One of the greatest sources of anxiety in many parts of the world is the extraordinarily rapid rate at which world population figures are increasing. This expansion has tremendous social implica­ tions in addition to the obvious anxiety it arouses about how the increased population can be fed. Not only has the world popula­ tion increased by four or five times in the last 150 years, but cur­ rent trends show that the rate of increase is accelerating. In­ creasing density of population has led to the formation of vast new urban areas, resulting, as discussed elsewhere, in radical upheavals of patterns of social and family life. The very fact of a big population increase compels social and family change on a wide scale.