We have found the oldest life on Earth, and it is Australian. A team of researchers from Down Under have found signs of "complex microbial ecosystems" in rock formations from the Pilbara region in Western Australia dating back 3.5 billion years, the Guardian reports. The discovery "pushes back evidence of life on Earth by a few more million years," author David Wacey says. Previously, the team had found life forms dating back 3.45 billion years, or about 50 million years younger than this find.
When those microbes were alive, most of Earth was covered in water, and cells with nucleoli—much less organisms with multiple cells—were still a long way off. Microbes would arrange themselves into complex communities, with bacteria that needed light, for example, moving to the top. The finding is exciting even beyond its age, Wacey explains, because "these kinds of ecosystems could be viewed by a rover, such as the one visiting Mars. … We would know that there was life at some point on another planet."