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Science

Scientists Find Rats Aren't Smarter Than Mice, and That's Important 154

HughPickens.com writes: There has long been a clear hierarchy of intelligence in the psychology lab, with monkeys are at the top, then rats, and finally mice at the bottom, "cute and fluffy but not all that bright." For at least a hundred years, researchers have used rats in their psychology experiments, assuming that they were the smarter of the two lab rodents. Now, Rose Eveleth reports at The Atlantic that new research shows this might not be true, suggesting mice can perform decision-making tasks in the lab just as well as rats can. "Anything we could train a rat to do we could train a mouse to do as well," says Tony Zador. This finding is important because using mice in experiments instead of rats could open up all kinds of new research options. For one thing, scientists have been able to manipulate a mouse's genome in really useful ways, silencing certain genes to figure out what role they play. There are mouse models for everything from Alzheimer's to Parkinson's. Being able to put those mice through the paces of a psychology experiment could help researchers connect diseases with the behaviors they impact.

So where did this idea that rats are smarter than mice come from, anyway? Zador says it's a historical bias. "There was 100 years of practice in training rats. And basically when people tried to treat the mice in exactly the way they treated the rats, the rats seemed smarter," says Zador. In other words, "over the course of 100 years people had figured out how to train rats, and that mice aren't rats." You might think that mice and rats would be basically the same when it comes to these kinds of things, but Zador points out that mice and rats diverged somewhere between 12 and 24 million years ago. For comparison, humans and chimpanzees split somewhere between 5 and 7 million years ago. So it's no surprise that mice behave differently than rats, and that the difference impacts their training in the lab. "The mouse is uniquely placed at the interface between experimental access and behavioral complexity, making it an ideal model for the study of adaptive decision-making. Successful behavioral paradigms, however, rely on targeting designs to the idiosyncrasies of the mouse from the outset, rather than simply assuming that mice are little rats."
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Scientists Find Rats Aren't Smarter Than Mice, and That's Important

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  • Here's my argument: experiments that depend on measuring problem solving and it's interaction with the brain have never really been better from smarter creatures. What's most useful is behavioral consistency. Between members of the species, and with one individual's performance. The more predictable the baseline is, the more useful results you can extract from fewer tests against your control group.

    Sure some thins are too complicated to hope to model so simplistically, like cultural learning, empathy,

  • Whoa whoa whoa... We know that for sure now? With real quantifiable evidence, that I can see without a paywall? I musta slept through that part of the newcast... Somebody clue me in...

    • Absolutely. You can tell because the chimps have a lot more body hair and don't make themselves miserable working 8+ hours a day at a job they hate.

    • Whoa whoa whoa... We know that for sure now? With real quantifiable evidence, that I can see without a paywall? I musta slept through that part of the newcast... Somebody clue me in...

      The chimps have already figured out how to get past the paywall.

    • Yes, it is true and verifiable, no matter how much the chimps try and deny they are in any way related to humans.

  • by Crashmarik ( 635988 ) on Thursday October 16, 2014 @01:16PM (#48160681)

    Because there are some things rats just wont do.

  • by volvox_voxel ( 2752469 ) on Thursday October 16, 2014 @01:20PM (#48160703)

    http://en.wikipedia.org/wiki/L... [wikipedia.org]

    The rat has an estimated 200E6 Neurons and 4.48E11 synapses, and the mouse has 71E6 neurons and ~1E11 synapses.

    There is at least some correlation between intelligence and the number of neurons. A cursory search found this: -- Fact or Fiction: When It Comes to Intelligence, Does Brain Size Matte? http://www.scientificamerican.... [scientificamerican.com]

    It would be interesting to find more definitive articles that support or contrast this.

    • Re: (Score:2, Insightful)

      by Anonymous Coward

      It's more than just a matter of brain size, it's also the ratio of brain size to body size. A bigger body requires a bigger brain just to coordinate.

      From your numbers, rats have about 3x as many neurons and 4x as many synapses as mice -- yet they're usually bigger than 3x or 4x times the size.

      • Does body mass tend to scale linearly with brain mass?
      • by Immerman ( 2627577 ) on Thursday October 16, 2014 @01:53PM (#48161071)

        Yeah, I've never understood why that should be. It's not like a larger body has more degrees of freedom to coordinate, and I'm pretty sure the motor control nerves also serve as signal amplifiers, so you don't need more brain cells to drive a larger muscle. The only thing I can think of that might scale with size is the number of sensory nerves in the skin - which would suggest that the portion of the brain associated with processing the input should scale with the square of linear size (or alternately with the 2/3 power of mass).

        • I'm pretty sure the motor control nerves also serve as signal amplifiers, so you don't need more brain cells to drive a larger muscle.

