Stories
Slash Boxes
Comments
Search

News for nerds, stuff that matters

Slashdot Log In

Log In

Create Account  |  Retrieve Password

New Theory Explains Periodic Mass Extinctions

Posted by Zonk on Thu Aug 02, 2007 03:12 PM
from the we're-not-due-for-a-little-while-yet dept.
Space Science
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."
+ -
story

Related Stories

[+] 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."'"
This discussion has been archived. No new comments can be posted.
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.

New Theory Explains Periodic Mass Extinctions 50 Comments More /

 Full
 Abbreviated
 Hidden
More
Loading... please wait.
  • Only 7 million years from now, for all you long range planners. Better stock up on beans, bottled water and relocate your house 1 kilometer underground.

    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...

    • So we have 7 million years to figure out space flight and/or a way to record the sum of our knowledge for future intelligences.

      We're hosed.

      • It's not every species that lasts 7 million years. It's just as likely we won't be here at all, and this event will only bother the emerging rat civilization.

        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.

        • Re:Huh. Better get to work! (Score:5, Funny)

          by Sponge Bath (413667) on Thursday August 02 2007, @03:43PM (#20092609)

          ... the emerging rat civilization

          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.

        • Re:Huh. Better get to work! (Score:4, Interesting)

          by Loke the Dog (1054294) on Thursday August 02 2007, @03:55PM (#20092795)
          Which is kind of cool to think about... Imagine if rats have built a civilization about on par with our current civilization, but they are just a few years from this catastrophic event when they discover this pattern. And they are desperately searching the human ruins in hopes of finding some kind of technology to deal with this. It would make a good movie, I think.

          • Re: (Score:3, Interesting)

            by fyngyrz (762201) *
            Imagine if rats have built a civilization about on par with our current civilization

            "Writing of the Rat" by James Blish, first published in Galaxy magazine, July 1956. Republished in "A Dusk of Idols" by Severn House, May 1996, 0-7278-4967-0.

            First we arose, then the rats, then us again. Well worth reading even today, as is so for many of his works.

        • I think we'll hit the crossroads in the next 500 years. Civilization will either keep advancing, or collapse. In the event of a collapse, it will be interesting to see what our distant proginy do to climb back up the hill. The Eden trilogy by Harry Harrison is interesting along those lines because it posits an advanced dinosaur based civilization based more on biotechnology than mechanical technology.

        • this event will only bother the emerging cat civilization.
          Fixed that for you. [sitcom.co.uk]

      • Re:Huh. Better get to work! (Score:5, Insightful)

        by slashname3 (739398) on Thursday August 02 2007, @03:46PM (#20092641)
        Only if you leave it to the government to figure out space flight.

        • Re:Huh. Better get to work! (Score:4, Funny)

          by bl8n8r (649187) on Thursday August 02 2007, @06:08PM (#20094703)
          If we leave it to the government, we won't have to wait 7 million years for mass extinction.

          • Needs money more than time. (Score:4, Insightful)

            by alienmole (15522) on Thursday August 02 2007, @07:25PM (#20095413)
            Given the benefit of current technology, including technology developed for the US space program, catching up with the US government is more a question of funding than time. With insufficient funding, it could take much longer than 50 years to catch up; if somehow enough money became available, it could be done much more quickly.

            In any case, commercial applications for interstellar probes seem unlikely, so you might never get that wakeup call.
    • It's a perfectly reasonable hypothesis if one accepts the premise that mass extinctions have an approximately 62 million year period. From Wikipedia [wikipedia.org], the last 6 extinction events happened 65 million years ago, 200 million years ago, 251 million years ago, 360 million years ago, 444 million years ago, and 488 million years ago. The time between extinctions being 135 million years, 51 million years, 109 million years, 84 million years, and 44 million years. I'm having a hard time wrapping even an approximate 62 million year period into those.

      • Re:Perfectly reasonable hypothesis? (Score:5, Funny)

        by gEvil (beta) (945888) on Thursday August 02 2007, @03:58PM (#20092849)
        Sounds like someone needs to edit Wikipedia to make this hypothesis fit a little better...

