POPULATION...

Biologist Robert W. Kates emphasizes that historically
there have actually been three waves of population explosions,
all of them coinciding with the introduction of new technology and science.
 
The first population explosion began about a million years ago
with the discovering of tool making, triggering the an increase
in world population from a few hundred thousand individuals to 5 million.
 
The second revolution which started about 10,000 years ago,
came with the discovery of agriculture and the domestication
of animals and plants.
 
This time, the population grew a hundredfold, to about 500 million.
 
The third population explosion started several hundred years ago with
the industrial revolution
and raise the world population to 1 billion by 1800.
 
 
1 billion 1800 (de 500 millones a 1000 millones
transcurrieron unos once o doce mil años)
2 billion 1930 (1930 - 1800 = 130 años)
3 billion 1960 (1960 - 1930 = 30 años)
4 billion 1974 (1974 - 1960 = 14 años)
5 billion 1987 (1987 - 1974 = 13 años)
6 billion 1999 (1999 - 1987 = 12 años)
7 billion 2011 (2011 - 1999 = 12 años)
 
Proyectado:
 
8 billion 2025 (2025 - 2011 = 14 años)
9 billion 2041 (2041 - 2025 = 16 años)
10 billion 2071 (2071 - 2041 = 30 años)
...
 
Michio Kaku, Visions - How Science will Revolutionalize the 21st Century
Anchor Books Doubleday (New York, 1999)