living largely on pieces of kelp that have broken off and drifted down to them. Where otters are absent, urchin numbers can rise very quickly and the animals move out into the open. They chew through the holdfasts, cutting the kelp loose from the sea floor so that whole plants drift away, and eat any young kelp that tries to grow in its place. The result is what ecologists call an urchin barren: a stretch of bare rock carpeted with urchins, where a forest once stood. This chain of effects, passing from predator to prey to plant, is known as a trophic cascade.

The fur that keeps the otter warm also made it extraordinarily valuable, and for much of the past three centuries its survival was far from certain. After Russian explorers returned from the North Pacific in the 1740s with sea otter pelts, hunters pushed along the Aleutian Islands and down the coast of North America, later joined by British and American traders who sold many of the skins in China. The hunt continued for more than 150 years. By the early twentieth century, a population that had once numbered in the hundreds of thousands had been reduced to perhaps no more than two thousand animals, scattered in small, isolated groups. In 1911 an international treaty finally banned the commercial hunting of the species.

The disappearance of the otters revealed what the animal had been doing all along. Where it vanished, urchins multiplied and kelp forests gave way to barrens that could persist for decades. The clearest evidence came in the early 1970s, when researchers compared islands in the Aleutian chain. Around islands where otters had recovered, divers found thick kelp, plenty of fish and only a few small urchins. Around an island where otters had never returned, the sea floor was dominated by urchins and there was almost no kelp at all.

Protection allowed the surviving groups to grow, slowly at first. One of them, off the central coast of California, was so small that for years it was believed to have died out altogether. Between the mid-1960s and the early 1970s, wildlife agencies also moved several hundred otters from Alaska to parts of the coast where the species had been wiped out, including British Columbia and Washington State. Not every attempt succeeded: animals released off Oregon failed to establish themselves, for reasons that are still debated. But where colonies took hold, the change could be rapid, and in some bays urchin barrens have turned back into kelp forest within a few years of otters moving in.

The return of the otter has not been welcomed by everyone. Because many of its favourite prey are also valuable to people, its recovery has brought it into conflict with shellfish fisheries. In parts of southeast Alaska, divers who harvest sea cucumbers, sea urchins and clams have reported steep falls in their catches where otters have returned, a serious loss for communities built around shellfish. Some fishers argue that what looks like the restoration of a natural balance is, from their point of view, simply the arrival of a very efficient competitor.

Supporters of the otter reply that the restored forests have value of their own. Young fish of many commercially important species use them as nurseries, the canopies reduce the force of waves reaching the shore, and the kelp absorbs carbon dioxide as it grows. Martha Ellery, a fisheries economist, weighed these gains against the losses on one stretch of coast and concluded that the benefits were likely to exceed the costs. Her critics note, however, that the gains are spread thinly across a whole region while the losses fall heavily on a few small communities.

The sea otter's story shows that an ecosystem does not always return to normal once a disturbance ends. A coast can settle into two quite different states, forest or barren, and a single species can determine which of them it is in. Protecting a predator, in other words, is rarely only about the predator. It is a decision about the whole shoreline, and about who will share in its gains and who will bear its costs.

Few states of mind have been as consistently maligned as boredom. Moralists once treated it as the doorway to vice, and educators have long regarded a bored pupil as evidence of a failing lesson. Today the condition is treated less as a sin than as a technical problem, and one for which we appear to have found a solution: the device in our pocket ensures that no queue, commute or pause in conversation need ever be endured unoccupied. It is worth asking, however, whether in abolishing boredom we have discarded something of value. My contention is that boredom is better understood as a signal than as a malfunction, an uncomfortable but informative message about the fit between a mind and its circumstances, and that a culture which reflexively silences that message may be depriving itself of more than it realises.

