I haven't seen this show, but it sounds very interesting.
I saw a different show a few months ago (narrated by Morgan Freeman) and one episode was about when/how life might have began on earth. (For those that believe in evolution).
Scientists have collected particles left behind from comets that have contained amino acids, which make up protein. They have theories which suggest life on this planet could have been brought here from elsewhere in space. They also think it's possible that life could have been brought here from Mars in the form of space dust.
Of course there's no way to actually prove any of this yet, but they are some very interesting ideas.