Historians have estimated that planet Earth could provide to human hunter-gatherers enough food for a maximum of thirty million individuals. In the four million years which required the evolution from “homo erectus” to modern man, that number could not be overcome. Possibly the total population of the Paleolithic period varies between six and ten million human beings.
The Neolithic revolution, lasted ten thousand years, evolved through the application of techniques and farming methods that allowed the first great expansion of the specie; It is estimated that from then the population began to grow at a rate that doubled its population every thousand and seven hundred years. At the beginning of our era has been calculated that a few hundred million people lived on earth: a third part in the Roman Empire, another third in the Chinese Empire and the rest disseminated around the world.
The crisis of the Roman Empire was accompanied by the first major epidemics that caused depopulation. In 1348 the Black Death expands throughout Europe, which is estimated reduced the European population by a third. Despite this, towards the year 1600 the Earth had reached the half a billion inhabitants. Thereafter the population explosion occurs and the population begins to duplicate every two hundred years. In 1800, two years after the publication of the “first essay on the principle of population” of T.R. Malthus, the nine hundred million inhabitants are reached. The pace continues to accelerate; in 1900 are reached the 1.6 billion; in 1960 there were three billion. In mid-1999 the 6,000 million above and beyond.
You can check how many people are on Earth right now on this link and see the rhythm the population is increasing. If this level of reproduction it is kept too much longer, in the year 2600 there will be no space left on Earth for another human to stand on. Because the number of people would be around 630.000.000.000… crazy numbers that confirm we need to change our way of living.
Fortunately the fertility rate is decreasing around the world and although the population will continue to increase due to the access to a longer life expectancy and a longer fertile age, much more numerous generations age. So, the continuation of current trends predict that world population will reach stability in the year 2110, when 10.529 million people will live on Earth. But until then the situation of world demographic imbalance will inevitably continue its deterioration.