Theoretical origin of life; ealiest possibly found (Introduction)

by David Turell , Wednesday, August 31, 2016, 22:53 (3006 days ago) @ David Turell

Greenland has the oldest rock on Earth. Previously fossil stromatolites were found in Australia at 3.5 byo. Now similar fossils may have been found in Greenland at 3.7 byo:-https://www.washingtonpost.com/news/speaking-of-science/wp/2016/08/31/3-7-billion-year-old-fossils-may-be-the-oldest-signs-of-life-on-earth/?wpisrc=nl_evening&wpmm=1-"It's a stunning announcement in a scientific field that is always contentious. But if confirmed, this would push the established fossil record more than 200 million years deeper into the Earth's early history, and provide support for the view that life appeared very soon after the Earth formed and may be commonplace throughout the universe.-"A team of Australian geologists announced their discovery in a paper titled “Rapid emergence of life shown by discovery of 3,700-million-year-old microbial structures,” published Wednesday in Nature.-"They made their find in July 2012 while doing field research in Isua, a region of Greenland so remote that they had to travel there by helicopter. The site is known for having the oldest rocks on Earth, in what is known as the Isua supracrustal belt.-"They examined the outcropping and immediately saw something intriguing: conical structures, just one to four centimeters (less than two inches) high. They look like fossilized microbial mats — basically, pillows of slime — known as stromatolites, which are formed today by bacterial communities living in shallow water.-“'We all said, 'This is amazing. These look like stromatolites,' " Nutman told The Washington Post.-"Subsequent laboratory analysis established that the formation is 3.7 billion years old, and turned up additional chemical signatures consistent with a biological origin for the conical structures, Nutman said. The scientists determined the age of the rocks through radiometric dating, measuring the abundance of elements created by the steady decay of uranium.-***-"They might really be biological but it's hard to absolutely refute the possibility that they formed by localized mineral precipitation from seawater. If we found these on Mars, would we plant a flag and declare that we had found life on Mars? I think not, but we would definitely get very excited and continue looking around for more information," she said.-“'We expect there will be some robust debate. That's what science is all about. There will be people surely who will put forward alternative hypotheses. But we think we've covered all those alternatives," Nutman said.-"The Australians' claim of Greenland stromatolites is "plausible and likely correct," said J. William Schopf, a pioneering paleobiologist at the University of California at Los Angeles who was not involved in the discovery.-***-"The Australian researchers do not contend that these stromatolites represent the first examples of life on the planet. Rather, these would have to be the descendants of the earlier life forms. Microbes capable of performing photosynthesis and forming communities are relatively sophisticated organisms. They presumably had less-sophisticated ancestors that lived more than 4 billion years ago, the Nature paper states.-“'Stromatolites are really complex, so you have to have a lot of evolution from when life started to when stromatolites appeared in the fossil record. So life either had to start earlier, or evolution is more rapid than you might expect," said Sara Walker, an astrobiologist at Arizona State University who was not involved in the new study.-"Earth, along with the other planets in our solar system, formed about 4.5 billion years ago from a cloud of dust and gas swirling around the embryonic sun. For hundreds of millions of years, ours was a harsh, molten world, heavily bombarded by debris."-Comment: An Earth 4.5 billion years old has somewhat complex single celled life at 3.7 byo. Life started quickly here. Startling. Can it be by chance?