          Not necessarily. I can easily imagine larger creatures needing finer motor control compared to their size (note that large humans are often described as "clumsy" and small humans as "graceful"). In a similar vein, I know one proposed theory about why humans are so much weaker than chimpanzees is because we dedicate way more brainpower to fine motor control (one source: http://www.smithsonianmag.com/... [smithsonianmag.com]).

          • Given the number of small clumsy people and large graceful ones I've seen, I think that's more of a media meme and/or perceptual preconception than an actual trend...

            That's an interesting article though, I hadn't thought of the fine muscle control aspect. I suppose neurons do pretty much fire in an all-or-nothing fashion, so it makes sense that if you want a more graduated response you need more nerves to be able to trigger smaller clusters of muscle fiber. A corollary to their theory about apes strength

      • It's more than just a matter of brain size, it's also the ratio of brain size to body size. A bigger body requires a bigger brain just to coordinate.

        Tell that to the Brontosa...er Apatosarus (poor creature. It went extinct twice!). Anyways, brain the size of a meatball - body the size of an articulated bus.

  • Divergence (Score:4, Insightful)

    by Empiric ( 675968 ) on Thursday October 16, 2014 @01:21PM (#48160719)
    ...mice and rats diverged somewhere between 12 and 24 million years ago.

    It'd be nice if my field's conclusions could be this broad...

    Between this range and the fact that every reproduction is a "divergence", and so the baseline here seems to be divergence from one arbitrary cluster of characteristics given a latin name, and another arbitrary cluster of characteristics given a different latin name...

    What does this even mean?

    Yes, I know. I'll be shortly told I'm too dumb to understand, instead of an explanation. Fair enough, stipulated. Now go ahead and inform me of stuff.
    • by Empiric ( 675968 )
      Oh, yes, forgot the other likely result. Summary downmodding. Thanks for the reminder of Slashdot tradition.
    • ...mice and rats diverged somewhere between 12 and 24 million years ago.

      ...

      What does this even mean?

      Part of the problem is that we want clear and distinctive buckets (labels) to put things into: this a rat, this is a mouse, ... Evolution, slow, gradual changes over time, doesn't work that neatly. 12 to 24 million years ago there was some animal with some its descendants became today's rats and some other of its descendants became mice. That animal could interbreed with others of its kind. At some point its descendants branch that eventually became rats and its descendants branch that eventually mice

      • by Empiric ( 675968 )

        So, you seem to be agreeing with me more than disagreeing. The categories are not clear and distinctive, which I went ahead and called "arbitrary", because that's what they are.

        So back to the quoted sentence...

        "...mice and rats diverged somewhere between 12 and 24 million years ago."

        I still have no idea what actual information this is supposed to convey. Or is it more of a "rah rah, evolution!" reaction thing?

        Pavlovian conditioning hasn't worked on me for a long time. Maybe that's my problem.

        • I still have no idea what actual information this is supposed to convey. Or is it more of a "rah rah, evolution!" reaction thing?

          You need something to compare it to; it's right in the article: "For comparison, humans and chimpanzees split somewhere between 5 and 7 million years ago"

          So mice and rats diverged somewhere between 12 and 24 million years ago, while the range is 5 to 7M for humans and chimps. Humans and Chimps are very different and we'd certainly not try to treat chimpanzees as 'small humans' in a lab setting. Yet we tried to do so with mice, treating them as small rats.

          Just a linear comparison would tell you that rats

          • by Empiric ( 675968 )

            Yes... maybe my viewpoint of directed evolution makes me more attuned to certain aspects of such a statement.

            I certainly agree that evolutionary processes are generally speaking most directly responsible for biological differentiation, but I'm unwilling to make the inference from that of "often, therefore always" and statements like the one quoted seem to border on pseudoscience in how broad, unspecific, and untestable they are. I personally think that science is best served by making scientific statements

            • by Fwipp ( 1473271 )

              Yes... maybe my viewpoint of directed evolution makes me more attuned to certain aspects of such a statement.

              That's... certainly a thing you can say.

              Less charitably, I might say "Your preexisting faith in the supernatural hinders your ability to comprehend the natural."

              • by Empiric ( 675968 )

                You might say that, and the only thing remaining would be to back it.

                Let's start with me simply noting that I comprehend the natural quite well, eh, I'll go ahead and say better than you, and leaving you to show otherwise. That will require some actual content or an actual argument.

                You see, I'm not one of those pushing the "religion versus science" false dichotomy who hope to damage religion and only end up damaging science. A frequent occurrence of people overextending their arguments with bias-driven ps

            • by HiThere ( 15173 )

              I would like to see *some* evidence that "directed evolution" occurs without human intervention. Mind you, we don't usually try to create new species. At one time we couldn't, these days we occasionally do. (For an exception, Corn [Maize] is a different species from Teotsine, but I'm not sure you could say people created it rather than merely preserved it.)

