Earth is the origin of Mankind, it has held them since hundreds of millions of years ago. It has changed alot, it's most rural settlements became Megacities in mere years. After Man landed on the Moon, the population was around 4 Billion, in less than 40 years it rose to around 7 Billion. Mankind's natural ability to reproduce so much in such a short amount of time helped them populate worlds up 2 Billion people in less than 200 years. Earth has seen many wars, most of them over pointless squabbles, including action during World Wars 1, 2, and 3. After Humans left Earth for a chance of Luna, Mars, and The Jovian Moons, Earths population was at a relieving level, 2.3 Billion. It previous level was around 10.6 Billion. When the other worlds and moons were populated completely, Earth's population went up at a slower rate until it reached 5 Billion in 2187. They were warned of a population spike and they started developing colony ships with Space Bender FTL technology, they were all ready by 2198. They were sent off to various worlds, which when they landed had population of 6 Million, within 300 years they had up to 4 Billion people. This went on and on until almost every world within 20 Lightyears of Earth had been colonized. There are now over 30 Human Colonies with over 1 Billion Population Level.