IELTS Academic Reading Practice Test 363

In 1728 there appeared in Paris a two-volume work entitled Le Chirurgien Dentiste, ou Traité des Dents — The Surgeon Dentist, or Treatise on the Teeth. Its author was a practitioner named Pierre Fauchard, and the book is generally regarded as the first comprehensive account of the teeth, the gums and their diseases. It is also a founding document of a profession, for it marks the point at which the treatment of teeth began to be understood as a branch of surgery with its own knowledge and standards, rather than as a sideline of barbers and travelling showmen.

Fauchard was born in 1678 in Saint-Denis-de-Gastines, a village in the west of France, into a family of modest means. Little is known for certain about his education. He is thought to have received some training in surgery, possibly at sea, but no reliable record of his early years survives, and much of what is said about his apprenticeship rests on later tradition rather than on documents. What is clear is that by his early forties he had settled in Paris and had begun to concentrate on the mouth, a specialisation that barely existed at the time.

Patients with toothache in the early eighteenth century had a limited choice. They could consult a barber-surgeon, whose training covered the whole body; they could visit a tooth-drawer, an itinerant operator who set up a stall at a fair and removed teeth in public with a lever that often broke the tooth or damaged the jaw; or they could pay an empiric who claimed to cure decay by driving out the worms believed to live inside a diseased tooth. Fauchard had no patience with the last of these groups, and he was among the first to call himself a chirurgien dentiste, a surgeon whose work was confined to the teeth.

Le Chirurgien Dentiste drew together everything he had learned. It discussed the anatomy of the mouth, the causes of decay, the treatment of diseased gums and the removal of the hard deposits now known as tartar. Fauchard recommended cleaning the teeth regularly and warned his readers against the corrosive powders and strong acids sold by quacks to whiten the teeth, which, he pointed out, destroyed the enamel and loosened teeth that might otherwise have been saved. He also described how cavities could be cleaned out and filled with lead or tin foil.

Loss of teeth concerned him as much as decay. Fauchard described sets of artificial teeth carved from ivory or bone, and he made use of human teeth as well, though he knew the objections to the practice. He designed dentures held in place by springs, an ingenious solution that could, unfortunately, propel the false teeth out of the mouth with force. He was also interested in teeth that grew in the wrong position, and he described a band of metal that could be tightened gradually to draw a misplaced tooth into line, anticipating the braces of the modern orthodontist.

His scepticism about the tooth worm was characteristic. Having examined a great many decayed teeth, Fauchard found no evidence of the creatures, and he argued instead that decay began in the substance of the tooth itself and spread inward. He was not right in every particular, and some of his explanations of disease now look strange. But the habit of testing a claim against observation rather than tradition is one reason why his book was taken seriously by surgeons who had previously left dentistry to others.

Fauchard's second ambition was to raise the status of his profession. He complained that anyone, however ignorant, could set up as a tooth-drawer, and he argued that a dentist should be able to read and write, should understand the structure of the mouth and should be examined before being allowed to practise. He took pupils and expected them to study anatomy before they treated anyone. Such proposals were not adopted at once, and formal training and licensing took many years to become normal, but the argument had been made in print by a respected practitioner.

His practice in Paris attracted well-to-do patients, and his book is written with an eye to readers who could afford careful treatment rather than a quick extraction. Yet he was also a close observer of ordinary mouths, and his case notes describe people of very different circumstances. The two volumes mix practical instruction, case history and opinion, which must have made unusual reading for a public accustomed to short manuals on the pulling of teeth.

The book's influence spread slowly but steadily. It was translated into other European languages, and later writers on dentistry borrowed from it freely, sometimes without acknowledgement. In the following century, as dentistry acquired schools, journals and examinations of its own, Fauchard's treatise was repeatedly cited as the work that had first set out the subject in an orderly way. Fauchard himself died in Paris in 1761, having practised for some four decades.

