WORLD POPULATION SET TO REACH 8 BILLION MID-NOVEMBER 2022, 10 BILLION 2057 

Did you know that the first humans on Earth are said to have emerged from east Africa as far back as 2.8 million years ago, and that since 1800 the world's population has jumped eight-fold, from an estimated 1 billion to 8 billion people?

The oldest fossils from the earliest known humans date back 2.8 million years and were found in east Africa. But estimates of the number of people that populated the Earth remained highly unreliable until the 19th century. What we do know is that our ancestors were hunter-gatherers, who had few children compared to later settled populations in order to maintain their nomadic lifestyle.

The planet's population was sparse also partly because hunter-gatherers needed a lot of land to feed themselves – around 10 square kilometers per person, according to Herve Le Bras, a researcher at the French Institute for Demographic Studies (INED). The globe's population did increase over time but very, very slowly.

The introduction of agriculture in the Neolithic era, around 10,000 BCE, brought the first known major population leap. With agriculture came sedentarization and the ability to store food, which caused birth rates to soar... The development of permanent settlements also brought hazards, however, with the domestication of animals causing humans to contract new deadly diseases. 

Child mortality rates were particularly high, with a third of all children dying before their first birthday, and another third before they turned 18. From around 6 million in 10,000 BCE, the global population leapt to 100 million in 2000 BCE and then to 250 million in the first century CE, according to INED estimates.​

The Black Death brought the population to a sudden halt in the Middle Ages. The pandemic, which emerged in Central Asia, in what is modern-day Kyrgyzstan, reached Europe in 1346 on ships carrying goods from the Black Sea. In just eight years, it wiped out up to 60 percent of the populations of Europe, the Middle East, and North Africa.

As a result of the Black Death, the human population dropped between 1300 and 1400, from 429 to 374 million. Other events, like the Plague of Justinian, which hit the Mediterranean over two centuries from 541 to 767, and the wars of the early Middle Ages in western Europe, also caused temporary dips in the numbers of humans on Earth.

From the 19th century on, the population began to explode, due largely to the development of modern medicine and the industrialization of agriculture, which boosted global food supplies. Since 1800, the world's population has jumped eight-fold, from an estimated 1 billion to 8 billion. For Crubezy, an anthropologist at the University of Toulouse in France, the development of vaccines was key, with the smallpox jab particularly helping zap one of history's biggest killers.​ The 1970s and 1980s brought another small revolution, in the form of treatment for heart disease, which helped reduce mortality among over-60s.

World population is expected to reach 8 billion people on November 15, 2022 according to the United Nations (The previous estimate of 2023 was revised in 2022). Population in the world is, as of 2022, is growing at a rate of around 0.84% per year (down from 1.05% in 2020, 1.08% in 2019, 1.10% in 2018, and 1.12% in 2017). The current population increase is estimated at 67 million people per year.

Annual growth rate reached its peak in the late 1960s, when it was at around 2%. The rate of increase has nearly halved since then, and will continue to decline in the coming years. World population will therefore continue to grow in the 21st century, but at a much slower rate compared to the recent past. 

World population has doubled (100% increase) in 40 years from 1959 (3 billion) to 1999 (6 billion). It is now estimated that it will take another nearly 40 years to increase by another 50% to become 9 billion by 2037. The latest world population projections indicate that world population will reach 10 billion persons in the year 2057.

Sources:

https://www.sciencealert.com/earths-population-explodes-to-8-billion-humans-this-month

https://www.worldometers.info/world-population/