Since the early periods of history, there have been conflicting ideas about the size of populations relative to human wellbeing and whether there is a certain size which is optimal. There are varying opinions regarding the idea that a growing population is desirable as it provides the country with a source of wealth, while others believe that an increase in population is only beneficial up to the optimal point. In contrast, some believe any increase in population will have damaging effects on countries and will ultimately lead to serious problems such as starvation and diseases. Thus, there have been strong contrary views about the problem of overpopulation.

The Malthusian theory is the earliest theory exploring the population of a country which considers the relationship between the growth in food supply and in population. According to the theory, a country is said to be overpopulated if it doesn’t produce sufficient food to feed the population. Malthus stated that populations increase in geometric proportions while the food resources available would increase only in arithmetic proportions. Therefore, if human population was allowed to increase in an uncontrolled way without any checks, then the number of people would increase at a faster rate than the food supply. Eventually, a point will be reached where the population of a country would reach the limit up to which food sources are able to support it. Further increases in the size of the population would be damaging and lead to a population crash due to natural phenomena such famine or disease.

The figure demonstrates the growth of the population as exponential, whereas the food supply is growing in a linear manner. At the point of intersection of the two lines, the Malthusian catastrophe occurs as the population begins to outrun the food supply causing there to be famine in the country. Hence, at this stage of population, population is too high, and the country is overpopulated.