It took humanity 200,000 years to surpass the one-billion-inhabitants mark, then barely 200 years to reach seven billion. Several factors fueled this extraordinary explosion, including the Industrial Revolution, the development of more robust transportation methods, and the discovery of antibiotics. If you want more detail on humanity's demographic evolution, this excellent video is for you.
A Slow Start, Then the First Explosion
As we have mentioned on previous occasions, the anatomically modern human appeared 200,000 years ago. After spreading across the African continent (or at least those habitable regions), humanity moved to Europe and Asia, although the "exit point" is still a matter of debate (some say Egypt, others Ethiopia). The population stayed relatively low (one million inhabitants on average), but around 10,000 BC the first demographic explosion took place, courtesy of agriculture and its later improvements. By the year 0, there were 170 million humans in the world.
What the Museum's Video Shows
However, our story was only just beginning, and that is exactly what the American Museum of Natural History teaches us in this excellent video. Despite the influence of powers such as the Roman Empire, the Han Dynasty, and the Maya Civilization, the human population gained only seven million inhabitants in 600 years. The video also mentions the birth of Islam, the smallpox scourge in Japan, and the creation of gunpowder. Humanity crossed the year 1000 with 255 million people, accelerating steadily until the mid-14th century, when the bubonic plague left Europe in check. Somehow the population recovered, "modern" explorers discovered America, and the transatlantic slave trade began.
Toward a Future of 11 Billion
From the year 1700, demographic growth took off. The Industrial Revolution and advances in medicine allowed humanity to enter the 19th century with more than a billion inhabitants, and not even the two world wars of the 20th century had enough impact to reduce the growth. Quite the opposite: with the end of World War II came the famous "baby boom", which in the United States registered 65 million births in 16 years. Current projections indicate that humanity will end the century with 11 billion inhabitants. From there, everything depends on the fertility rate, which by the way is declining around the globe. There is a chance we never reach those 11 billion if the most pessimistic assessments come true... or end up well above if the error goes in the opposite direction.
