Overpopulation can occur in any species, but in this post I will only discuss human overpopulation. In fact, overpopulation is more worrying in non-human species because of their inability to use artificial birth control or their awareness of the problem. Every species has a limit to how many individuals can exist because their food supply is limited by the species they eat. If their food supply is limited, such as restrictions on land, water, pests or other restrictions, then the number of individuals is limited. Animals will just breed until their carrying capacity is met and then subsequent members of their species will just die.


Humans can become aware of the problem, but realising the problem exists is not always straightforward. Each population has a carrying capacity and that’s where the main area of disagreement exists.

Growing Food to Eat

Obviously the first thing to come to mind is that we must have enough resources to grow enough food and water to survive. That sets the absolute upper limit on how many humans the world can sustain.

This is not just about having enough land and water to grow enough food to survive. We also need to have enough other resources to produce food. Some land needs to be dedicated to factories to process the food and we need to lock away vast tracts of land in reservoirs to store the water we need for irrigation. We need oil to power farm machinery, transport goods and to make fertilisers.

We also need to protect our farms from pests and extreme weather conditions. So the total number of humans we can feed is actually quite limited.

Quality of Life

Another example of the carrying capacity limit is in the food types we eat. We throw away so much usable food and what’s thrown away needs to be included in what’s grown too. Also certain crops are more efficient at turning resources into food. Eating meat is the most resource intensive way to make food. The human carrying capacity depends on what we choose to eat.

Just surviving is not all there is to life. We have other activities which require us to use our natural resources. For example, if we are to have land to ride trail bikes and other recreational activities, we are usually taking land that could otherwise be used for farming. We also need land for factories, ports and airports. While we could do without these things, it’s important to take them into consideration when looking at the number of humans we can sustain.

Overpopulation is not a simple problem and there is more to it than meets the eye. We need to consider many factors and maintaining a high quality of life is important. After all, there is no point in bringing more people into the world if they are going to live in misery.

Everyone needs to start raising awareness on overpopulation because I think that’s one thing that while become a concern in the future. We want to sustain our quality of life, so please think before breeding.

Dr Holly Haviland