Hugh Pickens writes "Cosmologist Adrian Mellott has an article in Seed Magazine discussing his search for the mechanism behind the mass extinctions in earth's history that seem to occur with a period of about 62 million years. Scientists have identified nearly 20 mass extinctions throughout the fossil record, including the end-Permian event about 250 million years ago that killed off about 95 percent of life on Earth. Mellott notes that as our solar system orbits the Milky Way's center, it oscillates through the galactic plane with a period of around 65 million years. 'The space between galaxies is not empty. It's actually full of rarefied hot gas,' says Mellott. 'As our galaxy falls into the Local Supercluster, it should disturb this gas and create a shock wave, like the bow shock of a jet plane,' generating cascades of high-energy subatomic particles and radiation called 'cosmic rays.' These effects could cause enhanced cloud formation and depletion of the ozone layer, killing off many small organisms at the base of the food chain and potentially leading to a population crash. So where is the earth now in the 62-million year extinction cycle? '[W]e are on the downside of biodiversity, a few million years from hitting bottom,' writes Mellott."
I read about it in books which must have been published 30 years ago, though I think the theory than was than the gravitational field of passing stars was changing the orbit of comets in the Oort cloud and causing comet impacts.
It's unlikely. Another star (the size of our Sun) needs to pass about 2 light-years near the Sun to significantly disturb the Oort cloud. And Sun-like starts are not that common.
However, Sun's gravitational field is so weak in the Oort cloud that even _Galactic tides_ can eject objects from it. Few years ago I helped my friend to write a computer simulation of this for his thesis.
Unlikely? With, *currently*, - Alpha Centauri [wikipedia.org] A+B massing 1.100 + 0.907 solar masses 4.365 ly away, and - Sirius [wikipedia.org] A+B massing 2.02 + 0.978 solar masses 8.6 ly away, I don't see what's so unlikely about having stars the size of our Sun passing within 2 light-years of the Sun once every 62 My.
I read about it in books which must have been published 30 years ago, though I think the theory than was than the gravitational field of passing stars was changing the orbit of comets in the Oort cloud and causing comet impacts.
Which was, as it happens, a completely different idea from the one discussed in TFA.
Do you have any idea how different the scales involved are -- the movements of a few local stars in the scenario you're discussing, vs. the movements of galaxies and clusters of galaxies in this case?
Not sure why you didn't post this when we last "debated" the idea.;)
All such theories should be described as tentative, in the absence of solid physical evidence (i.e. not just correlation). The CERN experiment will at least show what and how cloud condensation nuclei can be generated by Cosmic Rays. This may, or may not, be the start of a paradigm shift in Climate Science. We will wait and see.
How about calling them hypotheses? Let's reserve "theory" for something that actually has solid evidence.
That would go over well in a scientific forum. OTOH, in the mass media and the general population, "theory" is used the same way that scientists use "hypothesis", for a guess that's consistent with known data but hasn't been tested.
So the question is: Is slashdot a scientific or a general-reader forum? The best answer is "both". There are lots of techie geeks here; there are lots of non-techie readers with an interest in tech stuff. So we get what you'd expect: Different people use the terminology differently, and most of them can't be bothered to make their definitions clear.
I get as annoyed as others here at the frequent blatant disregard for the proper scientific terminology. But I remind myself that this isn't really a scientific forum; it's a general-reader forum with an emphasis on techological issues. So getting our terminological act together here is probably hopeless. A large fraction of the readers don't understand such issues. And a small fraction are actively opposed to correct terminology. All this is quite normal for a mixed-level forum such as this. And we need such forums to get better information out to the public than the mass media can provide.
Still, it probably doesn't hurt to occasionally point out the technical definition of a term, for the benefit of non-tech readers who are amenable to such details. In this case, we could just point out that in scientific circles, "theory" refers to a hypothesis that has been fairly thoroughly tested, has passed the tests, and is generally accepted as the best explanation we have at present. Something that explains all known data but hasn't been tested much isn't a "theory"; it's a "hypothesis".
We have good theories of cloud formation in low-level weather phenomena. For clouds at higher altitudes (>10 or 20 km), we mostly have hypotheses. People have done a lot of mathematical modelling, which is interesting but doesn't qualify as scientific testing, so the results aren't proper (scientific) theories yet. But to the mass media, they are theories, since the media is using a different dictionary.
