Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms.
Some geological evidence indicates that life may have arisen as much as 4.1 billion years ago.
Another convention capitalizes "Earth" when appearing as a name (e.g.
"Earth's atmosphere") but writes it in lowercase when preceded by the (e.g. It almost always appears in lowercase in colloquial expressions such as "what on earth are you doing? The formation and evolution of Solar System bodies occurred along with the Sun.
Humans have developed diverse societies and cultures; politically, the world has about 200 sovereign states.