The Malthusian trap is a theory originally proposed by economist Thomas Robert Malthus in the late 18th century. Malthus suggested that improvements in technology would inevitably lead to an increase in population that would put increasing strain on resources. This would lead to no change in quality of life, or a decrease in quality of life, as a result of those technological developments. He believed it was not possible to make social progress that would improve living standards and incomes, as any steps in that direction would just create more people and more social pressures.
Malthus wrote at an interesting period in history, when human societies were in the throes of rapid change. The Industrial Revolution was about to burst onto the world and prove Malthus wrong, in some senses. Malthus believed that increased population created a labor glut, driving wages down even as people competed for food and other supplies to drive cost up. One consequence of the Industrial Revolution was actually a decrease in cost for many goods because they were cheaper to produce.
The theory of the Malthusian trap relied heavily on means of production that tended to be highly individualized and demanded manual labor. Malthus wrote in an era when farming, for example, was done by hand and with animals. The development of mechanized tractors and other farming equipment enabled rapid and cheap food production in many regions of the world and led to a rise in the standard of living for many people.
Retrospectively, the Malthusian trap may apply to some historic human societies. Many cultures that Malthus would have studied as part of his training did enter a form of Malthusian trap, where technology improved, but few people benefited. Growing human populations also put tremendous strain on available resources and contributed to hardship among the lower classes. In some cases this led to situations like wars over resource scarcity as citizens competed for limited supplies even as their numbers grew.
Even in the Industrial Revolution, with its great social benefits, some members of society still experienced hardships that often seemed more extreme in contrast with the greatly improved standard of living available to other people. However, some benefits of this era applied to all; the Industrial Revolution brought about reliable supplies of clean water, for instance, and vast improvements in medical treatment. It seemed to disprove the Malthusian trap by showing that it was possible for technological advances to create social improvements.