Looking at Early Life

A sample of chert rock containing what may be the remains of microorganisms that lived 3.4 billion years ago. Dr. Manuel Reinhardt

Around 3.4 billion years ago, Earth hosted diverse communities of life, as evidenced by exceptionally preserved remains revealing a microorganism ecosystem with various sustenance methods. The complexity of this ancient ecosystem suggests that life had likely existed for hundreds of millions of years, starting early in Earth's history.

THIS ACADEMIC PAPER, focused on rocks from the Buck Reef Chert in South Africa, dating back 3.42 billion years. These rocks are believed to be remnants of the shallow seas around a chain of volcanic islands. The layers of rock contain microscopic carbon-based matter, likely the remains of microorganisms from the ancient seas.

Analyzing the chemical makeup of these remains, the researchers honed in on carbon isotopes, specifically carbon-12 and carbon-13. Living organisms prefer carbon-12, and the ratio between the two isotopes provides insights into an organism's metabolism. The material showed a carbon signature consistent with photosynthesis, indicating the presence of vast quantities of photosynthetic microbes near the sea surface billions of years ago.

However, some blobs exhibited lower levels of carbon-12, suggesting a different metabolic process. The authors propose that these microbes were likely feeding on acetyl coenzyme A. Other blobs with even lower carbon-12 levels indicated microbes producing methane or acetate as waste products, which were then potentially consumed by other microbes.

The distribution of these microorganisms is challenging to determine, but it is suggested that photosynthetic ones lived near the water's surface, while others might have resided in seabed sediments. It seems early life functioned similarly to present-day life.

The research also contributes to the growing evidence supporting an early origin of life on Earth, challenging previous fossil record interpretations. While widely accepted evidence for life is around 3.5 billion years old, older fossils from 3.7 billion years ago or earlier have been reported. However, the difficulty in detecting well-preserved rocks from that era makes it challenging to uncover the earliest history of life. But some suggest that life may have emerged during the Hadean eon, around 4.2 to 4.1 billion years ago.

Many readers of this blog will be amazed at the quality of this article. I did not write it! It was written by ChatGPT. I copied THIS ARTICLE from New Scientist and asked ChatGPT to summarise it in about 400 words, and it did it in 359. I modified the output slightly. Be aware that I will not be doing this on a regular basis but did it as an exercise to see the quality of the output - and I am impressed. Back to the less impressive me next time!