A while back I read a book called Extinction by Douglas H. Erwin. It was a history of the end-Permian event.
There were a few interesting takeaways:
1) When people started realizing that these dieoffs happened there was a belief that there was probably a common cause like impactors, but end-Permian almost certainly wasn't an impactor like K-T was. There are several things that can kick-off an extinction
2) One thing that is true is that the extinctions seem to follow the same script. Lots of things can kick them off, but once they start going it's a rock rolling down a hill very quicky. End-Permian seems tied to the Siberian Traps basaltic eruption, but that eruption had been going for thousands of years before the dieoff started.
K-T definitely happened within years following the impact, but end-Permian seemed to be a "first gradually, then suddenly" as pollution from the traps put more and more stress on the biosphere until suddenly...
3) He posed the question: are we currently in an great extinction. He wrote that we are not because they look at the fossil record of really fundamental creatures (stuff like krill in the ocean) upon which the whole biosphere relies, and we're not yet seeing them collapse. But once such a collapse begins, it will be something that is unstoppable.
4) He thought that there is a big gap in our knowledge of survival and recovery. Why have none of these massive events just turned the planet into a dead world? How does life come back? Historically the early-Triassic was seen as a really boring thing to study because there's not much evidence of life in it, but understanding how life soldiers on through these "wasteland Earth" episodes is potentially a fertile ground for research.
* End-Permian is associated with the Siberian Traps, but those in turn are associated with the Wilkes Land Crater impactor, which is antipodal to that event and may have seen antipodal seismic focusing.
* "Going on for thousands of years" - Dating the End-Permian has confidence intervals on the order of 30,000 years.
* Small size and diverse ecology almost guarantees survival of life. There is life basically everywhere we look, down to extremophiles living very slow lives in a random cubic meter of "solid rock" two kilometers deep. We have even evolved several chemical alternatives to photosynthesis as a primary energy source. Mammals and small birds deep in a cave somewhere appear to have been some of the only land vertebrates to survive K-T, and radiated out from there. Evolution does the rest.
Erwin discusses that theory but doesn't agree with it.
In any case, 1) there are other mass dyings that are definately not impactors like the oxygen crisis. 2) there are other basaltic eruptions on the scale of the siberian traps (like CAMP) where the cause is known and not an impactor.
P-T is likely not due to the Wilkes Land crater, which would be 2.5x the size of the K-Pg impact and would have left an comparable amount (or more) of iridium in the boundary sediments. There are elevated iridium levels in the P-T boundaries, but only sporadically.
The theory being something along the lines of "Large mantle plume under Siberia suddenly freed when surface crust is fractured in numerous places by extensive antopodal convergence of shockwaves from the Wilkes Land impactor".
If the Wilkes Land formation is an impact crater (not proven) it's 2x the size of Chicxulub. You don't need any vulcanization in Siberia to explain a mass extinction.
But it's not proven to be an impact crater, nor is its age determined with any specificity. There's the lack of Iridium, and Erwin also had complaints about the modeling for an "antopodal convergence crack."
> End-Permian seems tied to the Siberian Traps basaltic eruption,
> but that eruption had been going for thousands of years before
> the dieoff started.
The eruptions probably hadn't been "going for thousands of years." We can't "see" time periods as small as a few thousands years from a vantage point of 250 million years later.
Biologists like to proclaim that things are gradual when they're really more likely sudden. This often reflects mathematical ignorance. For example, if the last specimin of a certain rare fossil is found in a stratum slightly older than the K-T stratum, does that mean it went extinct earlier than the K-T event? Probably not; it just means the fossil is rare so your sampling error is larger.
I'm massively summarizing the book but he talks a lot about the history of the timeline for end-Permian.
At the time of writing of the book it was "less than 60k years" which seems like a long time, but when the extinction was first discovered it was believed to be a very gradual change taking place over 10 million years, turns out that it was believed that end-Permian and end-Guadalupian were the same event.
As isotope dating has gotten more and more accurate, the length of time for end-Permian has gotten shorter and shorter. There's also other evidence that it was a very sudden event, evidence of fungal explosions for instance during the event suggesting massive amounts of decomposition.
In any case, as I said the P-T took "no more than 60k years" but the Siberian traps were erupting for at least 120k years before, so there's at least 60k years unaccounted for between the start of the eruptions and the start of the extinction.
