How Long Does Mass Extinction Take?

http://www.smithsonianmag.com/science-nature/how-long-mass-extinction-180949711/

by zvanness • 12 years ago

83 50 12 years ago

jofer2• 12 years ago

I'm impressed, that's a surprisingly good pop-sci-style article. The writing is clear, correct, accessible, and a nice summary of the scientific context for the paper in question. The original PNAS article is also clearly linked.

At least with geoscience, science journalists usually manage to get things horribly wrong. Judging from previous articles, Helen Thompson (the writer) looks like she might be a biologist instead of a geologist, but she nailed the subject matter, regardless.

mathattack2• 12 years ago

I agree - well written. Perhaps the only quibble is that my intuition was that it would be much shorter. 60,000 years (or even 5,000) is a long time to react.

AutoCorrect2• 12 years ago

you say react as if there's an awareness by the group of organisms that they are dying out, when that's far from the truth. Think of a species as a network, with the leaf nodes around for only a specific length of time. Add in several events that isolate portions of the network, and it dies off in spurts, as each isolated portion becomes less fit and eventually ceases reproduction.

With the decline in our birthrate, it will be interesting to see (from a historical perspective, I'll be long dead) if we die out, or if we get out of this funk we're in now.

rquantz• 12 years ago

This reminds me of the recent episode of Radiolab that suggested the extinction event at the end of the Cretaceous might have taken only a few hours[1]. If you thought this article was pop-y, you might be in for a surprise, but I found it quite entertaining.

[1] http://www.radiolab.org/story/dinopocalypse/

DanielBMarkham• 12 years ago

Mankind has most likely already passed an extinction level event with the creation of solid-state circuits.

So I guess we'll be finding out shortly (i.e., the next 100-1000 years)

ASpring• 12 years ago

I don't follow. Care to expand?

benjamincburns• 12 years ago

I think what he's trying to say is "we're all gonna die!!!!"

iand• 12 years ago

Singularity

lettergram• 12 years ago

I really enjoyed this article, well written and informative.

That being said, it seemed to be posted with perfect timing; I was thinking about this walking to work today. What if all of these mass extinctions (hypothetically or other wise) were caused by some species on the planet similar to us. Granted there is NO EVIDENCE for this, but what if... It seems that all mass extinction events happen in similar ways, each time some parts of an ecosystem are disturbed and it collapses.

Then, the most highly adaptable (fungi, bacterium, viruses are the most due to their short lifespan) survive. It's interesting to note that it took 30,000 - 50,000 years for the humans to develop this extremely complex society and ecosystem. Perhaps so short that when if we were destroyed this very day nothing would remain, say from nuclear war. All of our buildings would decay and there would be very little remnant in the fossil record.

I am not claiming any of this to be true, nor do I even believe any of it to be true. It was just an interesting thought I had that horrified me, and I felt I would share it.

cbp• 12 years ago

A little off-topic but the fantasy series Broken Empire are set in a post-apocalyptic world similar to the one you described. When I read them I thought that was very original.

nicholas73• 12 years ago

I doubt there wouldn't be evidence. A steel building frame probably preserves better than bone. A global population of tool making beings should at least leave some fossil evidence even if their timeline was only 30-50k years. Lastly, the distribution of natural resources might leave some evidence (like not finding ore where you would expect it).

DougWebb• 12 years ago

Have you seen a steel bridge lately? They require constant maintenance to prevent them from rusting away. Even stainless steel will rust eventually. The only thing that lasts more than centuries is stone, and only the really hard stones will last for thousands of years.

The other problem is location. Humans like to build on coastlines, and coastlines shift. We have very little evidence of ice-age era settlements today, but the few sites we do know of show that there were some pretty sophisticated societies around at the time. It's very likely that there are/were more sites, but today they're under a few hundred feet of water off our coasts.

