Chapter 5. Chapter 5: Human Populations

What cultural and demographic factors influence population growth...

Why You Should Care

Development as it refers to nations is a process that includes shifts in the demographics of the nation, including a lowering of the total fertility rate and a shift in the age structure of the population to be more mature. The demographics of a country influence the standard of living for all. The age structure of a population relates directly to the social problems of that population: A very young population is likely to have more working-age individuals than jobs, and a mature population may have more people retired than working, which can overburden monetary and medical senior-care programs. Paying attention to the population structure in one’s own country will provide a forecast for issues that may be decades away.

Let’s do the math: There are a lot of different numbers involved in talking about population growth, but what do they all mean? Doing some calculations with the numbers will really help you learn the terms.

Percent Growth Rate

Percent growth rate of populations is the percent of the starting population that is added to it over the course of a certain period of time. That period is usually a year, as it is in the table from Infographic 5.3. So, by knowing the percent growth rate, you can determine how many people will be added each year to a given population.

EXAMPLE: The world annual percent growth rate is currently 1.2%. That doesn’t sound like much, does it? But the current world population is 7 billion people, so how many people are being added to the world population each year?

7 billion = 7,000,000,000 1.2% = 1.2/100 = 0.012 7,000,000,000 × 0.012 = 84,000,000

In other words, if we start with 7 billion people, the world’s population will increase by 84 million people in one year. That’s like adding the entire population of Germany or Vietnam to the planet each year! Clearly 1.2% is bigger than it first seems.

Question Sequence

1.

Now let’s compare developed and developing countries. Using the same method we used in the example, fill in the following table:

	Population Size	% Growth Rate	Number of People Added in One Year
Developed Countries	1.24 billion	0.17%
Developing Countries	5.76 billion	1.44%
Niger: an extreme example of a developing country	16 million	3.5%

999

Correct.

Try again. Remember that a billion is 1,000,000,000; a million is 1,000,000, and a percent is 1/100 or 0.01.

Incorrect.

2.

The percent population growth in developed countries is less than 15% of the world percent population growth rate. Can you explain the difference?

Family size is much smaller in developed countries. Typically, in industrialized countries, large families are somewhat of a financial liability, whereas in developing countries, large families can mean security for the parents in their later years.

3.

Take another look at Infographic 5.2 and find the size of the United States' population. How does 84 million people added worldwide per year compare to the U.S. population? Divide 84 million by the U.S. population to see what percentage of the U.S. population this is. Check your answer here (remember to enter the number in percent and round to the nearest whole number).

84 million is 27% of the U.S. population of 312 million.

Crude Birth Rate and Crude Death Rate

Both crude birth rate and crude death rate are typically listed in terms of number of individuals per 1,000 individuals per year. Expressing these rates per thousand instead of per hundred (percent) makes it easier to express them as whole numbers, and the rates per thousand are between 10 and 50 for most countries. So what does that mean?

EXAMPLE: The worldwide crude birth rate is 20.3 births per 1,000 people per year. If you want to find out how many births total that means, you can find out first how many thousands there are in the world population:

7 billion = 7 million thousands of people
Multiply 7 million thousands by 20.3 births per thousand per year, and you get 142.1 million births per year.

EXAMPLE: The worldwide crude death rate is 8 deaths per 1,000 people per year. This works out to 7 million thousands × 8 deaths per thousand, or 56 million deaths.

Make a Connection: 142 million births per year minus 56 million deaths per year is 86 million people added per year, which corresponds to the 84 million we calculated as the percent population growth rate multiplied by the world population.

Total Fertility Rate

The total fertility rate is the number of children a woman is likely to have in her lifetime. So, worldwide, the average woman is likely to have 2.6 children. You can’t have 0.6 of a child, so let’s say 2 to 3—more likely 3—children in her lifetime.

Infant Mortality Rate

The infant mortality rate is the number of children who die in their first year of life per 1,000 live births in that year. This is different from crude birth rates and crude death rates, which are the number of live births or deaths per 1,000 people. Let’s see how this works:

If you refer back to crude birth rate, we determined that currently there are 142.1 million live births each year because the crude birth rate was 20.3 births per 1,000 people for 7 billion people. Infant mortality is the number of infants who die per 1,000 live births. So, first we see how many thousands there are in 142.1 million: 142.1 million ÷ 1,000 = 0.1421 million, or 142,100 thousand.

142,100 thousand × 44 infant deaths per thousand = 6,252,400 infant deaths.

Recall from our discussion of crude death rates that there are 56 million deaths per year, so around 6.3 million of those 56 million deaths are infants.

Life Expectancy

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