Concerning: "Why have none of these massive events just turned the planet into a dead world?".
Among other rationales: survivorship bias / anthropic principle. Of all the worlds in which a mass extinction event has wiped out all life prior to the emergence of a technologically-advanced species, there would be no (indegenous) witnesses to the fact. We are only here to ponder that question because utter annihilation did not occur.
You can make a similar argument about any catastrophic risk/event, and I was delighted to discover a few years ago that Richard Posner (former US federal judge) did just that:
By definition, all but the last doomsday prediction is false. Yet it does not follow, as many seem to think, that all doomsday predictions must be false; what follow is only that all such predictions but one are false.
-Richard A. Posner, Catastrophe: Risk and Response, p. 13.
There are of course other points to be argued, including the resilience of life and its (possible) capacity to re-emerge multiple times. I suspect this was the case in the history of the early Earth, though of course there is vanishingly small prospect of finding any evidence of such an event.
Once life did become widespread (~3--3.5 bya) it does seem to have had remarkable tenacity.
>but end-Permian seemed to be a "first gradually, then suddenly" as pollution from the traps put more and more stress on the biosphere until suddenly...
Not an expert on this by any means, but I always found this short series [1] quite fascinating on how cyanobacteria over a period of 200-300 million years coverted the planet from being methane based to being oxygen based, created the ozone layer and paved the way for photosynthesis, oxygen and life as we know it. I can't remember if I'm being too optimistic when I'm recalling bacteria doing something similar for the mass extinctions?
I wonder if the P-T extinction was due not just to CO2 release from the volcanism (and the other bad effects from the magma intruding into the largest/oldest sedimentary basin in the world), but also due to authigenic clay formation in the ocean.
When clay forms in the ocean, it pulls calcium out of seawater. Calcium is normally balanced by two bicarbonate ions, so its removal causes the bicarbonate to shift back to carbonic acid/CO2. The ocean acidifies and CO2 is released. This has been called "anti-weathering", since it's the opposite of the normal process that draws down CO2 by weathering of silicates.
Sufficient injection of silicic acid and aluminum into the ocean could accelerate this process.
Not sure about clay I haven't heard anything about that. If it formed in large quantities at that time it should still be in sediments.
The ocean was acidic and anoxic and that was likely a cause of the extinction.
There definitely wasn't enough inorganic carbon released to fully account for the amount of warming that occurred (about 12°C). This was a big part of the book and highly technical (just the explanation of organic versus inorganic carbon was a chapter) so I'm afraid to try to summarize I think I'll get it wrong. But the author's theory was that methane was in the mix as well, released by cooking off carboniferous coal deposits.
The issue is not just the increase in CO2 at the P/T boundary, but the unusual persistence of high CO2 levels for 5 million years. In contrast, the CO2 spike from the CAMP flood basalts lasted only 300 thousand years. The paper proposes that the ocean became enriched in dissolved silica due to the loss of silica-secreting microorganisms (as indicated by lack of chert deposits during this time), and that this caused enhanced "reverse weathering" that kept CO2 levels high.
> He thought that there is a big gap in our knowledge of survival and recovery.
Well, you don't want to know how far you can safely bend over the cliff before falling down. I think attempts to gain such knowledge in a practical way should be explicitly banned.
Though I have extreme reservations about the current state of conservation science (on questions of nature and it's own agency), this is precisely why conservation is extremely important. We must protect what we have left to let nature adjust to what we become and want to be: https://eos.org/features/critical-zone-science-comes-of-age
I have heard that scientists estimate at something like 99.9% of all species that ever lived have ZERO evidence left in the fossil record.
While I think that a great many things can be learned by studying the relative few fossils discovered; making broad assumptions about ecosystems based on limited evidence seems like a bit of a stretch.
One way they do that is by focusing not on megafauna but on creatures that exist in immense numbers in a biosphere like insects or even smaller creatures. They also look at pollen and other biological matter that gets spread evenly.
They can also look at the effects life has on the structure and chemistry of earth. For instance, they know when oxygenation happened because there are chemicals in older rocks that can not form in the presence of oxygen, while there are chemicals in younger rocks that can only form in the presence of oxygen.