He is often called the father of modern dentistry, a phrase that compresses a long history into a single life. What can be said is that he gave the treatment of teeth a literature, a method and a claim to professional respect. Dental societies and academies still carry his name, and students are still introduced to the man who insisted that a tooth was worth saving rather than merely removing.

Stand up, walk across the room and pick up a cup. The action feels effortless, almost thoughtless, yet it depends on a chain of events that begins in the brain well before any muscle contracts. At least four things must happen: a decision must be made, a plan must be assembled, commands must be sent down the spinal cord, and the result must be checked and corrected. Each stage involves different groups of neurons, and each can fail on its own: a small stroke may leave a patient unable to grip, while damage elsewhere leaves the hand strong but clumsy.

The best-known region is the primary motor cortex, a strip of tissue on the precentral gyrus, immediately in front of the groove that separates the frontal lobe from the parietal. Its role was established in the 1930s and 1940s, when the neurosurgeon Wilder Penfield and his colleagues stimulated the exposed brains of patients during operations carried out under local anaesthetic. Stimulating a small patch of the strip produced a twitch in a particular part of the body; stimulating a neighbouring patch moved another. The result was a map, running from the toes at the top of the brain to the tongue and throat at the bottom, in which the hands and the face occupy disproportionately large areas — a reflection of how much fine control those parts require. Modern work treats the map less as a set of fixed points than as a pattern of activity across large populations of cells.

Motor cortex neurons send their axons downward in a bundle called the corticospinal tract. As the fibres pass through the brainstem, most of them cross to the other side, which is why damage to the motor areas on one side of the brain weakens the opposite side of the body. The tract ends in the spinal cord, where the axons connect, directly or through small interneurons, with motor neurons whose own fibres leave the cord and travel to the muscles. When a signal reaches the end of a motor neuron, it releases a chemical, acetylcholine, at the junction with the muscle, and the muscle fibre contracts.

A single motor neuron supplies a group of muscle fibres, and the size of that group determines how fine a movement can be: a muscle of the eye may be controlled by neurons serving only a handful of fibres, while a muscle of the leg is served by neurons supplying hundreds. The spinal cord, however, is not merely a cable through which orders pass. It contains circuits that can produce rhythmic patterns of movement by themselves; in cats whose spinal cord has been separated from the brain, electrical stimulation can still produce alternating stepping movements of the hind legs.

Two other structures are essential. The basal ganglia, a set of deep clusters of neurons, appear to be involved in selecting a movement and suppressing unwanted ones — in allowing one action to proceed while others are held back. Their importance is clear from Parkinson's disease, in which the death of dopamine-producing cells in a midbrain region called the substantia nigra deprives the basal ganglia of a crucial signal. The result is the slowness, rigidity and tremor that characterise the condition, and it is in the basal ganglia that deep brain stimulation, one of the standard treatments for advanced Parkinson's disease, acts.

The cerebellum, attached to the back of the brainstem, contains more neurons than the rest of the brain put together. It receives a copy of the commands sent to the muscles and a stream of sensory information about what the muscles actually did, and it compares the two. People with damage to the cerebellum can still move a limb, but their movements are clumsy, badly timed and poorly measured: they overshoot the cup or stop short of it. The cerebellum also seems to store the results of practice, which is why a skill learned slowly can eventually be performed without conscious attention.

The moment at which a movement begins is more puzzling than it appears. In the 1960s, researchers recorded a slow build-up of electrical activity over the motor areas of the scalp in the second or so before a person made a voluntary movement. This readiness potential, as it became known, was later found to begin a fraction of a second before the person reported being aware of having decided to move. Some have read this as evidence that the brain decides before we do. Others argue that the potential reflects a general preparation to act, not a decision about a particular movement, and the dispute is unresolved.

The recordings that fuel this argument are also the basis of a new technology. Electrodes implanted in the motor cortex of people paralysed by injury or disease can pick up the activity associated with an intended movement, and a computer can translate it into commands for a robotic arm or a cursor on a screen. In 2023 a Swiss-led team reported that an implant reading signals from one man's motor cortex, linked to stimulation of the spinal cord below his injury, allowed him to walk with support. Such devices remain experimental, but they are also a remarkable source of evidence about how the healthy brain produces movement.

