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One of those topics where the meta is richer than the actual science. I remember my Dad mentioning as a child. The public interest is interesting in itself. No

One of those topics where the meta is richer than the actual science. I remember my Dad mentioning as a child. The public interest is interesting in itself. Not the the science isn't interesting. Population/behavioural studies like this are quite interesting. Animal behaviour is interesting, especially group behaviours where dynamics can play out. That said, what was he actually trying to learn? If you take the same colony, and manually removed a few hundred juveniles every week... that's basically a mouse farm. So, we know from both logic and evidence that "overpopulation" is a thing that occurs. Organisms multiply at exponential rates, and there must be hard limits on growth somewhere. Meanwhile, rodents as especially known for boom/bust cycles. Is it surprising that behaviour gets weird during "peak mouse" events? Mice aren't cannibalistic. The colony was protected from disease. Food didn't run out. Eventually, it's so crowded and everyone is stepping on one another. Breeding becomes unsuccessful, and that's the limiting factor. What's the alternative, that the cube becomes literally full of mice before crashing? That mouse society adopts a super slow breeding rate to stabilize populations. What happened was, ultimately, a compromise between these two. In any case, if the goal is analogy to humans... where's the work. If it's a scientific endeavour, how do we get from insights about mice to insights about people?

NineStarPoint 4y ago
It’s interesting to me at least that the group’s population crashed completely to zero and not to just a low number that then began climbing again. This is undoubtably a consequence of mice not being able to escape from the chaos due to the small size of the territory, but I do wonder what the minimum viable size would be to allow for a full boom-bust-boom cycle to occur.
- Someone 4y ago
  But there wouldn’t be chaos anymore by the time population dropped to a few hundred. Between the two moments of equal population something must have changed in the population, either genetically or, IMO more likely, culturally.
- dalbasal 4y ago
  I don't think it's that surprising, especially as an occasional result. Consider that surviving severe overpopulation is trauma. Survivors are physically and/or psychologically sick. They're not good breeders and at this point. Happens frequently in aquariums. Guppies breed like guppies. Overpopulate, then die back. The proximate causes can be varied. Maybe there's an ammonia spike, oxygen deficiency or other consequence of overabundance. When the "crash" happens, survivors tend to be a precocious bunch. They're past breeding prime, and probably injured by the events of the crash and its precedents. Starting a colony with "poor stock" is always more difficult, and that's what you now have. It doesn't have to be overpopulation that causes a crash. Say you accidentally pollute the water with soapy hands. Some fish will die today. Some tomorrow. Dead fish rotting is also polluting. Fish surviving the ordeal will probably have reduced lifespans and breeding potential. My unqualified guess is that most extirpation events leave survivors, usually in less than ideal shape. The technical extirpation happens later, as survivors gradually drop off without successful reproduction. Good question about minimum population size for boom/bust cycles to occur. I suspect this is more about environmental richness than pure numbers. Some predation probably stabilizes things, and some boom/bust might be possible. If you had multiple colonies connected by 500m of tubing, this "distance" between territories might allow for "local" booms and busts to occur.
  - generalizations 4y ago
    > If you had multiple colonies connected by 500m of tubing, this "distance" between territories might allow for "local" booms and busts to occur. I was thinking the same thing. From the article I got the impression that the final collapse happened because all the survivors were the same age, and too old to spawn a new generation. Semi-separation would at least break the synchronization.
  - shard 4y ago
    > Consider that surviving severe overpopulation is trauma Recently there was an article posted on HN about how trauma experienced by parents are passed down to children through (a term that means it's related to activation of genes, I believe, but not DNA itself... I thought it was metagenomics but upon looking at the definition I don't think that's it). Perhaps the trauma of overpopulation activated or deactivated some genes which in turn reduced reproduction rate in offspring.
- gwern 4y ago
  The population didn't crash to zero, Calhoun merely claimed it was going to. But despite researching it for decades while being well-funded, what wound up happening (in that, as in almost all of the mouse experiments) remains a mystery because Calhoun published bizarrely little.
bannedbybros 4y ago
xenadu02 4y ago
We don't really know because Dr Calhoun didn't keep research notes or samples, published few scientific papers on his research, never captured or shared significant statistical data, had few controls and little regard for cofounds, and almost entirely failed to tell anyone anything about his other "universes". It also doesn't help that the two peer-reviewed studies that tried to replicate his results failed to do so. In many of those experiments the populations reached stable sizes, some without first experiencing a crash and others only after doing so. Some of the loosely-described "aberrant" behavior Calhoun claimed was never observed... not that we can be sure of that because Calhoun never gave us scientifically relevant observations of that behavior, only colloquial descriptions. It seems clear now Calhoun set out to achieve a specific result and worked hard to achieve it. Then people with an ideological axe to grind on all sides fill in the blanks to claim it proves their position. Calhoun for his part went to his grave claiming that mice/rat over-population experiments performed with inbred lab mice strains were in actual fact great models of human behavior and bemoaned that people didn't take his ideas seriously enough by rearchitect society to fit his conclusions.
titzer 4y ago
> That said, what was he actually trying to learn? > So, we know from both logic and evidence Just wondering where evidence comes from, if not experiments? I, for one, find the results of the experiment surprising and useful instead of the "logic" and vague notions that we might come up with by theorizing. > how do we get from insights about mice to insights about people? Science is a whole lot of looking at, studying, and cataloging things, and the "insights about people" aren't necessarily the goal. Rather, that part seems so often biased to support a worldview, philosophy, or political agenda that I hope we leave it out more often!

