A team of researchers from Germany and Switzerland discovered samples of microbial life from more than 3 billion years ago that are believed to have survived by hiding in subsurface cavities in order to evade UV radiation, according to a news release.
Life on Earth is believed to have come into existence approximately three and a half to four billion years ago in a period of time referred to as the Archaean aeon. During this time period, there was no ozone layer, meaning UV radiation was not filtered out. There was also no oxygen present in the Earth's atmosphere, meaning microbes likely survived in sheltered areas.
The new research supports this idea as fossils discovered in South Africa's Baberton greenstone belt show signs of ancient microbial activity in the cavities of the area's tidal sediment, which were formed by air bubbles. These fossilized microbial cells, which have been dated 3.2 billion years old, were located under a microbial mat that was likely pushed to the surface by volcanic activity.
The team conducted bulk carbon and SEM analysis as well as Raman micro-spectroscopy on the fossilized remains, which determined that the microbes were shaped like rods, similar to the many that inhabit the Earth today. Furthermore, their uniform shape and control of their own diameter and length also reflects the characteristics of modern microbes.
To date, all fossils found in South Africa's Baberton greenstone belt have been approximately 500 million years younger than currently known fossils, making the new findings some of the earliest forms of life found.
It is interesting to note that during the time period when life was first forming on Earth, environmental characteristics of the planet were much like those seen on Mars today, making these sorts of findings key to understanding the best ways to search for life on the Red planet.
The findings were published in the Dec. 4 issue of Geology.
