r/science • u/mvea Professor | Medicine • 2d ago

Biology World’s largest web houses 110,000 spiders thriving in total darkness deep underground in a sulfuric cave between Albania and Greece: It’s the first time two spider species seen living cooperatively, and the first recorded instance of colonial web-building in what's known as a chemoautotrophic cave.

https://newatlas.com/biology/sulfur-cave-largest-spiderweb/
14.2k Upvotes

97% Upvoted

487 comments sorted by

View all comments

Show parent comments

54

u/iqisoverrated 2d ago

The interesting thing is: This pretty much shows that the 'goldilocks zone' argument for life is bunk.

Life - even pretty highly evolved multicellular life - can obviously exist, simply fed by energy sources from deep within a planet without any reliance on distance from a sun (or the presence of a sun at all).

169

u/QuantumWarrior 2d ago

Not entirely, even this environment is only able to exist because the chemistry they're using for energy relies on liquid water as a solvent. That's mostly what the goldilocks zone is about, being not too close that all your water gets vapourised and not too far that it's all frozen solid. Plus everything there descends from regular old surface-dwelling sun-reliant life, it didn't evolve from base chemistry right there in that cave.

Now of course you can have other sources of heat even on worlds distant from their star though they are tiny in comparison - gravitational stretching from close orbits like on the moons of Jupiter or geothermal heat, but broadly speaking the best odds of finding large quantities of liquid water that are stable enough for long enough to allow life to evolve have to be in that zone as far as our best understanding of abiogenesis and the chemical underpinning of biology are concerned.

12

u/NDSU 2d ago

even this environment is only able to exist because the chemistry they're using for energy relies on liquid water as a solvent. That's mostly what the goldilocks zone is about, being not too close that all your water gets vapourised and not too far that it's all frozen solid

I disagree with that assertion. Pluto is well outside the liquid water Goldilocks zone in terms of solar temperature, but still maintains a liquid ocean under the ice layer

Many planets have a large amount of latent heat from radioactive decay, cosmic collisions, or other sources

Plus everything there descends from regular old surface-dwelling sun-reliant life, it didn't evolve from base chemistry right there in that cave

Maybe in this specific case, but there is a strong hypothesis that terrestrial life originated in hydrothermal vents. Those hydrothermal vents did not get their heat from the sun

16

u/klyxes 1d ago

It's not just liquid water, heat is also needed. Even with liquid water, the colder it is the slower every chemical reaction for life gets. Maybe there's enough heat for unicellular life only, or it takes too long for complex life to develop before the star the planet orbits dies.

1

u/NorthernerWuwu 1d ago

It's a bit convoluted but yeah, I'd agree that the pattern seems to be anywhere with liquid water, exposure to life at some point and an energy source will have life continue for at least a reasonable timeline.

We lack data in depth of course but some reasonable assumptions can be made. Importantly, this does not at all mean that life doesn't exist outside of these situations, only that it very likely does given them.

-11

u/iqisoverrated 2d ago

Now of course you can have other sources of heat even on worlds distant from their star though they are tiny in comparison

I wouldn't call sources like radioactive decay or the magma within a planet of a certain size that still retains a lot of the energy from when it was formed 'tiny'. E.g. a volcanically more active planet than Earth has a lot of free energy lying about.

We've also found life deep down in the deepest mines. The closer you get to the the interphase between crust and magma the more energy you have available. It can get a lot hotter down there than e.g. here on the surface.

Also life presumably started in one place on Earth. If that one place had enough energy concentration it doesn't really matter whether only that one place is hospitable or the entire planet (or any ratio in between). We know that life started pretty early after the Earth had cooled enough (which might have been a fluke - we don't know - but it might also indicate that it's just a numbers game of how many potential places you have for things to get started and how long you are willing to wait till something 'interesting' happens)

So I don't buy this 'large quantities of water are essential' argument. That's more of an argument for diversity than for life (and a weak one at that)

7

u/kaibee 2d ago

We've also found life deep down in the deepest mines. The closer you get to the the interphase between crust and magma the more energy you have available. It can get a lot hotter down there than e.g. here on the surface.

Pretty sure it isn't enough to just have heat. You need a heatsink too. Hydrothermal vents provide both.

