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Education Science

Lemming Population Flux Solved: Mass Suicide Not to Blame 181

quogmire writes "Australia's ABC reports that biologists from the Universities of Finland and Freiburg (Germany) have finally solved the question of lemming population fluctuations once thought to be caused by lemmings mass-suiciding by plunging off cliffs. 'Lemming populations, they say, surge spectacularly and fall just as quickly, thanks to the combined feasting of four predators: the stoat, arctic fox, snowy owl and a seabird called the long-tailed skua.' The original article (Login required) is published in Science."
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Lemming Population Flux Solved: Mass Suicide Not to Blame

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  • by alex_ant ( 535895 ) on Saturday November 01, 2003 @02:44PM (#7367190) Homepage Journal
    There will always be another sequel.
  • good! (Score:5, Funny)

    by Dorothy 86 ( 677356 ) * on Saturday November 01, 2003 @02:44PM (#7367192) Homepage
    well, at least now I know that its just not God pushing the mushroom cloud button!
    • Don't tell Homeland security. Next thing you know we'll be invading Scandinavia.
  • by Phosphor3k ( 542747 ) on Saturday November 01, 2003 @02:44PM (#7367194)
    because I keep clicking the bomb icon and blowing them up?
  • When I read the slashdot bit, but before I read the article itself, I thought the article was reffering to the computer Lemmings in the video game. Anyone else think that?
  • Pingus (Score:5, Funny)

    by MooCows ( 718367 ) on Saturday November 01, 2003 @02:45PM (#7367197)
    Why study Lemmings when you can study Pingus [seul.org]?
    • Because it's a vastly inferior game when compared to the original. Playability was entirely scratched in favour of sticking an oversized geek mascot in there, in turn sacrificing all of the magic, atmosphere, well-designed levels and proportion which made the idea work in the first place.
      • Re:Pingus (Score:2, Interesting)

        by Kent Recal ( 714863 )
        I played some early pingus-demo (4 levels i think) and I didn't find it _that_ bad at all.
        Ofcourse it's not the original lemmings and most of the levels lacked the "Doh!"-effect of the original, but it is definately worth a look also for those who played the original lemmings back and forth.

        Post-It-Side-Note: I didn't really like the original lemmings past Lemmings II. Some of the bonus packs (X-Mas Lemmings etc.) were nice. But starting with Lemmings III they put in so many new modes (and very bad one
        • I (and probably any Lemmings fan ever) would agree that the series died after Lemmings II. You're certainly not alone there.
          • agreed, the Lemmings 3D really disappointed me.

            Worms 3D seems to be pretty cool though if you like that sorta game, download the demo [3dgamers.com], I'll be buying it when its out.
            • Well, if they only made a linux-version, I'd definately give it a shot...

              I'm curious if they could actually make worms "work" in 3d. Lemmings3d was so awful, I didn't even bother to finish level 1. (Playtime: ~45 minutes)
              • Well the 3D aspect is cool, but once you've set your view you don't need to spent a hundred hours rotating the camera every which way. I'm not sure if it's anything you can narrow down, just has a good feel to it once you un-invert the mouse which is inverted by default.
              • Re:Pingus (Score:2, Funny)

                by yourmom16 ( 618766 )
                Unfortunately most worms(Slammer, Blaster, SoBig, etc) are for Windows.
          • My g/f bought lemmings 3D for 4.99 at staples, and she still got *ripped off*. If I saw a psygnosis developer lying in the street bleeding I'd kick him as I walked by.
  • by dauvis ( 631380 ) * on Saturday November 01, 2003 @02:46PM (#7367205)
    I thought it was because I should have had one build that bridge across the chasm. I didn't consider that the game had predators as well.
  • by Chmarr ( 18662 ) on Saturday November 01, 2003 @02:46PM (#7367207)
    What? There are STILL people that believe that lemmings mass suicide?! Geez, what a hoax.

    It's well known, by me at least, that the whole 'lemming suicide' thing was something that Disney cooked up during their 'bad documentary' era. In this case the lemmings were hearded off a cliff by the documentary crew, and was filmed as a 'mass suicide'.

