HISTORY: Most likely, you're one of these, so we'll skip to the "present day" (approx.2522 A.D.). The Human race is homeless. After Muar destroyed Earth, they settles into the far end of the galxy (mostly on floting space stations, and large transport ships) until the floating planetoid of the Guardsmen was built for them by the dodlers. Once introduced into the Galactic Congress, the Humans volunteered to become the peacekeepers of the galaxy (as they had no previous alliances, and were politically nuetral). Not all humans join the guardsmen, however. They are given a choice to go or stay, and can decide any time between their 18th and 25th birthdays. About 70% of the Humans decide to become uardsmen in their adulthood.
FUN FACT: Humans arrived in the early years of the Galactic Congress, and it was decided that their language (English)was the most simplistic, and therefore would be used as the common tongue in the galaxy.