Its also possible that my opening of a coke can will unsettle the quantum state of the water molecules vaporized in the air consequentially causing a pony to spontaneously appear. But as much as i wish it to be true, it aint going to happen (at least not for a really long time).
The whole point of the 65 million year cycle was not only the extinctions, but also the discover of elements in the ground only found as a result of asteroid impacts. Tha'ts why researches spend to much time trying to find a large mass that could disturb the Kuiper belt.
Its also possible that my opening of a coke can will unsettle the quantum state of the water molecules vaporized in the air consequentially causing a pony to spontaneously appear.
Which is precisely why Coke kill a pony for every can they make;)
Its also possible that my opening of a coke can will unsettle the quantum state of the water molecules vaporized in the air consequentially causing a pony to spontaneously appear.
Which is precisely why Coke kill a pony for every can they make;)
As others have noticed, this is hardly new. I'm starting to think we just have too much knowledge these days. I've lost count of the number of 'discoveries' that are already known, both in IT and the wider areas of science and beyond. It's effectively impossible for people to fully grasp the entire sum of knowledge in their field with the result we're starting to spend time 'reinventing the wheel' to a depressing level.
I'm starting to think we just have too much knowledge these days. I've lost count of the number of 'discoveries' that are already known, both in IT and the wider areas of science and beyond.
People have always been reinventing the wheel, that is when we haven't had dark ages and lost the wheel in the first place. It just shows the importance of putting knowledge in a context. By all means I'm not saying wikipedia is perfect in content, but the basic idea of hyperlinking up documents to related concepts makes it 1000% user-friendlier than the dead tree encyclopedias I grew up with.
We do have a few books like that too, trying to give a bird's eye view of a topic. I remember using one of those in
Take a look at wikipedia's graph of extinctions [wikipedia.org] from the article about the history of life [wikipedia.org]. I haven't done any actual signal analysis on this data.
I would buy that there is a bit more energy in the per 62 million years signal, but I wouldn't call it clockwork-like regularity. If they came up with a p-value of 0.01, I'd say that there must be something happening, but I would expect a little more consistency out of a big cosmic event like the one they're describing.
I don't know that I'd expect that much consistency. The actual effects are indirect, cosmic ray flux leads to climate change leads to decreased biodiversity leads to ecological collapse. I would expect large amounts of variation in the timing in any one of those steps, just due to their chaotic nature.
So, statistically speaking, the case loosens up quite a bit. I would need to see more evidence of the mechanisms to be persuaded one way or the other.
Usupported by actual data. If you look at the Phanerozoic biodiversity data, it doesnt validate the 62 million years extinction cycle theory. You cant just take a small subset, selectively ignore data points that don't fit into your theory and preach the end of the world. Admittedly that does seem to sell books.
This is twice in a week that someone has made assertions about mass extinctions, and both times their (different) numbers don't match the commonly accepted numbers http://en.wikipedia.org/wiki/Milky_way [wikipedia.org] . (No, the Big W is not necessarily authoritative, but the sources referenced are.)
The solar system orbits the galactic center in 220 Myr. It oscillates through the galactic plane 2.7 times per orbit. That's a period of 81.5 Myr, and each crossing at half-period being 40.75 Myr. I doubt anyone would consider that an acceptable error margin.
Furthermore, the matter density in the galactic plane oscillates with a period 1/2 that of the galactic rotation, expanding out from the center in waves (density wave 25 Myr; spiral structure 50 Myr). Passing through the plane would have little effect unless these two coincide.
you're so f**king right man. this article is f**cking stupid. i get you cause i drank a barrel of wine earlier too. OBVIOUSLY, the gas cloud is orbiting the milky way at 62 million year intervals and we're the ones standing still. IDNTRTFAWIDTBYDE (i don't need to read the f**king article when i'm drunk too because you didn't either)
This is about the motion of our star relative to the disk. Because our orbital inclination around the galactic core is different from other stars in the galaxy we tend to drift above the disc, then we get pulled back by gravity and pop out the bottom of the disc. When we pass through the disc we encounter more objects such as stars and gas clouds.
theory about 20 years ago. However that one suggested the reason for the mass extinctions was because the stars in the galactic plane are much closer together so the likely hood of being in close proximity to a supernova and all the incumbent radiation that entails is much higher. This also explains why occasionally mass extinction skips a beat. Of course the 2 scientists who postulated this theory were promptly laughed at and ridiculed by the scientific community in that very grown up way that scientists do.
theory about 20 years ago. However that one suggested the reason for the mass extinctions was because the stars in the galactic plane are much closer together so the likely hood of being in close proximity to a supernova and all the incumbent radiation that entails is much higher.
