Final answer:
Thomas Malthus connected human population growth with environmental degradation, proposing that population increases faster than food supply, leading to poverty and unsustainable conditions. His theory highlighted war, famine, and disease as limiting factors to population growth.
Step-by-step explanation:
Early in the 18th century, Thomas Malthus recognized the connection between human population growth and environmental degradation. In his work, An Essay on the Principle of Population, Malthus argued that human population was increasing at a geometric rate, whereas the food supply could only increase arithmetically. Thus, he believed that without sufficient food, poverty and other forms of environmental degradation were inevitable.
According to Malthusian theory, three factors, termed "positive checks," would limit human population growth once it exceeded the earth's carrying capacity. These factors were war, famine, and disease, all of which would increase mortality rates and help keep the population in check. Despite controversies and later disprovals of his predictions, the Malthusian perspective significantly influenced views on population and environmental sustainability at the time.
Malthus also highlighted the concept of 'preventive checks,' which would control population by reducing fertility rates through means such as birth control and celibacy.