A Few drinks have travelled as far, or changed as many lives, as tea. According to a well-known Chinese legend, it was discovered entirely by accident almost five thousand years ago. The Emperor Shen Nung, who insisted that his drinking water be boiled for safety, was resting beneath a wild bush when a few leaves drifted down into his pot of boiling water. Curious about the pleasant smell, he tasted the result and found it refreshing. Whatever the truth of the tale, the earliest records make one thing clear: for a very long time tea was valued not as a pleasure but as a medicine, taken to aid digestion and to sharpen the mind.

B From China the habit spread eastwards to Japan, carried in the ninth century by Buddhist monks who had studied on the mainland and brought seeds home with them. There, over several hundred years, drinking tea grew into something far more elaborate than a simple daily custom. A whole ceremony developed around it, in which every movement — the folding of a cloth, the turning of a bowl — was carefully prescribed. Far from being a hurried refreshment, the preparation of tea became an art form, prized for the calm and concentration it demanded of both host and guest.

C Tea did not reach Europe until the seventeenth century, when Dutch and Portuguese ships began carrying it back from the East. At first it was fabulously expensive, a rarity that only the wealthiest households could afford, and it was often kept locked away in a special box. Governments were quick to see an opportunity, and the leaf was taxed heavily wherever it was sold. For decades, then, tea in the West was a luxury — a symbol of status as much as a drink.

D Nowhere did the leaf take deeper root than in Britain. As prices slowly fell, tea reached ordinary homes, and by the nineteenth century it had become the national drink, taken at all hours and across every class. For a time it was even sold and enjoyed in fashionable outdoor tea gardens, where families would walk and listen to music. The trade itself grew enormous, shaping shipping routes and, less happily, the politics of empire, as vast quantities were shipped halfway round the world to satisfy British demand.

E Today tea is the second most widely consumed drink on the planet, behind only water, and it is produced in dozens of countries far beyond its Chinese homeland. Scientists have taken a fresh interest in it too, studying the antioxidants it contains and their possible role in protecting the heart. Whether or not these benefits are fully proven, the appeal of tea shows no sign of fading. A drink that began, if the legend is to be believed, with a few stray leaves and a pot of hot water has become a genuinely global habit.

A A honeybee colony is not a loose crowd of insects but a highly organised society, and every member has a fixed part to play. At its centre is a single queen, whose sole task is to lay eggs — sometimes as many as two thousand in a day. The great majority of the colony are workers, all of them female, who between them clean the hive, feed the young, guard the entrance and gather food. The only males are the drones, which take no part in this labour; their one purpose is to mate with a new queen, after which they die.

B One of the most remarkable things about bees is how they share information. A worker that has found a rich patch of flowers cannot simply describe it, yet she can tell the others exactly where to go. She does this by performing a curious movement on the honeycomb known as the "waggle dance". The direction in which she waggles indicates the way the flowers lie in relation to the sun, while the length of the dance signals how far away they are. In this way a single successful forager can send dozens of her sisters straight to the food.

C Making honey is a slow, cooperative process. Foragers first suck up nectar, a sugary liquid, from flowers and store it in a special "honey stomach". Back at the hive, they pass this nectar to younger house bees waiting inside. These bees add natural chemicals, called enzymes, which slowly break the nectar's sugars down into simpler forms. At the same time, the nectar is far too watery to keep, so the bees beat their wings hard over the open cells, fanning a current of air across them until much of the water has evaporated. Only when the liquid has thickened into honey do they seal each cell shut beneath a thin lid of wax, preserving the food for the winter ahead.

D The importance of all this activity reaches far beyond the hive. As bees move from flower to flower in search of nectar, they carry pollen with them, and in doing so they fertilise the plants they visit. A very large share of the crops that people eat — from apples and almonds to many vegetables — depends on this service. Without bees and other pollinating insects, the cost of producing such food would rise steeply, and some of it might not be produced at all.

E For these reasons, the recent decline of bee populations in many regions has alarmed scientists. The causes appear to be several and to act together: certain pesticides used on farms, the spread of diseases and parasites, and the steady loss of the wild flowers on which bees feed. In some places whole colonies have suddenly collapsed, their workers vanishing for reasons that are still not fully understood. Protecting bees, researchers warn, is not a matter of sentiment but of guarding a system on which much of our food quietly depends.

A Zoos remain among the most popular attractions in the world, drawing hundreds of millions of visitors every year. Yet few institutions divide opinion so sharply. To their supporters, zoos are places of learning and conservation that do real good; to their critics, they are little more than prisons that keep wild animals behind bars for human amusement. The truth, as so often, is more complicated than either side allows.

B Those who defend zoos point first to conservation. A number of species that had all but disappeared in the wild — from certain horses to particular frogs and birds — survive today only because zoos bred them in captivity and, in some cases, later released them. Good zoos also fund research and protection work in the animals' natural habitats, money that would otherwise be hard to raise. And they argue that seeing a living animal, rather than a picture of one, can awaken in visitors, especially children, a concern for wildlife that lasts a lifetime. It is one thing to read that a species is endangered; it is another to stand a few metres from it.

C Critics answer that these benefits come at too high a price, and that the price is paid entirely by the animals. However spacious a modern enclosure may be, they argue, it cannot reproduce the range over which a large animal would naturally roam. Confinement, they say, leads to boredom and stress, which show themselves in the repetitive pacing and swaying often seen in captive creatures — behaviour almost never observed in the wild. Some go further, questioning whether the educational value is real at all: a family that watches an animal for ninety seconds before moving on, they suggest, is being entertained rather than taught.

D Where, then, does the balance lie? The honest answer is that it depends almost entirely on the zoo. A well-run, properly regulated institution that gives its animals genuine space, keeps them occupied, breeds endangered species and pours its profits into protecting wild populations is doing something valuable, and the case against it is weak. A cramped roadside collection that exists only to make money from a few miserable animals is doing something indefensible, and no appeal to "education" can rescue it. The question, in the end, is not whether zoos should exist, but whether a particular zoo puts the welfare of its animals before every other consideration.