User blog comment:Nicola Polito/Mass Effect 3:Desperate Survival DLC/@comment-4826433-20120414220139/@comment-1679409-20120415000510

Not necessarily. In the real world, we humans immigrate to and travel to other countries all of the time. The armed forces of different countries will hold joint exercises. I would assume the same happens in the Mass Effect universe with different species. With Earth being the human homeworld, I would assume there may be diplomats, tourists, visiting armed forces members, business leaders, asari partnered to humans living on Earth, immigrants etc. from other species at Earth when it is attacked, trapping them there. Some of them could have decided to fight along side the humans.

Not to mention, the news stories indicate batarian refugees. While it may be questionable that such refugees, from humanity's nemesis, will be settled on Earth, it's possible.