The main factors which affect population size and growth 

“Why Study Population Growth?”

    Population ecology is the study of how populations change over time and space and interact with their environment. Studying how and why populations grow helps scientists make better predictions about future changes in population sizes and growth rates. Scientists know that some salmon populations are declining, but do not necessarily know why. If scientists do not understand what is causing the declines, it is difficult for them to do anything about it.

And remember, learning what is probably not affecting a population can be as informative as learning what is.

    Studying population growth gives scientists insight into how organisms interact with each other and with perspective environments. This is especially meaningful when considering the potential impacts of climate change and other changes in environmental factors.

Another point is that studying population growth  has a great impact on adjusting the economic status of a particular state.

“What about Human Population Growth?”

        Human population surpassed six billion people in 1999, and is expected reach nine billion before 2050. Viewing population growth in different geographic regions shows that the human population is not growing the same everywhere. Economic, cultural, and social factors determine how the population grows, and the Earth's carrying capacity.

Population growth is the increase in the number of individuals in a population. Global human population growth amounts to around 83 million annually, or 1.1% per year.

         The “human growth rate” is the rate at which the number of individuals in a population increases in a given time period as a fraction of the initial population. Specifically, population growth rate refers to the change in population over a time period, often expressed as a percentage of the number of individuals in the population at the beginning of that period.

In conclusion, One of the major consequences of population growth is the potential for widespread food shortages.

Most scientists agree that humans and human population growth are causing climate change by emission of the greenhouse gas carbon dioxide (CO2).

 

Factors influencing population growth.

 Population growth

 The population size refers to the total number of people in the population. The number of people in a given region is referred to as population density. The size of the population is changing through time, which is referred to as population growth.

 Economic development.

Countries that are still in the early stages of economic development have higher population growth rates. Children are seen as prospective income earners in agrarian societies. They can assist with domestic activities and harvesting from an early age. In addition, in countries where state pensions are not available, parents frequently desire more children as a form of retirement security. It is assumed that children will look after their parents as they grow older. Because child mortality rates are generally higher, more children are needed to ensure that the parents have enough offspring to care for them in their old age.

 Education

Education is normally compulsory until the age of 16 in developed countries. Children are no longer economic assets, but rather economic costs when schooling becomes mandatory. In the United States, it is predicted that a child will cost around $230,000 by the time they graduate from college. As a result, the cost of raising children acts as a motivator to lower family size.

Quality of children

Gary Becker produced a paper in 1973 with H. Gregg Lewis which stated that parents choose the number of children based on a marginal cost and marginal benefit analysis. In developed countries with high rates of return from education, parents have an incentive to have a lower number of children and spend more on their education – to give their children not just standard education but a relatively better education than others. To be able to give children the best start in life, it necessitates smaller families. Becker noted rising real GDP per capita was generally consistent with smaller families.

Welfare payments/State pensions.

Couples do not need to have children to give effective retirement support when they are elderly, thanks to a large state pension program. Because children are seen as "insurance" to look after them in old life, family numbers in developing countries are larger. This is no longer necessary in modern society, and as a result, birth rates are declining.

Social and cultural factors.

India and China (before one family policy) had strong social attachments to having large families. In the developed world, smaller families are the norm.

v Availability of family planning.

Increased availability of contraception can enable women to limit family size closer to the desired level. In the developing world, the availability of contraception is more limited, and this can lead to unplanned pregnancies and more rapid population growth. In Africa in 2015, it was estimated that only 33% of women had access to contraception. Increasing rates would play a role in limiting population growth.

 

v Female labor market participation.

Female education and social mobility are frequently lower in emerging economies. Women in societies where women receive superior education are more likely to choose work above starting a family. In the industrialized world, women frequently choose to marry later and have children later (or not at all) in order to work and focus on their careers.

 

     

 Death rates

         Availability of medical services. Often, death rates fall before birth rates fall, resulting in a population boom at a specific time in a country's economic progress. Medical treatments improved rapidly throughout the nineteenth and early twentieth centuries, allowing many fatal diseases to be treated. Death rates have decreased, while life expectancy has climbed.

      Immigration levels

                     Some countries biggest drivers of population growth come from net migration. Traditionally, the foreign population in the Philippines consists of people of Chinese origin (some 80 percent of overseas Chinese are in Southeast Asia) and some people of Indian origin who came to settle in the country years ago. Presently, there are 36,150 foreign nationals working and residing in the Philippines. Countries like Japan with very strict immigration laws have seen a stagnation in the population.

  Historical factors/war.

                     In the post-war period, western countries saw a ‘boom’ in population, as couples reunited at the end of the Second World War began having families. The ‘baby-boomer’ period indicates population growth can be influenced by historical events and a combination of factors which caused a delay in having children until the war ended.

 Related

• GDP and development
• Harrod-Domar Growth model
• Does GDP measure economic development?
• Causes of economic growth