As far as natural resources: apparently there are extensive empty holes in the ground around the great lakes that used to be full of copper ore, based on what's left in the walls. So much copper ore that the mining must have gone on for centuries, or involved tens of thousands of people. No one knows who did that, but a likely possibility is the Phoenicians during the Bronze Age. So that's one example of the type of evidence you're talking about, albeit for a more recent period. To go back much further, we'd have to know what kind of resources they were after and where, and hope that the landscape hasn't changed so much that we can't recognize the evidence of resource mining.

icegreentea• 12 years ago

Actually, once the frame collapses and gets covered in earth, it'll likely decay way faster than bone. Note the incredible lack of early iron age tools compared to bronze age tools.

That said, it's super unlikely that all, or even most traces of humanity will be gone. As you point out, the redistribution of resources - most specifically our landfills will probably be clear signals on the time scales of at least 10s or maybe 100s of thousands of years.

Steuard3• 12 years ago

Unless the intelligent Velociraptors had a "World War 3" that featured a massive, targeted asteroid strike near what's now Mexico, I think there's geological evidence for non-intelligent causes for a lot of these. (Or, building on this article, did the Trilobite People trigger the massive Siberian lava flows that ended the Permian?)

Still a fascinating question, mind you! (But honestly, I'm dubious that anything humanity could do today would lead to a Permian-scale mass extinction. That one was remarkable.)

vanderZwan2• 12 years ago

It's interesting to note that it took 30,000 - 50,000 years for the humans to develop this extremely complex society and ecosystem. Perhaps so short that when if we were destroyed this very day nothing would remain, say from nuclear war. All of our buildings would decay and there would be very little remnant in the fossil record.

That reminds me of something:

The [Science of Discworld] also features a fictional crab civilization and the dinosaurs (both of which are wiped out by comets/asteroids colliding with the earth), before jumping ahead to when an advanced civilization (presumably humans) has evacuated the earth due to an impending natural disaster.

http://en.wikipedia.org/wiki/The_Science_of_Discworld

Anyway, I wouldn't be surprised if (for example) the field of astrobiology is thinking about what could be used as indirect proof of intelligent lifeforms tampering with an ecosystem. Also, while you are obviously are aware of this, I think it's worth emphasizing that all mass extinctions showing a similar pattern is not a proof agency.

PakG1• 12 years ago

This is exactly the scenario that was presented by Ian Malcolm in Michael Crichton's The Lost World.

Blahah• 12 years ago

John Baez's excellent Azimuth project has a really good summary of current scientific understanding of mass extinction events: http://www.azimuthproject.org/azimuth/show/Extinction.

ChuckMcM2• 12 years ago

Its a great way of trying to get a more precise timeline. Now I wonder if we should start planting radiometric time capsules, time capsules with long half life materials, a description of what is happening, and a bit of isotope and its stats. Every 10 years you could do another one. And when the next extinction hits, should the life after that be intelligent again, they could find this set of events and date them relative to where they are now. Perhaps we could finish with "Hey we were too silly to leave the planet, don't make that mistake, its totally worth it to figure out how to survive off planet."

mitchty• 12 years ago

This strikes me so much of mass effect 3 and the "sit on your butt and don't decide" ending.

Actually its a fun thought problem. How would we convey to a follow up intelligent species what we did wrong if things go bad?

Lets assume squid take over the planet (hey why not they're smart), what would we have to do to allow them to understand?

We have to control for a lot of situations: * Assume they don't consider past relics a heresy to their religion (assuming again that they even have a corrolary). If they're destroyed in that regard its pretty much wasted effort. * Try and assume how long it would take for intelligent life to re-appear. The timeline for this is somewhat critical to any decision we make on how we build a marker/library of "don't eff this up and get off this rock pronto". Or whatever we choose.

I'm sure there are more but I"m at work so not much time to devote to this thought experiment.

TeMPOraL• 12 years ago

A little off-topic; I got that ending when after few minutes of careful consideration and weighting my moral values I got angry, turned around and shot the hologram. Damn, ME3 has some deep moments. I ultimately went with "take control" ending, saying to myself "please please, don't be evil", as it was the only one that seemed reasonably right.

I don't remember any other game where I literally thought for like 10 minutes before making a choice.

erikpukinskis4• 12 years ago

I've heard this "survive off planet" concept over and over, and inevitably someone points out that even after the worst conceivable environmental disasters, Earth will still be more habitable than any planet within 1000 years travel.