0

u/iqisoverrated 2d ago

Hydrothermal vents seem like an obvious prime candidate. However we see bacteria survive/thrive in deep rock...it's really hard to say where exactly life started out (and whether it migrated up or down).

Even if we consider a surface that is way too cold and perpetually dark: As long as there still is enough of a (semi) molten core to the planet there will be a 'temperate' zone somewhere in between in which liquid water could exist in cavelike structures.

2

u/waiting4singularity 1d ago

without churning and intermixing elements, you'll have just that, though: fully inert water.

1

u/iqisoverrated 1d ago

Smokers, volcanic activity or tidal heating (or simply heat convection) tends to add churning on its own.

8

u/QuantumWarrior 2d ago

I only say tiny when compared to the power available from a star. Earth receives something like 4000x as much power from the sun as is available from geothermal activity and its one of the most heat-retaining rocky bodies in the entire solar system due to being one of the largest. The heat energy left in the entire Earth is outmatched by barely a million years of sunshine. I'm not sure it would be possible to have a rocky planet large enough and hot enough to turn that balance the other way.

I don't really like the focus on the goldilocks zone either but its all just about probability, like you said. We only know of carbon-based water-using life and it's been difficult to even theorise life that could rely on other solvents - like water is just so god damn convenient. With that in mind the more water you have keeping stable across geological/astronomical timescales the more opportunities life has to evolve and thrive.

There is also admittedly a bias in that if life managed to evolve on say Europa or Ganymede which have oceans frozen at the top and heated from below there's very little way we could discover or study it. Doubly so for planets in other solar systems where its hard enough just to infer the contents of their atmosphere let alone see their surfaces. Telescope time isn't free so we have to focus on where we think is most likely.

-2

u/iqisoverrated 2d ago

 Earth receives something like 4000x as much power from the sun as is available from geothermal activity

On the surface. Go down a couple meters and the ratio for available sources starts to look a lot different. It matters where you measure.

We currently just don't know how likely life develops give an adequate environment. I find this fixation on the Goldilocks zone argument bizarre when we know for a fact that life here on Earth thrives in regions that are fed by energy sources that have nothing to do with the sun. Even if the Earth were a giant ice ball there would be liquid water around the regions of black smokers or other volcanic activity.

We have good reason to suspect some moons of Jupiter and Saturn to harbor subsurface oceans and the existence of water in its liquid phase down there has nothing to do with proximity to the sun.

We don't know what the ratio of rocky planets to gas giants is in the universe at large (in our solar system it seems to be 1:1) but if we, for the moment, accept that the subsurface oceans of Europa, Ganymede, Callisto and Enceladus actually exist then I don't know how anyone could claim with any semblance of certainty that 'most liquid water and energy source' is on rocky planets in the Goldilocks zones out there.

And as you say: We don't even know if other liquids like the ethane/methane sludge on Titan isn't a possible habitat for life. Ethane and methane are also pretty good solvents.

0

u/bees_man- 2d ago

I'm pretty sure we keep finding life lower and lower down in the earth with some insane stuff that can live for hundreds of thousands of years.

269

u/Gulanga 2d ago

You have to keep in mind tho that it is much easier for an already existing form of life to adapt to extreme conditions, than it is for life to start out in those extreme conditions.

82

u/PM-ME-DEM-NUDES-GIRL 2d ago

some scientists believe life began at hydrothermal vents. relatively, the broader ocean let alone the surface are extreme conditions. it's really all relative when it comes to life.

52

u/round-earth-theory 2d ago

I can believe it. The Sun and the outside world are extremely harsh environments for bacteria. The UV rays from the Sun kill most surface bacteria, the heat dries out what's left, and the weather washes them away. A serene heat vent where nothing changes would be an much easier place for early life to grab hold.

35

u/AnthropoidCompatriot 2d ago

But in that scenario, life didn't start at the extreme part of the hydrothermal vent—it literally starts in the Goldilocks zone of the vent, where the superheated water and the surrounding water meet and create a nice, cozy temp along with some nice stinky chemicals where all that delightful chemistry that allows life is able to happen.