Nerds are likely to recognize a similar scenario from Larry Niven's 1966 short story "At the Core" (now in his collection Crashlander [amazon.com] ), where the stars packed together near the galactic core set off a chain reaction of supernova
I read about this back in the 80's, and from what I remember, the theory was that passing through the galactic plane put more gravitational stress on the solar system and we got more kuiper/oort belts items falling in, and therefore, more impact events. I think it was Omni magazine but might have been Discover, if it was around back then.
Our solar system is one little tiny node that makes up part of one of the spiral arms, and we move with those arms as they rotate around the galactic center.
Your grade school called - they've revoked your graduation certificate. The arms don't rotate around the galactic center. We don't move with the arms. We're also not currently in one of the arms. So you're batting a thousand there - got everything in your statement completely wrong.
All the stars in the galaxy orbit the center. The arms are merely a density wave in the disc. As stars enter the wave, they slow down and "bunch up", forming the "arms". As they leave, they speed up and spread out. It exactly the same phenomenon as traffics jams on the freeway, and scientists use the same math when doing calculations on both.
Anywho, our solar system passes through the arms about once every 200 million years, and the last one we passed through was about 60 million years ago. Scientists don't think it's a coincidence that the last time we passed through an arm was also when the dinosaurs went extinct.
The interval between extinctions is 62 million years only if you accept ~30 millions of year of error margin.
The current downfall of biodiversity is really fast compared to the time scale mentioned here. Its most likely reason has two legs, two arms, a big brain and a various set of forest-destroying machines as well as a bad habit of dumping various materials into the ocean.
You're right! It's people that is the problem. Please write your congressman and tell them to expand Cap'n Trade to cover Humans. All that human breathing is producing unacceptable levels of CO2.
We could put a life clock on everyone's hand, and only allow a few people selected by lottery to live past age 35. That should keep the population down enough to save planet Earth!
This isn't the first time a speices (or multiple species in that case) destroyed life on Earth. The anarobic bacteria were perfectly happy until they stupidly unleashed all that oxygen.
Is it really flamebait to say that humans are the most likely cause of biodiversity downfall?
No; it's only considered flamebait in political/religious circles.;-)
In scientific circles, it's conventional to attribute most of the current extinction event to human activity. Thus, we don't really know when humans first arrived in the Americas, and there are estimates at high as 30,000 years ago for the first. However, it does seem fairly clear that humans were rare on those continents before about 12,000 years ago, when there was a huge increase in the human population. At the same time, large numbers of large animal species went extinct. Some of those would have died out anyway, but the mass extinction is generally attributed to humans. After all, if you introduce a new major predator, you'd expect that the sort of prey it likes (large, meaty critters in this case) would start to disappear.
So the human-caused extinction has long been the default hypothesis. There are other possibilities, but if you want to argue for them, you should have some pretty good evidence, and such evidence doesn't seem to exist. Death at the hands of a new, powerful predator is just too reasonable to be dismissed without evidence, and it quite properly the primary hypothesis when there is evidence of such a predator. And, unlike in political discussions, there is rather little scientific argument about this. Rather, there are lots of scientists looking for evidence wherever they can find it. Other contributing factors have been reported, but so far nothing much that seriously challenges the primary hypothesis.
(Actually, there is a good recent example of the opposite process. Starting about 500 years ago, there was a mass extinction of humans in the Americas. It is common to attribute this to the introduction of a different human subspecies that had better weapons. But we have the evidence, and it shows that weaponry was a minor factor in the extinction, and only in the eastern coastal areas. It turns out that most of the people in the interior died from the diseases that the new humans unknowingly brought along, long before the newcomers reached the interior. Both groups of people attributed the plagues to acts of various gods, since neither had any understanding of microorganisms at the time. It wasn't until the 1800s that "germs" were understood, and the newcomers started using biological warfare in a controlled fashion against the original inhabitants. This produced a second extinction event, but it was much smaller than the one in the 1500s.)
