User blog comment:Sky-Dragoon-Twilight/Are the Wall Titans allies or enemies?/@comment-25107612-20140702142409/@comment-25244540-20140703182549

Wow... just wow. Your reasoning is one of the most unique and possibly even the most backed up I've seen. For one the first episode and chapter are both called "To You, 2000 Years From Now" which makes the older than 2000 years old civlization mention a very likely possibilty.

And then there was the chapter based off the original draft of the series which I recall mentioned the Titans were born due to some of humanity's experiments. Although going by the key Eren's father left him, its possible that the experiment was an accident or someone altered it to gain control of the world and Eren's father is from a line of people who are one of if not the only ones who know the truth.

If that's the case then the reason Eren's father asked him to reach the cellar most likely means its where this information is being kept, info that many don't want to reach the public. Whatever the truth is, the fact how the Beast Titan turned a whole village into Titans seems to hint that something 107 years ago something horrible happened that turned many humans into Titans either by accident... or intentionally.