Other trends too have made modern farming better for the planet. Now that weeds can be controlled by herbicides rather than ploughing (the main function of a plough is to bury weeds), more and more crops are sown directly into the ground without tilling. This reduces soil erosion, silt run-off and the massacre of innocent small animals o f the soil that inevitably attends the ploughing of a field – as flocks of worm-eating seagulls attest. Food processing with preservatives, much despised by greenchic folk, has greatly reduced the amount o f food that goes to waste. Even the confinement of chickens, pigs and cattle to indoor barns and batteries, though it troubles the consciences (mine included) o f those who care for animal welfare, undoubtedly results in more meat produced from less feed with less pollution and less disease. When bird flu threatened, it was free-range flocks of chickens, not battery farms, that were at greatest risk. Some intensive farming of animals is unacceptably cruel; but some is no worse than some kinds o f free-range farming, and its environmental impact is undoubtedly smaller.
There is one respect in which the environmental critique of modern agriculture has force. In the pursuit of quantity, science may have sacrificed nutritional quality of food. Indeed, the twentieth-century drive to provide a growing population with an ever faster-growing supply of calories has succeeded so magnificently that the diseases caused by too much bland food are rampant: obesity, heart disease, diabetes, and perhaps depression. For example, modern plant oils and plentiful red meat make for a diet low in omega-3 fatty acids, which may contribute to heart disease; modern wheat flour is rich in amylopectin starch, which may contribute to insulin resistance and hence diabetes; and maize is especially low in the amino acid tryptophan, a precursor of serotonin, the ‘feel-good’ neurotransmitter
Consumers will rightly be looking to the next generation of plant varieties to redress these deficiencies. They could do so by eating more fish, fruit and vegetables. But not only would this be a land-hungry option, it would suit the wealthy more than the poor, so it would exacerbate health inequalities. Arguing against vitamin-enriched rice, the Indian activist Vandana Shiva, echoing Marie-Antoinette, recommended that Indians should eat more meat, spinach and mangoes rather than relying on golden rice.
Instead, genetic modification provides an obvious solution: to insert healthy nutritional traits into high-yielding varieties: tryptophan into maize to fight depression, calcium transporter genes into carrots to help fight osteoporosis in people who cannot drink milk, or vitamins and minerals into sorghum and cassava for those who depend on them as staples. By the time this book is published soybeans with omega-3 fatty acids developed in South Dakota should be on the way to supermarkets in America. They promise to lower the risk of heart attacks and perhaps help the mental health of those who cook with their oil – and at the same time they can reduce the pressure on wild fish stocks from which fish oils are derived.