Did Life On Earth As We Know It Come From ‘Geological Life’?

by Elizabeth Howell on March 13, 2014

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Hydrothermal vents. Credit: NOAA

Hydrothermal vents. Credit: NOAA

When it comes to life on Earth, we’re not sure if it came from the outside (transported by comets) or on the inside. A new theory focuses on the “interior ” theory, saying that microbes could have evolved from non-living matter such as chemical compounds in minerals and gases.

“Before biological life, one could say the early Earth had ‘geological life’. It may seem unusual to consider geology, involving inanimate rocks and minerals, as being alive. But what is life?” stated Terry Kee, a biochemist at the University of Leeds in the United Kingdom who participated in the research.

“Many people have failed to come up with a satisfactory answer to this question. So what we have done instead is to look at what life does, and all life forms use the same chemical processes that occur in a fuel cell to generate their energy.”

When thinking of a car, the research team says, they point out that fuel cells create electrical energy through the reaction of fuels and oxidants. This is called a “redox reaction”, which takes place when a molecule loses electrons and another molecule gains them.

In plants, photosynthesis creates electrical energy when carbon dioxide breaks down into sugars, and water is oxidized into molecular oxygen. (By contrast, humans oxidize sugars into carbon dioxide and break down the oxygen into water  – another electrical energy process.)

Now, let’s go a step further. Hydrothermal vents are hot geysers on the sea floor that are often considered an interesting spot for life studies. They host “extremophiles”, or forms of life that exist (“thrive” is the better word) despite a harsh environment. The researchers say these vents are a sort of “environmental fuel cell” because electrical energy is generated from redox reactions between seawater oxidants and hydrothermal vents.

And this is where the new research comes in. At the University of Leeds and NASA’s Jet Propulsion Laboratory, the researchers put iron and nickel in the place of the usual “platinum catalysts” found in fuel cells and electrical experiments.

Rendering showing the location and size of water vapor plumes coming from Europa's south pole.

Rendering showing the location and size of water vapor plumes coming from Europa’s south pole.

While the power was reduced, electricity did indeed flow. And while researchers still don’t know how non-life could have transformed into life, they say this is another step to understanding what happened. What’s more, it could be useful for future trips to other planets.

“These experiments simulate the electrical energy produced in geological systems, so we can also use this to simulate other planetary environments with liquid water, like Jupiter’s moon Europa or early Mars,” stated Laura Barge, a researcher from the NASA Astrobiology Institute* who led the research.

“With these techniques we could actually test whether any given hydrothermal system could produce enough energy to start life, or even, provide energetic habitats where life might still exist and could be detected by future missions.”

You can read about the research in the journal Astrobiology.

Source: University of Leeds

Disclosure: The author of this article is also a freelancer for the NASA Astrobiology Institute.

About 

Elizabeth Howell is the senior writer at Universe Today. She also works for Space.com, Space Exploration Network, the NASA Lunar Science Institute, NASA Astrobiology Magazine and LiveScience, among others. Career highlights include watching three shuttle launches, and going on a two-week simulated Mars expedition in rural Utah. You can follow her on Twitter @howellspace or contact her at her website.

Torbjorn Larsson OM March 13, 2014 at 4:56 PM

Likely yes, but then only from alkaline hydrothermal vents which had the same differential cell voltage as our cells.

Maybe the Leeds/JPL group has forgotten that. Their press release speaks of “trying … to bridge the gap between the geological processes of the early Earth and the emergence of biological life on this planet.” But already Lane & Martin 2013 suggested that the chemical garden growths that a Hadean alkaline hydrothermal vent would have built in the acidic (CO2 soaked) ocean have homologies, shared inherited traits, to biological cells. Such homologies are the asked for bridges.

A more complete list of homologies could be something like:
- element ratios of ocean (so not fresh water hydrothermal systems)
- cell
- cell membrane (inorganic vs organic)
- pH difference
- import part of chemiosmosis [Russell et al]
- electron bifurcating atoms, primarily Mo, making metabolic feedback loops possible [Russell et al]

Then, by phylogeny, such geochemical systems would be our most remote cousins!

In our neutral oceans of today they are dead of course. Interestingly Russell et al predicted their existence a few years before the first one, the Lost City, was discovered. (These pathways are highly predictive, which is promising.) That is situated several km down, but an analogous fresh water vent with a chemical garden (“white smoker”), Strýtan, is within diving depth (15-70 m) on the north coast of Iceland, a day trip for experienced dry suit divers from the nearest town. [ http://www.strytan.is/diving-place/strytan/ ]

The Leeds/JPL paper looks interesting, unless I am mistaken they have looked at the FeS minerals that mostly builds the inorganic semipermeable membranes that are central in most of the theories on vents vs abiogenesis.

weeasle March 14, 2014 at 3:24 AM

Nice very well informed comment Torbjorn. Good to see – hadnt seen ur comments for a while, nor L Crowell’s which i miss. I hope he is well.

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