Thomas Robert Malthus

Malthus vs Boserup

Holly Story sizes up two theories of population growth

Humans, like members of all populations of plants and animals, are in competition with one another for the Earth’s resources. The global human population is growing at a rate of around 1.2 per cent per year, and as it does the competition for resources increases.

One of those resources is food. In high-income countries food supply is relatively secure; Britain has not experienced a widespread food shortage since the Second World War. But as demand for food increases, supplies come under greater pressure. In 2012 a drought in the USA caused a drop in the global production of maize, and the effects were felt around the world as the prices of staple foods such as bread increased. In the future will we be able to produce enough food to support the ever-increasing human population?

While this seems like a 21st-century problem, it is actually a question that has concerned economists for hundreds of years (and farmers since the first days of agriculture).

Malthus’s theory

In the 18th century an economist called Thomas Robert Malthus wrote an essay outlining his response to the problem. The work, entitled ‘An Essay on the Principle of Population’ (1798), set out Malthus’s theory of population growth: a theory of how and why the size of the population would change.

Malthus thought that if the human population continued to grow, food production would not be able to keep up with demand and there would not be enough food to go around. The result, he warned, would be a terrible famine that would kill many people.

In ecological terms, Malthus was arguing that the human population was at risk of outgrowing its carrying capacity (the number of individuals that can be supported by a specific habitat). There are examples of this happening to particular populations of animals and insects, such as the reindeer on St Matthew Island.

Malthus reasoned that this disastrous outcome could only be avoided if the population stopped growing. He described two types of ‘checks’ that could stop population growth: a negative check that would cause a drop in the birth rate (eg increased use of contraceptives) and a positive check that would increase the death rate (eg disease or war). These checks, he argued, were more likely to take effect as the population got closer to its carrying capacity, either because governments would take steps to stop the population getting any bigger or because of increased competition and hardship within the population. This, Malthus thought, was what would save us from large-scale starvation.

But the population has not stopped growing. Since Malthus’s lifetime the number of humans on the planet has continued to increase, and in 2011 the population reached 7 billion. According to Malthus’s theory, this should not have been possible. Where did he go wrong?

Malthus’s theory was based on the assumption that the population would grow exponentially (1, 2, 4, 8, 16, 32) whereas food production would grow linearly (1, 2, 3, 4, 5), much more slowly. At the time when he was writing the Industrial Revolution had not yet arrived, and without developments such as pesticides and fertilisers the amount of food that could be produced per acre of land was much smaller than it is today.

Over the 250 years since Malthus published his essay, advances in technology and innovations in farming methods have allowed food production to grow quickly enough that we can now, in theory at least, provide sufficient food for the world’s 7 billion inhabitants. Malthus did not account for these advances in his population theory, but another economist, Ester Boserup, did.

Boserup’s theory

Ester Boserup (1910–1999) was a Danish economist who specialised in the economics and development of agriculture. She worked for the United Nations and her experience working in low- and middle-income countries such as India helped to shape her theory of the relationship between human population growth and food production.

In her work ‘The Conditions of Agricultural Growth: The economics of agrarian change under population pressure’ (1965), Boserup challenged Malthus’s conclusion that the size of the human population is limited by the amount of food it can produce. She suggested that food production can, and will, increase to match the needs of the population.

Drawing on her knowledge of farming in the developing world, where populations were growing quickly, Boserup argued that the threat of starvation and the challenge of feeding more mouths motivates people to improve their farming methods and invent new technologies in order to produce more food.

Boserup described this change as ‘agricultural intensification’. For example, a farmer who has four fields to produce food for his family might grow crops in three of the fields, but leave the fourth field empty as the ground is dry and his crop will not grow there. However if the farmer has two more children, the pressure to produce more food might drive him to build irrigation canals to bring water to the fourth field or to buy a different type of seed that will grow in drier ground. He would change the way he farms to make sure that he has enough food to support a larger family.

Is there a limit?

Boserup’s theory seems to provide a model for continuous population growth, but there are those who argue that Malthus was right and that there is a limit to the amount of humans the planet can support.

As modern environmentalists, scientists and politicians debate the future of the world’s climate and resources, we must hope that Boserup was right to believe that human beings are capable of remarkable ingenuity in the face of a problem.

Lead image:

Wellcome Library, London CC BY

Questions for discussion

  • Can you find an example of an individual or a group that thinks Malthus was right? What are their arguments?
  • Food is not the only resource that we need to survive. Can you think of other resources that humans compete for? What would happen if they ran out?

Further reading

About this resource

This resource was first published in ‘Populations’ in June 2014.

Statistics and maths, History, Health, infection and disease
Education levels:
16–19, Continuing professional development