Ocean vents were promising but a vital precursor isn't very abundent:-http://www.sciencedaily.com/releases/2014/04/140409094330.htm-"As for the search for the origins of life, Reeves agrees that hydrothermal vents are still a very favorable place for life to emerge, but, he says, "maybe methanethiol just wasn't a good starter dough. The hydrothermal environment is still a perfect place to support early life, and the question of how it all started is still open.'"