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The first humans originated in Africa's Great Rift Valley, a large lowland area caused by tectonic plate movement that includes parts of present-day Ethiopia, Kenya and Tanzania. Human …

Scientists can infer the early use of language from the fact that humans traversed large swaths of land, established settlements, created tools, traded, and instituted social hierarchies and cultures.

Investigating how early humans evolved and lived helps us answer these questions. Most people give our big brains all the credit, but that’s only part of the story.

Review the immune system, its functions, and how it protects the human body from pathogens in this high school biology resource.

Learn about the cells and functions of the immune system.

About 25,000 years ago, our human ancestors began making their way up into the interior of the Eurasian steppe and then crossing what was either an iced-over land bridge or using tiny …

Every day we are alive, humans encounter potentially harmful disease causing organisms, or “pathogens”, like bacteria or viruses. Yet most of us are still able to function properly and live …

Khan Academy ... Khan Academy

Why didn't the first farms, the first cities, and the first empires emerge in sub-Saharan Africa, where our ancestors had roamed for hundreds of thousands of years?