LUCA’s origins pushed back further in time


I wrote a month ago about the finding of 45 specimens of fossils of deuterostomes that date back to 540 millions years ago, the earliest from the Cambrian period. These form part of the fascinating search for LUCA, the Last Universal Common Ancestor that we all share, even though the search might never actually yield it because when we go back far enough, the ‘tree of life’ that could point to a unique organism could become a ‘web of life’ where such an entity ceases to be identifiable.

But deuterosomes are pretty complex organisms. Yesterday comes reports of findings of “putative fossilized microorganisms that are at least 3,770 million and possibly 4,280 million years old”, which, if confirmed, would be the earliest found so far. You can read the paper published in Nature here and Eric Betz explains the significance of the finding.

Four billion years ago, as a faint young sun beat down on the newly-formed Earth, a cluster of creatures—each less than half the width of a human hair—were already thriving around volcanic vents.

“The microfossils already contain significant complexity,” says Dodd, who was lead author on the research. He points to microscopic features like twists and curls that scientists would expect from more advanced microbes. “These features show life had evolved beyond a simple cell occurring by itself — like a protocell.”

We know modern hydrothermal vents are home to all manner of complex life — including 10-foot-tall tube worms, crabs, clams, etc. And the microfossils found at the ancient vents are more like the bacteria found around vents today.

Dodd says their findings mesh well with life starting at a hydrothermal vent. However, he also points to a study published in Nature last September that found 3.7 billion year old stromatolites in southwest Greenland — not far away from these microfossils. Stromatolites are built by microbes living in shallow seas and feeding on sunlight. That means these two vastly different lifeforms thrived on two totally different energy sources just 70 million years apart.

Previously, the oldest microfossils found around hydrothermal vents were a mere 3.2 billion years old — 500 million years younger. And scientists have found other potential signs of life around hydrothermal vents in Greenland from 3.8 billion years ago.

What is interesting is that since the age of the Earth is currently thought to be 4.55 billion years old, this means that life could have come into being in just a few hundred million years after its formation. This may suggest that although we have not been able to synthesize life yet in the laboratory (and the definition of what defines ‘life’ is itself not without controversy), that may not be due to the fact that life is hard to create but that we have such a poor idea of what the early conditions that created it were like.

Pretty exciting stuff!

Comments

  1. Alexis says

    Wow “life could have come into being in just a few hundred million years after its formation”. And critics (YECs and IDs) are amazed that in just few labs in just a few decades, we could not reproduce what took place on a whole planet in a few hundred million years. /s

  2. busterggi says

    Perhaps conditions to create the ioriginal Terran life no longer exist either -- what worked a billion years ago might not survive today even if we did duplicate the conditions under which it was created originally.

  3. anat says

    busterggi, well, any attempt at reconstructing something like abiogenesis is typically conducted in a sterile environment with some specialized gas mixture (and no oxygen).

  4. ShowMetheData says

    If you want to dig deeper into the abiogenesis science, check out the Nick Lane’s book “The Vital Question: Energy, Evolution, and the Origins of Complex Life”

    The over-all model is one of tracking the energy gradient by shifting ions/protons over a membrane.
    It builds a solid testable model for creating cells, has a good model for the formation of the very complex eukaryotic cells (there are evolutionary effects when endosymbosis brings together the mitochondria with DNA ) and informs the debate of sexes.

    The latest chapter I’m reading talks about the evolutionary value of having mitochondria and DNA swap genes that are then tested by selection.

    Best science book I have picked up recently.

  5. derek lactin says

    I’m always amused and bemused (can I move farther into the alphabet with the prefixes?) when I read “just a few hundred million years”; it’s still a mind-f*ckingly long time. For example, the Cambrian was “just a few hundred million years” ago.

  6. says

    derek lactin@#6:
    And the Cambrian “explosion” was 200 million years. For a planetologist that’s like a flashbulb, but it’s still a long time! Long enough for humans to evolve from austraulopithecenes 100 times over.

  7. Owlmirror says

    And the Cambrian “explosion” was 200 million years.

    No.
    According to the latest stratigraphic chart, the beginning of the Cambrian was ~541mya, and the end was ~485mya. Not even 60 million years total.

    For a planetologist that’s like a flashbulb

    I’d question this, too. 200my is still about 4% of Earth’s age. I’m not sure what it might be compared to, but a flashbulb is a little too brief.

  8. Holms says

    Further, the ‘explosion’ portion of the Cambrian period only lasted about 20-25 million years, pretty much a tenth of the claimed 200 million.

  9. KG says

    I echo ShowMeTheData’s recommendation of Lane’s book @4, but there’s what looks like a “mental typo”:

    The latest chapter I’m reading talks about the evolutionary value of having mitochondria and DNA swap genes that are then tested by selection.

    For “DNA” read “the nucleus”. Both nuclear and mitochondrial genes are of course made of DNA.

    I’m somewhat sceptical of the claims for these “fossils”, although I don’t claim any relevant expertise. There’s a great temptation to say “We found the earliest X” on flimsy evidence. The Discover article (the comments, incidentally, are deeply depressing) notes that the claims are “controversial”.

  10. KG says

    Sorry, blockquote fail@10. All but the first quoted paragraph are mine.

    [Note: I have made this correction to your comment in #10. Hope that’s ok. -- Mano]