(And it'll be interesting to see whether this gets any "flamebait" mods. There's gotta be at least a few people who'll read it that way. I've already got both "flamebait" and "insightful" for one post; now I'm trying for "flamebait" + ("informative" || "insightful") + "funny".;-)
The sun at this point is well over halfway through its yellow-phase lifetime. Earth only has a few billion more years left to reach whatever culmination it's going to. There's not really enough time to evolve another species to our level from scratch. A mere 95% extinction wouldn't be as bad, but if it's only 60-some-odd million years from now the next sentient species is going to have to make due with dramatically fewer energy reserves left on the planet to bootstrap its civilization.
In short, if you value sentience we're a pretty valuable resource for the solar system.
There's not really enough time to evolve another species to our level from scratch.
Well, perhaps not from scratch, but even the most massive of mass extinctions wouldn't destroy all life. There'd be plenty of bacteria, amoebas, and various other "simple" organisms around. Given that the majority of evolutionary time was spent developing these basic organisms, life would start out with a rather large head start as compared with starting from nothing.
A mere 95% extinction wouldn't be as bad, but if it's only 60-some-odd million years from now the next sentient species is going to have to make due with dramatically fewer energy reserves left on the planet to bootstrap its civilization.
Well, not necessarily. Fossil fuels aren't completely nonrenewable - they're just nonrenewable on any sort of human timescale. 60 million years is about the age of the coal and oil we're burning now. If there was a 95% extinction today, then the next sentient species would start out at with about the same amount of fossil fuel reserves that we had.
Not a new idea (Score:2, Offtopic)
Re:Not a new idea (Score:5, Informative)
It's unlikely. Another star (the size of our Sun) needs to pass about 2 light-years near the Sun to significantly disturb the Oort cloud. And Sun-like starts are not that common.
However, Sun's gravitational field is so weak in the Oort cloud that even _Galactic tides_ can eject objects from it. Few years ago I helped my friend to write a computer simulation of this for his thesis.
Parent
Re: (Score:3, Informative)
Unlikely? With, *currently*,
- Alpha Centauri [wikipedia.org] A+B massing 1.100 + 0.907 solar masses 4.365 ly away, and
- Sirius [wikipedia.org] A+B massing 2.02 + 0.978 solar masses 8.6 ly away,
I don't see what's so unlikely about having stars the size of our Sun passing within 2 light-years of the Sun once every 62 My.
Re:Not a new idea (Score:4, Interesting)
Niven & Pournelle's "Lucifer's Hammer" started out with a nice description of this happening.
Parent
Re: (Score:3, Interesting)
And also: (Score:3, Informative)
Nightfall [wikipedia.org] (Isaac Asimov, 1941, and Isaac Asimov & Robert Silverberg, 1990)
Re: (Score:3, Insightful)
I read about it in books which must have been published 30 years ago, though I think the theory than was than the gravitational field of passing stars was changing the orbit of comets in the Oort cloud and causing comet impacts.
Which was, as it happens, a completely different idea from the one discussed in TFA.
Do you have any idea how different the scales involved are -- the movements of a few local stars in the scenario you're discussing, vs. the movements of galaxies and clusters of galaxies in this case?
Not news (Score:3, Informative)
Clouds? (Score:5, Informative)
Re:Clouds? (Score:5, Interesting)
This [web.cern.ch] should help our understanding.
Parent
Re:Clouds? (Score:5, Informative)
A recent paper shows that this may indeed by the case [uwaterloo.ca]
Given that Svensmark's team has been granted an experiment slot at CERN [web.cern.ch], at least many of those in the Physics community believe it's a plausible hypothesis. There is research out there demonstrating some causal link between cloud cover and Cosmic Rays. [harvard.edu] Science is all about reaching beyond what is known. It would be pretty a pointless exercise otherwise.
Parent
Re:Clouds? (Score:4, Informative)
All such theories should be described as tentative, in the absence of solid physical evidence (i.e. not just correlation). The CERN experiment will at least show what and how cloud condensation nuclei can be generated by Cosmic Rays. This may, or may not, be the start of a paradigm shift in Climate Science. We will wait and see.