    I've seen some pretty amusing/sad documentaries that came out of Disney, including one that had the antics of a Jaguar eating various creatrues. It was OBVIOUS that it was a jaguar in a rather well done habitat where they threw in various animals, mostly eels, for the jaguar to attack. It was exceptionally amusing, but sad, too, that they thought to do something like this and pass it off as truth.
  • by iggymanz ( 596061 ) on Saturday November 01, 2003 @02:48PM (#7367210)
    those Disney lemmings didn't commit suicide, they were MURDERED! *gasp*
    • In fact, they were. My sister met someone who worked on the project. He said that if you actually look closely at the Disney footage, you can see the lemmings trying to swim back to the shore! They were apparently taking them and throwing them off by the bucketful...

      The person's excuse was that he was a poor college student and needed the money. Makes one wonder what other atrocities have been committed by poor college students? *grin*
  • Oh, crap (Score:4, Funny)

    by pipingguy ( 566974 ) on Saturday November 01, 2003 @02:49PM (#7367218)
    So is the old Psygnosis game [wikipedia.org] now obsolete and environmentally incorrect?
  • The snopes.com link is really shocking. I notice it dates to '96... I'm surprised I hadn't heard about it until now.
  • aha! (Score:5, Funny)

    by Joe the Lesser ( 533425 ) on Saturday November 01, 2003 @02:49PM (#7367222) Homepage Journal
    They're not suicidal, they're just tasty!
  • Not true (Score:1, Redundant)

    by CGP314 ( 672613 )
  • I guess I can sleep now that I know the mystery behind lemming population flucuations.
  • by indros13 ( 531405 ) * on Saturday November 01, 2003 @02:52PM (#7367235) Homepage Journal
    ...get a game mod out for the original Lemmings. It just won't be the same...

  • by spektr ( 466069 ) on Saturday November 01, 2003 @02:53PM (#7367241)
    This doesn't concur with the results I got from my private investigations regarding the behaviour of lemmings. I did some massive computer simulations during the 90's, which showed that lemmings are stupid animals which will walk into one direction until they fall off the cliff. Only few of them can use jack-hammers or parachutes, and even that not without explicit order.
  • Oh no! (Score:5, Funny)

    by FrostedWheat ( 172733 ) on Saturday November 01, 2003 @02:54PM (#7367251)
    *puts hands on head* Oh-no!!!

  • Chaos theory was in part defined following studies of populations of just TWO animals, the arctic hare and the the Canadian lynx. This was around 1989. [google.com]

    So why should it be surprising that populations of lemmings are chaotic?

    What, exactly, is the news here?
    • They aren't chaotic. They're very cyclical, following a four-year pattern, allowing you to predict when the next population rise or drop will be. That's the opposite of chaotic.

    • Uh, if you had RTFA, you would see that the cycle isn't chaotic, but is actually precisely 4 years long.

      It's not news really, that cycle has been going on for centuries, probably millenia before it was posted on slashdot... I guess it kind of depends on your definition of news.

      <fight... urge..... to... make... crack-shot comment>

    • I have no idea which book you are talking about. Nor why you want to talk about chaos theory, which is clearly inappropriate here (although a trendy word).

      Even my fathers high-school math books had examples of populations of two animals, one predator, and one herbivore. This is about the simplest differential equation you can get, and has probably been well-known for quite a few centuries. If anyone has felt the need to use chaos theory here, they must clearly have worked with completely different example

    • Chaos theory was in part defined following studies of populations of just TWO animals, the arctic hare and the the Canadian lynx. This was around 1989.

      Chaos theory was well established by 1989. The term "chaos" was coined in 1975 (Li & Yorke), and Lorenz' original paper was in 1963.

  • I suspect that the human population will go through a similar cycle. Exponential growth, exceed the carrying capacity and then population crash. We're seeing it at the local scale but with globalisation, I don't see anything to stop it on a global scale.

    At the moment, the western industrialised nations are fairly steady state but the developing and 3rd world nations are definitely not. We can look forward to wars over resources in the relatively near future (have they started already, iraq just the preque
    • by kfg ( 145172 )
      Even in the "steady state" western nations you can have local overpopulations with dramatic consequences.

      Gang violence, school shootings, "going postal"?