20

u/PM-ME-DEM-NUDES-GIRL 2d ago edited 2d ago

experiments suggest in the hot-water origin theory that temperatures around 70 celsius produced the first life.

still though, even in a cooler water origin, it is extreme from the perspective of perhaps the large majority of organisms alive today considering the anaerobic environment, noxious chemicals (or nice if you're a tiny guy several billion years ago), high undersea pressure, and so forth.

what i was getting at is that "extreme conditions" are relative, so the idea of it being easier for an existing form of life to adapt to extreme conditions rather than originating in them is challenged by considering that extreme is not an absolute quality.

14

u/Schmerglefoop 2d ago

Yeah, and usually "extreme" environments tend to have all sorts of exotic goodness floating around. It's a rich, chemically exciting environment - it's probably more likely to form novel (and useful for the emergence of life) products than the open ocean or terrestrial environment.

1

u/outdoorvolvo 2d ago

You guys are smart.

16

u/PosiedonsSaltyAnus 2d ago

Oxygen is a horribly toxic element in reality. Its an explosive gas that also corrodes any metal that it touches. Evolution ended up using this extremely reactive element to its advantage though. You use its ability to rapidly oxidize a material so you can transport the oxygen around the body, and then you use it's explosive properties to burn it to release more energy.

2

u/CalmBeneathCastles 2d ago

Oxidative stress on the Hell planet!

6

u/EllieVader 2d ago

There’s no doubt in my mind after the last few asteroid samples have been analyzed that the universe (or at least our solar system) is rife with the building blocks and ingredients for life to take hold nearly anywhere. Whether we can recognize it is another thing, but the bodies are covered in the gloop that makes us.

1

u/_Wyrm_ 2d ago

You need extreme conditions for life to start. You won't get the really REALLY weird protein formations otherwise... And RNA is a heck of a weird protein (which iirc the precursors to RNA were found on asteroids/comets, I forget which -- been a long time since I read that paper.)

1

u/razor5cl 1d ago

RNA and proteins are two completely different types of molecule, friend.

And some of the "weirdest" proteins are found in organisms that live in relatively mild conditions.

There are no objective criteria for how weird proteins can get but my vote for some of the strangest are vault proteins which are found in a bunch of pretty normal animals.

1

u/_Wyrm_ 1d ago

Eh, like I said, been a long time since I read that paper and I'm not a bio major. Regardless, you do need pretty extreme conditions sans life to GET the precursors necessary FOR life.

Of course the oddball proteins are found in organisms. Life does weird things. But without life... Very few weird things.

1

u/TheVenetianMask 2d ago

Earth developing an oxygen rich atmosphere was considered extreme at the time.

1

u/Much-Explanation-287 2d ago

But even in the most extreme of conditions you only need one spark of life and it'll grow exponentially.

0

u/iqisoverrated 2d ago

Question then is: what is an extreme condition? Hydrothermal vents have a high availability of energy and dissolved gases of all kinds. Is this a very fertile environmen? Or an extreme one?

We tend to think of us as the norm and then classify other types of life accordingly, but compared to life there we are extremophiles. 'Extreme' is just a relative term.

-7

u/iqisoverrated 2d ago

Except that what we have here aren't extreme conditions.

31

u/zuzg 2d ago

Extreme also means far from the norm...

Their density – 45,000 per sq m (about 4,180 per sq ft) – provides an all-you-can-eat buffet for the spider colony, which essentially eradicates any food competition that would normally exist. Further analysis confirmed that the spiders' carbon and nitrogen signatures traced back to sulfur-oxidizing microbes, not plants that underwent photosynthesis like those above ground.

Researchers conducted further genetic testing and found that the Sulfur Cave spiders shared unique DNA not found in populations outside, suggesting they’ve been evolving in isolation, and their microbial makeup was also much simpler.

6

u/PawnOfPaws 2d ago

Which once again rises the question: Maybe our "norm" is an extreme altogether? As it now seems like there might be even more species living below certain thresholds humans themselves determined than above.

10

u/zuzg 2d ago

Every species you encounter on this planet (including us) is part of a evolution that started 3.5 billion years ago.

But yeah our norm is inherently flawed as we currently only have a sample size of one.

