Population Growth

Human beings are always found in groups, which compete for resources found in a given area, to sustain their lives. Such groups of individuals are termed as population. Moreover, no individual will ever exist in isolation at any given time. 

Individuals from different groups also potentially interbreed among themselves to increase their number. This is known as population growth,  a phenomenon that is becoming a growing problem nowadays. 

The following article discusses the concept of Population Growth and Explosion in detail, covering the various characteristics associated with them as well as their causes.

What is Population Explosion? 

The increase in the number of individuals in a group, above a certain level is called population explosion. Such an increase in the number of individuals is not a static process, and can change depending on the availability and scarcity of resources. It also depends upon environmental conditions like the weather and destructive natural calamities like floods, droughts, famines, earthquakes, amongst many others. 

These conditions can cause many individuals to get displaced.
Population explosion then, is an increase in the numbers of living organisms. 

Attributes of Population:  

(i)Natality – Also known as birth rate, it is the number of people born during a given period. An increased birth rate inturn causes the number of people in a population to grow. 

(ii) Mortality – The term mortality refers to the number of deaths in the population during a given time frame. It causes a decrease in the number of people in the population.  

(iii) Immigration – Immigration refers to the number of individuals of the same species, moving from one area to another during a particular period, causing the population to increase or grow.

(iv) Emigration – Emigration refers to the movement of population, leaving a locale and migrating to another area, resulting in a decrease in population and its growth.

The population in an area depends upon two factors:  

1. Additive factor  

2. Subtractive factor   

The additive factors include natality or birth rate, and immigration. Whereas the subtractive factors are mortality or the death rate, and emigration   

On the basis of these factors, the formula to calculate population numbers is as follows:  

Nt+1 = N t + [(B + I) – (D + E)]  

Where:  

N t = number of people at time t  

Nt+1 = number of people at time (t+1) 

B = number of births  

D = Number of deaths  

I = Immigration rate 

E = Emigration rate  

Based on the growth factors, there are two types of models:  

1. Exponential growth 
2. Logistic growth  

Exponential Growth: 

For the population of a geographical location to grow, large amounts of resources that are ideally readily available becomes a predominant necessity. As such when resources and basic necessities in a habitat are unlimited, each species present there potentially interbreeds thereby increasing in density and number. In such a situation, the population grows exponentially or geometrically.  

This geometric progression signifies that the number of individuals increases by a factor of 2, which results in a greater number of offspring.  

Logistic Growth: 

In the absence of indefinite basic resources required for the population of any habitat, individuals cannot fulfil or utilise their full potential. The lack in turn leads to members of the same group to compete with themselves or other groups, to secure the required resources. This eventually results in the population being able to grow only till a certain limit. Such a phenomenon is called Logistic growth.
According to this model, there is acceleration and deceleration in the growth of a population until it reaches a constant. This constant is called asymptote.  

The formula to calculate logistic growth is as follows:  

dN/dt = r N (K – N / K)  

Where r = intrinsic rate of increase  

 K = Carrying capacity  

 N = Number of people initially in a population. 

Data of Population Explosion:  

• Until the 1800s, the world’s population growth was gradual. 
• In the 19th century, the world’s population growth reached the one billion mark. 
• The world’s population reached three billion in the 1970s. 
• Within 30 years, in 1999, the population rate doubled, reaching the six billion mark. 
• The global population growth rate is now one billion for every 15 years, and can be called a population explosion.  

Causes of Population Explosion : 

• High Birth rate: 

An increase in birth rate is the leading reason for the rapid growth of population. In India, although the birth rate has declined from 45.4 per thousand during the 19th century to about 25.5 per thousand in 2002, it is still considered to be substantially high. Despite proper family planning, population education and awareness, the birth rate is yet to be controlled.   

• Low Death Rate 

The phenomenal fall in the death rate in recent years is another important factor contributing to rapid growth of population. The death rate in India was about 8.7 per thousand in 2002.  Due to the increasing quality of medicines, health care facilities, and nutrition, there has been a decrease in the death rate. Moreover, with the development of better healthcare infrastructure, there has been a decrease in post-natal deaths. There is, in turn, a decrease in the infant and maternal mortality rate, further leading to a growing population.  

• Early Marriage 

The practice of early marriage is another major reason for the rapid rise of the growth rate in India. The age of marriage for girls is 18 years, which is considerably less than the other countries around the world, which is about 23 years. As a result, there is an increase in reproductive capacity.  

• Social and Religious reasons: 

In a joint family system, constant pressure from the family contributes to population explosion. People focus only upon the expansion of the family, with a desire to get a male child in most cases.  

•  Poverty: 

Poverty is another cause that causes population growth, since children are usually considered a source of income for the family. There is a lack of proper awareness and education. 

Conclusion:

This article gives a detailed study of the definition, terms, and causes of population explosion and growth. The purpose of this article was to provide you with detailed information and brief knowledge of  terms such as death rate, birth rate, as well as exponential and logistic growth.