This paper discusses a basic ecological process of the transition from nomadic hunter-gatherer life to sedentary life of food producers in human history. Through examining from an ecological viewpoint the value of starchy seeds, which comprise the most important food resource of both contemporary and prehistoric hunter-gatherers, and the demerits of sedentary life, it is concluded that a food producing sedentary life may have been a second choice of prehistoric hunter-gatherers for coping with the population increase and food crisis which began about ten thousand years ago. It is also suggested that food producing economy may have been a by-product of sedentary life.