Malthus’ “principle of population” states that eventually, population growth will exceed the capacity of agricultural production, which will lead to widespread starvation and suffering. Over the years, many detractors have proposed various arguments in opposition to Malthus’ theories. Two of the most prominent arguments are that a) population growth will slow due to the availability of contraception and the desire of governments to limit growth and b) technological innovation can lead to dramatic improvements in agricultural production, which allow it to keep up with the growth in population.

A population pyramid is used to show the percentage of the population who fit into various age groups. If a population pyramid is rectangular, that means the bottom section (where babies are represented), the middle section (where working adults are represented), and the top section (where older people who are often retired are represented) are roughly similar sizes. This generally means the population of a country is close to steady, but is possibly growing slightly. A country like Norway or the United Kingdom would have a rectangular population pyramid.

The stationary population level (SPL) is the level at which a population cannot grow any more.

In highly developed countries like the United States the natural increase rate is generally very low, it might even be negative. But, the natural increase rate only reflects the changes in population caused by births and deaths; it does not consider immigration and emigration. Much of the population growth in the United States is driven by immigration and the fact that newly arrived immigrants are much more likely to have large families.

Quinary economic activities are sometimes considered as a subset of quaternary economic activities. Other times, they are considered to be an independent group of economic activity. Quinary economics are separate from quaternary because they use collaborative research projects, data analysis, and scientific inquiry designed to improve policy-making of governments and decision-making of corporations. It is an extremely modern branch of economic activity and one that is still being defined.

Quinary economic activities are sometimes considered as a subset of quaternary economic activities. Other times, they are considered to be an independent group of economic activity. Quinary economics are separate from quaternary because they use collaborative research projects, data analysis, and scientific inquiry designed to improve policy-making of governments and decision-making of corporations. It is an extremely modern branch of economic activity and one that is still being defined.

All of these countries are in either stage two or stage three (the transitional stages) of the demographic transition model, except Japan, which is in stage four. Stage four is generally considered the final stage of the demographic transition model. In stage four, the birth rates and the death rates are both low and generally steady. In Japan, the death rate is very low and the birth rate is very low, leading to a steady population and perhaps even a slight population decline.

Gentrification describes urban renewal that leads to the displacement of the occupying demographic. It is commonly associated with rising property values in previously low-income urban areas, which may force current residents to move away.

Walt Whitman Rostow's 1960 model of stages of economic growth describes how societies become modern, industrial economies over five separate stages. The "take-off" stage, which is the third step, describes the moment when societies move toward full industrialization in certain specific ways, such as technological innovations, urbanization, production of secondary goods such as textiles, and intense growth in specific sectors.

An Essay on the Principle of Population, published at the end of the eighteenth century, was written by Thomas Malthus. In this essay, Malthus argues that the rate of food production grows arithmetically, whereas population grows exponentially. Malthus argued that this would lead to a situation where population outstrips food production, leading to widespread famine and starvation. His writings are extremely influential even to this day; however, many geographers dispute his conclusions and argue that technology augments food production, allowing it to keep up with population growth. It remains to be seen whether Malthus’ predictions will come true in the twenty-first century or beyond.