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HUMAN POPULATION GROWTH
Until the domestication of cattle (8000 BC), there were less than 10 million people on earth.
--Caesar's time, 250 million
--early 1800s, 1 billion
--World population remained under 1 billion until the nature of disease was discovered.
--1923 2 billion
--1975 4 billion
--1994 5.6 billion
--2000 6.0 billion
--94 million babies are born each year; the world's population is increasing at 1.8% annually, at this rate the population will double in 40 years; 1/3 of the world's population is under 18
world’s population increases by 23 people every 5 seconds. This is a rate of increase of almost 400,000
a day and 145 million per year. In
1998, the population increase was equivalent to adding another
--As of 2003, there are more than 6.2 billion people living on the planet. By the year 2050, it is estimated that there will be 7.9 to 10.9 billion people. Currently, about 1.2 billion people—almost ¼ of the world’s population live on less than $1/day and are very vulnerable to disease and environmental changes.
In the year 2005, the estimated world population reached 6.5 billion people. The percentage of the world’s populations which inhabits less developed countries is growing and is currently estimated at 5.3 billion. Almost 4 billion people live in Asia (United Nations, 2005).
In 1950, the ten most populated countries on earth (in order) were China, India, the U.S., the Russian Federation, Japan, Indonesia, Germany, Brazil, the United Kingdom, Italy, and France. In the year 2005, the 11 most populated countries are China, India, the U.S., Indonesia, Brazil, Pakistan, the Russian Federation, Bangladesh, Nigeria, Japan, and Mexico. Given current rates of growth, it is estimated that the most populated counties in the year 2050 will be India, China, the U.S., Pakistan, Indonesia, Nigeria, Brazil, Bangladesh, Congo, Ethiopia, and Mexico (United Nations, 2005).
Currently, 1.8 billion people in the world are under the age of 15 (almost 1.1 billion of which live in Asia) (United Nations, 2005).
Some countries have a median age of more than 40 (Japan, Italy, Germany, Finland, Switzerland, Belgium, Croatia, Austria, Bulgaria, and Slovenia) while others have a median age of under 16 ½ (Uganda, Niger, Mali, Guinea-Bissau, Burkina Faso, Dem. Republic of Congo, Malawi, Chad, Congo, and Liberia) (United Nations, 2005).
A family size of 2.1 children per woman is considered replacement-level fertility. A higher level will increase overall population size while a lower level will decrease population size (United Nations, 2005).
Some countries have an average fertility of less than 1.3 children per woman ( Macao, Hong Kong, Ukraine, Czech Republic, Slovakia, Slovenia, Moldova, Bulgaria, Bealrus, Greece, Poland, and Latvia). In contrast, in other countries the total fertility can range between 6.7 and 7.9 (Dem. Republic of Congo, Angola, Liberia, Burundi, Mali, Uganda, Guinea-Bissau, Afghanistan, Timor-Leste, and Niger) (United Nations, 2005).
How many people can the earth hold? There are two factors which must be considered when determining the earth’s carrying capacity: the human population and the natural resources used per person. It is true that some developing nations are straining the earth’s capacity by having large families, For example, the family size estimated to be the “replacement fertility” (the family size in which births will balance deaths) is 2.1 children. There are dozens of African nations in which the average family size is more than 6. Population growth rates vary in different parts of the world. Developing countries tend to have the largest percentages of people in the youngest age groups; developed countries tend to have more even distributions. As a result, population doubling times also vary: North America 93 years, Latin America 33 years, Europe 266 years, USSR 80 years, Africa 24 years, South Asia 37 years, and Australia 57 years.
While the number of children is certainly
a factor in determining the earth’s carrying capacity, it must be considered
together with resource use. Small
families, especially in the
How many people can the earth hold? If all the people of the world adopted the American standard of living, there would already be far more people on earth than the planet could hold.
In the following images, each red dot represents a concentration of one million people or more.
|If the earth were a village of 1,000 people:|
--28 children will be born this year, 2 of which will die in their first year
--330 (one third) of the village are children and have not yet begun to reproduce
--10 people will die this year (including those two children)
-- as a result, next year the village contains 1018 people
|Number with Cars||70 (some of which have more than one)|
|Number with access to clean, safe drinking water||330 (One-third)|
|Number of adults which are illiterate||335 (of 670; half)|
|Average Salary per person in the village||$3000|
|Percentage of village budget received by top 20%||75% ($11,250 per person)|
|Percentage of village budget received by the bottom 20%||2% ($300 per person)|