Malthus

Thomas Malthus was a scholar who, back in the 19th century, dedicated some of his time into thinking about population growth and decrease. Some of his ideas, known as the core principles of Malthus, are:food is necessary for human existence;

Human population, if not checked, tends to grow faster than the Earth’s capacity to produce subsistence;

the effects of these two unequal powers must be kept equal;

misery is the mechanism that balances human requirements and available resources;

Nature's requirement that the imbalance between demand and supply be resolved forms the "strongest obstacle in the way of any very great improvement of society," and thus makes "the perfectibility of man and society" a theoretical and practical impossibility;

The Principle of Population, i.e., the inevitability of misery due to the power of a population to overwhelm resources, provides the mainspring behind the advance of human civilization by creating incentives for progress.

For those that have a lazy brain, let me translate this into a picture:

Essentially, a population can’t grow without resources. A bit like this:

This last picture represents bacterial growth. In optimal conditions, as long as bacteria have resources available (aka nutrients) they tend to grow exponentially. After some time, the resources start to be depleted, toxic metabolic biproducts also accumulate in the medium, and growth slows down, eventually stabilizing (the number of dividing bacteria equals the number of dying ones). Inevitably, unless new nutrients are added, death follows.

Y, you may ask, am I writing all of this? Simple. The trend of bacterial growth is easily applied to Human population growth. This isn’t new, this is something that any biologist learns. Unfortunately, this knowledge isn’t given in every school, to every kid. Nor do the kids search for this kind of knowledge. And so, Humans go about their lives thinking that they have a great and sustainable way of life and that they can keep this up indefinitely, without thinking of potential consequences.

Can someone live without knowing the basic and essential biological principles? Yes. But that makes life so much harder for those that follow.