Scientists find a place on Earth where there is no life

FECYT – Spanish Foundation for Science and Technology

Hyperacid, hypersaline and hot ponds in the geothermal field of Dallol (Ethiopia). Despite the presence of liquid water, this multi-extreme system does not allow the development of life, according to a new study. The yellow-greenish colour is due to the presence of reduced iron.  Credit: Puri López-García

Hyperacid, hypersaline and hot ponds in the geothermal field of Dallol (Ethiopia). Despite the presence of liquid water, this multi-extreme system does not allow the development of life, according to a new study. The yellow-greenish colour is due to the presence of reduced iron. Credit: Puri López-García

Living beings, especially microorganisms, have a surprising ability to adapt to the most extreme environments on our planet, but there are still places where they cannot live. European researchers have confirmed the absence of microbial life in hot, saline, hyperacid ponds in the Dallol geothermal field in Ethiopia.

The infernal landscape of Dallol, located in the Ethiopian depression of Danakil, extends over a volcanic crater full of salt, where toxic gases emanate and water boils in the midst of intense hydrothermal activity. It is one of the most torrid environments on Earth. There, daily temperatures in winter can exceed 45° C and there are abundant hypersaline and hyperacid pools, with pH values that are even negative.

A recent study, published this year, pointed out that certain microorganisms can develop in this multi-extreme environment (simultaneously very hot, saline and acid), which has led its authors to present this place as an example of the limits that life can support, and even to propose it as a terrestrial analogue of early Mars.

However, now a French-Spanish team of scientists led by biologist Purificación Lopez Garcia of the French National Centre for Scientific Research (CNRS) has published an article in Nature Ecology & Evolution that concludes otherwise. According to these researchers, there is no life in Dallol’s multi-extreme ponds.

“After analysing many more samples than in previous works, with adequate controls so as not to contaminate them and a well-calibrated methodology, we have verified that there’s no microbial life in these salty, hot and hyperacid pools or in the adjacent magnesium-rich brine lakes,” stresses López García.

“What does exist is a great diversity of halophilic archaea (a type of primitive salt-loving microorganisms) in the desert and the saline canyons around the hydrothermal site,” the biologist explains, “but neither in the hyperacid and hypersaline pools themselves, nor in the so-called Black and Yellow lakes of Dallol, where magnesium abounds. And all this despite the fact that microbial dispersion in this area, due to the wind and to human visitors, is intense.”

This is confirmed by the results of all the various methods used by the team, including the massive sequencing of genetic markers to detect and classify microorganisms, microbial culture attempts, fluorescent flow cytometry to identify individual cells, chemical analysis of brines and scanning electron microscopy combined with X-ray spectroscopy.

López García alerts that some silica-rich Dallol mineral precipitates may look like microbial cells under a microscope, so what is seen must be analysed well: “In other studies, apart from the possible contamination of samples with archaea from adjacent lands, these mineral particles may have been interpreted as fossilized cells, when in reality they form spontaneously in the brines even though there is no life.”

According to the authors, this work “helps to circumscribe the limits of habitability and demands caution when interpreting morphological bio-signatures on Earth and beyond,” that is, one should not rely on the apparently cellular or ‘biological’ aspect of a structure, because it could have an abiotic origin.

“In addition, our study presents evidence that there are places on the Earth’s surface, such as the Dallol pools, which are sterile even though they contain liquid water,” stresses Lopez Garcia. This means that the presence of liquid water on a planet, which is often used as a habitability criterion, does not directly imply that it has life.

In this case, the researchers have found two physical-chemical barriers that prevent the presence of living organisms in ponds: the abundance of chaotropic magnesium salts (an agent that breaks hydrogen bridges and denatures biomolecules) and the simultaneous confluence of hypersaline, hyperacid and high-temperature conditions.

“We would not expect to find life forms in similar environments on other planets, at least not based on a biochemistry similar to terrestrial biochemistry,” points out Lopez Garcia, who insists on the need to have multiple indications, to analyse all types of alternatives and to be very prudent with interpretations before reaching any conclusions in astrobiology.

