Evidence for Early Origin of Life on Earth

In summary, this study found that eleven microfossils found in Australia are bacteria that date back 3.5 billion years ago and have been analyzed with secondary ion mass spectrometry. The authors argue that this supports the claims that the fossils are biological in origin and that bacteria and archaea have both evolved (diverged) prior to the formation of the fossils.
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BillTre
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Science news reports:
(original report abstract here)
Eleven micro-fossils though to be the remains of bacteria (some dispute this) from Australia dated to 3.5 billion years ago have been analyzed with secondary ion mass spectrometry (SIMS).
This has revealed different ratios of different weight carbon atoms suggesting they represent 5 different kinds of organisms.
"Two types of microfossils had the same carbon ratio as modern bacteria that use light to make carbon compounds that fuel their activities—a primitive photosynthesis that did not involve oxygen. Two other types of microfossils had the same carbon ratios as microbes known as archaea that depend on methane as their energy source—and that played a pivotal role in the development of multicellular life. The ratio of a final type of microfossil indicated that this organism produced methane as part of its metabolism."

The authors argue that this:
1) supports the claims that the fossils are biological in origin,
2) that bacteria and archaea have both evolved (diverged) prior to the formation of the fossils, and
3) supports claims or an earlier origin of life (perhaps 4 billion years ago).

#3 would support claims that life is not so difficult to get started (at least on earth).
 
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Biology news on Phys.org
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If you accept that those are bacterial fossils, it does provide a strong assertion that abiogenesis is a frequent occurrence through out the universe. Our big problem right now is no first hand evidence for another non-Earth place where life evolved. Unless an alien intelligence makes itself known to us or we find early life some place like Enceladus, then we are stuck without any substantive proof of a second instance of life.
 
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  • #3
jim mcnamara said:
Our big problem right now is no first hand evidence for another non-Earth place where life evolved.
Just out of curiosity, is evolution to more complex forms guaranteed or could it be that abiogenesis although common throughout the universe, the conditions for supporting complexity are more rare and most life doesn't progress past bacterial size forms.
 
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  • #4
Seems common enough on earth.
I am sure there people who would argue it should be.
Don't really know elsewhere though.

Arguments might use ideas like complexity will build on complexity (predators on non-predators, predators on those, etc.) or chnages in an environment will provide new niches for new forms.
 
  • #5
I think the implication of the paper we're looking at is that very simple life forms may be found in many places. More advanced forms, no comment really. Advanced cell respiration would probably modify the original atmosphere, example: the Great Oxygenation Event on Earth. The advancements in terms of cell efficiency are due to organisms developing aerobic respiration which was only possible when free oxygen became available. This is one of the reasons why everyone is intensely interested in exoplanet atmospheres. Methanogenesis is another reason.
 
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Related to Evidence for Early Origin of Life on Earth

1. What is the earliest evidence for life on Earth?

The earliest evidence for life on Earth is in the form of fossils, which are preserved remains or imprints of ancient organisms. These fossils date back to approximately 3.5 billion years ago, during the Archean Eon.

2. How do scientists study the early origins of life on Earth?

Scientists study the early origins of life on Earth through various methods, including examining ancient rocks and minerals, analyzing chemical signatures, and studying ancient fossils. They also use computer simulations and experiments to recreate the conditions of early Earth to understand how life may have originated.

3. What is the RNA world hypothesis?

The RNA world hypothesis suggests that RNA, a molecule that can both store genetic information and catalyze chemical reactions, was the first self-replicating molecule on Earth. This hypothesis proposes that RNA may have been the precursor to DNA and proteins, which are essential for life as we know it.

4. What evidence supports the RNA world hypothesis?

There are several lines of evidence that support the RNA world hypothesis. For example, scientists have discovered self-replicating RNA molecules in the lab, suggesting that RNA could have been the first self-replicating molecule on Earth. Additionally, RNA can catalyze chemical reactions, making it a potential candidate for the first enzyme-like molecule in early life forms.

5. What is the significance of finding evidence for early life on Earth?

Finding evidence for early life on Earth is significant because it helps us understand the origins of life and how it evolved over time. It also provides insight into the conditions that were present on early Earth and how life may have adapted and changed in response to these conditions. This knowledge can also help us in the search for life on other planets and moons in our solar system and beyond.

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