Biology

Human Population

Big Picture

The human population is one of the most fast growing and dispersive populations on the planet. However, 200,000 years ago there were not many Homo sapiens. This is because the human population grows exponentially. Our transition into such an inflluential species can be described by demographic transition, which has four stages. Depending on the wealth and power of a nation, countries can be categorized by which stage they are in.

Key Terms

Demographic Transition: Changes in population that occurred in Europe and North America around the 18th century.

Human Population Growth

Homo sapiens, the scientific name for humans, were the first nomadic hunters and gatherers that arose about 200,000 years ago in Africa.

  • Initially, both birth and death rates were fairly high, so population growth was slow.

Past Population Growth

The demographic transition describes major changes in human population. Demographic transition can be described in in four stages.

  • Stage 1: High birth rates and death rates create a slow population growth.
  • Stage 2: Death rates decrease but birth rates remain high, leading to a faster population growth.
  • Stage 3: The birth rates begin to decrease, and the population growth slows.
  • Stage 4: The birth rate reaches the same level as the death rate, and the population growth slows to zero.
Image Credit: NikNaks93, Public Domain
demographic  transition
Figure: A graph showing the stages of demographic
transition.

These major changes in human population growth began in the 18th century in Europe and North America. Death rates first fell, followed by birth rates.

  • Death rates fall
  • New knowledge from the Scientific Revolution in the 18th century led to improved hygiene, water supplies, and hospitals.
  • Food production grew because of the Agricultural Revolution.
  • The Industrial Revolution led to new sources of energy, which increased production and transportation of food.
  • Birth rates fall
  • As machines began to do more work, farming families no longer needed as many children to work in the fields.
  • Laws were passed requiring children to attend school.

Notes

Human Population cont.

Biology

Population Growth

Recent Population Growth

Stage 1

All countries have passed through stage 1 of demographic transition.

Stage 1
Stage 2

Many undeveloped and poor nations are stuck in stage 2 of demographic transition, where there is a high birth rate.

Stage 2
Stage 3

Third world countries are those generally stuck in stage 3 of demographic transition, where the birth rates are decreasing.

Stage 3
Stage 4

Most developed nations are in stage 4. Belgium is an example of a country in stage 4 because their birth rates have been low for a long period of time. Therefore, the rate of population growth is reaching zero.

Stage 4
Stage 5

In some countries, birth rates have dropped even lower than death rates, forming the new Stage 5 in demographic transitions. This causes the population growth to become negative.

Stage 5
Image Credit: NikNaks93, Public Domain

Future Population Growth

It has been predicted that by 2050, there will be 9 billion people on planet earth.

Potential solutions:
  • Use technology and better use resources to support more people.
  • Change bad human habits of overusing to help control how much we consume.
  • Distribute resources more equally among the world’s people.