Parent
Re: (Score:3)
How about calling them hypotheses?
Let's reserve "theory" for something that actually has solid evidence.
Re:Clouds? (Score:5, Insightful)
How about calling them hypotheses?
Let's reserve "theory" for something that actually has solid evidence.
That would go over well in a scientific forum. OTOH, in the mass media and the general population, "theory" is used the same way that scientists use "hypothesis", for a guess that's consistent with known data but hasn't been tested.
So the question is: Is slashdot a scientific or a general-reader forum? The best answer is "both". There are lots of techie geeks here; there are lots of non-techie readers with an interest in tech stuff. So we get what you'd expect: Different people use the terminology differently, and most of them can't be bothered to make their definitions clear.
I get as annoyed as others here at the frequent blatant disregard for the proper scientific terminology. But I remind myself that this isn't really a scientific forum; it's a general-reader forum with an emphasis on techological issues. So getting our terminological act together here is probably hopeless. A large fraction of the readers don't understand such issues. And a small fraction are actively opposed to correct terminology. All this is quite normal for a mixed-level forum such as this. And we need such forums to get better information out to the public than the mass media can provide.
Still, it probably doesn't hurt to occasionally point out the technical definition of a term, for the benefit of non-tech readers who are amenable to such details. In this case, we could just point out that in scientific circles, "theory" refers to a hypothesis that has been fairly thoroughly tested, has passed the tests, and is generally accepted as the best explanation we have at present. Something that explains all known data but hasn't been tested much isn't a "theory"; it's a "hypothesis".
We have good theories of cloud formation in low-level weather phenomena. For clouds at higher altitudes (>10 or 20 km), we mostly have hypotheses. People have done a lot of mathematical modelling, which is interesting but doesn't qualify as scientific testing, so the results aren't proper (scientific) theories yet. But to the mass media, they are theories, since the media is using a different dictionary.
Parent
Re:Clouds? (Score:5, Funny)
http://xkcd.com/326/ [xkcd.com]
Parent
Its also possible... (Score:4, Funny)
Its also possible that my opening of a coke can will unsettle the quantum state of the water molecules vaporized in the air consequentially causing a pony to spontaneously appear. But as much as i wish it to be true, it aint going to happen (at least not for a really long time).
The whole point of the 65 million year cycle was not only the extinctions, but also the discover of elements in the ground only found as a result of asteroid impacts. Tha'ts why researches spend to much time trying to find a large mass that could disturb the Kuiper belt.
Re:Its also possible... (Score:5, Funny)
Which is precisely why Coke kill a pony for every can they make ;)
Parent
Re:Its also possible... (Score:5, Funny)
Which is precisely why Coke kill a pony for every can they make ;)
Ah, the well known Pony Preservation Principle.
Parent
Re: (Score:3, Funny)
Brain full? (Score:4, Insightful)
Re:Brain full? (Score:5, Funny)
I'm starting to think we just have too much knowledge these days. I've lost count of the number of 'discoveries' that are already known, both in IT and the wider areas of science and beyond.
Sorry, somebody already thought of that.
Probably the Simpson's.
Parent
Re: (Score:3, Insightful)
People have always been reinventing the wheel, that is when we haven't had dark ages and lost the wheel in the first place. It just shows the importance of putting knowledge in a context. By all means I'm not saying wikipedia is perfect in content, but the basic idea of hyperlinking up documents to related concepts makes it 1000% user-friendlier than the dead tree encyclopedias I grew up with.
We do have a few books like that too, trying to give a bird's eye view of a topic. I remember using one of those in
Crap (Score:4, Funny)
Re:Crap (Score:5, Funny)
Research my ass.
I've just got the research report about your ass, and you're not going to like the findings.
Parent
From a Galactic Origin (Score:5, Funny)
Examine It For Yourself (Score:5, Insightful)
Take a look at wikipedia's graph of extinctions [wikipedia.org] from the article about the history of life [wikipedia.org]. I haven't done any actual signal analysis on this data.
I would buy that there is a bit more energy in the per 62 million years signal, but I wouldn't call it clockwork-like regularity. If they came up with a p-value of 0.01, I'd say that there must be something happening, but I would expect a little more consistency out of a big cosmic event like the one they're describing.