      • Re: (Score:3, Interesting)

        by fimbulvetr (598306)
        It looks like it just got sensationalized from "Varied levels of cosmic radiation" to "Mass extinctions". What the paper does a better job describing is how such cycles would account for increased diversity in lifeforms. Consider, for instance, the cambrian explosion. Based on what we know about evolution, such an explosion is unprecedented and highly unlikely, despite the evidence. Perhaps increased Cosmic Rays caused a massive amount of mutations that forever changed the genetic data of organisms by makin

      • Re:Perfectly reasonable hypothesis? (Score:5, Informative)

        by ajs (35943) <ajs@nOspam.ajs.com> on Thursday August 02 2007, @04:13PM (#20093049) Homepage Journal

        It's a perfectly reasonable hypothesis if one accepts the premise that mass extinctions have an approximately 62 million year period. From Wikipedia [wikipedia.org], the last 6 extinction events happened 65 million years ago, 200 million years ago, 251 million years ago, 360 million years ago, 444 million years ago, and 488 million years ago.
        You're looking at the largest of the extinction events. This theory is attempting to explain a particular set of events which result in only an approx. 10% drop in biodiversity, and which are about 60ish million years apart.

        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.
            • Cycle:Min Diversity:Max Diversity
              1:59 My:74 My
              2:115 My:121 My
              3:177 My:184 My
              4:250 My:273 My
              5:298 My:308 My
              6:372 My:400 My
              7:441 My:454 My
              8:497 My:501 My

              My calculations:
              MinAgeDiff:MaxAgeDiff
              56 My:47 My
              62 My:63 My
              73 My:89 My
              48 My:35 Mr
              74 My:92 My
              69 My:54 My
              56 My:47 My
              Personally, I'm not impressed by the 62 My period conclusion based on the data they provide. Just how approximate are we talking here?

      • Re: (Score:3, Interesting)

        by Burz (138833)
        As ajs pointed out, the hypothesis is concerned with much smaller extinction events than the large ones you listed.

        However there is at least one supportable theory [sciam.com] for several of the larger ones: Death by hydrogen sulfide eruptions. Briefly, global warming leads to ocean anoxia and the spread H2S-spewing bacteria; death of aerobic ocean life accelerates the bacteria growth in a positive feedback until H2S concentrations also begin to spew from the oceans and kill life on land.

      • Re: (Score:3, Interesting)

        by Tatarize (682683)
        And why exactly do we have this very exactly dated impact in the Yucatan with little bits of it everywhere on Earth, tracing back to the right time period? What are we suppose to do with this massive amount of evidence right at the K-T switch if we are to suppose that it was just solar winds wiping out most life?

        It seems like a lot of evidence to have for something with nothing to do with it.

        • Re: (Score:3, Interesting)

          by ajs (35943)

          not only that but mass extinctions happened a lot earlier than that and with a far less predictable pattern. which leaves us to wonder why this cycle is this recent? why isn't there a cycle like this stretching back over a billion years?

          I haven't read the original paper, and the article is thin on details, so I'm not sure exactly how many events they considered... HOWEVER, I do not think you're correct about the conditions being static across spans of billions of years.

          Our sun (Sol) is a member of a cluster of stars that were birthed by a nebula of gas and dust around the same time. That cluster (like all stellar nurseries within a galactic disk) tended to break apart as time went on, due to the difference in orbital speeds around the cen

        • Re: (Score:3, Informative)

          by gEvil (beta) (945888)
          not only that but mass extinctions happened a lot earlier than that and with a far less predictable pattern. which leaves us to wonder why this cycle is this recent? why isn't there a cycle like this stretching back over a billion years?

          As far as the fossil record is concerned, the only things that existed beyond 550 million years ago are basically algae, bacteria, simple worms, etc. It wasn't until after that time that biodiversity really took off. It's entirely possible that this pattern goes back thro

    • Re:Huh. Better get to work! (Score:5, Funny)

      by Anonymous Coward on Thursday August 02 2007, @03:36PM (#20092507)
      Dude... A house 1 kilometer underground, and you want to stock up BEANS??

      • Re: (Score:3, Informative)

        by Gospodin (547743)

        Because what matters is the galactic plane, not the solar ecliptic. It's going to take a while (read: about as long as it'll take the Solar System) for the probe to get a decent reading.

  • It burns... (Score:5, Funny)

    by unchiujar (1030510) on Thursday August 02 2007, @03:16PM (#20092117)
    Will my tinfoil hat protect me ?

  • Err.. (Score:4, Insightful)

    by HitekHobo (1132869) on Thursday August 02 2007, @03:19PM (#20092179) Homepage
    How about 'new hypothesis may explain...'

