Felipe Fernandez-Armesto: We eat too much. We throw too much away. Go figure

Britain's love-hate relationship with supermarkets reveals a lot about this country. People love them because they deliver cheap choice - abundance on a budget. People hate them, among other reasons, because they waste food.

Britain's love-hate relationship with supermarkets reveals a lot about this country. People love them because they deliver cheap choice - abundance on a budget. People hate them, among other reasons, because they waste food.

These are very British reasons. So far, the only uncontested general election pledge is "No VAT on food". Cheap food has replaced the monarchy as the only British institution the British agree about. No other rich nation is so thrifty about food. In the 20th century, nanny stopped saying, "Leave something for Mr Manners" and began to say, "Eat up". Wartime rationing reinforced the message. Other countries rapidly recovered from austerity and rediscovered the value of food. But in Britain a paradox abides: food is under-appreciated and wasted food is treated as a sin against the starving.

Yet in today's world, these British values are wrong. Cheap food is bad for the world. Waste is morally neutral: it's just one of the consequences of undervaluing what we eat.

Cheap food is a recent phenomenon. At the start of the 20th century, an average family spent at least a third of its income on food. Nobody in Britain spends anything like that amount now. The results are dire.

Mass-produced foods, with low unit profits, make fantastic fortunes if marketed on a large enough scale. For farmers in rich countries, subsidies cushion the effects. Meanwhile, most of the world's peasants are locked into a global system of over-production: helping to generate massive surpluses from which they can hardly make a living. Where prosperity grows and food becomes abundant, diets deteriorate. People in booming cities are cut off from the sort of food their ancestors ate: painstakingly grown, freshly harvested, locally prepared. A switch to mass-produced food has occurred in just about every major urbanising environment in the world. One result is a pandemic of obesity. Another is the scandal of waste. They are closely related: overeating is a particularly pernicious form of waste. If you undervalue food, you treat it with gluttony or profligacy. Abundance, it seems, is there to be exhausted. Given the chance, people gorge until, in effect, they burst, or until they empty the fridge.

Cheap food does some people good. Not the poor of rich countries: it encourages them to over-eat. Not the peasants of poor countries: it condemns them to low prices. In Britain, the big beneficiaries are supermarkets.

Tesco's broke the £2bn profit barrier last year and became the most profitable food-delivery operation in British history.

What can we do about it? The supermarkets are our servants. Their excesses are responses to consumers' bad habits. So we have to reform those habits.

First, we have to value food more highly. The best way to help the poor of the world is to buy rare foods from them at a high price, and stop encouraging them to supply cheap pap for the world. This may be easier than it sounds. The big growth in food markets today is for non-standard, traditional, local, "slow" and artisanal foods.

Second, we can get rid of traditional inhibitions that make British tables humdrum. By global standards, mass-produced food is a luxury: consumers should be penalised. We could tax food the way we tax petrol - as long as we use the revenues wisely, to reward farmers who enrich biodiversity. Our current system encourages the hungry to grow standard varieties of food for their own consumption. What they really need to do is grow exotica and sell them to us at a profit. Thirdly, we can make waste a virtue. As far as we know, there has never been a society free of conspicuous consumption. The world's biggest wastrels were our palaeolithic ancestors, who would drive a whole herd of mammoths over a cliff whenever they wanted a meal.

Next, we can abandon genetic modification programmes. GM might guarantee cheap food for the future. But this would entrench over-production and deprive producers of the opportunity to specialize in expensive foods for rich markets. GM would make the poor poorer by forcing them to buy seed to produce goods they could not sell.

Expensive food would solve many of the world's problems. It would slim down the problem of obesity. It would bridge global disparities in wealth. It would give poor farmers something to sell. It would compensate rich farmers for the withdrawal of subsidies. It would help to make genuinely free trade in food possible.

It might even cut waste. Great unsolved problems of recent history include: why do people consume so much more than they need? And why do they demand so much more than they can consume? Anthropologists and philosophers blame "spiralling desire" - an instinct, or maybe a pathology, that makes people want whatever is available, or envy whatever others have. Growing, spreading prosperity seems to accentuate the effects.

We need to find ways of controlling those effects before they start causing conflicts and depleting the resources of the world.

Felipe Fernández-Armesto is Professor of Global Environmental History at Queen Mary, University of London, and author of 'Food: a History'