Both the French-Spanish group, in which researchers from the Geological and Mining Institute of Spain and the Autonomous University of Madrid participate, and other international teams continue to investigate the extreme environment of Dallol, where completely sterile pools could alternate with others with slightly better biophysical conditions that allow the presence of archaea and other extremophilic microorganisms. In any case, this is an exceptional environment to continue studying the limits of life.

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References:

Jodie Belilla, David Moreira, Ludwig Jardillier, Guillaume Reboul, Karim Benzerara, José M. López-García, Paola Bertolino, Ana I. López-Archilla & Purificación López-García. “Hyperdiverse archaea near life limits at the polyextreme geothermal Dallol area”. Nature Ecology & Evolution 3: 1552-1561, 28 October 2019.

From EurekAlert!

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39 thoughts on “Scientists find a place on Earth where there is no life

    • Not sure what your post means…there really *is* such a thing as a negative pH, although it has a very small magnitude (has to do with how the pH is calculated using a Log function).

  1. In Jujuy Province of Argentina at about 4000m elevation there are salt lakes of all the colours of the rainbow. I am not aware of any life in these lakes, although it may be possible that some microscopic forms of life exist in them.

    Hundreds of miles to the west and 4000m lower down, at the Atacama Desert in northern Chile, there are places where it has not rained in 50 years. I bet you could dig down in the ground there and not even find viruses.

      • Maybe so, but those critters must live in the wetter parts of the driest place on earth. 🙂

        I recall looking out across the Atacama, and there was not so much as a single speck of vegetation. There was dry soil, and nothing else!

        I have been to many drylands: the Sahara Desert, the Central Asian Desert, deserts in the USA and Mexico, the high deserts of the Puna in the Andes in South America, and they all had some plant life – but the Atacama had nothing.

        • The article says that signs of life were found in the driest part of the Atacama:

          Previous studies had found signs of microbial life in the Atacama’s hyper-arid soils, but it was possible that these microbes were wind-borne interlopers that promptly died in the harsh landscape. To tell whether anything truly lives there, researchers would need to track the soils over time, to see how they responded to changes in their environment.

          In March 2015, a team led by Dirk Schulze-Makuch, an astrobiologist at Technical University Berlin, ventured into the Atacama weeks after a years’ worth of rain fell in the region and triggered floods and dramatic flower blooms in some areas.

          The team dug trenches up to three feet deep in areas they chemically determined were otherwise untouched by humans. They returned in 2016 and 2017 to collect more samples, to see how any microbes present changed as the desolate landscape dried out once again.

          Back in the lab, team biologists examined the soil and found DNA, which revealed that wetter areas closer to Chile’s coastline had larger, more diverse microbial populations than drier spots farther inland. They also saw evidence of a molecule called ATP—cells’ universal currency for storing and transporting energy—as well as the building blocks for cell membranes.

          As the soils dried out after the 2015 rains, researchers watched as ATP levels decreased—exactly what you’d expect to see if microbes awakened by rain had reentered hibernation.

          The findings are a testament to “the amazing adaptability of life even to sustain itself … where it rains sometimes only once a decade,” says Schulze-Makuch. “Just a bit of moisture, and life can persist and make that area—with very little water, high UV irradiation rates, and chemical stresses—a habitat, at least a transient one.”

  2. I would not be that – bacteria has been recovered from the mid Proterozoic deeps at the Rand mines and from spores in the mid Devonian in the USA mid west and successfully redeployed.

  3. Earlier today I was reading paper to bring seawater and life to this region, plus generate energy. The article: “Danakil-Depression and Red Sea Solution to the Ecological, Political and Economical Challenges among Nile River Basin Countries,” International Conference on Agricultural, Ecological and Medical Sciences
    https://iicbe.org/upload/3632C714076.pdf
    Excerpt, bottom of page 18:
    “With the Danakil Depression situated only a few kilometers
    inland and about 125 meters below sea level, Eritrea and
    Ethiopia could develop a hydroelectric and potable water
    generation capacity from the Red Sea. The two countries can
    be self sufficient in a short period with a renewable and
    environmentally friendly efficient energy source from the Red
    Sea Fig. 3. The coast line on the Red Sea, from Marsa Fatima
    to Tio, which covers about 90 kilometers distance along the
    coast of Red Sea, is a flat land, without hills or ridges.

