Cities developed, empires grew and shrank. The Roman Empire collapsed, possibly under its own weight. Its excesses, such as indoor plumbing, disappeared. What I call the Green Ages ensued in Europe. It was a time of organic farming, local economies, and local government. People used renewable energy technologies of wind, water, and muscle power. Everyone believed Earth was the center of the Universe.
Earth kept the numbers of people at carrying capacity by periodic plagues and famines. Lack of transportation prevented food from being moved from places of plenty to places of want. The organic farms had to be large enough to grow fodder for the draft animals; local economies made money and banking unnecessary; and the local governments made sure all knew their place in the rigid social hierarchy. Constant raids by one local economy on another likewise kept human numbers down. It was a violent time with homicides up to a hundred times more frequent than at present in western Europe. Almost everyone was an illiterate peasant, living a short life in abject poverty.
In 1543 Nicolaus Copernicus showed Earth revolved around the sun. It took another century for this idea to become widely accepted, but Earth lost its place as the center of the Universe.
In the 18th century, people discovered coal could be used to fuel the new steam engines which allowed twenty pounds of coal to do as much work as a hundred horses could do in an hour. (Two hundred fifty years later Prophet Al Gore* predicted Earth would fry and drown because of fossil fuel use.) By the beginning of the 19th century, more technology had grown the number of humans to about a billion.
Prophet Malthus** warned that populations rise geometrically, but agricultural capacity rises arithmetically. People didn’t listen. Instead, they thought of new ways to increase agricultural capacity, such as how to fix nitrogen from the air for fertilizer. After the ravages of two World Wars in the 20th century, prosperity and population grew. Prophet Ehrlich*** reiterated Malthus’ warning, predicting famines everywhere in the 70s and 80s. People still didn’t listen.
By 2012 there were seven billion people on Earth. Part of the increase was due to the doubling of life expectancy since 1900. Better public health, medical care, and agricultural technology allowed many more people to live out their natural life span. The rate of population growth slowed as educated women pursued careers instead of motherhood.
By 2015, instead of almost everybody being abjectly poor, more than half the people in the world were healthier, richer, and longer lived beyond the imagination of the illiterate peasants who practiced Earth-centered living in the Green Ages.
* An Inconvenient Truth, 2006
** Essay on Population, 1798
*** The Population Bomb, 1968