Prior to the late 18th century, agricultural practices were totally dependent on crude handtools, crop landraces, and mixtures of these landraces. Then came the Industrial Revolution with an associated population explosion that transformed the subsistence nature of agriculture and its farming systems forever. In the mid-19th century, Mendel (and later other pioneering plant geneticists) provided a new knowledge of plant genetics and breeding that made it possible to increase dramatically the production and production potential of agriculture. Undeniably, the wonders of crop improvement have resulted in the erosion of genetic diversity of many crops in farmers' fields, induding wheat, due to the replacement of landraces and old farmers' varieties with modem high yielding varieties. Fortunately, our understanding of the sources of genetic diversity and their distribution and interrelationships between cultivated crops and their wild relatives has rapidly expanded in the latter half of the 20th century. This enh nced awareness has resulted in the present-day concept that genetic resources are our heritage and consequently should be preserved, protected, and made available without restrictions to aIl who need them.