  • Nah this is not correct either. (Score:5, Funny)

    by 140Mandak262Jamuna (970587) on Thursday August 02 2007, @03:20PM (#20092187) Journal
    What? Sun? Galactic Plane? Intergalactic Rays? You guys are watching way too many reruns of Star Trek.

    Everyone knows the extinctions were perfectly explained using the Theory of Intelligent Smiting.

    • Re:Nah this is not correct either. (Score:5, Funny)

      by Himring (646324) on Thursday August 02 2007, @03:37PM (#20092521) Homepage Journal
      lol! I love making fun of god. It's ok too, cuz god's gotta sense of hu

      [NO CARRIER]

          • Re:Nah this is not correct either. (Score:5, Informative)

            by AJWM (19027) on Thursday August 02 2007, @05:40PM (#20094375) Homepage
            You forgot to mention Christopher Columbus's theory that the earth is round... [...]when the rest of the so called "Intelligent" people of the world said it was flat.

            LOL! You still believe that nursery school myth?

            NO intelligent person in Columbus's time thought the world was flat -- as it clearly is not to anyone sufficiently observant. Columbus's problem is that he wanted to go to Asia via a western route, and everyone intelligent knew that with a circumference of about 25,000 miles, Eratosthenes having calculated it about 240 BC (as others had since). Hence they "knew" that with the sailing technology of the day, there was no way Columbus could make the voyage.

            They were right, too. Had the Americas not been in his way, his expedition would have perished before he got as far as the longitude of Hawaii.

            There is some evidence that Columbus may in fact have known that there was some land mass to the west considerably before Asia (the Vikings certainly did, and it is quite possible that fishermen who went as far as the Grand Banks were also aware). Whether from that he decided that Eratosthenes was wrong and the circumference was smaller (possibly influenced by Ptolemy's maps (from Geographica) which underestimated the circumference at about 18,000 miles), or whether he was just arguing that way to get backing for an expedition (with the secret purpose of discovering and exploiting just whatever land mass was there), we have no way of knowing.

            That mistake alone discredits the rest of your post as to make it not even worth reading.

            • Re:Nah this is not correct either. (Score:5, Informative)

              by AJWM (19027) on Thursday August 02 2007, @05:50PM (#20094495) Homepage
              BTW, even though Columbus "discovered" the Americas, it was Juan Sebastian Elcano who proved the world was round by sailing westward (modulo a few detours) until he returned to Spain. Yeah, everyone says it was Magellan, but Magellan died on the expedition in the Philippines, it was Elcano who assumed command at that point and finished the circumnavigation (along with a dozen or so shipmates).

  • Figure 4 in the paper (Score:5, Interesting)

    by Pausanias (681077) <oyyndcf02&sneakemail,com> on Thursday August 02 2007, @03:20PM (#20092193)
    Check out Figure 4 at the end of the linked paper. It shows that the periods of highest diversity coincide with the periods where the cosmic ray flux is lowest. Really amazing correlation if you ask me.
    • I recall reading one guys work on galactic dynamics where he suggested that our solar system "orbits" or oscillates (planar) through one of the arms (dense areas - we're not a pinwheel) of the galaxy. He suggested that as we pass through the middle, we're more likely to be hit by other objects. This was his explanation for the extinctions. Now we see that someone has concluded such an oscillation is really happening, however they suggest the a different phase relationship. The guy I was talking about would

  • Not only is this not a new theory (Score:3, Informative)

    by clusterlizard (1136803) on Thursday August 02 2007, @03:23PM (#20092267) Homepage
    It's not even a new slashdot article [slashdot.org].

  • Or Maybe... (Score:5, Insightful)

    by MxTxL (307166) <mlutterNO@SPAMgmail.com> on Thursday August 02 2007, @03:26PM (#20092319)
    The researchers suggest that an increase in the exposure of Earth to extragalactic cosmic rays causes mass extinctions.

    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)

    by ggvaidya (747058) on Thursday August 02 2007, @03:26PM (#20092327) Homepage Journal

    ... extragalactic cosmic rays causes mass extinctions ...

    Can we please oh please oh please call them death rays?

  • -1, Totally Irrelevant (Score:3, Interesting)

    by athloi (1075845) on Thursday August 02 2007, @03:34PM (#20092459) Homepage Journal
    Humanity's chances of avoiding self-destruction or regression to a simian mean within the next 7 million years approximate zero, or worse (Cantor sets).

