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New Theory Explains Periodic Mass Extinctions
Posted by
Zonk
on Thu Aug 02, 2007 04:12 PM
from the we're-not-due-for-a-little-while-yet dept.
from the we're-not-due-for-a-little-while-yet dept.
i_like_spam writes "The theory that the dinosaurs were wiped out by an asteroid impact, the K-T extinction, is well known and supported by fossil and geological evidence. Asteroid impact theory does not apply to the other fluctuations in biodiversity, however, which follow an approximate 62 million-year cycle. As reported in Science, a new theory seems to explain periodic mass extinctions. The new theory found that oscillations in the Sun relative to the plane of the Milky Way correlate with changes in biodiversity on Earth. The researchers suggest that an increase in the exposure of Earth to extragalactic cosmic rays causes mass extinctions. The original paper describing the findings is available online."
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Baiji River Dolphin May or May Not Be Extinct 175 comments
ozmanjusri writes "Major news outlets are reporting that after 20 million years, Baiji (Yangtze River Dolphin) are now officially extinct. This is apparently actually old news; it was announced on a Baiji conservation website in December of last year. One outlet, though, is claiming they may not quite be completely dead yet. The same scientist that filed the report leading the the declaration of extinction is still hopeful: '"This is only one survey and...you can't have a sample in a survey, so you cannot say the baiji all is gone by the result of only one survey," he said. "For example, there is some side channels or some tributaries [where] we cannot go because of a restriction of navigation rules, and also we don't survey during the night-time so we may miss some animals in the Yangtze River." Professor Ding says based on anecdotal evidence, he remains confident the dolphins are still out there. "I'm pretty much sure there are a few of them left somewhere in the Yangtze River," he said. "I keep receiving reports from fishermen, they say they saw a couple of baiji somewhere, sometime."'"
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Huh. Better get to work! (Score:5, Interesting)
It's a perfectly reasonable hypothesis, though it'll be a while before we can test it. It's always a little weird though, to think of extra-solar events as relevant on a "local" scale. I mean, in the same way that Earth is endangered by rogue meteorites and asteroids, the whole solar system is vulnerable to a rogue star or brown dwarf. Anyone ever read Jack McDevitt? He's obsessed with that sort of disaster (pun intended).
Hard to get your mind around it...The odds are so long...
Re:Huh. Better get to work! (Score:5, Funny)
We're hosed.
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Re:Huh. Better get to work! (Score:5, Insightful)
I'd be surprised if we haven't shot our bolt one way or the other in the next ten thousand years, and that's a conservative estimate.
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Re:Huh. Better get to work! (Score:5, Funny)
Let me guess: the rats are the warriors, the hamsters are the scientists,
and a bright orange guinea pig named Dr Zeus will be in charge.
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Re:Huh. Better get to work! (Score:5, Insightful)
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Perfectly reasonable hypothesis? (Score:5, Interesting)
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Re:Perfectly reasonable hypothesis? (Score:5, Funny)
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Re:Perfectly reasonable hypothesis? (Score:5, Informative)
The KT event, for example, had a much larger impact on biodiversity but happened off-cycle, and is pretty clearly the result of a specific meteor strike that we already know about.
Other events may have been volcanic or meteoric or the result of something we didn't know about.
All extinction events being triggered by only one type of external condition was never very likely.
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Biodiversity (Score:5, Informative)
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Re:Huh. Better get to work! (Score:5, Funny)
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Re:You'd have to pass through the heliopause first (Score:5, Informative)
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It burns... (Score:5, Funny)
Nah this is not correct either. (Score:5, Funny)
Everyone knows the extinctions were perfectly explained using the Theory of Intelligent Smiting.
Re:Nah this is not correct either. (Score:5, Funny)
[NO CARRIER]
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to quote inidana jones: (Score:5, Insightful)
Indiana Jones says, "Archaeology is the search for fact... not truth. If it's truth you're looking for, Dr. Tyree's philosophy class is right down the hall."
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Figure 4 in the paper (Score:5, Interesting)
Or Maybe... (Score:5, Insightful)
Or maybe, the increased radiation merely causes some periods of increased mutations... extinctions follow as species are outcompeted for resources.
(5am posting, sorry) (Score:5, Funny)
Can we please oh please oh please call them death rays?
Well... (Score:5, Funny)
Some hasty objections (Score:5, Informative)
* My boss (David Penny, Massey University) argues that the mammals and birds were already outcompeting the dinosaurs at the end of the cretaceous, so the asteroid was at best a coup-de-grace for them.
* The "periodic extinctions" idea has been around for decades, including the possible link to oscillations through the galactic plane.
* Mass extinctions are sudden. The increase in extragalactic cosmic rays exposure would be slow, over millions of years.
* The extragalactic cosmic ray exposure changes should be highly regular. The extinctions are irregular.
NOT About Mass Extinctions! (Score:5, Informative)
Better summary title - "Life's Diversity changes with Solar Galactic Orbit". Or something like that.
Re:Does anyone make.... (Score:5, Funny)
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Re:Well, that would explain (Score:5, Informative)
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Why not? (Score:5, Insightful)
Lot of the things we assumed about radiation back in the day (e.g. mutants and Godzilla) have turned out to not really happen so much. DNA isn't as fragile as we assumed, and while the extra rads may kill you quicker (only live to 60 instead of 80), it's not quick enough to keep you from reproducing.
We're not talking some kind of galactic nuke here...It's just a significant upswing in radiation. Hell, the fact that we've had these historically is maybe why the ecosystem tolerates increases in radiation so well.
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Re:Well, that would explain (Score:5, Informative)
That's odd. The post-9/11 research into the effects of jet contrails [sciencedaily.com] suggested that they have two faint effects: mild warming and mild day/night temperature moderation. But the above quote seems to contradict that.
I am now even more suspicious of the conclusions of the contrail research, coming (as it did) in the middle of the global warming craze. Right now you can't even publish the simple observation that plants will grow usefully faster on a warmer Earth; no, you have to spin it as "OMG poison ivy will get worse!" [google.com].
I'm ready to go nuclear/solar/wind, and drive an electric car, because I've always hated the power that petronomics gives to the backwards nations... but come on guys, can we at least give both sides a fair hearing?
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