... Volcanic Rock Discovery Calls Theories About Life's Origins Into Question Yasmin Tayag Inverse ... But on Thursday, the scientists behind a study soon to be published in Nature report that oxygen in the atmosphere didn’t rise to significant levels until after complex life arose — suggesting that oxygen wasn’t all that important after all. ... said study co-author Daniel Stolper, Ph.D., an assistant professor of Earth and planetary science at the University of California, Berkeley, in a statement. https://www.yahoo.com/news/volcanic-rock-discovery-calls-theories-195900920.html Though all present-day life on Earth requires oxygen to survive, the sea and sky were not oxygen-rich when life first emerged. One of the world's oldest fossil animals is Dickinsonia, which lived in the oceans 550 million years ago.