A big evidence that the end-Permian effected land as much as the ocean is the behavior of rivers. When plants are present, rivers tend to meander because plant roots hold onto the river banks. When plants are not present, the river is able to take the shortest path to the ocean. Rivers banks laid down at the end of the Permian meander, river banks laid down at the start of the Triassic do not.
> Rivers banks laid down at the end of the Permian meander, river banks laid down at the start of the Triassic do not.
* subject to relative flatness
But what an interesting thought, I'd never considered how river topography might indicate world conditions. So start of Triassic really was a blow to life!
What is this anti-scientific comment doing on hacker news? Evolution is a fact. It happened and it's still happening. The exact way species evolved is theoretical based on existing facts.
We literally know how genes change which cause evolution can do it ourselves, can measure how genes have changed between different groups of people and compared to animals and regularly evolve ecoli in real time for medical research
Nah, evolution is much more predictive than creation myths -- to the point we've been able to cause speciation in labs simulation conditions aligned to evolutionary theory. Evolution isn't based solely on fossil records, and truth be told Judeochristian creationism couldn't account for extinction which the fossil record indicated. The 0.01% evidence is just a biased sample, but even a biased sample can be useful in context.
Remember -- a good theory fits the evidence, and a good metaphysical framework allows adaption and update of truth with new evidence.
Genetic algorithms work, and you can observe evolution in
bacteria simply by exposing them to an acidic environment for several generations, so what do you mean by creation myth?
Latin "Terra" actually meant "dry", so it was the proper term for dry lands, as opposed to seas and oceans. For instance, "continent" is an abbreviation for "terra continens", i.e. dry land that is contiguous. Spanish "tierra" and the cognate words in the other Romance languages, which usually correspond to English "land", have remained closer to the original meaning of the word.
The entire planet was very seldom, if ever, referred as "Terra". The correct Latin word for the entire planet was "Tellus" (whence the adjective "telluric"), whose likely meaning was "support" in the sense "the earth that supports us on it".
It does stand to reason that if there was life on Mars there might still be life on Mars. Everywhere we look on Earth, life exists, even in extreme environments and independent of the sun's energy.
I think the first alien we'll find will be an extremophile bacteria or other microorganism.
Almost certainly microorganism, but not necessarily extremophile. It depends what you mean by "find". We might "find" oxygen in an exoplanet atmosphere and go, "yay, they have... algae?" :D
With N=1, we know that life exists but not how common different development might be. Algae on another planet would suggest panspermia of common development pathways.
Well, you don't actually get an id as specific as earthlike algae from an atmospheric spectrum (I guess I didn't actually say that's what I was thinking. Oops :D). If you actually went there and found earthlike DNA, then yes.
Life will survive what humans have done. When our numbers are dropped substantially by many C's of climate change a lot of wildlife will be able to repopulate and survive although much wont because it will be too hot for correls and many other species. We are taking many species with us every year at the moment, its a mass extinction event, but even if we fire all our nuclear weapons we wont wipe out all the land animals and fauna. Its not just humans being put in jeopardy by what we are doing but it ought to be enough to get off this maybe extinction path.
1.5C done, Onwards to 2C, should hit it before 2030.
A while back I read a book called Extinction by Douglas H. Erwin. It was a history of the end-Permian event.
There were a few interesting takeaways:
1) When people started realizing that these dieoffs happened there was a belief that there was probably a common cause like impactors, but end-Permian almost certainly wasn't an impactor like K-T was. There are several things that can kick-off an extinction
2) One thing that is true is that the extinctions seem to follow the same script. Lots of things can kick them off, but once they start going it's a rock rolling down a hill very quicky. End-Permian seems tied to the Siberian Traps basaltic eruption, but that eruption had been going for thousands of years before the dieoff started.
K-T definitely happened within years following the impact, but end-Permian seemed to be a "first gradually, then suddenly" as pollution from the traps put more and more stress on the biosphere until suddenly...
3) He posed the question: are we currently in an great extinction. He wrote that we are not because they look at the fossil record of really fundamental creatures (stuff like krill in the ocean) upon which the whole biosphere relies, and we're not yet seeing them collapse. But once such a collapse begins, it will be something that is unstoppable.
