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Lemming Population Flux Solved: Mass Suicide Not to Blame

Posted by CowboyNeal on from the games-to-stand-as-is dept.

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."

37 of 181 comments (clear)

  1. Don't worry if you ever lose Lemmings off a cliff by alex_ant · · Score: 3, Funny

    There will always be another sequel.

  2. good! by Dorothy+86 · · Score: 5, Funny

    well, at least now I know that its just not God pushing the mushroom cloud button!

    --
    Game Overdrive - Gaming News
  3. I thought it was by Phosphor3k · · Score: 5, Funny

    because I keep clicking the bomb icon and blowing them up?

  4. Pingus by MooCows · · Score: 5, Funny

    Why study Lemmings when you can study Pingus?

    --
    The path I walk alone is endlessly long.
    30 minutes by bike, 15 by bus.
    1. Re:Pingus by Kent+Recal · · Score: 2, Interesting

      Hum.
      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 ones, too, like the "Jump"-Lemming and others that depended on SplitSecondMouseclickTiming(tm)) that it ruined the great "usability" known from Lemmings I+II.
      In that light pingus has a really nice balance of just the right number of not-so-over-the-edge (bazooka-lemming anyone?) modes.

      Another-Really-Small-Sticky-Note:
      One mode that's really been missing from all Lemmings-Clones I know would be
      the "PacMan"-mode, tho... ;-)

    2. Re:Pingus by yourmom16 · · Score: 2, Funny

      Unfortunately most worms(Slammer, Blaster, SoBig, etc) are for Windows.

      --
      "We have got to make Stan understand the importance of voting, because he'll definitely vote for our guy." - South Park
  5. This is good news... by dauvis · · Score: 5, Funny

    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.

  6. Suicide theory is a fraud! by Chmarr · · Score: 5, Informative

    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.

    1. Re:Suicide theory is a fraud! by Anonymous Coward · · Score: 3, Informative

      Yep. Here's a Snopes link for those who believe that everything that isn't on that site to be true:

      http://www.snopes.com/disney/films/lemmings.htm

    2. Re:Suicide theory is a fraud! by vidarh · · Score: 5, Informative

      You're partly wrong. The lemming suicides were NOT cooked up by Disney - the idea of lemmings mass suicides preceeded their documentary by half a century at least. Disney faked their documentary because they believed the mass suicide story but they didn't manage to get any film of it, and instead of questioning whether the suicides actually happened they faked a scene to illustrate what they thought was supposed to happen.

    3. Re:Suicide theory is a fraud! by vidarh · · Score: 4, Insightful
      I think you can safely assume that Disney treated a lot of their "documentaries" as they would any fiction: Write the script, and go out and film the scenes. And when you expect to follow a script and nature starts being difficult, they did what they could with the same persistence as they'd fake weather or scenery for any other movie.

      I guess they thought it was only the end product that mattered.

  7. sounds like exceprt from formula mystery novel by iggymanz · · Score: 4, Funny

    those Disney lemmings didn't commit suicide, they were MURDERED! *gasp*

    1. Re:sounds like exceprt from formula mystery novel by Mattcelt · · Score: 2, Interesting

      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*

  8. Oh, crap by pipingguy · · Score: 3, Funny

    So is the old Psygnosis game now obsolete and environmentally incorrect?

    1. Re:Oh, crap by Wakkow · · Score: 2, Interesting

      I wanted to post a link to DHTML Lemmings (the original Lemmings in your browser) but it looks like they had to take it down. Help the guy figure out who, exactly, is the owner of Lemmings!

  9. aha! by Joe+the+Lesser · · Score: 4, Funny

    They're not suicidal, they're just tasty!

    --
    "I only speak the truth"
    Karma: null(Mostly affected by an unassigned variable)
  10. Someone needs to... by indros13 · · Score: 4, Funny
    ...get a game mod out for the original Lemmings. It just won't be the same...

    --
    Under capitalism man exploits man. Under communism it's the other way around.
  11. I'm sceptical by spektr · · Score: 5, Funny

    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.

  12. Oh no! by FrostedWheat · · Score: 4, Funny

    *puts hands on head* Oh-no!!!

    *POP*

  13. Carrying capacity by Moderation+abuser · · Score: 2, Insightful

    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 prequel?).

    --
    Government of the people, by corporate executives, for corporate profits.
    1. Re:Carrying capacity by kfg · · Score: 2, Insightful

      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.

      KFG

    2. Re:Carrying capacity by Persecuted_Telemarke · · Score: 5, Interesting
      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.

      --

      Persecuted Telemarketers Unite!

    3. Re:Carrying capacity by kfg · · Score: 2, Interesting

      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 proportionality between crowding and violence, and I did not do so. It is, however, demonstrably one of the expected responses in virtually all of the mammals, especially those that are carnivorous.

      As crowding goes up and shortages occur there is a certain probability of violence increasing, as there is a certain probability of certain other phenomenon as well.

      KFG

    4. Re:Carrying capacity by plastik55 · · Score: 2, Informative

      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.

      --

      I have a positive modifier on Troll. When I mod someone Troll their karma should go UP!

