The part of France that eats the most duck fat has the fewest heart attacks in the country. When the world found out in 1991, it gave the credit to the wine. The place is Gascony, in the south west. Its great dish is confit. You take the legs of a fattened duck or goose, salt them overnight, and cook them for hours, very slowly, submerged in their own melted fat. Then you pack them into a stone crock, pour the fat over the top until they are sealed, and put them in the cellar. They will keep all winter. Everything else is cooked in what is left. Potatoes are fried in duck fat. Beans are stewed with it. A Gascon housewife traditionally kept no cooking oil and little butter, because the bird supplied all she needed. The same region produces most of the world's foie gras, and eats a great deal of it. In 1991 a French researcher gave the figures to an American television programme. Among middle-aged men, deaths from heart attack ran at about 315 per 100,000 in the United States. For France as a whole it was 145. In Gascony it was 80. The programme called it the French paradox and suggested the answer might be red wine. Sales of red wine in America jumped by nearly half within weeks. Nobody rushed out to buy a crock of goose fat. It was only a paradox if you began by assuming the fat was the danger. The Gascons never assumed that. They had been preserving meat under it since before France existed. The healthiest hearts in the country belonged to people who kept a duck in a jar of its own dripping.

In the early 1980s doctors in Cambridge laid premature babies on lambswool, and the babies grew faster. They were the smallest patients in the hospital. 34 infants, born weighing about two and a half pounds, lying in incubators. The standard bedding was a cotton sheet. A psychologist and a paediatrician had heard that mothers in Australia and New Zealand put newborns to sleep on lambskins, and that the babies seemed more settled. So they ran a proper trial. Half the babies were nursed on cotton. Half were nursed on a pad of lambswool. Nothing else was changed. The result went into the Lancet in 1983. The babies on wool put on 22.7 grams a day. The babies on cotton put on 18.6. That is nearly a quarter more growth, in children for whom every gram is a step away from danger, from changing what they lay on. Nobody was entirely sure why. Wool holds a layer of still, warm air against the skin. It takes up moisture without feeling damp. It gives under a body where a sheet does not. Hospitals had known a version of this for a long time. For decades a patient who was bedbound was put on a sheepskin to stop the skin breaking down, and trials in Australia later confirmed that real sheepskin prevents bedsores. Then came the synthetic version. A sheet of polyester pile that could be boiled and cost a fraction as much. It looked the part. It does not do the job. A ewe grows the best thing ever found for a newborn to lie on, and a lamb is born onto it. The hospital tested that against the alternative and wool won. The alternative was cheaper, so that is what most babies get.