NineStarPoint 4y ago

It’s interesting to me at least that the group’s population crashed completely to zero and not to just a low number that then began climbing again. This is undoubtably a consequence of mice not being able to escape from the chaos due to the small size of the territory, but I do wonder what the minimum viable size would be to allow for a full boom-bust-boom cycle to occur.

Someone 4y ago
But there wouldn’t be chaos anymore by the time population dropped to a few hundred. Between the two moments of equal population something must have changed in the population, either genetically or, IMO more likely, culturally.
dalbasal 4y ago
I don't think it's that surprising, especially as an occasional result. Consider that surviving severe overpopulation is trauma. Survivors are physically and/or psychologically sick. They're not good breeders and at this point. Happens frequently in aquariums. Guppies breed like guppies. Overpopulate, then die back. The proximate causes can be varied. Maybe there's an ammonia spike, oxygen deficiency or other consequence of overabundance. When the "crash" happens, survivors tend to be a precocious bunch. They're past breeding prime, and probably injured by the events of the crash and its precedents. Starting a colony with "poor stock" is always more difficult, and that's what you now have. It doesn't have to be overpopulation that causes a crash. Say you accidentally pollute the water with soapy hands. Some fish will die today. Some tomorrow. Dead fish rotting is also polluting. Fish surviving the ordeal will probably have reduced lifespans and breeding potential. My unqualified guess is that most extirpation events leave survivors, usually in less than ideal shape. The technical extirpation happens later, as survivors gradually drop off without successful reproduction. Good question about minimum population size for boom/bust cycles to occur. I suspect this is more about environmental richness than pure numbers. Some predation probably stabilizes things, and some boom/bust might be possible. If you had multiple colonies connected by 500m of tubing, this "distance" between territories might allow for "local" booms and busts to occur.
- generalizations 4y ago
  > If you had multiple colonies connected by 500m of tubing, this "distance" between territories might allow for "local" booms and busts to occur. I was thinking the same thing. From the article I got the impression that the final collapse happened because all the survivors were the same age, and too old to spawn a new generation. Semi-separation would at least break the synchronization.
- shard 4y ago
  > Consider that surviving severe overpopulation is trauma Recently there was an article posted on HN about how trauma experienced by parents are passed down to children through (a term that means it's related to activation of genes, I believe, but not DNA itself... I thought it was metagenomics but upon looking at the definition I don't think that's it). Perhaps the trauma of overpopulation activated or deactivated some genes which in turn reduced reproduction rate in offspring.
gwern 4y ago
The population didn't crash to zero, Calhoun merely claimed it was going to. But despite researching it for decades while being well-funded, what wound up happening (in that, as in almost all of the mouse experiments) remains a mystery because Calhoun published bizarrely little.

bannedbybros 4y ago

xenadu02 4y ago

We don't really know because Dr Calhoun didn't keep research notes or samples, published few scientific papers on his research, never captured or shared significant statistical data, had few controls and little regard for cofounds, and almost entirely failed to tell anyone anything about his other "universes". It also doesn't help that the two peer-reviewed studies that tried to replicate his results failed to do so. In many of those experiments the populations reached stable sizes, some without first experiencing a crash and others only after doing so. Some of the loosely-described "aberrant" behavior Calhoun claimed was never observed... not that we can be sure of that because Calhoun never gave us scientifically relevant observations of that behavior, only colloquial descriptions. It seems clear now Calhoun set out to achieve a specific result and worked hard to achieve it. Then people with an ideological axe to grind on all sides fill in the blanks to claim it proves their position. Calhoun for his part went to his grave claiming that mice/rat over-population experiments performed with inbred lab mice strains were in actual fact great models of human behavior and bemoaned that people didn't take his ideas seriously enough by rearchitect society to fit his conclusions.

titzer 4y ago

> That said, what was he actually trying to learn? > So, we know from both logic and evidence Just wondering where evidence comes from, if not experiments? I, for one, find the results of the experiment surprising and useful instead of the "logic" and vague notions that we might come up with by theorizing. > how do we get from insights about mice to insights about people? Science is a whole lot of looking at, studying, and cataloging things, and the "insights about people" aren't necessarily the goal. Rather, that part seems so often biased to support a worldview, philosophy, or political agenda that I hope we leave it out more often!