Lost Worlds: Aliens from Earth?

Was there a technologically advanced species living on Earth long before humans? And if one had existed, how would we know? This is the first episode of our new four-part series, Lost Worlds. For more, go to http://vox.com/unexplainable It’s a great place to view show transcripts and read more about the topics on our show. Also, email us! unexplainable@vox.com We read every email. Support Unexplainable by making a financial contribution to Vox! bit.ly/givepodcasts Learn more about your ad choices. Visit podcastchoices.com/adchoices Learn more about your ad choices. Visit podcastchoices.com/adchoices