    • An even bigger depression below sea level in Egypt is the Qattara Depression in the northern part of the country near the Mediterranean. It is large enough that if sea water was fed by gravity from the Med that perpetual evaporation would allow this project to basically work forever. There is about 300-400 net average head below sea level. The Dead Sea (about 1200 feet below sea level) is another good candidate which is actually drying up and losing its water level due to the incoming Jordan River being utilized and extensive evaporative mining. It is my understanding that Israel and Jordon are working on a joint project with a canal from the Red Sea feeding a hydro project/desal plant. The beauty of a desalination plant would be that gravity fed sea water would be the pressure for the reverse osmosis membranes water filters and the brine/salt/fertilizers could be further mined in evaporative ponds. A lot of fresh water in a desert could be a real good thing. Maybe they all so busy making money there is no need to fight anymore.

      https://en.wikipedia.org/wiki/Qattara_Depression

      • If these projects went ahead what affect would they have on sea levels? While the Straits of Gibraltar would presumably constrain much change beyond, grabbing a tankful of the Red Sea would be an interesting experiment. Win win or sin bin?

        • I don’t know that it would lower global sea levels much, maybe a few mm per century but it would be a deficit on sea level, not additive. Maybe it would offset some of the mountainous glacial melt and at least it couldn’t be blamed for SLR. Besides costs, some of the stated environmental issues are the possibility of evaporative imbalance in the local area, although a bit more rain in a desert area might not be a bad thing. The other is displacing any amount of land area life that reside in these large desert areas, such as the Sahara Cheetah although there isn’t an abundance of wildlife in these areas. The amount of electricity generated would be similar to a very large river hydro project, with an inexhaustible supply of water. Tourism and agriculture could be other big winners.

    • Gregory Rehmke:
      “…Danakil-Depression and Red Sea Solution to the Ecological, Political and Economical Challenges among Nile River Basin Countries,”
      The Qattara depression in Egypt’s western desert is another even larger area which could become an inland sea fed from the mediterranean. Almost 20,000 sq. kilometers averaging 60 meters below Sea Level with deepest parts 150 meters, it could generate hydroelectric power, change the climate by raising the humidity and rain fall, lowering sea level a bit, start a fishing industry… all good things for the Greens to promote.
      Then there’s the Dead sea, Death Valley California, Lake Clare Australia and plenty more places where Solar energy could be used to make water (evaporation) and lower sea levels.. sustainably!
      Cheers
      Mike

  4. There must be other places where there’s absolutely no life…Have they never looked in the brains of Extinction Rebellion storm troopers? Or Greenpeace zealots?

    • You confuse life with intelligent life. Parasitic lifeforms exist all over the place, including those you mention. They may act as if there must be some intelligence somewhere in them, but it turns out just to be random activities and reinforcement (usually the bad kind).

  5. This makes sense to me…Life requires rather complex chemistry to occur, and if you put it into an environment where that chemistry is disrupted, life can’t survive. Molten magma would be a good example, or plasma. Surely a chemical fluid can exist so hostile to life chemistry that life just can’t survive there.

    Now, at the edges…well that’s a different story entirely. At the boundaries where conditions change to be more suitable, you can get all sorts of evolved single celled critters that adapt to the so-called “extreme environments”.

    • I worked in a genetic research lab for a few months as a student. They told me that they sometimes throw away supposedly sterile liquids because they got contaminated. Once they threw away a vat of pure sulphuric acid because something grew in there.

  6. A good place for dipping your instruments before surgery!

    ”Now just lie down on this rock and I’ll be with you in a minute”……..

  7. I think we might be on safer ground with “there may be life there, Jim, but not as we know it!”

    Given the ability of all sorts of life forms to exist and even thrive in all sorts of environments it seems a little arrogant of us in our, still incomplete, knowledge of the universe to be quite so categorical! Mrs N takes the view that this is simply an area the planet hasn’t found a use for — yet!

  8. Just because extremophiles aren’t living there, it doesn’t mean that they couldn’t. It all depends on the historical evolution of life in that location, or of life that has access to that location.

    In any case, so what? You won’t find life in volcanoes containing molten rock either. The real story remains that life is so well established on this planet as to be almost indestructible, just like Captain Scarlet. Yet some people like to claim that a further rise of one or two degrees is some sort of a problem when all the evidence actually says the opposite.

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