Chapter 1. Introduction: The Theoretical Background

1.1 Development of ideas about demographic cycles
The modern science of population dynamics begins with the publication in 1798 of An Essay on The Principle of Population by Thomas Robert Malthus. Malthus pointed out that when population increases beyond the means of subsistence food prices increase, real wages decline, and per capita consumption, especially among the poorer strata, drops. Economic distress, often accompanied by famine, plague, and war, leads to lower reproduction and higher mortality rates, resulting in a slower population growth (or even decline) that, in turn, allows the subsistence means to “catch up”. The restraints on reproduction are loosened and population growth resumes leading eventually to another subsistence crisis. Thus, the conflict between the population’s natural tendency to increase and the limitations imposed by the availability of food result in the tendency of population numbers to oscillate. Malthus’s theory was extended and further developed by David Ricardo in his theories of diminishing returns and rent (Ricardo 1817).