Part of the difficulty is that boredom has proved surprisingly elusive to define. It is not the same as apathy, in which the desire to act has faded altogether; the bored person, by contrast, is often restless, even agitated, precisely because the desire persists. Nor is it simply the absence of stimulation, since people report being bored in the middle of noisy, eventful situations. The psychologist Hannah Ekwall, who has spent much of her career studying attention, has proposed that boredom is fundamentally a failure of attention: a state in which the mind is primed for engagement but cannot find anything on which to settle. On this account, the fault lies less in the environment than in the relationship between the environment and the attentional resources we bring to it, which is why the same lecture may absorb one listener and leave her neighbour in torment. I find this formulation persuasive, not least because it explains why attempts to banish boredom simply by supplying more stimulation so often fail.

If boredom is a failure of engagement, what, if anything, might it be for? One answer comes from research on creative thinking. In a series of experiments, Oliver Pratt and his colleagues asked volunteers to spend twenty minutes on a deliberately tedious task, matching pairs of identical shapes, before inviting them to suggest as many uses as they could for an ordinary household object. Compared with volunteers who had spent the same period on an absorbing puzzle, the bored group produced more ideas, and independent judges rated a greater proportion of them as original. Pratt interprets the result as evidence that boredom prompts the mind to wander in search of the stimulation its surroundings deny it, and that this wandering can be fertile. The finding has been widely reported, often under headlines implying that boredom makes people more creative in general. That is a larger claim than the evidence will bear. The effect, while consistent, was modest, the task measured only one narrow kind of inventiveness, and it remains unclear whether anything comparable occurs outside the laboratory.

A second line of argument concerns meaning rather than creativity. Ines Carvalho, whose book on motivation draws on twenty years of laboratory work, suggests that boredom functions much as physical pain does: it is aversive precisely so that we will act to end it. What it signals, in her view, is not that we lack stimulation but that our current activity has ceased to seem worthwhile. In her studies, participants who had been made to feel bored were subsequently more inclined than others to choose tasks they regarded as meaningful, such as volunteering, even when those tasks were more demanding than the alternatives. If Carvalho is right, boredom is not the enemy of purposeful activity but one of the mechanisms that steers us towards it.

Not everyone is persuaded by this rehabilitation. Rafael Mendel, a psychiatrist at a large teaching hospital, points out that people who are prone to frequent boredom are over-represented among those who struggle with depression, problem gambling and substance misuse, and he regards the case for boredom's benefits as a comfortable view, available mainly to those who experience it rarely and briefly. This objection seems to me to be largely correct, and it ought to temper any enthusiasm for boredom as a kind of mental tonic. Yet it is directed at something rather different from the claim I am defending. Mendel is concerned with a chronic disposition; my concern is with the passing state that most of us experience several times a day. A signal that sounds continuously is certainly a problem, but that hardly shows that the signal itself serves no purpose.

The more pressing question is what happens when the signal is routinely suppressed. Yuki Sato, whose team spent a year recording how people use their phones during idle moments, found that many participants reached for their devices within a few seconds of a lull, often before they reported feeling bored at all. Sato argues that such devices do not cure boredom so much as postpone it: the relief they provide is brief, and those who checked their phones most often during the study also rated themselves as more bored overall. The correlation does not, of course, establish the direction of cause, since habitually bored people may simply reach for their phones more. But it is at least consistent with the idea that constant distraction prevents boredom from doing whatever work it might otherwise do.

None of this amounts to a case for deliberately inflicting boredom, still less for defending dull teaching or pointless work on the grounds that they are somehow good for us. A signal is useful only to someone who is in a position to respond to it, and a great deal of boredom, in classrooms, offices and factories, arises where the bored person has no power to change anything. For them, the message that their activity lacks meaning is accurate but useless. What I would suggest is more modest: that the brief boredom of an unoccupied moment deserves rather more tolerance than we usually give it. It may yield nothing. But if Ekwall and Carvalho are even partly right, it is one of the few moments in a crowded day when the mind is invited to ask what it would rather be doing, and the answer to that question is not always trivial.