  • Well... (Score:5, Funny)

    by Chouonsoku (1009817) on Thursday August 02 2007, @03:36PM (#20092491) Homepage
    I for one welcome our new cosmic ray-based overlords! (I just felt like I hadn't seen that lately. :'( Mod me as you wish. But, be gentle.)

  • Some hasty objections (Score:5, Informative)

    by Michael Woodhams (112247) on Thursday August 02 2007, @04:07PM (#20092971) Journal
    OK, I've only read the summary (I have a lecture to give half an hour from now to prepare for) but I can see some objections:

    * 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)

    by markk (35828) on Thursday August 02 2007, @04:28PM (#20093313)
    The title of the summary is totally wrong. This has nothing to do with mass extinctions. Its looking at fossil Species and Family counts vs time correlated with Solar motion. The 62 MY cycle barely touches the Mass extinction events.
    Better summary title - "Life's Diversity changes with Solar Galactic Orbit". Or something like that.

  • Eulogies (Score:3, Funny)

    by StikyPad (445176) on Thursday August 02 2007, @06:00PM (#20094613) Homepage
    I, for one, would like to commemorate a few periodic mass extinctions:

    Dear AU, what has become of you? You may not be extinct, but I can never find you.
    Humble Promethium. Your existence was "predicted" long after your demise.
    Oh 271 Seaborgium, how did you decay? Let me count the ways. Alpha decay. Spontaneous fission.
    272 Roentgenium, we hardly knew you. Half extinct at the tender age of 1.5ms. You're the one we'll truly miss.

  • New paper, old theory (Score:3, Informative)

    by syousef (465911) on Thursday August 02 2007, @07:35PM (#20095523) Journal
    I'm sure I've seen this before, possibly found out about it on /.

    Here's an article from March 2005
    http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2005/ 03/10/MNGFIBN6PO1.DTL [sfgate.com]

    It's only one of many theories. The wikipedia page that points to the article above discusses them all
    http://en.wikipedia.org/wiki/Mass_extinction [wikipedia.org]

    • Re:Well, that would explain (Score:5, Informative)

      by eln (21727) * on Thursday August 02 2007, @03:22PM (#20092223) Homepage
      The article suggests that this does not explain the K-T event, which is already adequately explained by the asteroid impact theory. This theory explains the cyclical decreases in biodiversity that seem to happen about once every 62 million years. The K-T event is not part of this cyclical pattern.

      • Why not? (Score:5, Insightful)

        by SatanicPuppy (611928) * <Satanicpuppy@gmai3.14159l.com minus pi> on Thursday August 02 2007, @03:43PM (#20092595) Journal
        Radiation doesn't kill things off that well. Look at Chernobyl or the Savannah river plant...Both shut down, both radioactive, both experiencing a resurgence of pretty healthy wildlife across the board.

        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.

        • Re:Why not? (Score:5, Interesting)

          by smellsofbikes (890263) on Thursday August 02 2007, @05:42PM (#20094395) Journal
          I have some friends with PhD's in nuclear science who claim that radiation is beneficial. They go further: life started when there was a lot more radiation, so most of our genetic machinery is designed to work with far higher radiation than what we're seeing, which is to say we can stand a lot more radiation with little harm. They go further and claim that because there's less radiation now, we have more problems -- higher background radiation might act to suppress immune system malfunctions (sitting in radioactive hot springs does seem to reduce the symptoms of arthritis.) Life survival vs. number of cells should be inversely proportional as radiation level rises: if a bacterium has its DNA badly injured by a radiative event, it's less likely to survive than an animal with a million cells. (I've read in other places that every strand of DNA in every cell experiences tens of damage events requiring repair every day.) My friends the PhD's go so far as to claim that the reason that the seven counties in the US with the longest average lifespan are all on the Continental Divide in Colorado [plosjournals.org] where the radiation levels are highest because of the elevation.
          (Sorry I can't find a better link for the Eight Americas dataset: you have to download an Excel spreadsheet to get the raw data.)

      • Re:Well, that would explain (Score:5, Informative)

        by inviolet (797804) <pineminder AT yahoo DOT com> on Thursday August 02 2007, @04:51PM (#20093669) Journal

        Fewer cosmic rays mean fewer clouds will be formed, and so there will be a warmer Earth. If the sun and the solar wind are not so active, then more cosmic rays can come in. That means more clouds [reflecting away more sunlight] and a cooler Earth.

        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?

All trademarks and copyrights on this page are owned by their respective owners. Comments are owned by the Poster. The Rest © 1997-2009 Geeknet, Inc.