      We pack a lot of large, predatory animals with a complex social structure based on submission/dominance into small spaces with artificial local shortages.

      Can you say, "Too may rats in the cage," boys and girls? I knew you could.

      • Even in the "steady state" western nations you can have local overpopulations with dramatic consequences.

        Gang violence, school shootings, "going postal"?

        By that logic, Hong Kong and Tokyo should have the highest violent crime rates in the world...

        • Re:Carrying capacity (Score:2, Interesting)

          by kfg ( 145172 )
          Please note that I made no argument as to the "casue" of violent crime. I made an anecdotal reference to a known phenomenon and understand it as such.

          It is a mistake to consider that people are rats, or dogs, or chimpanzees. This does not preclude the idea that studying the behaviour of such cannot reveal to us clues about our own behaviours.

          Nor did I even imply that violence is the only possible response to overcrowding and local shortages. Since it is not there is no reason to imply direct proportionali
          • I might also point out that crime and violence are seperate issues. One is a behaviour and the other is a violation of a code of behaviour.

            Boxing is not a crime. Boxing is violent.

            Violence can increase as violent crime decreases. There is no logical connection between crime and violence, only a social connection based on local mores.

    • Birth rates are dropping on an almost global scale. As societies modernize the birth rate falls at a blistering place.

      For example in India:

      Birth Rate per 1k @1970 - 41.2
      Birth Rate per 1k @1995 - 28.3

      Sure improved medicine helps but so does the education and rise of women's rights in societies. We are currently in the end of our world's population explosion for humans.
    • Re:Carrying capacity (Score:5, Interesting)

      by Persecuted_Telemarke ( 717360 ) <persecuted_telemarketerNO@SPAMyahoo.com> on Saturday November 01, 2003 @03:34PM (#7367396) Journal
      Actually, it depends pretty radically on which type of model you're considering.

      For example, if you assume that the population is governed by a continuous-time model, i.e. by a differential equation, then it is not really possible for a population to exceed a carrying capacity, and then crash. What happens is that the population asymptotically approaches the carrying capacity, but can never go above it. I think it is reasonable to put humans in this case, as our growth rate is a smooth frunction of time (no breeding season, for example).

      Aside note: for those who may not know, the term "carrying capacity" is a term used in population dynamics which sort of represents the available resources. In most models, what happens is that there is some amount of population which can be supported by the existing resources, and if the population is below that, it should grow, and above that, it should shrink. Most "reasonable" models of population dynamics have such a carrying capacity, and I can even state a theorem: if you have any model where the growth rate of a species depends on its size, AND it is true that this growth rate becomes negative for some sufficiently large value of the population, then you will have a carrying capacity. Furthermore, if nothing in the system changes, the population will approach this value and stay there forever.

      Now, I'm not saying a crash is impossible, but you need a more complicated system. There are several ways to add complexity to the system. One way is to consider a predator-prey type of system, but of course humans have nothing which can really be called a predator. The only thing I can think of is some sort of disease, but this leads to a different model altogether (some sort of "epidemological model"), and these models rarely predict population crashes, as they have a different character, which is disease needs to be carried by disease-carrying individuals (ok, duh) but then these tend to die out. So the predator carries its own destruction around with it, in some sense, and it corrects itself.

      Another postulate one can make, and I think this is somewhat reasonable, is that the carrying capacity of the earth might change radically in the future (and of course, radically downward would be the interesting case in this discussion). This could happen any number of ways. And if it turns out that the carrying capacity moves on some very quick timescale (much more rapid than the change in growth of the population), then we could see a "crash". For example, if it turned out that our ability to grow food took a big hit for some reason or another, then this could happen.

      One last way to get population crashes is to consider the case of the discrete system. For example, this does apply to species which have a discrete (say, yearly) breeding system. The population does not change smoothly over time, but is simply a function of one year to the next. It is somewhat surprising, but true, that the dynamics of a population with a discrete model can be much more complicated than those with a continuous model. In fact, a discrete model can actually have what satisfies the mathematical definition of "chaos". Thus you can see any type of behaviour you might imagine, including crashes, but also including periodicity (say, a 17-year cycle for population values). I do not think it is reasonable to assume that humanity can be modeled by this sort of model, even in a coarse-grained sense, because we breed day in and day out all the time. This (and this is somewhat surprising) makes our population a much more stable quantity.

