In the face of a population explosion, food and energy become critical issues. some experts feel that the only way to feed the world is to rely on ever more intensive farming methods. Rather than farmers growing several varieties of a fruit or vegetable. Scientists are designing crops that will meet optimum criteria, regarding not only their nutrient content but also their ease of harvesting and packing, shelf life, resistance to spoilage, uniformity of size, and so on. In more and more cases only one variety of seed is used. But this makes the entire crop more vulnerable to disease and insect damage. In additon, these new crops require the use of pesticides and herbicides, as well as fertilizers and ripeners. As a result modern farming methods are making much of the third world dependent on the products of the chemical industry. In turn, this requires a change in traditional farming methods, an alteration of entire social structures and reliance on the products and assistance of the industrial nations.