Although the evolution of the food and agricultural system in developed countries seems to be progressing at an ever-increasing rate, in reality this trend has largely been realized as small bursts of progress followed by relatively dormant periods until another break-through is achieved. These break-throughs occur in a variety of ways, including the scientific, such as the development of new hybrids and genetic lines, useful chemicals etc., the political, such as the opening of trade with China and other communist countries, and the behavioral changes such as the shift toward leaner meats, more natural food products, and more highly processed "heat and serve" preferences among consumers.