      • This is very interesting, so I only say this a bit tongue-and-cheek...

        If your model does not predict poplution crashes, and there are, in fact, population crashes, you have problem. Your model is not very good.

        You have two choices... change your model, or exterminate the subject of your model and get rid of all the evidence...
        • I agree with your first comment completely, and I wouldn't even think it was tongue-in-cheek... If we see a phenomenon in nature, and the model doesn't predict that, then the model is not good. Certainly.

          What makes life complicated is there are tons of models out there, and who knows which one goes with which real system? That's why scientists get paid the "big bucks". Now that is tongue-in-cheek.

      • Re:Carrying capacity (Score:3, Informative)

        by plastik55 ( 218435 )
        It is not true that a continuous-time model can not be chaotic. Consider the Lorentz strange attractor which was discovered on an analog computer. The three-body problem in orbital mechanics also behaves chaotically.
        • It is not true that a continuous-time model can not be chaotic.

          This is very true. But it is true in the one-dimensional case, which I claim is the case for the dynamics of the population of humans.

          All that being said, why does the model for the population have to be one-dimensional? This is a reasonable objection. An answer to that is, no matter how many dimensions the system has, there should be a way to coarse-grain it and get an essentially 1-D system.

          For example, let the population of humans

    • We can look forward to wars over resources in the relatively near future

      I think they haven't "already started", they've been going on for at least 30 years since the first Petroleum crisis of the seventies.

      Aside from that though, the earth is humoungous, we will kill each other well before we run out of harvestable food bearing land. Just a number: something 80% of american produce is wasted (in transport or other places).

      The reason ethiopia doesn't have food is not exactly because they don't have l

      • We can look forward to wars over resources in the relatively near future

        I think they haven't "already started", they've been going on for at least 30 years since the first Petroleum crisis of the seventies.

        I'd go even further. I'd say almost all wars in human history were, at least to some degree, a fight over limited resources. At the very least, once colonization became a major factor in, say, 1500 or so, that's all it's been about. The big boys fighting over the resources...

  • For American readers, that's a Long-tailed Jaeger.
  • by FollowThisLogic ( 710628 ) on Saturday November 01, 2003 @03:12PM (#7367312)
    Apparently it has also been found that when the lemmings do jump off the cliff, they all have little umbrellas to make it down safely.
  • RTFA? (Score:4, Informative)

    by Persecuted_Telemarke ( 717360 ) <persecuted_telemarketerNO@SPAMyahoo.com> on Saturday November 01, 2003 @03:13PM (#7367314) Journal
    Ok, fine, I guess most people can't get to the original Science article. I had to do some funky proxy shit with my university's library server. So it should be somewhat forgiven.

    But I just wanted to point out that the ABC article is somewhat misleading. The original research article at no point addresses or attempts to refute the mass-suicide myth. Because, honestly, no scientist believed that was possible. The question they considered was much more reasonable: do the large deviations come from predators eating lemmings, or from a lack of vegatation for the lemmings to eat? It seems as though they have resolved that the crashes in population come from predator over-population, not from food scarcity.

    This article will probably not shake the foundations of population dynamics. As some other posters have pointed out, it is not so surprising that one sees immense highs and massive crashes in a predator-prey system, because these phenomena exist even in simple mathematical models of pred-prey systems. So for a mathematician this should fly right under the radar.

    On the other hand, to a population dynamics guy, this is somewhat interesting, as in that field it is typically considered hard to model these dynamics accurately. It seems as though these guys have determined some parameters in the population dynamics model experimentally, and this is what it is interesting.

  • Now that we are discussing suicide, and how we had a whole messed up definition of what the suicider-lemmings were doing, I wonder if we have a similarly messed up understanding of the suiciders ...

    I know that POTUS has defined it in pretty much black and white, and the LUNATIC calls them the deadenders, the military calls them operatives ... but whatever ... basically the question that pops in my head is whether the operating definition of a suicide-bomber that is currently in vogue is comprehensive or n
    • Our own cultural view of suicide is the anomoly and derives, essentially, from Jewish tradition and thus Christian. Even if one does not subscribe to any religion and does not believe in God the social culture that you grew up in, and thus absorbed, is at its heart based on Judeo-Christian ethics and morality.