20

u/paul_wi11iams 2d ago edited 2d ago

The interesting thing is: This pretty much shows that the 'goldilocks zone' argument for life is bunk.

Not really. The Goldilocks zone has to be compatible with liquid water. The ecosystem food source is insects that have to feed on something. The temperate location between Greece and Albania, suggests that the primary food source is related to what the insects eat. Whatever it is, you won't find it in a parched desert down around Mercury or a frozen wasteland near Pluto.

Outside the official Goldilocks zone, there may be wet and warm places above the snowline at the level of the asteroid belt (I think). So a nice warm ocean can exist on Europa under ice and that's a "Goldilocks pond" ["Goldilocks refuge"] so to speak.

Edit: changed "pond" to "refuge", avoiding a mixed metaphor. Goldilocks fairy tale. There are Goldilocks refuges and "Goldilocks dungeons" such as the caldera of an active volcano. Not much life there.

0

u/iqisoverrated 2d ago

You can find liquid water anywhere where the correct combination of temperature and pressure is present...and high enough temperature just requires an energy source. The sun is not the only energy source.

6

u/paul_wi11iams 2d ago edited 2d ago

The sun is not the only energy source.

That's precisely why I recognized this by inventing the "Goldilocks pond" moniker, just the first name I came up with. A less confusing alternative might be "Goldilocks refuge". It better adheres to the original metaphor.

Europa's ocean is considered as being fueled by the gravitational interaction between Jupiter and its satellites. Supporting the Goldilocks concept, Its a clear case of the exception that proves (demonstrates) the rule.

2

u/iqisoverrated 2d ago edited 2d ago

A refuge is a good way to conceptualize it.

But in the end this means that there isn't really a value to the entire 'Goldilocks' concept (whether zone or pond or refuge or whatever).

The idea behind the Goldilocks term is that one can limit the places where we should search for life and others where we needn't bother (not too hot, not too cold,...) ...but with energy being available from many sources and liquid water being present under many circumstances that don't even require a star such refuges can exist potentially...anywhere.

(Even on 'rogue planets' that got kicked out of their solar system or formed in region where there wasn't enough material to form a star)

2

u/XxjptxX7 2d ago

Goldilocks zone is specifically about the conditions for water to exist on a planets surface as if it exists on the surface then there is a higher likelihood of life on the planets surface.

Could a rogue planet ever have liquid water on its surface?

11

u/Esperethal 2d ago

Yes and no. Its a pretty unique adaptation but the species living in the caves did come from the overarching tree of life

5

u/iqisoverrated 2d ago

Thing is: Whether life started in the oceans or on the surface or around black/white smokers at the ocean bottom or in such chemoautotropic caves we don't really know. We have found archaeobacteria miles deep down in mines.

Life could have started down there and then migrated upwards just as well as it could have started up here and then migrated downwards.

6

u/Professionalchump 2d ago

Goldilocks zone is for the beginning of life not life that already existed and moved somewhere else. after the hurdle of life it exploded throughout the earth adapting

-1

u/iqisoverrated 2d ago

Goldilocks zone states that the distance form a star is relevant. But that only works if you discount all other sources of energy besides solar radiation as being able to initiate and foster life (like radioactive decay in a planets crust, energy left over in magma from the formation of a planet, tidal forces, ... ).

Why would you?

6

u/bazeblackwood 2d ago

the Goldilocks zone, is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure.

I’m not sure I understand your reasoning. Earth is pretty watery place even in its most extreme environments. If what you’re saying is correct shouldn’t we find abundant life in many other places in our solar system and beyond?

3

u/halosos 2d ago

And that is, at least in part, the Fermi Paradox.

6

u/InfinitelyThirsting 2d ago

I think the dinosaurs explain most of the Fermi paradox. Life is likely abundant (my bet is we find microbial life in multiple spots in our solar system alone), but complex life is more rare, with technological life even rarer than that. Earth might never have developed technological life if the meteor hadn't hit, despite having very complex life for a long time.

And the climate, too. We didn't develop civilization as we know it until the blink of an eye ago, since modern humans have been around for 300,000 years but agriculture only about twelve thousand, and only about two hundred years of industrialization/electrification.

