Human Population: the Past and Present

VICTORIA BOEREMA

INTRO

The current population of the world is 7.5 billions
Humans have the ability to develop habits and move into climate zones that were never lived into before
Carrying Capacity: this is the maximum size that a population can be in an environment, given that the things necessary for living are in that environment
People have gotten rid of some things that were limiting population growth
The earth’s natural resources are under stress
- However, God is protecting; there will always be some source of resources; God will always provide
There needs to be a way that we can learn to manage the earth’s population growth and make it so that there are enough resources for everyone and so that everyone has access to these resources
The human population isn’t spread out evenly over the surface of the Earth
Some area’s of the earth are very dense while others’ populations are declining
This chapter is about the effect the changing human population has on the natural environment and how we can lessen this effect
Ecological Footprint: a measure of the resources needed and the pollution that is created to be suitable for humans’ needs

A BRIEF HISTORY OF HUMAN POPULATION GROWTH

Density-dependent environmental factors: environmental variables that have an effect on a population in some sort of way; for example,how accessible water, food, and shelter are
In the past 200 years the population of the world has grown exponentially
Demographers: people who study the populations of humans, and the characteristics of their populations
Demographers have found 4 ways that people have avoided factors that limit the growth of population size and keep a population from fluctuating
Density-dependent regulating factors:factors that limit the growth of population size and keep a population from fluctuating

People have expanded their/our geographic range
- Geographic Range: the area which people are found in
- By doing this people got rid of most of the competition to find space
- This was able to happen because people overcame limiting factors by knowing how to make fire, making shelter, clothing, and tools, and learning survival skills
  - And these were passed on through the generations

2. The carrying capacity in many areas increased

This is because of the shift from the culture of hunting and gathering to agriculture
People learned how to plant and harvest and how to domesticate animals in order to have food and make work
This caused the amount of food supplies available to increase which also caused the carrying capacity and the rate of population growth to increase

3. People learned how to get energy from fossil fuels

In countries that were industrialized the amount of food supplies and the carrying capacity increased by the 20th century
- This was mostly because of synthetic fertilized, pesticides, also because of new transportation methods and the distribution of food

4. Public health became better which make the effects of some limiting factors smaller; factors like malnutrition, contagious diseases, and bad hygiene

Some of these advances in public health were made many years ago, in ancient Rome, for example, there were around 1 million people. These people did so well because of the way they distributed food, there was fresh water, and the way the dealt with human waste.
In the last 200 years technology and social services have advanced to lead to a huge increase in population growth.
Things like proper plumbing, food handling, and medicine have bigger effects on populations than one might think.

PEOPLE AND PATHOGENS: DISEASES ON THE RISE

Pathogen: something that causes a disease
When people started to live in big, permanent communities there were effects
- This made is easier for diseases to be spread. Even a simple pathogen can cause an epidemic.
Epidemic: spreading of a disease outside of a small population or a region
Animal domestication helped with the spread of diseases because diseases spread from the animals to the people.
- Diseases rose in areas where the populations were more dense and there was more animal domestication.
- China, South East Asia, North Africa, and Europe went through some of the worst epidemics ever. These people were able to develop resistance to these diseases, but when they moved to other parts of the world they accidentally infected others
- The Black Death is an example of disease being spread from animals to people, aka. the bubonic plague. The Black Death caused millions of people around the world to die.
When explorers came from around the world they exposed the aboriginals to diseases that were new to them and the diseases spread fast. An example of this is smallpox in the 1800's. This diseases brought huge tragedies and great loss in communities. Despite this, the human population to grow because of industrialization, agriculture, and technology.

Want to learn more about the Black Death and the effect it had on the human population? Watch the video below:

HUMAN DEMOGRAPHICS

2000 CE: Worldwide annual growth of human population was 1.26%
- Experts expect this to decline but the population is said to be over 9 billion by 2050
The growth rates in countries vary from 1% to 3% or more
- Industrialized countries (e.g. in Western Europe) have reached a population growth of almost 0%
- At the same time countries like ones in Africa and Asia will have big population increases in the next 20-25 years

Example: The map above shows the rate of population growth worldwide in 2013.

AGE STRUCTURE

Population pyramid: a graph/diagram that shows how the ages of males and femlaes are distributed in a population
Difference in ages can have huge effects on growth rates

Example: This population pyramid shows the population distribution of Nunavut is 2011. It is showing that Nunavut is experiencing varying and different growth rates at different ages.

POPULATION GROWTH AND ECONOMIC DEVELOPMENT

Demographic transition model: a diagram that shows changes in how people live to explain shifts in population sizes
There has been a lot of study on the relationship between population growth and economic development
- The more people there are, the more competition there is for resources and also there would be more people who need to be cared for, causing a lower income per capita, and a lower standard of living in comparison to countries that have a lower birth rate
- This relationship is called demographic transition model, but we do not know if it accurately shows the future for developing countries
Today in countries that are in the industrial stages, for example the USA, Canada, and Australia, the growths rates are slowly decreasing. In some countries the birth rates are even lower than death rates, so the populations are decreasing.
- Countries that are developing have fast population growth because their death rates are decline without the birth rate going down

PLANNED REPRODUCTION

Most governments have realized that large population size can cause depletion of resources, pollution, and a decline in quality of life
- In order to make the population smaller, either the birth rate must decrease or the death rate must increase
- Some countries even support reproductive alternatives to lower the birth rate
Replacement rate: the rate that people have children to replace them when they die
In order to have a population increase to be zero the average replacement rate needs to be a little bit higher than 2 children for each couple
- In less industrialized countries the the replacement rate is around 2.5 while in more industrialized countries it averages to be 2.1
What are reproductive alternatives?
- This could be as simple as a woman waiting to have children because this delay could reduce family size
- This could also help slow down population growth

REFERENCES

Douglas Fraser , Barrry Le Drew, Angela Vavitsas, and Meredith White-McMahon (2012). Biology 12. University Preparation. Canada: Nelson