This is exciting news for anyone interested in what the Earth was like billions of years ago.
A team from the University of Western Australia and Oxford University claims to have found the world’s oldest fossils. The pieces they’ve discovered have evidence pointing to cells and bacteria that indicate they lived in a world free of oxygen some 3.4 billion years ago.
Volcanic activity took up the majority of the Earth’s surface during this time, creating a hot and violent place with a grey, cloudy sky that trapped heat in, regardless of the weaker levels of the sun. The oceans sat at a comfortable 40-50 degrees, much warmer than the icy water we’re hesitant to step in today, as well as much stronger currents. Land masses were tiny, rarely larger than the size of a small Caribbean island, with huge tidal ranges.
The reason there was so little oxygen is because plants and algae had yet to evolve, therefore there was no oxygen-producing life. Early life during this time was sulfur-based, using sulfur for growth and energy as opposed to oxygen.
According to the researchers, who published their findings in the journal Nature Geoscience, the bacteria found in these fossils are still common today, found in soil, hot springs, smelly ditches, and hydrothermal vents. Basically, anywhere with small amounts of oxygen that allow them to live off organic matter.
The fossil pieces were found in the Strelley Pool, a remote location in Western Australia. They were found between quarts sand grains of the oldest beach on Earth, containing some of the oldest rocks on earth. This all lines up with the fossils, dating back 3.4 billion years. They passed the test to prove they are biological and have not produced over time through a mineralization process, confirming they are authentic and true fossils.
Aside from determining just how long the Earth has existed, this gives additional motives for scientists to look for life on other planets, and shows what life may look like on planets where there is no oxygen. The researchers believe these microfossils would look similar to rocks found on other planets and their moons.
Image credit: David Wacey