There’s been a lot of theories popping up over the last few years that mankind might not be the only intelligent species to walk the face of the Earth in its long history. It’s hard to prove it without actually going back in time and it does seem very unlikely, but we need to keep our mind open to the possibility if we ever want to find the proof. The most commonly known theory in this regard is the Ancient Alien theory, that says that humanity was in a big part created and manipulated by aliens that shared their technology with us.
