Forecasting Societal Growth: Malthusian Theory and its Evolutionary Impact

During the latter years of the eighteenth century, English reformers such as William Godwin and his fellow Utopians foresaw a virtually limitless improvement of societal life, where population growth would produce more workers, leading to greater national wealth, prosperity, and a higher quality of life for all. However, one dissonant voice foresaw dire consequences arising from an unbridled expansion of the population. An essay appeared in 1798 predicting that the expanding population, especially among the lower socioeconomic classes, would exceed the available supply of food by the middle of the nineteenth century.

The author of “An Essay on the Principle of Population” was the thirty-two-year-old English political economist and demographer Reverend Thomas Malthus, who was fascinated (one might say obsessed) with all aspects of populations — including births, deaths, and the ages at which marriage and childbirth occurred. While the food supply was increasing arithmetically (1, 2, 3, 4, 5 . . .), Malthus projected that the human population was expanding at a geometric rate (2, 4, 8, 16, 32 . . .), which, if not brought under control, would, in short order, lead to poverty and starvation. He advocated “preventive checks” to reduce the birth rate including marrying at a later age, birth control, and abstaining from procreation. Failing these, “positive checks,” such as disease, war, disasters, and starvation, would augment the death rate. His essay’s popularity was exemplified by the appearance of a final sixth edition in 1826, but happily his predictions never materialized, as they failed to anticipate the coming of the agricultural revolution.

Malthus’s writing was, however, the spark that independently influenced both Charles Darwin and Alfred Russel Wallace in their respective evolving theories of natural selection that were presented some twenty years later. Darwin, as he acknowledged in his autobiography, transferred Malthus’s concepts from humans to the natural world. He recognized that all living species routinely over-reproduce and that, in a challenging environment, only some species and individuals possess a trait that enables them to have a selective advantage to survive, reproduce, and transmit this trait to their offspring.

This illustration, dating back to the time of the Great Famine of 1876–78, portrays "The Famine in India: Natives Waiting for Relief at Bangalore," as originally captioned in the Illustrated London News (1877).