Doubing Time
Doubling time is the time required for a population to double if the current growth rate continues. To calculate the doubling time you simply divide 70 by the current growth rate of the country and that yields the number of years required for the double. The table on the next slide shows the growth rates and estimated doubling times for selected countries based on 2008 estimates. The world's population should double in 58 years. Liberia on the other hand should double its population in only 23 years.
From the 2008 World Population Data Sheet:
| Country or Region | Growth Rate | Doubling Time in Years |
|---|---|---|
| More developed | 0.2 | 350 |
| Less developed | 1.5 | 47 |
| Africa | 2.4 | 29 |
| Latin America/ Caribbean | 1.5 | 47 |
| Asia (excluding China) | 1.5 | 47 |
| China | 0.5 | 140 |
| Liberia | 3.1 | 23 |
| Canada | 0.3 | 233 |
| Mexico | 1.6 | 44 |
| United States | 0.6 | 116 |
| Italy | 0.00 | Can't Calculate |
| Japan | 0.00 | Can't Calculate |
| Word | 1.2 | 58 |
Most of the world's population that lives in the less developed regions of the world will double in about 47 years. There are approximately 68% of the 6.7 billion peoples of this world who now live in less developed countries. That is roughly 4.56 billion people living in less developed countries. In the year 2055 (2008 + 47 years = 2055) there should be 9.12 billion people living in the less developed regions of the world. The more developed regions of the world will not double in any of our lifetimes. It would be the year 2358 according to these data.
The more developed regions of the world will not double in any of our lifetimes. It would be the year 2358 according to these data. Zero population growth occurs when a population neither shrinks nor expands from year to year.
Based on other factors in the demographic equation, including death and migration, you can see various results. To understand why some countries have higher or lower rates, you must first understand some theoretical backgrounds. There are two distinct perspectives that relate to births in a population.
Antinatalist is a perspective which opposes childbearing. Antinatalists oppose birth, support contraceptive, abortions, and sterilization along with the education of women. Educating a woman is the most effective way of lowering her fertility.
Pronatalist is a perspective which promotes birth and increased population. Pronatalists support birth, large families, extended families, and the governmental support of childbearing.
The first antinatalist was Thomas Malthus (1766-1834). He was a Reverend and English scholar who took a strong stance against the unprepared parents of his day. To Malthus prepared parents had established their education and livelihood, their household, and their marriage before they considered getting pregnant.
Keep in mind that there were very few effective methods of birth control at this time, so Malthus came across as a hardliner against parenting. He published half a dozen editions of his work, An Essay on the Principles of Population (1798-1830). While his work was extremely controversial, it was carefully read by many influential people of his day.
For Malthus, the problem was that populations grew more rapidly than the production of food. To him, this was the cause of many social ills in the new industrial societies of Europe. He declared that no sex before marriage, forced sterilization, and criminal treatment of unprepared parents would be the new conservative norm.
Indeed history has shown that famines, wars, plagues, and other terrible conditions do occur. The antinatalists blame too many babies and people, too much destruction of the natural environment, the existence of the traditional family, and capitalistic profit-seeking at the cost of global well-being. A contemporary antinatalist named Paul Ehrlich wrote the book, The Population Bomb in 1968.
The environmental impact of population growth is complex, because it is based not only on population growth but also on affluence/consumption and technology. For example, the U.S. population is about one-fourth as large as that of China or India, but the United States currently uses far more energy. This is because Americans are more affluent and use their wealth to buy energy-intensive goods like cars and electronics. But China and India are growing and becoming more affluent, so their environmental impacts will increase because of both population size and consumption levels in the next several decades.
Neo-Malthusian is an antinatalist who agrees with Malthus, but rejects his conservative and religious proscriptions. Many of the governmental organizations in the world today are antinatalistic in theory but do not procribe to Malthus's strict rules and ideas.
The pronatalists point out that there is plenty of food in the world and always has been. They blame political and social mismanagement for social ills, not high birth rates. Look at the chart on the next slide to see the estimated world population from 10,000 BC to 2009 AD. Note: these are only estimated since there were very few government statistics prior to the industrial revolution.
There were millions and millions of people on the earth throughout the history of the world. Pronatalists argue that for the most part, civilizations ate, lived, and thrived – and still do today. When they starved it was typically some political or natural disaster factor not a Malthusian shortage that explained it. Besides, they argue, Malthus underestimated the enormous gains in medical, agricultural, environmental, political, and other sciences that have given this world the highest standard of living it has ever known.
Do you feel a bit confused? The truth is that there is ample evidence to support both antinatalist's and pronatalist's perspectives. The bottom line is that the World Health Organization, World Bank, United Nations, United States, and all of the other more developed nations of the world are somewhat Neo-Malthusian/Antinatalistic. The people of the less developed regions of the world live more of a pronatalist lifestyle and thereby are mainly responsible for the rapidly increasing growth of births into the world population.
Keep in mind that there are many cultural factors which impact why a society might have a high birth rate. Some are religious. For example, many countries with high Catholic populations have high birth rates because of the church’s stance against birth control. In the Hindu faith, it is traditional to have the oldest son light the funeral pyre of his parents. Given the low survival rates for infants in many Hindu countries, many people have large families to ensure at least one son will live to adulthood.
Other factors are simply economic. Some need large families to work in agriculture. In agricultural countries with high infant death rates, it does not make a lot of economic sense to limit the size of one's family. As you can see, the issue is complicated. In the next section, you will learn about infant mortality rates and the impact they can have on a culture.
