Earth, like most other bodies in the Solar System, formed about 4.5 billion years ago from gas and dust in the early Solar System. The formation of the ocean and the subsequent development of life occurred during the first
billion years of Earth's history. Life spread globally and has been altering Earth's atmosphere and surface, leading to the Great Oxidation Event two billion years ago. Humans emerged 300,000 years ago in Africa and have spread across every continent on Earth. Humans depend on Earth's The Modern English word Earth developed, via Middle English, from an Old English noun most often spelled eorðe.[23] It has cognates in every Germanic language, f