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!