    5. Re:Carrying capacity by Persecuted_Telemarke · · Score: 2, Informative
      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 be P(t). If we make the assumption that the growth rate of humanity depends only upon the number of people alive, then it can be written

      dP/dt = f(P) P,

      where f(P) is some unknown function which absorbs all of the possible variables. For example, we could say that there are thousands of factors which impinge on the growth rate of people, like availability of food, prevalence of pollution, etc. Now, our only assumption is that all of these factors depend on the size of the population. Then we can say that the growth rate is really a function only of P.

      Now, to be fair, it is possible that there are factors which don't depend on the size of the population. But I think it is reasonable, in that all of the standard constraints to growth, like prevalence of pollution, limits of food, etc., can depend only on population.

      Now, if this model is correct, then it is true that this system is not chaotic at all, but that there is complete regularity. For example, as long as it is true that for sufficiently large P, this function f(P) is negative, then there is a number, called the carrying capacity for the system, and any initial population will tend towards it.

      I do agree that it is possible that this function f can depend on some other things, for example imagine that for some strange reason, tomorrow the availability of the food supply takes a big hit, and that f becomes much smaller without P changing. Then we could have a crash of some sort, but my feeling is that although this is possible, it's not reasonable. I think that on the other hand it is reasonable to expect that this function f will depend only on P.

      --

      Persecuted Telemarketers Unite!

  14. Re:Gee. by Jodaxia · · Score: 4, Insightful

    I guess whoever did this study failed their first ecology course in college.

    Almost every ecology teacher beats several key things into your heads.
    1. Survival of the fittest
    in other words an individual does not do something for the benifit of the species, mainly due to the fact that doing so diverts energy that could be used to producing more young so that their genes survive. The individual will do things to benifit their genes, but not for unrelated individuals of the same species. Social species do have some altruistic behaviours, but their communities are generally made up of individuals that are related. However these altruistic behaviors do not include suicide.

    2. The lynx and Hare.
    Classic example of what is going on with the lemmings here. As the hare population increases there is more food for the lynx, thus more offspring are produced. As the lynx population increases there are fewer hare to eat and the lynx population declines, and so on.

    So this study on lemmings is not surprising, actually I'm quite shocked that someone didn't figure it out sooner.

    --
    crowbar??
  15. Beyond the article... by FollowThisLogic · · Score: 3, Funny

    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.

  16. RTFA? by Persecuted_Telemarke · · Score: 4, Informative
    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.

    --

    Persecuted Telemarketers Unite!

  17. Re:University of Finland? by AvantLegion · · Score: 2, Informative
    A little Googling reveals that the professor listed in the article is of the University of Helsinki, which, once upon a time, was the Imperial Alexander University of Finland (so changed to U of Helsinki a couple of years after Finland gained independence).

  18. This is new information? by azaris · · Score: 3, Interesting

    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.

  19. Pingus by yerricde · · Score: 2, Funny

    If the Lemmings were running Linux

    Then they'd be Pingus

    --
    Will I retire or break 10K?
  20. Survival Strategies by Detritus · · Score: 3, Interesting

    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.

    --
    Mea navis aericumbens anguillis abundat
  21. Re:Gee. by WalksOnDirt · · Score: 2, Insightful

    Yes, but the details of the altruism seem to be missed in a lot of popular science writing. Evolution is working on behavior here, and the more complicated a behavior is the harder it is to appear and persist. So, if a simple response of helping a neighbor at only a minor cost usually benefits a relative, the fact that nearby non-relatives sometimes get helped isn't violating some evolutionary principle.

    --
    a,e,i,o,u and sometimes w and y (at be if of up cwm by)
  22. "Computer Lemmings"? You mean Windows users? by Prof.+Pi · · Score: 2, Funny

    "Time for another upgrade/mass-migration!"

  23. Re:Deja vu all over again by joto · · Score: 2, Insightful
    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 examples.

    Furthermore, nobody is surprised that lemming populations are chaotic. The reason is that lemming populations are not chaotic. And we are not surprised about this either, is we've had the chance to observe lemming populations out in the nature for several millennia, and so far, they've been pretty regular in their cycles.

    There is one thing I can agree with you about. Yes, there were no news here. Anyone half-way educated about biology would know better than to believe that lemmings do mass-suicide. Unfortunately, I haven't got access to nature and the original article, but I assume the "breakthrough" if any, would be more akin to a more reliable model, or better insight into why some model already works well. Solving differential equations for populations with 3 or 4 species shouldn't exactly be beyond the abilities of most biologists working with population.

  24. I'm afraid you're mistaken by GQuon · · Score: 2, Informative

    Universities of Finland. And I'm sure that Finland have several universities.
    I'm afraid you misread that. The post says "Universities of Finland and Freiburg (Germany)", while the ABC article says "University of Finland, and Benoit Sittler of the University of Freiburg in Germany."
    The university in question is the University of Helsinki, Finland. (I have university access to the Science articles.)

    --
    Irene KHAAAAAAN!
  25. Lemmings are Terrorists by Laconian · · Score: 2, Funny

    especially those suicide bomber ones!

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