Researchers from University College London have found that life appeared a very short time after the Earth formed. The authors of the study believe that this is potential evidence for the existence of extraterrestrial life. Discussions continue about the samples themselves.
The authors of a new study, published in the journal Science Advances, studied a rock found near Inukjuak in northern Quebec, Canada. It was estimated to be about 3.75 to 4.28 billion years old.
In an earlier article published in the journal Nature, researchers from University College London (UCL) suggested that the tiny threads, protrusions and tubes found in the rock were created by bacteria about 300 million years before the generally accepted date of the first signs of life on Earth.
At the time, some in the scientific community disagreed that the structures found inside the rock were of biological origin and therefore not a sign of early life.
So University College London staff re-examined the rock, which was once a piece of seafloor. Samples were collected by the study's lead author, Dr. Dominic Papineau, in 2008. Cutting the rock into sections the thickness of a regular paper sheet, the authors determined that its age ranges from 3.75 to 4.28 billion years - such a conclusion was made due to the presence of rare-earth elements in its composition. These elements were at the same level as other samples of ancient rocks of similar age.
Scientists used various microscopes and a supercomputer to create 3D models of the rock structures. They confirmed that the rock was undulating and contained organic carbon, a substance that is part of organic compounds. This characterizes bacteria that specialize in iron oxidation.
The researchers suggest that the bacteria inside the rock left behind mineralized chemical byproducts that correspond to the way ancient microbes fed on iron, sulfur, and possibly carbon dioxide.
The authors also used imaging, which allowed them to detect a centimeter-long stem with parallel branches on one side. Although some of the structures revealed in the rock may have been created by chemical reactions, the stem was likely of biological origin.
"So life could have originated just 300 million years after the formation of the Earth," Papineau noted. - "Geologically speaking, that's fast: about one revolution of the Sun around the center of the galaxy.
Prior to this discovery, the next oldest biological sample of early life was found in Australia, which is about 3.46 billion years old. Although some in the scientific community are also disputing these samples, again arguing that they may not be of biological origin.
The new rock sample should help us understand how life is formed and whether it can exist beyond Earth. "These findings have implications for the possibility of extraterrestrial life. If life emerges relatively quickly, under the right conditions, it increases the likelihood of life on other planets," Papineau concluded.