Who, what, where, when, why, and how? These are the questions that good journalists ask. They are also the same inquiries that origin-of-life researchers make about first life on Earth. When did life first appear? What were the original life-forms like? And how did life on Earth originate?
To address these questions, researchers probe the oldest rock formations on Earth for evidence of ancient life. As Hugh Ross and I described in the book Origins of Life, geochemical and fossil evidence seems to indicate that life was present on Earth as far back as 3.8 billion years ago. (Go here, here, and here for articles that present more-recent evidence in support of life's early appearance on Earth.)
One important piece of evidence that scientists cite for ancient life is the approximately 3.5 billion-year-old stromatolite remains recovered from rock formations in western Australia. These macroscopic structures were presumably produced by microbes, possibly photosynthetic bacteria.
Still, a number of investigators question the authenticity of the ancient stromatolites. They argue that these structures were produced by inorganic processes and only superficially resemble the structures produced by microbes. Some origin-of-life researchers have also expressed concerns about other fossils and geochemical markers interpreted as life remains. Again they argue that inorganic mechanisms produced these structures.
This skepticism stems partly from the discomfort created for the evolutionary paradigm if metabolically complex life appeared that early in Earth's history. Most origin-of-life models maintain that life emerged from a "primordial soup" only after an extensive percolation time. That first life should have been relatively simple and only later evolved metabolic complexity.
A team from Cal Tech and Harvard University weighed in on this controversy. They examined putative stromatolites recently recovered from the Strelley Pool Formation in western Australia. These structures are unusually well-preserved, which allowed the researchers to perform a detailed characterization of the stromatolites' morphology. From this analysis they concluded that the geological features were indeed produced by microorganisms.
Stromatolites harbor complex microbial ecosystems. The bioauthenticity of ancient stromatolites then suggests that complex microbial communities were already present on the planet 3.5 billion years ago. Establishing the presence of stromatolites on early Earth also helps bolster the case that other fossil remains and geochemical signatures in ancient rocks dating as old as 3.8 billion years ago are biogenic (produced by life processes) in origin.
While the recognition that life existed quite early in Earth's history raises confounding questions for evolutionary origin-of-life models, it comports well with the biblical creation accounts and satisfies two important predictions made by RTB's scientifically testable creation model for the origin of life—a discovery worthy of the news.*(Go here for an article that outlines the model and delineates its predictions.)
*When this discovery was made, it did indeed generate headlines. I discussed the implications of this work on the August 3, 2009 edition of our podcast, Science News Flash.