Scientists: Soil-Based Life in Earth May Be Significantly Older
New studies on microfossils of ancient landscapes in Australia may open new horizons in understanding nature with the help of advanced imaging and analysis techniques.
A team from the University of Oregon reported that the soil on the planet was "alive" way before the evolution of trees. This is from a close examination of microfossils in northwestern Australia.
According to Science Daily, UO paleontologist Gregory Retallack said a closer look at the dusty salt minerals of rocks from Australia suggests they had to have experienced evaporation on land. This deviates from the marine origin commonly associated with the 3,000-million-year-old rocks.
He added other mineral and chemical tracers in the rocks indicated they may have been weathered in soils of the distant geological past. He concluded that life was not only present but "thriving" in soils of the planet about third-thirds of the way back to its formation. The origin of the solar system occurred some 4.6 billion years ago.
The study outlines a microbiome of at least five kinds of microfossils recognized from size, shape, and composition. The largest and the most unique are spindle-shaped hollow structures of mold-like actinobacteria, which is still mainly a terrestrial group of decomposers responsible for the earthy smell of soil.
Other sphere-shaped fossils are similar to purple sulfur bacteria. These photosynthesize organic compounds in the absence of oxygen while leaving abundant sulfate minerals in the soil.
Retallack explained that the cell densities of over 1,000 per square millimeter and a diversity of "consumers and producers" indicate that the microfossils represent a "functioning ecosystem." He added that this evidence was critical to the cycles of carbon, sulfur, nitrogen, and phosphorus early in the planet.
The study is potentially controversial because a lot of scientists have pointed to stromatolites -- a life-form from 3.7 billion years ago -- and other marine life as evidence that life evolved in the sea and found their way in rock formations.