Many people believe that overpopulation is the greatest threat to the world's security and prosperity. It was probably Malthus who first pointed out that population growth is exponential, while agricultural growth is arithmetic. He reasoned that every population must inevitably outgrow its food source. Political instability and border insecurity naturally follow, when growing populations seek to nervously protect their shrinking resource base.
Critics of Malthus pointed out that human populations, unlike bacteria, do not grow exponentially; fertility rates vary geographically and over time. New economic models, including those that factor labour as capital, valued large populations as assets rather than detriments, allowing industrializing nations to convert population to production and therefore to wealth, allowing them to purchase needed resources.
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The predicted Malthusian collapse did not occur, due largely to improvements in agricultural sciences and something called the Demographic Transition. It's this latter thing that gives many demographers hope that the world's population growth might be slowing, soon to be plateauing, and eventually reversing.
The Demographic Transition was first proposed by Warren Thompson in the 1920s and is well described on BBC's educational site. From observing changes in Europe over the centuries, Thompson and his intellectual heirs suggested that societies evolve through five stages of demographic development.
In Stage 1, we live pre-industrial lives, dependent on the land and at the mercy of the elements. Diseases are plenty, lifespan is short. Infant mortality rates are very high, such that we don't even name our children until we are sure they will live beyond infancy. The cost of a child is simply the price of feeding that child, whereas its value as a labourer is high. Both death rates and birth rates are high, and the population is neither growing nor shrinking.
So many countries have entered Stage 3 that the human race is now a majority urban species.
In Stage 2, with the arrival of public health and hygiene measures, infectious diseases recede, and mortality declines, particularly among children. But the cost of children is still low, while their utility is high. Thus, reproduction behaviours remain unchanged. But overall population size increases dramatically. Many so-called developing countries would have been in Stage 2 in the late 19th and early 20th centuries, accounting for their explosive growth.
In Stage 3, social factors intervene to lower the birth rate. When infants survive and women are socially empowered, fertility rates drop. As economies shift from agrarian to industrial bases, more people move to cities. In fact, so many countries have entered Stage 3 that the human race is now a majority urban species.
The widespread introduction of contraception methods, and the use of new wealth to invest in public education (especially for women), leads to smaller families. The cost of children increases with housing and educational demands, while their utility diminishes, as they are no longer needed as labourers.
Thus, in Stage 3 population size is still increasing, but more slowly. Western Europe began emerging from Stage 3 in the 19th century. India and China, with their expanding middle class, are in the latter half of Stage 3 or beyond.
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In Stage 4, we transition to a services and information economy, with few economic incentives for reproduction. Birth and death rates are balanced, and there is minimal population growth.
Canada is likely a Stage 4 nation. Rapidly modernizing Stage 3 nations may be progressing to Stage 4 quickly. China is approaching a sort of demographic cliff, since a majority of its people are over the age of 30 and are having fewer children than their recent ancestors.
Some recognize a fifth stage in which birth rate drops below death rate, and the population shrinks. Japan is a Stage 5 country. Subsequent generations are too small to provide an adequate tax base for maintaining social programs. Immigration policies must be re-thought, and governments begin to experiment with strategies for encouraging larger families.
The Demographic Transition is a theoretical construct with some vulnerabilities. It is unclear whether deep religiosity can compel modernized generations to reproduce at rates against their economic self-interest, leading to what some call a "demographic trap."
Total world population should plateau at about 13 billion by 2100, and actually decline thereafter.
Also, it is possible that globalization is a disincentive for modernization, compelling some populations to remain agrarian or manufacturing-based, never to progress to an information-based economy. Climate change, antibiotic resistance, and the unpredictability of international affairs can confound a nation's linear progression through the stages.
However, given that the basic tenets of the Demographic Transition are being observed in real time in such living social laboratories as India, China, and parts of Africa, it is reasonable that the world is in the process of transitioning.
With investments in public health, reproductive rights, and wealth-building programs, we have seen dramatic recent reductions in the global fertility rate. Most of humanity is transitioning to Stage 4, which means that while total population size is still growing, growth is slowing down.
Human population growth is expected to drop to one per cent by 2020, though we are still on schedule to reach the 9 billion mark by 2050. Total world population should plateau at about 13 billion by 2100, and actually decline thereafter.
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Some projections, like that of the International Institute for Applied Systems Analysis in Austria, are more optimistic, suggesting that total fertility rate will drop below replacement rate in the 2070s, plateauing around the 9 billion mark.
It took wealthy nations like the United Kingdom a century for fertility rates to fall from over six babies per woman to fewer than three per woman. It took China and Iran a mere decade, because economic and human development initiatives are better understood and better targeted. There is every expectation that current nations with high fertility rates, like Niger and Somalia, can perform similarly.
Draconian measures driven by xenophobia are not necessary to slow the expansion of our numbers. Nor do we need pandemics, famines or wars to cull our numbers. So long as we continue to invest in education, public health, access to contraception and global trade, our numbers are likely to decline naturally and painlessly.
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The world’s second smallest country is also one of the richest, with more millionaires and billionaires per capita than any other country in the world. It also seems like a dream to give birth in Monaco: The antenatal and postpartum care sounds downright magical, and the country has some of the lowest infant mortality rates on earth. So what gives on the low birth rate, at just 6.72 births per 1,000 people? One theory is that the population is considerably older than the global median, which means lower fertility rates. Couple advanced age with the higher education typical of the people of Monaco, and you’re looking at fewer babies for this densely populated nation.
The declining birth rate in Japan, at 8.4 births per 1,000 people, is actually cause for alarm: The country’s population has dropped by nearly a million people over the past five years, when you compare the low birth rate with the high death rate. This is such an appalling stat that the Japanese government is taking measures to bolster their population in years to come, including major changes to their policies affecting women, children and seniors. Other reasons for the decline include the climbing cost of raising a family, the number of women in the workforce and the older average age of marriage.
Just 8.2 babies were born per 1,000 people over the past five years in this European nation, putting it neck and neck with Japan. Experts are conflicted as to why the birth rate is dropping, but myriad theories include more women focusing on career before family, the trend toward later-in-life childbearing, difficulty accessing child care, and confusing social policies as reasons for the downturn.
Declining birth rates are actually a concern across Asia but South Korea, with a birth rate of 8.55 births per 1,000 people and its steep decline of people under the age of 40, is in danger of becoming one of the oldest countries, population-wise, in the world. Like other countries, extreme work culture and more women in the labour force are to blame, but lack of immigration is also a factor. Other countries can supplement low birth rates with immigration, but South Korea is notoriously difficult when it comes to permitting naturalized citizens.
At just 8 births per 1,000 people, Italy is in a population collapse. There were just 488,000 births in the country in 2015, which is lower than any year since the modern state was founded in 1861. Officials are keeping close tabs on the situation and are offering up potential benefits for growing families. The policy changes include a baby bonus (which was not well-received, for its small amount and the limited number of kids it covers) and a national Fertility Day campaign urging young women to listen to their biological clocks, and young men to avoid smoking for the health of their sperm. Italy’s declining population can be chalked up to high unemployment numbers, lower wages for women, and inadequate childcare and social services.
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