The young Earth supported little multicellular life until its atmosphere acquired a healthy portion of oxygen. That change has been credited to the rise of cyanobacteria, known as blue-green algae, that produce oxygen by photosynthesis. Now, scientists argue that oxygen couldn’t have built up in the atmosphere until a crucial geological mechanism kicked in and set the scene for the rise of more-complex forms of life.
Log in
Subscribers, enter your e-mail address for full access to the Science News archives and digital editions.