Ancient traces of microbial life that are between 3.77 billion and 4.29 billion years old might have been unearthed in a rocky outcropping in Canada, a new study suggests. However, some scientists are casting doubt on what the findings truly mean.

If the new microfossils truly are evidence of primordial life that once sprang up in ancient hydrothermal vents, it suggests that life began on Earth soon after the planet coalesced, the study authors said.

“We can say life managed to emerge on Earth very rapidly almost soon after the oceans had condensed on the surface of the Earth 4.4 billion years ago,” said study lead author Matthew Dodd, a biogeochemistry graduate student at the University College London. “What this means is that life may not be such a difficult process to start once we have the right conditions and ingredients.”

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There is an existing thread on this topic, fourth from the top in the view by topic.

dv said:

There is an existing thread on this topic, fourth from the top in the view by topic.

Yes, yes, but mine has bigger, brighter fossils.

Ian said:

dv said:

There is an existing thread on this topic, fourth from the top in the view by topic.

Yes, yes, but mine has bigger, brighter fossils.

Amazing fossils, some people tell me they are the best fossils ever, it’s incredible.

Looks a bit like penne pasta.

After reading the article in Nature (URL below), I find it quite convincing.

If that URL doesn’t work, go to the livescience site and use their token…

http://www.nature.com/articles/nature21377.epdf?referrer_access_token=v-JOe-XtN9IMetBSjawkztRgN0jAjWel9jnR3ZoTv0OZLj_4udImjr9-hwwqMBMYbZa4nYk3vfqQ-rbmVfHiA9KvG1cjuRzDakAwx1kaxAxS7SLIYQq86NKdtQJTCfDnNWgfr8XDL1faNsEuyDg_gFYB8VkhhUnhQmyR0IsS2gJQHHiU5czWm2F0Dmc5TlePyvuIKgY2BtyH8clEryydrw_TSIdutGDSD4tJNXKhwnM5EI_kQ99kOkFd1V8EOFDh&tracking_referrer=www.livescience.com

Michael V said:

After reading the article in Nature (URL below), I find it quite convincing.

If that URL doesn’t work, go to the livescience site and use their token…

http://www.nature.com/articles/nature21377.epdf?referrer_access_token=v-JOe-XtN9IMetBSjawkztRgN0jAjWel9jnR3ZoTv0OZLj_4udImjr9-hwwqMBMYbZa4nYk3vfqQ-rbmVfHiA9KvG1cjuRzDakAwx1kaxAxS7SLIYQq86NKdtQJTCfDnNWgfr8XDL1faNsEuyDg_gFYB8VkhhUnhQmyR0IsS2gJQHHiU5czWm2F0Dmc5TlePyvuIKgY2BtyH8clEryydrw_TSIdutGDSD4tJNXKhwnM5EI_kQ99kOkFd1V8EOFDh&tracking_referrer=www.livescience.com

“These structures occur as micrometre-scale haematite tubes and filaments with morphologies and mineral assemblages similar to those of filamentous microorganisms from modern hydrothermal vent precipitates and analogous microfossils in younger rocks. The Nuvvuagittuq rocks contain isotopically light carbon in carbonate and carbonaceous material, which occurs as graphitic inclusions in diagenetic carbonate rosettes, apatite blades intergrown among carbonate rosettes and magnetite–haematite granules, and is associated with carbonate in direct contact with the putative microfossils. Collectively, these observations are consistent with an oxidized biomass and provide evidence for biological activity in submarine-hydrothermal environments more than 3,770 million years ago.”

I find it convincing, too. But then I found the original paper about microfossils in the Mars meteorite ALH 84001 convincing too, at first. That had very similar mineralogy, particularly the “magnetite–haematite granules” and the multiple independent collective observations. No one accepts ALH 84001 any more.

A case of “once bitten twice shy”.

What sets this new find apart from ALH 84001 is the size of the fossils. Whereas the Mars fossils were too small to be alive, the present fossils are the right size and complexity. But then, geological processes on Earth near hydrothermal vents could be quite complicated.

The images in the original Nature article remind me of how hematite tubes can form abiologically in jasper.

The microcrystalline quartz that forms the bulk of the jasper is deposited by water. This water has to flow in order for the deposition to continue and because jasper is impermeable it has to flow through channels. These channels slowly reduce in diameter until they become filaments. The same can be seen in modern jaspers.

Finally, the filaments become totally blocked at the ends and minerals that don’t deposit as easily, including hematite, form at tube around the outside of the trapped water filaments.

The following figure is of moss agate rather than jasper, so the filamentous structure due to the above mechanism is large enough to be seen without a microscope. But you can see the similarity to the shapes in the Nature paper. No biological mechanism necessary.

Do you have references to back any of those postulates up, moll?

mollwollfumble said:

nom nom. Go nicely on my Jatz crackers with pickled onions and salami.

Michael V said:

Do you have references to back any of those postulates up, moll?

No. I have seen jasper that had fine dendritic patterns like those in moss agate. And moss agate can certainly have abiologically-looking dendritic shapes like those seen in the putative fossils. Similar mineral composition for the tubes even. Jasper and moss agate are both silica deposited from hydrothermal circulation. The rest – in particular the blockage of tubes – I made up because I can’t think of any other good explanation.