You are here

Human Characteristics: What Does it Mean to be Human

Part of what it means to be human is how we became human. Over a long period of time, as early humans adapted to a changing world, they evolved certain characteristics that help define our species today.

This section of our website focuses on several human characteristics that evolved over the past 6 million years. As you explore the scientific evidence for these characteristics, you will discover that these traits did not emerge all at once or in any one species. There were important milestones along the way. For example, early humans began walking upright before they began making tools. A rapid increase in brain size occurred before early humans began using symbols to communicate. And all of these traits emerged before humans began domesticating plants and animals.

image of Australopithecus afarensis walking and leaving footprints

Walking Upright

The earliest humans climbed trees and walked on the ground. This flexibility helped them get around in diverse habitats and cope with changing climates.

Bone Harpoon, Katanda Zaire

Tools & Food

Early humans butchered large animals at least 2.6 million years ago. By at least 500,000 years ago, early humans made wooden spears and used them to kill large animals.


As early humans spread to different environments, they evolved body shapes that helped them survive in hot and cold climates. Changing diets also led to changes in body shape.

a fossil endocast from a Homo erectus skull


As early humans faced new environmental challenges and evolved bigger bodies, they evolved larger and more complex brains.

silhouette of mother holding a baby

Social Life

Sharing food, caring for infants, and building social networks helped our ancestors meet the daily challenges of their environments.

Assyrian Lapis Lazuli Cylinder Seal and Clay Impression

Language & Symbols

From pigments to printing presses, symbols changed the way humans lived and provided new ways to cope with an unpredictable world.

African woman sitting cross legged in front of world map with timeline indicator

Humans Change the World

Within just the past 12,000 years, our species, Homo sapiens, made the transition to producing food and changing our surroundings. We have been so successful that we have inadvertently created a turning point in the history of life on Earth.