According to some estimates, there were 4 million Earthlings 10,000 years ago, when agriculture appeared. And human population growth has been rather slow, reaching 190 million people 2,000 years ago.
For thousands of years, the birth rate was generally higher than today, but there have been significant fluctuations in the number of humans on the planet, depending on epidemics, wars and famines or other disasters, but a small increase.
However, suddenly, the demographic curve experienced an ascent with the industrial revolution that began in the West in the 19e century: in just over 100 years, the world’s population has grown from one billion in 1800 to two billion in 1927.
Several factors have contributed to the reduction in mortality and therefore to this population growth, including the increase in the standard of living, health advances, medical discoveries – particularly antibiotics –, the construction of collective hygiene infrastructures such as sewers and the explosion of agricultural production capacity or goods and services.
Subsequently, the size of the population increased from three billion people to six billion in just 40 years, from 1960 to 1999 – with differences in growth according to the regions of the world. From the year 2000 to today, it has grown by two billion people, to reach eight billion in total.
If it was first in the West that the first phase of what is called the “demographic transition” occurred in the 19e century, i.e. the reduction in mortality, it also first experienced the second phase of this transition, i.e. the decline in fertility, so much so that most of the more recent growth takes place in Asia and in the countries of the South , which began their first phase following the Second World War.
