Environmental Engineering Reference
In-Depth Information
For most of human history, the total population has been relatively small. In 1804, the human population was 1
billion; today, it's more than 6.9 billion. Many changes in human society worked together to create the dramatic
increase in world population in just over 200 years.
The initial human population is thought to have been stable at approximately 1 million because, at that time,
humans were mainly hunters and gatherers, a lifestyle that ensured a low population. With the agricultural re-
volution about 10,000 years ago, humans began to transition from hunting and gathering food to growing their
own food. Studies have shown that in seven or eight locations around the world, agriculture developed inde-
pendently. The nomadic human society of hunters and gatherers was changed into a sedentary society, which
led to the development of villages and small towns. As societies grew and developed, they altered the lands
they used to grow their crops, and they selected crops that would increase production, longevity, and other be-
neficial features. The availability of more food and access to it year-round helped push the population to nearly
a billion at the beginning of the Industrial Revolution. By far, the larger populations were in agriculturally de-
veloped countries compared to societies that continued to hunt and gather.
As harvests began to supply a surplus, fewer people had to grow crops, which led to specialization of tasks,
such as the development of the blacksmith, baker, shoemaker, and many more trades. The development of the
arts and music as we know them today can be credited to the specialization brought about by the changes in so-
ciety during the agricultural revolution.
A look through human history shows many periods of dramatic decline in human population. These declines
can be attributed to more densely populated societies living in villages and towns. Diseases spread easily and
were more difficult to isolate with higher numbers of people living closely together. One notable period in
world and European history was the Black Death pandemic of the 14th century, when the estimated world pop-
ulation of 450 million was reduced to between 350 million and 375 million. Approximately 200 years passed
before Europe regained its 1300 population level.
At the beginning of the Industrial Revolution, the human population began to climb. One cause was a drop in
infant mortality rates from roughly 75 percent in the 1730s to 32 percent in the 1820s. Then, in the later 1800s,
with the development of an understanding of the transmission of diseases and improvements in medical prac-
tices, dental care, and food pasteurization, a dramatic reduction in death rates affected all age levels. The popu-
lation of the world began to grow rapidly. The following table shows the historic human population from 1804
to the present with estimates for the future as well.
Based on a 2010 list maintained by the United Nations (UN), the world has 230 countries, 38 of which are
identified as developed. The remaining countries are considered to be developing. The ten most populated
countries include China, with the greatest population; India, close behind at number two; and the United States,
a distant third. Of the ten countries with the largest populations, only three—the United States, Russia, and
Japan—are completely developed. China is fast becoming a developed country.
The world growth rate is 1.17 percent, but many of the poorest countries have rates higher than 2 percent.
Fifty-two countries have a growth rate higher than 2 percent. Seventy-five countries are experiencing a growth