Every weekend, hundreds of thousands of children head a football. For most of them the experience is brief and unremarkable: a clearance, a corner, a moment of contact, and the game goes on. In the past few years, however, the question of whether children should head the ball at all has moved from the margins of parental concern to the centre of sports policy. Several governing bodies have restricted heading in training, and a few have begun to remove it from matches at the youngest ages. Is this a sensible precaution or a well-meant overreaction? The anxiety of parents who watch a child head a heavy ball is easy to understand; the evidence is harder to read.

The debate was transformed in 2019 by a study of former professional players in Scotland. Researchers compared the causes of death recorded for several thousand former players with those of people of similar age and background in the general population. Deaths from neurodegenerative disease, including dementia, were about three and a half times more common among the former players. The same study found that the players died less often than expected from some other conditions, including heart disease, which makes it harder to explain the figures away as a matter of general health.

What such a study cannot do is tell us why. It recorded deaths, not headers; it had no information about how often individual players headed the ball as children, and it concerned professionals, whose exposure over a career is far greater than that of a pupil in a school team. A threefold increase in a rare cause of death is also easy to misread, since neurodegenerative disease remains uncommon in absolute terms. Above all, the study cannot tell us whether heading, concussion or something else entirely is responsible. The link is real and troubling; it is not proof of cause and effect.

There are nevertheless reasons to suspect that heading could matter. A football is a hard object with a mass of between about 410 and 450 grams, and heading it involves a brief but substantial acceleration of the head. Measurements suggest that the acceleration produced by a ball is far smaller than in the collisions that cause concussion, so the concern is not a single blow but accumulation: hundreds or thousands of small impacts over years of practice and play. Studies that have looked for links between heading frequency and memory or brain structure have reported some differences, but the samples are small and the findings inconsistent.

It is also worth asking where concussions in youth football actually come from. Studies of injuries in the youth game generally find that most head injuries result from collisions with another player, a tackle or a fall, not from the ball striking the head. Some researchers argue, therefore, that a ban on heading deals with a small part of the problem while leaving untouched the contacts that cause most damage, and that attention would be better directed at coaching, refereeing and the treatment of players who have been concussed.

Against this must be set the costs of a ban. Heading is a skill, and skills are learned young; a player who first heads a ball at 14 will be behind those who have practised for years, and may be discouraged from continuing. It is often argued that heading is rare in matches involving the youngest children, because the ball spends most of its time on the ground, but that is an argument about how often the rule would matter rather than about whether it is justified. A rule that officials cannot enforce consistently creates its own problems.

Rules have nevertheless begun to change. In the United States, the national federation agreed in 2015 to prohibit heading for children aged ten and under and to limit it in training for those up to 13, as part of the settlement of a lawsuit brought by parents. In England, the Football Association has advised that primary-age children should not head the ball in training, and in 2022 it announced a trial in which deliberate heading was removed from matches for under-12 teams in a number of grassroots leagues.

If the aim is to protect young brains, other measures might achieve more. Teaching children to head the ball with the forehead rather than the top of the head, using smaller and lighter balls at young ages, limiting repetitive heading drills in training, and taking concussion seriously when it occurs, by removing the player from the game and not returning them the same day, all have support. The evidence that any of these measures reduces long-term harm is, however, thin, because the outcomes being studied take decades to appear.

Where does that leave the youngest players? Two principles pull in opposite directions: a liberal reluctance to prohibit an ordinary part of a popular game on the basis of circumstantial evidence, and a precautionary instinct to remove a hazard whose consequences, if real, are serious and irreversible. In my view the second should prevail, but only in a narrow form. Removing deliberate heading from matches for the youngest age groups, children of primary school age, is a small and reversible change whose costs fall mainly on the shape of the game, and whose potential benefit is the protection of a developing brain. To extend the ban to all youth football, by contrast, would be to accept real costs for a benefit that is far from demonstrated.