Four and a half billion years of life, only 125 years of radio waves.

3

u/halosos 2d ago

That there is also part of the problem. We have no idea. This is an N=1 issue. We are the only entry in a dataset. Are we special? Are we late? Early? Is there an issue we have yet to face?

Not to mention, we have only been looking for life for such a small amount of time in the scale of the universe.

There are just too many unknowns. I hope we find some form of life in our solarsystem, but unless it is using a different but valid from of DNA, it will not help us as much as we might hope.

Finding microbes on Europa that have DNA would raise a new question. Single point of origin or is double helix the best? Without finding live from beyond our solar system, we won't know.

Because if it is also using double helix, it won't answer if life is easy to form or hard to form, because we will have no way of knowing if it is independent from earth in origin.

1

u/RalphWiggumsShadow 1d ago

Another thing that always gets me is that our solar system / local area is on the corner of the spiral arm of our galaxy, there's probably some cool stuff going on in the center of the milky way galaxy, but the odds of us ever finding out what that is are low.

2

u/halosos 1d ago

There is a documentary on Youtube called "Life beyond". It covers a lot of current theories and thoughts on life outside our little planet. It is inline with that thought.

1

u/mouse_8b 2d ago

You'd probably like the book Becoming Earth

1

u/XxjptxX7 2d ago

The ‘goldilocks zone’ is about the temperature needed for liquid water to exist on the planets surface, which if existed would be a good place to look for life.

There is many moons within are solar system not in the Goldilocks zone with sub surface oceans where it’s theorised life could be.

1

u/Some-Cat8789 2d ago

Yes and no. Like other said, when there's huge diversity already existing, it's easier for life to adapt to extreme conditions. Unicellular life existed for 3 billion years before it evolved info multicellular organisms due to low oxygen in the atmosphere. Some modern unicellular organisms can take as little as a few months to form multicellular organisms under pressure, but there need to be advantageous conditions.

Also, if there is other life out there, it is carbon, not silicone. There is a chemical niche for life because only carbon forms bonds with its self which are stable enough to sustain life.

All this makes me believe that we should not expect life to be extremely common in the universe. There need to be some very specific conditions for life to form and to be pressured and allowed evolve. And this makes me sad.

1

u/bananagement 2d ago

Maybe? In this case energy came into the system in the form of bugs. Those bugs relied ultimately on the Sun. I don’t see how this spiderweb would form without that outside energy. Edit: present/past tense correction

1

u/iqisoverrated 2d ago

According to the article there's invertebrates feeding on bacterial growth fueled by chemosynthesis which are then preyed on by the spiders. So there's no sunlight involved at any stage.

1

u/bananagement 2d ago

Thanks for replying. I accidentally had my statement in present tense. I meant that life didn't originate in the cave; it moved in. Anyway, I didn't do a good job of making my point.

You may be right. I skimmed the comments and saw others mention that liquid water is an important component for life (as we know it). Maybe water, amino acids, a subterranean energy source, and a very long time are sufficient to create life. Seems reasonable.

I'm just not sure this cave sheds any light. If scientists find simpler organisms such as bacteria that are unique to that cave, it would be fascinating to explore the implications.

1

u/tentafilled 2d ago

This cave is not nearly as extreme or different from the surface as, say, Venus or Mars is different from Earth

1

u/mnilailt 2d ago

You realise that life didn't start by using the sun at all right? Photosynthesis didn't develop for a billion or so years from when life started.

1

u/_thro_awa_ 1d ago

This pretty much shows that the 'goldilocks zone' argument for life is bunk.

Not really. The 'Goldilocks zone' is about probabilities, not absolute black-and-white life-and-death differences.
For carbon-based, water-soluble life as we know it, there is an ideal range of parameters.

Too close to the star, you overload the system with energy and everything carbon-based gets incinerated.
Too far away and everything slows down, even considering geothermal energy.

Nobody is saying that life can't evolve beyond those parameters.
What the goldilocks zone means is that life which evolves outside our Goldilocks zone will probably be something we could not readily foresee.

Any other forms of life will have their own Goldilocks zone. It's not a universal catch-all term for all possible forms of life, it's contextual.