Quote (Caedus @ Mar 12 2012 11:22am)
It has to be after Humans appeared because they would have no explanation for why all the aliens were speaking English when they didn't even know humanity existed...
Except they don't all speak English, what you hear is the translator. Shepard makes reference to this translator when speaking to Thane. Tali constantly uses phrases that don't translate.
There's also evidence of a universal language called galactic, a language recognized by all races for trading, which is what you're actually hearing in the game. Shepard asks someone to repeat what they said in galatic.