Theoretical origin of life; hunting for stromatolites (Introduction)

by David Turell , Monday, March 30, 2020, 23:46 (1482 days ago) @ David Turell

Then one must locate traces of biological life:

https://www.smithsonianmag.com/science-nature/earth-earliest-life-fossils-stromatolites...

"The search for signs of Earth’s earliest forms of life isn’t quite like looking for dinosaur bones protruding out from desert outcrops. The oldest species on our planet were microscopic, nothing more than itty-bitty specks. Detecting them, and verifying their identity, is a complicated task that often relies not only hunting town tiny remains but also on chemistry and perceiving how those microorganisms modified their environments.

"Picking out the evidence of Earth’s earliest life is more than a needle-in-a-haystack problem. The entire planet is the metaphorical haystack, while the needles are no more than microscopic cells or faint chemical traces. Even when scientists can pin down possible candidates, it’s can be hard to know for sure when something is a signature of ancient life rather than a plain-old geologic phenomenon.

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"In 2016, a team of researchers from Australia proposed that they had found evidence of stromatolites being formed about 3.7 billion years ago, which would make them a remnant of some of the earliest known organisms. The Earth itself, after all, is only about 4.5 billion years old.

"But other experts weren’t convinced. The fossils preserved only the stromatolite structure, not the organisms that created them, and some researchers argued that the rocks were formed by other geological processes. However, a study published just last year put forth stronger evidence, including geochemical analysis, that suggests some 3.5-billion-year-old stromatolites found at a different site in Australia do record and contain evidence of some of Earth’s oldest microbes.

"The search for the signs of early life, what experts call biosignatures, often focuses on four different lines of evidence, says University of New South Wales astrobiologist Tara Djokic. The first kind of evidence is relatively large and can be seen with the naked eye, such as the stromatolites. Other traces are much harder to find, and that group includes chemical traces of fossils, degraded biological compounds, and fossils of microorganisms themselves.

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“'Thanks to billions of years of the rock cycle, there are not so many rocks which are even suitable to search in for signs of early life,” Olcott says. Searching for early life requires understanding—and correcting for—the factors that may obscure the truth. “It’s like coming to a crime scene and having to piece together what has happened and who was involved,” Djokic says.

"At present, the starting date for life on Earth is still rough. “There is no specific site that is considered [to be] 100 percent proof of the earliest signs of life on Earth,” Djokic says. One of the oldest, least controversial sites is the 3.4-billion-year-old Strelley Pool Formation in Australia, Olcott notes. Researchers have found stromatolites, microbial mats, chemical signatures indicative of life and more. Older sites hold potential but are controversial. A roughly 3.8-billion-year-old site in Greenland may contain even older traces of life, but this spot is more contentious, Djokic says, because the rocks there have been through the geological ringer and are more difficult to interpret."

Comment: This information has been presented before, but is worth reviewing. What is amazing is how early life might have arrived on an Earth estimated as 4.5 byo. Certainly looks as if the Earth was well-prepared in advance for life to start. As Paul Davies notes, life sure looks like a miracle. I view it as God planning well.