"<a href=""https://www.youtube.com/watch?v=Gfr50f6ZBvo&amp;t=1h28m00s"">1:28:00</a> min. - Humanity as a technologically advance species has been retarded by the occasional", cyclical catastrophic event that essentially demands re-inventing the wheel, post each epoch. Aliens are present on the planet but recognize we have not yet evolved to a state warranting their presence, YET! If we don't blow ourselves up in the next decade, or there be a micro-nova, or whatever, maybe they'll finally come out and show themselves.