Re: (Score:3, Insightful)
So, statistically speaking, the case loosens up quite a bit. I would need to see more evidence of the mechanisms to be persuaded one way or the other.
The reapers are coming! (Score:4, Funny)
Ohai-Thanks for the mindnumbing oversimplification (Score:3, Insightful)
Not fault of galactic arms (Score:3, Informative)
Spiral Arms Did Not Cause Climate Change on Earth
A new map of the Milky Way galaxy proves that the sun's motion through the spiral arms could not have caused a well-known climate-change cycle.
http://www.technologyreview.com/blog/arxiv/23763/ [technologyreview.com]
20 Million Years Late... (Score:4, Informative)
... and a dollar short.
This is twice in a week that someone has made assertions about mass extinctions, and both times their (different) numbers don't match the commonly accepted numbers http://en.wikipedia.org/wiki/Milky_way [wikipedia.org] . (No, the Big W is not necessarily authoritative, but the sources referenced are.)
The solar system orbits the galactic center in 220 Myr. It oscillates through the galactic plane 2.7 times per orbit. That's a period of 81.5 Myr, and each crossing at half-period being 40.75 Myr. I doubt anyone would consider that an acceptable error margin.
Furthermore, the matter density in the galactic plane oscillates with a period 1/2 that of the galactic rotation, expanding out from the center in waves (density wave 25 Myr; spiral structure 50 Myr). Passing through the plane would have little effect unless these two coincide.
Only One Question Matters (Score:3, Insightful)
Re:What a f**king dick (Score:5, Insightful)
What an incoherent rant. Perhaps you should lay off the vino before posting to slashdot.
Parent
Re:What a f**king dick (Score:5, Funny)
Parent
Re:What a f**king dick (Score:4, Informative)
>> IDNTRTFAWIDTBYDE (i don't need to read the f**king article when i'm drunk too because you didn't either)
I finally realized that, today, for the first time I've been on Slashdot too long.
I was able to understand your acronym without the explanation just by looking at the letters.
OMG.
Parent
Re: (Score:3, Insightful)
Re:What a f**king dick (Score:4, Funny)
Parent
Heard a similar (Score:5, Interesting)
theory about 20 years ago. However that one suggested the reason for the mass extinctions was because the stars in the galactic plane are much closer together so the likely hood of being in close proximity to a supernova and all the incumbent radiation that entails is much higher. This also explains why occasionally mass extinction skips a beat. Of course the 2 scientists who postulated this theory were promptly laughed at and ridiculed by the scientific community in that very grown up way that scientists do.
Cold fusion anyone?
Parent
Re: (Score:3, Informative)
Nerds are likely to recognize a similar scenario from Larry Niven's 1966 short story "At the Core" (now in his collection Crashlander [amazon.com] ), where the stars packed together near the galactic core set off a chain reaction of supernova
Re: (Score:3, Interesting)
I read about this back in the 80's, and from what I remember, the theory was that passing through the galactic plane put more gravitational stress on the solar system and we got more kuiper/oort belts items falling in, and therefore, more impact events. I think it was Omni magazine but might have been Discover, if it was around back then.
Man, 40+ years on this rock and it's all a blur.
Re: (Score:3, Interesting)
Re:Heard a similar (Score:5, Insightful)
Your grade school called - they've revoked your graduation certificate. The arms don't rotate around the galactic center. We don't move with the arms. We're also not currently in one of the arms. So you're batting a thousand there - got everything in your statement completely wrong.
All the stars in the galaxy orbit the center. The arms are merely a density wave in the disc. As stars enter the wave, they slow down and "bunch up", forming the "arms". As they leave, they speed up and spread out. It exactly the same phenomenon as traffics jams on the freeway, and scientists use the same math when doing calculations on both.
Anywho, our solar system passes through the arms about once every 200 million years, and the last one we passed through was about 60 million years ago. Scientists don't think it's a coincidence that the last time we passed through an arm was also when the dinosaurs went extinct.
Parent
Re:awesome (Score:5, Funny)
Parent
Re:Just no (Score:5, Funny)
The interval between extinctions is 62 million years only if you accept ~30 millions of year of error margin. The current downfall of biodiversity is really fast compared to the time scale mentioned here. Its most likely reason has two legs, two arms, a big brain and a various set of forest-destroying machines as well as a bad habit of dumping various materials into the ocean.
