Back here? From Phys.org:
“What we concluded is that, by discounting hydrogen peroxide oxidation, anoxygenic photosynthetic micro-organisms are the most likely mechanism responsible for Earth’s oldest iron formations,” Ernesto Pecoits of the Université Paris Diderot and lead author on the study told astrobio.net.
Microorganisms that photosynthesize in the absence of oxygen assimilate carbon by using iron oxide (Fe(II)) as an electron donor instead of water. While oxygenic photosynthesis produces oxygen in the atmosphere (in the form of dioxygen), anoxygenic photosynthesis adds an electron to Fe(II) to produce Fe(III).
“In other words, they oxidize the iron,” explains Pecoits. “This finding is very important because it implies that this metabolism was already active back in the early Archean (ca. 3.8 Byr-ago).”
Here’s the abstract:
It is widely accepted that photosynthetic bacteria played a crucial role in Fe(II) oxidation and the precipitation of iron formations (IF) during the Late Archean–Early Paleoproterozoic (2.7–2.4 Ga). It is less clear whether microbes similarly caused the deposition of the oldest IF at ca. 3.8 Ga, which would imply photosynthesis having already evolved by that time. Abiological alternatives, such as the direct oxidation of dissolved Fe(II) by ultraviolet radiation may have occurred, but its importance has been discounted in environments where the injection of high concentrations of dissolved iron directly into the photic zone led to chemical precipitation reactions that overwhelmed photooxidation rates. However, an outstanding possibility remains with respect to photochemical reactions occurring in the atmosphere that might generate hydrogen peroxide (H2O2), a recognized strong oxidant for ferrous iron. Here, we modeled the amount of H2O2 that could be produced in an Eoarchean atmosphere using updated solar fluxes and plausible CO2, O2, and CH4 mixing ratios. Irrespective of the atmospheric simulations, the upper limit of H2O2 rainout was calculated to be paywall)
This is despite the complexities of photosynthesis?
See also: Does nature just “naturally” produce life?
Can all the numbers for life’s origin just happen to fall into place?
Hat tip: Phillip Cunningham
10 Replies to “Photosynthesis from 3.8 billion years ago?”
Have any scientists from the ID community taken a look at this data? I’m trying to understand how it fits in with a Design scenario. Can someone here help?
Another troll bursts forth on the scene, fully formed.
Billions and billions of light-sensing spots, and still no bacteria with eyes.
Adapa @ 1
Well, my guess would be that the Designer knew that some of the Designer’s more advanced designs (T. rex, wombats, humans, etc.) needed oxygen to operate and that producing large amounts of oxygen on Earth would take quite a long time. So the Designer designed and installed Life that did NOT need oxygen for its own operations, but produced oxygen as a waste product.
But then I also assume that the Designer very carefully designed the entire solar system for the benefit of Earth. And that these designs included from the beginning the need to have a Mars-size planet collide with Earth some billion or so years after it formed. The scale of such designs is hard to grasp.
For those who aren’t big on Jehovah, I keep imagining that Douglas Adams came closer to the real explanation then he guessed whilst discussing Slartibartfast and the company that made planets to order. Earth was built as an analog computer…
Well heck. Even a light sensing spots is irreducibly complex?
Why don’t trillions of bacteria have eyes, if an eye can so easily evolve from a light-sensitive spot? Bacteria lack any way to sense light?
This looks like a pretty important finding. It certainly creates problems for people who believe in abiogenesis!
Very interesting. Personally, I tend to think that photosynthesis may be much older than sometimes assumed, and I am not completely convinced of the primary role of chemosynthesis in OOL. Unfortunately, data are still too vague.
But we will see. I am an optimists, and I believe that research will find a lot of information about OOL which is not yet apparent. Strangely, I do not share the general attitude of our neo darwinist friends, who often seem to hope that details about OOL will never be empirically available. Instead, I eagerly hope that they will be found.
Whyever such different attitudes? 🙂
As an optimist, you must be very interested in being able to tell the difference between an eye and an eyespot!
Try Google. It really helps a lot.
Bacterial responses to light often involve the oh so irreducible complex flagellum.