And I've never heard a compelling response to that, so why do people still think leaving the planet is important for our survival?

The only scenario I can think of where a radiation-soaked pocket in the Canadian mountains is less habitable than "off planet" is when the Sun starts dying. But that's not really a pressing concern.

AutoCorrect2• 12 years ago

depends - with water and sunlight we should be able to colonize several planets in our solar system - getting sustainable crops going might be a problem, but once the soil biome is established: profit!

svachalek• 12 years ago

I think it's more of an "eggs in one basket" issue than thinking there's any better home for us out there.

Gravityloss• 12 years ago

Even during the disasters there's gas pressure and radiation shielding at least.

sgk284• 12 years ago

Who says we need to move off of this planet and on to another? See the Stanford Torus[1].

We could live in stations such as that and hop down to planets to mine new materials (or from asteroid mining) when we had to. The entire world's population could fit in about 30,000 of those stations (assuming it's designed for 140,000 people). Having the human race distributed across 30,000 stations scattered around the solar system / galaxy would certainly make the race more robust to mass extinction events.

[1] http://en.wikipedia.org/wiki/Stanford_torus

gizmo686• 12 years ago

I agree that a (human) extinction level event is unlikely on Earth. However, from my perspective, the surivale benifits of moving to another planet is more to protect us from sudden unforeseen changes. Even if Earth is still more habitable then, say, Mars, we would have already set up and been using the infrastructure on Mars needed to survive, whereas our current life on Earth is much more dependent on planet supplied infastructure, which is at liberty to change suddenly. The other benifit is that we can take lessons and technologies applied to living off world, and apply it on world.

brownbat4• 12 years ago

Right, and I'd add that once your species has survived interstellar travel at sublight velocities, you are no longer a planetary species.

The day we have ships that can get us to new planets will be the day there's no reason to go there.

Steuard3• 12 years ago

If we had a self-sufficient colony on Mars (or wherever), that could provide a reservoir of both population and (perhaps more importantly) civilization and technology that would allow our descendants to return and re-colonize the Earth (or rebuild its infrastructure) after a major disaster.

Even though Mars is clearly less habitable than Earth in general, the point is that the humans living there would be ready for it. If there were a disaster here that killed off most of our crops or something, society would collapse and have trouble recovering.

ChuckMcM2• 12 years ago

I'd be happy to have a self supporting technology base on the moon so that the earth could be re-colonized.

abdullahkhalids• 12 years ago

There are lots and lots existential crises that could befall mankind. To avoid having our eggs in one basket it is best to colonize other planets. (of course there are other reasons for colonization).

Short list of extinction events: global nuclear war, major asteroid hit, deadly disease that can't be contained, skynet like scenarios if AI turns out to be possible, global warming making us go Venus like etc etc.

The chance of each of these events is very small (except probably the last one which many would say is almost certain), but why would you not hedge your bets? When colonization would be so cool - the final frontier after all.

jofer2• 12 years ago

We basically already are.

I'm not 100% certain on this, but all porcelain/ceramic pieces should be dateable through Potassium-Argon and Argon-Argon methods.

You'll never see it used in archeology as it's only useful for fairly old (greater than a few hundred thousand years) samples, but Potassium-Argon (and the complimentary Argon-Argon) is a _very_ common dating method for geologic samples.

Porcelain is mostly made from kaolinite, but usually includes quite a bit of various feldspars as well. I think (?) the process of making ceramics should get the feldspars involved up above the Curie temperature, if not entirely melting and re-crystallizing them.

If so, you should be able to date porcelain/ceramics in the far, far distant future.

lafar65022• 12 years ago

Previous mass extinction took 60000 years so even if another mass extinction event is happening now we won't even notice it.

hyperbovine• 12 years ago

Because a_k = x implies a_{k+1} = x for all k.

lafar65022• 12 years ago

how did you know?

duvander• 12 years ago

Between 12,000 and 108,000 years

How Long Does Mass Extinction Take?

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