Sulfur analysis supports timing of oxygen’s appearance

Rice University News & Media reports thatScientists have long thought oxygen appeared in Earth’s lower atmosphere 2.7 billion years ago, making life as we know it possible. A Rice University researcher has added evidence to support that number.

The sulfur record held by ancient rocks marks the dramatic change in the planet’s atmosphere that gave rise to complex life, but rocks are local indicators. For the big picture, Rice biogeochemistMark Torresused water that flows over and erodes the rocks as a proxy.