• The Earth's estimated age is 4,600 million years.
  • The oldest acknowledged traces of life date back 3,000 million years.
  • The first land vertebrates left the ocean around 400 million years ago.
  • Dinosaurs started developing 200 million years ago,
  • and became extinct 65 million years ago.
  • The first mammals also appeared around 200 million years ago,
  • but they first started developing only after the extinction of the dinosaurs.
  • The first hominids appeared in Africa approximatively  4 million years ago.
  • Human beings have mastered fire for 0,5 million years..
  • Modern humans date back only to 0,04 million years ago.
  • They first started building megaliths 0,007 million years ago.
  • They first started writing 0,004 million years ago.
  • They invented the steam engine 0,0002 million years ago.