Life expectancy
Life expectancy is the number of years the average person in a population lives. For most of human history life expectancy was somewhere around 35-40 years. This does not mean that almost nobody lived to the age of 50, this is an average number. In other words, very high rates of infant mortality (children who die before their 1st birthday) balanced out the people who lived until 70 or 80.
Today, life expectancy world wide is over 70 years, and over 80 in developed countries such as Japan, the US and Western European countries. What has changed? In the 1800s a French scientist called Lois Pasteur created the Germ Theory of Disease, which said that many diseases are caused by micro-organisms such as bacteria and viruses. This understanding lead to modern medicine, in particular vaccines which protect against viruses and antibiotics which allow people to have surgery without getting bacterial infections.
Infant mortality rate and population growth
It is probably not surprising to learn that in places where the infant mortality rate is higher, the average number of children women have is also higher. Very simply if you want 2 children but you expect half of your children not to reach their 1st birthday, it makes sense to have 4 children. However, in reality people are not so calculating. What usually happens is that as the infant mortality rate decreases, people continue to have large numbers of children, causing population growth. Only when the infant mortality rate drops below 5% people start having on average 2 children. This has now happened in most of the world, except Sub-Saharan Africa (Africa south of the Sahara desert). This is why some people argue that the only way to stop the world population growing out of control is to improve healthcare in Sub-Saharan Africa to reduce the infant mortality rate.
Aging populations
In countries other than Sub-Saharan Africa, in particular in developed countries, the birth rate has already dropped. For the first time in history we have a large number of people living past their 70th birthday, without an increasing number of children being born. This leads to a new problem. The ratio between the working population and the retired population is changing, meaning more people needing healthcare but fewer people to care for them, and more people receiving pensions but fewer people paying taxes. In Europe and America these problems have been offset by immigration, although this has upset some people in the pre-existing population. In Asian countries like Japan, China and South Korea however, levels of immigration are not high enough to compensate for the declining birth-rates.
Lesson 12 Reading
Article 12a - Singapore
Article 12b - Canada
Article 12c - Malaysia
Article 12d - China
Article 12e - South Korea
Article 12f - EXTRA - world
Life expectancy is the number of years the average person in a population lives. For most of human history life expectancy was somewhere around 35-40 years. This does not mean that almost nobody lived to the age of 50, this is an average number. In other words, very high rates of infant mortality (children who die before their 1st birthday) balanced out the people who lived until 70 or 80.
Today, life expectancy world wide is over 70 years, and over 80 in developed countries such as Japan, the US and Western European countries. What has changed? In the 1800s a French scientist called Lois Pasteur created the Germ Theory of Disease, which said that many diseases are caused by micro-organisms such as bacteria and viruses. This understanding lead to modern medicine, in particular vaccines which protect against viruses and antibiotics which allow people to have surgery without getting bacterial infections.
Infant mortality rate and population growth
It is probably not surprising to learn that in places where the infant mortality rate is higher, the average number of children women have is also higher. Very simply if you want 2 children but you expect half of your children not to reach their 1st birthday, it makes sense to have 4 children. However, in reality people are not so calculating. What usually happens is that as the infant mortality rate decreases, people continue to have large numbers of children, causing population growth. Only when the infant mortality rate drops below 5% people start having on average 2 children. This has now happened in most of the world, except Sub-Saharan Africa (Africa south of the Sahara desert). This is why some people argue that the only way to stop the world population growing out of control is to improve healthcare in Sub-Saharan Africa to reduce the infant mortality rate.Aging populations
In countries other than Sub-Saharan Africa, in particular in developed countries, the birth rate has already dropped. For the first time in history we have a large number of people living past their 70th birthday, without an increasing number of children being born. This leads to a new problem. The ratio between the working population and the retired population is changing, meaning more people needing healthcare but fewer people to care for them, and more people receiving pensions but fewer people paying taxes. In Europe and America these problems have been offset by immigration, although this has upset some people in the pre-existing population. In Asian countries like Japan, China and South Korea however, levels of immigration are not high enough to compensate for the declining birth-rates.
Lesson 12 Reading
Article 12a - Singapore
Article 12b - Canada
Article 12c - Malaysia
Article 12d - China
Article 12e - South Korea
Article 12f - EXTRA - world
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