4) He thought that there is a big gap in our knowledge of survival and recovery. Why have none of these massive events just turned the planet into a dead world? How does life come back? Historically the early-Triassic was seen as a really boring thing to study because there's not much evidence of life in it, but understanding how life soldiers on through these "wasteland Earth" episodes is potentially a fertile ground for research.
* End-Permian is associated with the Siberian Traps, but those in turn are associated with the Wilkes Land Crater impactor, which is antipodal to that event and may have seen antipodal seismic focusing.
* "Going on for thousands of years" - Dating the End-Permian has confidence intervals on the order of 30,000 years.
* Small size and diverse ecology almost guarantees survival of life. There is life basically everywhere we look, down to extremophiles living very slow lives in a random cubic meter of "solid rock" two kilometers deep. We have even evolved several chemical alternatives to photosynthesis as a primary energy source. Mammals and small birds deep in a cave somewhere appear to have been some of the only land vertebrates to survive K-T, and radiated out from there. Evolution does the rest.
> associated with the Wilkes Land Crater impactor
Erwin discusses that theory but doesn't agree with it.
In any case, 1) there are other mass dyings that are definately not impactors like the oxygen crisis. 2) there are other basaltic eruptions on the scale of the siberian traps (like CAMP) where the cause is known and not an impactor.
P-T is likely not due to the Wilkes Land crater, which would be 2.5x the size of the K-Pg impact and would have left an comparable amount (or more) of iridium in the boundary sediments. There are elevated iridium levels in the P-T boundaries, but only sporadically.
The theory being something along the lines of "Large mantle plume under Siberia suddenly freed when surface crust is fractured in numerous places by extensive antopodal convergence of shockwaves from the Wilkes Land impactor".
If the Wilkes Land formation is an impact crater (not proven) it's 2x the size of Chicxulub. You don't need any vulcanization in Siberia to explain a mass extinction.
But it's not proven to be an impact crater, nor is its age determined with any specificity. There's the lack of Iridium, and Erwin also had complaints about the modeling for an "antopodal convergence crack."
Biologists like to proclaim that things are gradual when they're really more likely sudden. This often reflects mathematical ignorance. For example, if the last specimin of a certain rare fossil is found in a stratum slightly older than the K-T stratum, does that mean it went extinct earlier than the K-T event? Probably not; it just means the fossil is rare so your sampling error is larger.
I'm massively summarizing the book but he talks a lot about the history of the timeline for end-Permian.
At the time of writing of the book it was "less than 60k years" which seems like a long time, but when the extinction was first discovered it was believed to be a very gradual change taking place over 10 million years, turns out that it was believed that end-Permian and end-Guadalupian were the same event.
As isotope dating has gotten more and more accurate, the length of time for end-Permian has gotten shorter and shorter. There's also other evidence that it was a very sudden event, evidence of fungal explosions for instance during the event suggesting massive amounts of decomposition.
In any case, as I said the P-T took "no more than 60k years" but the Siberian traps were erupting for at least 120k years before, so there's at least 60k years unaccounted for between the start of the eruptions and the start of the extinction.
Concerning: "Why have none of these massive events just turned the planet into a dead world?".
Among other rationales: survivorship bias / anthropic principle. Of all the worlds in which a mass extinction event has wiped out all life prior to the emergence of a technologically-advanced species, there would be no (indegenous) witnesses to the fact. We are only here to ponder that question because utter annihilation did not occur.
You can make a similar argument about any catastrophic risk/event, and I was delighted to discover a few years ago that Richard Posner (former US federal judge) did just that:
By definition, all but the last doomsday prediction is false. Yet it does not follow, as many seem to think, that all doomsday predictions must be false; what follow is only that all such predictions but one are false.
-Richard A. Posner, Catastrophe: Risk and Response, p. 13.
<https://archive.org/details/catastropheriskr00posn/page/13/m...>
(Previously mentioned: <https://news.ycombinator.com/item?id=34647615>).
There are of course other points to be argued, including the resilience of life and its (possible) capacity to re-emerge multiple times. I suspect this was the case in the history of the early Earth, though of course there is vanishingly small prospect of finding any evidence of such an event.
Once life did become widespread (~3--3.5 bya) it does seem to have had remarkable tenacity.
>but end-Permian seemed to be a "first gradually, then suddenly" as pollution from the traps put more and more stress on the biosphere until suddenly...
