The relationship between population growth and economic growth is of great interest both for demographers and for development economists. Thomas Robert Malthus, the English political economist who first raised concerns about world population two centuries ago, claimed that population growth has a negative effect on well-being. His theory was simple: given that there is a fixed quantity of land, population growth will eventually reduce the amount of resources that each individual can consume, because the increase of population will take place in a geometric progression, while food supply will increase arithmetically. At the time, he was misunderstood and heavily criticised by critics. What Malthus got wrong was his failure to anticipate the "technological revolution"—technologies to use the land, water and other limited resources more efficiently that would raise agricultural productivity to meet the need of the increased population. However, today many believe that Malthus will be proved right.

When Bangladesh gained independence in 1971, the population was around 71 million. Seeing this large population, the then government recognised population growth as the foremost national problem of the country. During the 1970s and early 1980s, a very successful family planning campaign was carried out by government agencies and supported by non-government organisations (NGOs) with slogans like "a small family is a happy family", "boy or girl, two children are enough", "not more than two children, one is better" etc, proliferated in different media outlets, conveying a message regarding the benefits of small families. As a result, fertility rate fell substantially, from 6.3 children per woman in 1975 to 2.04 children per woman in 2018. Even though the country has taken control of population growth and has achieved considerable success in reducing fertility, it is still adding approximately two million people to its population every year.

At present, the country has more than 167 million people, but strangely, the topic of "overpopulation" or "population explosion" receives little attention. Moreover, some quarters in our country tend to see this large population as an economic asset. There is no denying the fact that the population of a country is the greatest social capital a nation can have, but unchecked population growth can be detrimental to economic development. Some empirical studies have found that an unchecked rising population comes with several economic and social challenges. It diminishes the availability of capital per head by limiting access to food, housing, sanitation, healthcare, education and employment, which in turn reduces the productivity of its labour force. It often has devastating effects on the environment as well.

Different research suggests that overpopulation coupled with high population density is a primary reason for degradation of natural resources, depleting both ecosystems and environment. In an area of roughly 148,460 square kilometres, Bangladesh is one of the most densely populated countries in the world. High population density has contributed to the intense use of forests, fisheries and to a certain extent, even soil and water resources. According to a report prepared by the Global Forest Watch, 278,000 acres of forest land in Bangladesh was destroyed from 2001 to 2018. This constitutes almost eight percent of the country's forest land. Recent statistics show that forest area as percent of land area is 10 percent in 2017, but according to the global forest policy, it should be at least 25 percent of the total land area of a country.

Bangladesh was once known as the land of the rivers, but today these rivers are dying slowly, mainly because of the pollution caused by human intervention. As per a survey of the Bangladesh Water Development Board (BWDB), there are 310 rivers in Bangladesh. Out of these rivers, the condition of 175 is miserable, and 65 are almost dead. Eighty percent of the rivers lack proper depth. However, by citing these statistics, I am not trying to put the entire blame of environmental degradation in Bangladesh on population growth alone, because much of it resulted from market and policy failures also.

The interconnections between population health and the economy are well known. Without a healthy population, there can be no healthy economy. While Bangladesh has met, for the second time, all the three eligibility criteria for LDC graduation involving income per capita, human assets, and economic and environmental vulnerability, 29.5 percent of the population still lives in poverty, with one in every seven persons suffering from undernourishment, according to the 2019 Global Hunger Index (GHI). In another report prepared by the Cabinet Division of the Government of Bangladesh and World Food Programme (WFP), one in eight, or more than 21 million people, cannot afford a nutritious diet in Bangladesh. According to the Food and Agricultural Organization (FAO), nearly two-thirds of the regular diet includes mostly rice, some vegetables, a little amount of pulses and small quantities of fish if and when available. Bangladesh is also lagging behind in providing appropriate nutrients to infants and young children—most suffer from high rates of micronutrient deficiencies, particularly vitamin A, iron, iodine and zinc deficiency. This scenario becomes more worrisome when we see, over the last decade, the number of undernourished people has risen by almost a million—from 23.85 million between 2004-06 to 24.2 million in 2018. It is a proven fact that a healthy and well-nourished population will perform better in economic activities than an unhealthy one.

Research shows that the Bangladesh population is likely to grow between 230-240 million by 2050. Such a large population will be demanding more food, water, energy and space in the future. The country is already struggling to meet current demand to house the existing population, let alone house any additional persons. Each year, Bangladesh loses a vast tract of agricultural land due to the extreme pressure of population. A report on the loss of agricultural land based on a study carried out by the Soil Resource Development Institute (SRDI) indicated that nearly 69,000 hectares of agricultural land have been shrinking annually due to rapid industrialisation, unplanned urbanisation and increase in rural settlements. Such a situation is putting the country's food security at risk. The report also predicted that there will be no cultivable land left in Bangladesh in 50 years if land is taken away for non-farm purposes at the current annual rate.

We cannot deny that overpopulation is one of the biggest challenges the country is facing and it has a significant impact on many of our socio-economic problems; yet, it is often left out of the conversation. Therefore, the sooner we acknowledge the scale of the problem and deal with the challenge, the greater the benefits will be in economic, environmental and social terms. And those who often take pride in the "demographic dividend" that overpopulation has bestowed upon us need to understand that demographic dividends are not automatic. To realise the dividends, we need to turn this huge population into human capital by investing much more in education, health and nutrition, and ensure good employment opportunities so that they can participate in the overall development of the country. On the other hand, if we fail, they can become a threat to stability and turn into a "demographic burden". There is a wide range of plausible futures, and which one happens depends to a great extent on decisions and actions taken today. Nothing is preordained.

Abu Afsarul Haider is an entrepreneur. He studied economics and business administration at the Illinois State University, USA.

Email: afsarulhaider@gmail.com