Thomas Malthus published his influential theory of population growth in 1798, proposing that human populations grow geometrically while the food supply grows arithmetically, inevitably leading to famine unless checks on population occur. Malthus suggested "positive checks" like famine and disease and "negative checks" like delayed marriage that reduce birth rates. While controversial, his theory inspired Darwin's concept of the struggle for survival and examined the relationship between population and resources. Malthusian catastrophe predicts population will be forced to return to subsistence levels once it outstrips agricultural production. His theory remains debated but influenced later thinkers exploring limits to economic and population growth.