AKA the Seneca effect. See https://terebess.hu/keletkultinfo/seneca.pdf
Thanks for adding to this.
Not an expert on this by any means, but I always found this short series [1] quite fascinating on how cyanobacteria over a period of 200-300 million years coverted the planet from being methane based to being oxygen based, created the ozone layer and paved the way for photosynthesis, oxygen and life as we know it. I can't remember if I'm being too optimistic when I'm recalling bacteria doing something similar for the mass extinctions?
See also [2]
[1] https://www.bbc.co.uk/programmes/p09xj73n
[2] https://asm.org/Articles/2022/February/The-Great-Oxidation-E...
I wonder if the P-T extinction was due not just to CO2 release from the volcanism (and the other bad effects from the magma intruding into the largest/oldest sedimentary basin in the world), but also due to authigenic clay formation in the ocean.
When clay forms in the ocean, it pulls calcium out of seawater. Calcium is normally balanced by two bicarbonate ions, so its removal causes the bicarbonate to shift back to carbonic acid/CO2. The ocean acidifies and CO2 is released. This has been called "anti-weathering", since it's the opposite of the normal process that draws down CO2 by weathering of silicates.
Sufficient injection of silicic acid and aluminum into the ocean could accelerate this process.
Not sure about clay I haven't heard anything about that. If it formed in large quantities at that time it should still be in sediments.
The ocean was acidic and anoxic and that was likely a cause of the extinction.
There definitely wasn't enough inorganic carbon released to fully account for the amount of warming that occurred (about 12°C). This was a big part of the book and highly technical (just the explanation of organic versus inorganic carbon was a chapter) so I'm afraid to try to summarize I think I'll get it wrong. But the author's theory was that methane was in the mix as well, released by cooking off carboniferous coal deposits.
This is the paper I was thinking of:
https://pubs.geoscienceworld.org/gsa/geology/article/50/6/65...
The issue is not just the increase in CO2 at the P/T boundary, but the unusual persistence of high CO2 levels for 5 million years. In contrast, the CO2 spike from the CAMP flood basalts lasted only 300 thousand years. The paper proposes that the ocean became enriched in dissolved silica due to the loss of silica-secreting microorganisms (as indicated by lack of chert deposits during this time), and that this caused enhanced "reverse weathering" that kept CO2 levels high.
> He thought that there is a big gap in our knowledge of survival and recovery.
Well, you don't want to know how far you can safely bend over the cliff before falling down. I think attempts to gain such knowledge in a practical way should be explicitly banned.
His point was people should be more interested in the early Triassic.
Some total niche bacteria doing millenias of groundwork.
Thanks for the great summary!
The technical term, as mentioned in the article, is refugium: https://en.wikipedia.org/wiki/Refugium_(population_biology). Using the term oases is mildly irking, haha.
Though I have extreme reservations about the current state of conservation science (on questions of nature and it's own agency), this is precisely why conservation is extremely important. We must protect what we have left to let nature adjust to what we become and want to be: https://eos.org/features/critical-zone-science-comes-of-age
Source: I work in palaeoecology.
I have heard that scientists estimate at something like 99.9% of all species that ever lived have ZERO evidence left in the fossil record.
While I think that a great many things can be learned by studying the relative few fossils discovered; making broad assumptions about ecosystems based on limited evidence seems like a bit of a stretch.
Scientists are aware and account for that.
One way they do that is by focusing not on megafauna but on creatures that exist in immense numbers in a biosphere like insects or even smaller creatures. They also look at pollen and other biological matter that gets spread evenly.
They can also look at the effects life has on the structure and chemistry of earth. For instance, they know when oxygenation happened because there are chemicals in older rocks that can not form in the presence of oxygen, while there are chemicals in younger rocks that can only form in the presence of oxygen.
A big evidence that the end-Permian effected land as much as the ocean is the behavior of rivers. When plants are present, rivers tend to meander because plant roots hold onto the river banks. When plants are not present, the river is able to take the shortest path to the ocean. Rivers banks laid down at the end of the Permian meander, river banks laid down at the start of the Triassic do not.
> Rivers banks laid down at the end of the Permian meander, river banks laid down at the start of the Triassic do not.
* subject to relative flatness
But what an interesting thought, I'd never considered how river topography might indicate world conditions. So start of Triassic really was a blow to life!
