Most of us are used to the current size of the human population but it was not always this large. In this lesson, we will explore the history of human population growth and the future of its growth.
Human Population Growth
How many people do you think the human population grows by each year? Maybe one million? Ten million? More? As of 2012, over 80 million people were added to the human population each year. To give you perspective, this would be equivalent to the populations of California, Texas and New York combined. On a shorter scale, we add 2.6 people to the population every second! This would mean that each day you could fill two large football stadiums with the number of people that were added to the human population.
As of 2013, the human population is around 7 billion people, and it has taken many years for the population to grow to this size. Over this long amount of time, some periods have had slow growth while others have had more rapid growth. Due to these fluctuations and how large the human population has become, scientists have begun to investigate the growth of the human population.
Demography is the study of the size, density and distribution of the human population. This area of study takes into account birth rates, death rates, age distribution and any other factors that influence the size and growth of a population. Demographers have identified three distinct periods of human population growth that help explain the history of how our population has changed.
The pre-agricultural period is the first period of human population growth. This period is considered anything before 10,000 years ago. During the pre-agricultural period, human population growth was very slow, and it took tens of thousands of years for the human population to double.
Although growth was slow, the population was able to increase due to the development of tools. As people developed more advanced tools, they were able to travel to new lands and use their skills to adapt. This made it possible for people to spread to new regions of the world and expand the coverage of the human population. When the pre-agricultural period ended around 10,000 years ago, the human population was estimated to be somewhere between five and ten million people.
The agricultural period is the second period of human population growth. This period ranges from 10,000 years ago to about 1,000 years ago. During this time period, the human population started to grow more rapidly due to advances in agriculture. It was during this time that plants and animals were domesticated for farming. There were also advances in irrigation and plowing techniques that increased overall crop yield. As a result of increased food availability and more nutritious food, the human population grew faster than ever.
Unlike during the pre-agricultural period, when it took tens of thousands of years for the human population to double, during the agricultural period, it only took around 1,000 years for it to double in size. At the end of the agricultural period, the human population had increased a great deal to around 500 million people.
The industrial period was the third period of human population growth. This period is from 1,000 years ago to current day and is characterized by advances in technology. Although there were advances in technology during the early part of this period, it wasn't until the Industrial Revolution in the 1800s that the advances in technology started to have a profound influence on the human population.
During this time period, there were technological advances in agricultural techniques that made it possible to grow crops on land that had previously been unusable. This resulted in another increase in the amount of food available, and therefore increased the number of humans that could survive. Technology was also used to improve medicine and sanitation, which helped save lives and increase the lifespan of the average person.
As a result of the technological advances of the industrial period, the human population grew at a rapid pace. Over the industrial period, the time it takes to double the population decreased a great deal. During the beginning of the period, it took around 500 years to double the population, but more recently, the number has decreased to 50 years to double. During the industrial period, the human population grew from 500 million people to the 7 billion people we now have on earth.
Human Population Carrying Capacity
Now that we have examined the history of the human population, what do you think the future holds? Will the human population continue to grow at the same rate, slower or stay stable? For most species, their population growth is controlled by their carrying capacity, which is the maximum population size of a species that an ecosystem can support indefinitely. For example, if a forest only has enough food to support 50 individuals of a species and the population grows larger, not all the individuals will survive. The population will decrease until it is at or under the carrying capacity, which is where there would be enough food for all individuals.
Although many people are interested or concerned about the future growth of the human population, unfortunately it is not possible to precisely determine the carrying capacity of humans on earth. Some scientists estimate that the world could support between 1-2 billion people if they are living prosperously and in a healthy environment. On the other hand, they also estimate that the world could support over 33 billion people if people are living in extreme poverty with very degraded environments.
There are many factors and characteristics about human life that make it difficult to determine how many people Earth can support, but the most powerful factor is technology. Humans have the intelligence to create technology that helps save lives, increase food availability, increase lifespan, and therefore challenge the carrying capacity. There were times in human history where there were mass starvations and some thought we had reached our carrying capacity. But, due to technology, we were able to combat the starvation by producing more food, and therefore helping the population continue to grow.
Now, let's review the history of human population growth and the human carrying capacity. Demography is the study of the size, density and distribution of the human population. This area of study has been used to determine three distinct periods of human population growth. The pre-agricultural period is the first period of human population growth and was characterized by the development of tools. With new tools and skills, humans were able to adapt to new environments and expand their range to new habitats, which resulted in a slow population increase to between 5-10 million people.
The agricultural period was the second period of human growth and was characterized by advances in agriculture. As a result of increased food production and healthy food, the human population grew more rapidly to around 500 million people. The industrial period was the third period of human population growth and was characterized by advances in technology. This period brought about technological advances in medicine, food production and sanitation that helped support a rapid increase in the human population to the nearly 7 billion people that now inhabit the earth.
Due to the rapid increase in the human population, many people wonder about the carrying capacity, which is the maximum population size of a species that an ecosystem can support indefinitely. Unlike other species, humans have been able to exceed their estimated carrying capacity due to technology. Human intelligence and advances in technology have made it possible for humans to find ways to support the population and ensure increase despite natural pressures to decrease the population. This might always be the case, or someday our population may become so large that the earth cannot support us all.
When this lesson has been completed, you could be able to:
- Understand the history of the world population
- Restate the three time periods that stand out
- Convey the fact that every species has a 'carrying capacity'