Prehistoric time line, geologic time scale, photos, facts, maps, and more from National Geographic. Humans have walked the Earth for 190,000 years, a mere blip in Earth's 4.5-billion-year history.

Scientists have made new discoveries about the origins of dinosaurs, suggesting they first emerged in dry, arid regions of ...

Narrator: Excuse me. Yes, you. Ever wondered what prehistoric Britain was like? Great! Well let’s start at the beginning.The ancestors of humans first appeared in Britain around 900,000 years ago.