For the vast majority of human history, the world had a population of less than 1 billion. If you look at the world population by century during this time, you will notice that while the population trend steadily increases, there are noticeable reversals.
This is due to the fact that significant events had a huge impact on the lower overall world population. For instance, the Black Death in the 14th century and other subsequent plagues had a huge negative impact.
Other significant events include the collapse of political entities that stabilized entire regions. Examples of this include when the Western Roman empire fell (3rd-5th centuries), and the transition from the Ming to Quing dynasties in China (17th century).
With the loss of stability and order these political entities provided, famines, warfare, and disease were rampant.
Despite this, the world population has steadily trended upwards since the 1400’s. See the next section for a chart showing the World Population by Century.
World Population by Century
Hundreds of thousands of years of human history passed before the population reached 1 billion in roughly 1804.
It took just over another hundred years for the world population to gain another billion (estimated in 1927). From there, due to the rapid advances in science, technology, and public health (among others) the world population grew rapidly. 3 billion was reached in 1960; 4 billion in 1974.
Even the deadly World War II and other wars of the early to mid 20th did not have an impact on these figures.
7 billion was surpassed in 2011, with the current world population estimated to be at roughly 7.8 billion.
While the global population is still expanding, it is estimated that the growth rate will begin to decline in the next several decades due to a variety of factors.
Birth rates in developed countries have been steadily declining. There is also the question of the capacity of the earth to be able to support and feed an ever burgeoning population. These are questions we currently do not have answers to.
2024 will be the next year to watch as that is current prediction for when the word surpasses a population of 8 billion. Until then, we will have to wait and see if the current trends continue.
Source: Our World in Data