[flagged]
What is this anti-scientific comment doing on hacker news? Evolution is a fact. It happened and it's still happening. The exact way species evolved is theoretical based on existing facts.
[flagged]
Make reddit style claims, get reddit style responses [0] [1]
[0] https://imgflip.com/i/voggo
[1] https://tenor.com/view/watch-it-gif-3524753964604521397
I feel like the basis of your argument requires you to very heavily misinterpret the word theory as being equal to the word belief.
There's a reason those two things have different words for them. You know that, right?
Don't feed the troll. Especially don't feed them with tricky semantic distinctions.
We literally know how genes change which cause evolution can do it ourselves, can measure how genes have changed between different groups of people and compared to animals and regularly evolve ecoli in real time for medical research
That's 0.01% more evidence than competing theories, no?
Nah, evolution is much more predictive than creation myths -- to the point we've been able to cause speciation in labs simulation conditions aligned to evolutionary theory. Evolution isn't based solely on fossil records, and truth be told Judeochristian creationism couldn't account for extinction which the fossil record indicated. The 0.01% evidence is just a biased sample, but even a biased sample can be useful in context.
Remember -- a good theory fits the evidence, and a good metaphysical framework allows adaption and update of truth with new evidence.
I think we agree. Regardless of the actual numbers, we clearly have more evidence for evolution than anything else.
Genetic algorithms work, and you can observe evolution in bacteria simply by exposing them to an acidic environment for several generations, so what do you mean by creation myth?
[dead]
I love the retro cgi article image, it gives me fuzzy nostalgic feelings for the 90s era of Myst, Reboot and The Mind's Eye.
The artist appears to be committed to the bit:
https://fineartamerica.com/profiles/corey-ford?tab=artwork
Ok I went looking through those paintings. That is an ... odd account. AI? Not AI? Looks like mostly just screenshots from some 90's computer games.
I think it's safe to say she learned 3D art in the early 2000s and has not updated her PC since.
Yeah it reminds me of POV-Ray, in a fun way!
> Scientists have debated whether this event caused nearly as much terrestrial destruction.
Is this the right phrasing? I thought the whole planet was terrestrial
Not a distinction between sea and land life
Latin "Terra" actually meant "dry", so it was the proper term for dry lands, as opposed to seas and oceans. For instance, "continent" is an abbreviation for "terra continens", i.e. dry land that is contiguous. Spanish "tierra" and the cognate words in the other Romance languages, which usually correspond to English "land", have remained closer to the original meaning of the word.
The entire planet was very seldom, if ever, referred as "Terra". The correct Latin word for the entire planet was "Tellus" (whence the adjective "telluric"), whose likely meaning was "support" in the sense "the earth that supports us on it".
Using "terrestrial" to refer only to land-based life is proper, i.e., it's a common and accepted definition of the word.
It seems to me that “refugia” would be more apposite word for this phenomenon than “oases.”
<https://news.ycombinator.com/item?id=43436432>
Yes, and the oasis was Noah's ark.
This is also why some hypothesize that Mars may not be a dead rock.
It does stand to reason that if there was life on Mars there might still be life on Mars. Everywhere we look on Earth, life exists, even in extreme environments and independent of the sun's energy.
I think the first alien we'll find will be an extremophile bacteria or other microorganism.
Almost certainly microorganism, but not necessarily extremophile. It depends what you mean by "find". We might "find" oxygen in an exoplanet atmosphere and go, "yay, they have... algae?" :D
That would be hugely important, actually.
With N=1, we know that life exists but not how common different development might be. Algae on another planet would suggest panspermia of common development pathways.
Well, you don't actually get an id as specific as earthlike algae from an atmospheric spectrum (I guess I didn't actually say that's what I was thinking. Oops :D). If you actually went there and found earthlike DNA, then yes.
Life will survive what humans have done. When our numbers are dropped substantially by many C's of climate change a lot of wildlife will be able to repopulate and survive although much wont because it will be too hot for correls and many other species. We are taking many species with us every year at the moment, its a mass extinction event, but even if we fire all our nuclear weapons we wont wipe out all the land animals and fauna. Its not just humans being put in jeopardy by what we are doing but it ought to be enough to get off this maybe extinction path.
1.5C done, Onwards to 2C, should hit it before 2030.