World population

The world population is the total number of humans living on Earth at any given time. This number is a key part of demography, which is the study of how populations change. On November 15, 2022, the United Nations estimated that the human population exceeded 8 billion people. By 2026, that number had risen to approximately 8.3 billion.

Understanding these numbers helps us see how human history has changed. It took roughly 300,000 years of human existence to reach the first one billion people. However, it took only 218 more years to go from one billion to 8 billion.

For much of prehistory, human population patterns were very different. Before 9000 BC, most humans were hunter-gatherers. They lived in small bands and relied on hunting animals or gathering wild seeds and nuts. This way of life was often unstable. If animal supplies dwindled, humans faced starvation. Because they had not yet domesticated animals, they could not easily control their food supply.

One very rough estimate suggests that about 8 million hunters lived around 9000 BC.

A massive change occurred during the agricultural revolutions in the eastern hemisphere. Around 9000 BC, some groups in the Middle East began to domesticate and graze sheep. Cultivating plants also began independently in different parts of the world. In the Middle East and Europe, people grew wheat between 6500 and 3500 BC. In Southeast Asia, rice cultivation began around 6800 BC. In Central America and Peru, corn was grown starting about 2500 BC.

This new technology allowed for a steady food supply that could be stored for a year or more. This minimized the risk of famine and allowed the population to grow.

Agriculture changed the structure of human society. Farming required systematic human exertion and more workers. Because every new person could help plant and harvest, children became very valuable in these societies. People also built irrigation systems to provide stable water for crops. These systems were used in places like Egypt, Mesopotamia, India, China, Peru, and Mexico. These agricultural practices allowed people to live in permanent villages and eventually form large states.

However, growth was often slowed by high death rates, especially among infants and children.

History shows that the population has not always grown steadily. Large-scale events have caused significant declines. For example, the Plague of Justinian caused Europe's population to drop by about 50% between the 6th and 8th centuries AD. Later, the Black Death pandemic hit in the 14th century. Between 1340 and 1400, the global population fell from about 443 million to between 350 and 375 million. In China, the population dropped from 123 million in 1200 to 65 million in 1393 due to Mongol invasions, famine, and plague.

These events show how vulnerable large groups of people can be to disease and conflict.

Modern history has seen much faster growth due to changes in medicine and food. During the Industrial Revolution, life expectancy for children increased. In London, the percentage of children dying before age five dropped from 74.5% in the mid-1700s to 31.8% by the early 1800s. The introduction of new crops also helped. In the 16th century, Portuguese and Spanish colonists brought new crops from the Americas to Asia and Europe. Maize and cassava became staple foods in Africa after being introduced by Portuguese traders.

These improvements helped the population grow much more quickly than in previous centuries.

Today, the way the population grows is shifting again. The highest growth rates occurred between 1955 and 1975, peaking at 2.1% per year between 1965 and 1970. Now, the growth rate is declining. The UN Department of Economics and Social Affairs projects the population will reach 9 to 10 billion by 2050. They also suggest the population could reach between 10 and 12 billion by the end of the 21st century.

However, some demographers believe the population may actually begin to decline in the second half of the century if fertility rates continue to fall. The global median age as of 2026 was 31.1 years.