      Thou shalt not steal.
      Thou shalt not kill.


      If you believe you belong to God than harming yourself, God's property, is a sin. I have a friend who cannot be buried in his family plot because he has
  • What with this .. 'Lemming populations, they say, surge spectacularly and fall just as quickly, thanks to the combined feasting of four predators: the stoat, arctic fox, snowy owl and a seabird called the long-tailed skua.

    and this .. This page was generated by a Group of Trained Rabbits for RabidStoat (689404) it's been quite a day !

  • This Article [ec.gc.ca] suggests that the population flux may be strongly linked to the evolution of the species through natural selection. Here is the relevant quote:

    Although several species of small rodents that live in temperate climates also reach peaks of abundance about every four years and some of them reach much higher densities at the peak than lemmings do, none can equal the extreme scarcity of lemmings at the nadir. Such extreme scarcity raises the spectre of extinction. But passing through a population "

  • Oh no..

    *sounds of lemmings exploding*
  • I wonder why it took them so long to come up with a model for lemmings' weird population behavior. I think such "boom and bust" cycles have also been observed for caribou and the arctic wolf. A rise in the caribou population causes a corresponding rise for wolves and both fall dramatically afterwards. I'm not completely sure about this, so please feel free to correct me here.

    Also, it is interesting that suicidal behavior among animals does exist. This Everything2 node [everything2.com] provides some very interesting informa
  • by azaris ( 699901 ) on Saturday November 01, 2003 @03:32PM (#7367389) Journal

    Apart from the "University of Finland" and all the cutesy Lemmings jokes, does this strike anyone as horrificly unscientific? I mean, it's been observed for ages that the growth of the population of the prey causes a growth in population of the predator. Then your population growth for the lemmings looks something like:

    dL/dt = bL/2 - hP

    where L is the lemming population, b is the average number of lemmings born in a time interval, P is the number of predators and h is some constant. P on the other hand is related to L by some observed relation:

    dP/dt ~ L

    Given suitable values for b and h we can predict the behaviour of the lemming population without having to invent catastrophic events to explain the fluctuations of L without any empirical evidence to support them.

    • This model is a a nice start, but would benefit from a few refinements. I'm not sure I have time to work out the math here and now, so I'll leave that as an exercise for the student :-). Some specific suggestions include:
      1. Consider adding carrying capacity, which is quite critical in arctic populations, since there is substantially less biomass and hence food in arctic environments (due to reduced solar energy).
      2. Additionally, your equation appears to assume that the sex ratio (male to female) is 1:1, but
    • It is new information because it was not previously known exactly how the predator populations and the lemming populations interacted. In this case it's not nearly as simple as you describe.

      One of the problems was that not all of the predators involved in the cycle have lemmings as their primary food - only the stoat do. The other predators that eat lemmings only resort to lemmings when they are so plentiful that hunting them is too easy to miss out on.

      Another issue was that the lemming cycle is extreme

  • by Anonymous Coward
    Back in the day, THE thing to study at university was Chemical Engineering, since graduates were in high demand and earned a fortune.

    Guess what ? 3 years later, there was a glut and they couldn't find jobs.

    Parallels with today's job market anyone ?

    Parallels with lemming population ?
  • Survival Strategies (Score:4, Interesting)

    by Detritus ( 11846 ) on Saturday November 01, 2003 @04:10PM (#7367590) Homepage
    A popular survival strategy for many insects is to synchronize their breeding so that they produce a huge number of offspring within a short period of time. The predators can stuff themselves silly but there are plenty of survivors.
  • I am always amused when foreigners imagine that in small foreign countries there is just one big kick-ass organization of each kind and then this is called the X of Novistrana... it's almost as if it came straight from South Park. We have a bunch of universities in this country, but none of them are called the University of Finland...
  • Is this offtopic?

    http://www.amnh.org/exhibitions/expeditions/trea su re_fossil/Treasures/Dodo/dodo.html
  • especially those suicide bomber ones!

    (double clicks the mushroom cloud)
    OH NO! ...pop!

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