You're right! It's people that is the problem. Please write your congressman and tell them to expand Cap'n Trade to cover Humans. All that human breathing is producing unacceptable levels of CO2.
We could put a life clock on everyone's hand, and only allow a few people selected by lottery to live past age 35. That should keep the population down enough to save planet Earth!
Parent
Re: (Score:3, Funny)
This isn't the first time a speices (or multiple species in that case) destroyed life on Earth. The anarobic bacteria were perfectly happy until they stupidly unleashed all that oxygen.
Re:Just no (Score:5, Informative)
Is it really flamebait to say that humans are the most likely cause of biodiversity downfall?
No; it's only considered flamebait in political/religious circles. ;-)
In scientific circles, it's conventional to attribute most of the current extinction event to human activity. Thus, we don't really know when humans first arrived in the Americas, and there are estimates at high as 30,000 years ago for the first. However, it does seem fairly clear that humans were rare on those continents before about 12,000 years ago, when there was a huge increase in the human population. At the same time, large numbers of large animal species went extinct. Some of those would have died out anyway, but the mass extinction is generally attributed to humans. After all, if you introduce a new major predator, you'd expect that the sort of prey it likes (large, meaty critters in this case) would start to disappear.
So the human-caused extinction has long been the default hypothesis. There are other possibilities, but if you want to argue for them, you should have some pretty good evidence, and such evidence doesn't seem to exist. Death at the hands of a new, powerful predator is just too reasonable to be dismissed without evidence, and it quite properly the primary hypothesis when there is evidence of such a predator. And, unlike in political discussions, there is rather little scientific argument about this. Rather, there are lots of scientists looking for evidence wherever they can find it. Other contributing factors have been reported, but so far nothing much that seriously challenges the primary hypothesis.
(Actually, there is a good recent example of the opposite process. Starting about 500 years ago, there was a mass extinction of humans in the Americas. It is common to attribute this to the introduction of a different human subspecies that had better weapons. But we have the evidence, and it shows that weaponry was a minor factor in the extinction, and only in the eastern coastal areas. It turns out that most of the people in the interior died from the diseases that the new humans unknowingly brought along, long before the newcomers reached the interior. Both groups of people attributed the plagues to acts of various gods, since neither had any understanding of microorganisms at the time. It wasn't until the 1800s that "germs" were understood, and the newcomers started using biological warfare in a controlled fashion against the original inhabitants. This produced a second extinction event, but it was much smaller than the one in the 1500s.)
(And it'll be interesting to see whether this gets any "flamebait" mods. There's gotta be at least a few people who'll read it that way. I've already got both "flamebait" and "insightful" for one post; now I'm trying for "flamebait" + ("informative" || "insightful") + "funny". ;-)
Parent
Re:First Post (Score:5, Interesting)
The sun at this point is well over halfway through its yellow-phase lifetime. Earth only has a few billion more years left to reach whatever culmination it's going to. There's not really enough time to evolve another species to our level from scratch. A mere 95% extinction wouldn't be as bad, but if it's only 60-some-odd million years from now the next sentient species is going to have to make due with dramatically fewer energy reserves left on the planet to bootstrap its civilization.
In short, if you value sentience we're a pretty valuable resource for the solar system.
Parent
Re:First Post (Score:5, Insightful)
There's not really enough time to evolve another species to our level from scratch.
Well, perhaps not from scratch, but even the most massive of mass extinctions wouldn't destroy all life. There'd be plenty of bacteria, amoebas, and various other "simple" organisms around. Given that the majority of evolutionary time was spent developing these basic organisms, life would start out with a rather large head start as compared with starting from nothing.
A mere 95% extinction wouldn't be as bad, but if it's only 60-some-odd million years from now the next sentient species is going to have to make due with dramatically fewer energy reserves left on the planet to bootstrap its civilization.
Well, not necessarily. Fossil fuels aren't completely nonrenewable - they're just nonrenewable on any sort of human timescale. 60 million years is about the age of the coal and oil we're burning now. If there was a 95% extinction today, then the next sentient species would start out at with about the same amount of fossil fuel reserves that we had.
Parent
Re: (Score:3, Funny)
Re: (Score:3, Informative)
Wikipedia is your friend. [wikipedia.org]