              • by Empiric ( 675968 )

                So, you agree in principle with directed evolution, in that you directly say man is one cause of it?

                I imagine there's one, and only one, source of design you categorically reject. I wonder what that would be...

                • by HiThere ( 15173 )

                  Do you imagine that you provided evidence?

                  Admittedly, once evidence was provided, I would attempt to judge it's quality before accepting it, but I didn't see that you even offered any.

      • a "Gee, we could interbreed last night but not this morning" kind of deal.

        I think we've all been there.

    • by AA1 ( 842917 )
      The large range is exactly due to the fact that the point of "divergence" is essentially arbitrary, especially considering nobody was there to observe. The concept of individual species itself is arbitrary, and many exceptions exist to the "able to reproduce and produce fertile offspring" rule. Its nothing more than a useful baseline that aids in communication, sorta like lewis structures in chemistry
      • by HiThere ( 15173 )

        It's not an arbitrary point of "divergence", it's a retrospective one. You can't know that these two individuals who are siblings are members of a different species until considerably later you observe that their descendants can no longer interbreed (or never choose to do so). Picking those two individuals as the fork isn't arbitrary, but it's also impossible to do at the time, you can only do it by looking at their descendants.

    • I think evolutionarily speaking "divergence" means the point at which members of the respective subgroups (mostly) stopped interbreeding, and it is a very fuzzy line. I mean dogs and wolves diverged many millenia ago, but they still *can* interbreed, they just mostly don't. Foxes on the other hand diverged far longer ago than that, and are no longer capable of interbreeding.

      Measuring the distance in years seems somewhat ridiculous though, generations would be far more telling. I can think of only two reas

    • by Boronx ( 228853 )

      The arbitrariness of species is one of the realizations that lead to Darwin's book. It forms a key part of his argument. Divergence time means "time to last common ancestor". If we take these arbitrary groupings, and say these are mice, and these are rats, then we can take a rat and a mouse and use genetic tests to guess how long it has been since they shared an ancestor.

      What we'll probably find, even though our initial grouping was arbitrary, that for the most part a given mouse and a given rat's common

  • I always new that show was real.

  • But it takes more than brains to get out of NIMH. you need to be big enough to not get sucked into the ventilation system.
  • by Anonymous Coward

    As someone who's had both rats and mice as pets, rats are much more comfortable being handled and are somewhat affectionate. Mice tend to be jumpy and skittish and don't seem to bond to people so much. Lab mice are very retarded and slow (for very good reasons) compared to wild caught mice or their offspring.
    Mice might be as smart, but rats are much more fun to work with.

  • Mice are smart enough to con researchers into using rats instead. Proof that Douglas Adams was correct..
  • by Daetrin ( 576516 ) on Thursday October 16, 2014 @02:10PM (#48161239)
    "You might think that mice and rats would be basically the same when it comes to these kinds of things" [About training the two species]

    It doesn't seem like it makes much sense to believe that rats and mice are different enough for one species to be measurably smarter than the other, but not to also believe that they're different enough to have different behavior patterns and responses to various stimuli.
  • we can pay a mouse 1/3 fewer pellets, pack them into 1/5 the space, and still be just as abusive!

  • Rats vs Snakes (Score:3, Interesting)

    by TechnoCore ( 806385 ) on Thursday October 16, 2014 @02:17PM (#48161317)
    I used to work a small zoo. We fed the python snakes either rats or mice. Mostly live animals, since it was hard to get the snakes to eat otherwise. The mice didn't seem to even notice the snakes. They often climbed all over the curled snakes. I remember at one time a mouse climbed up on top and sat on the head of the python and cleaned itself. (before it got eaten)

    The rats on the other hand immediately detected the snake as a threat. They hid behind things, keeping themselves obscured from direct line of sight of the snakes.

    I have also had both rats and mice as pets. The rat I could teach to come to me when I whistled, the mice not so much... though maybe that was because I never tried to really train the mice. But I'm not convinced.
  • "There has long been a clear hierarchy of intelligence in the psychology lab, with monkeys are at the top, then rats, and finally mice at the bottom, "cute and fluffy but not all that bright."

    So where do the scientists fit in? Somewhere in the middle? Just above rats? Hmm...

  • Having worked in labs with both mice and rats, I'll take a nice Sprague-Dawley any day. They're like little dogs: they hang out, they like to be petted, they're clean and smell nice.

    On the other hand, as soon as you lift the lid off the mouse cage, one of those little buggers levitates three feet in the air and rockets off in a random direction, probably sinking their teeth into someone's earlobe. No thanks.

    • one of those little buggers levitates three feet in the air and rockets off in a random direction

      Sure you're not confusing them with squirrels?

  • by mspohr ( 589790 )

    Slartibartfast: [talking about the Earth] Best laid plans of mice.
    Arthur: And men.
    Slartibartfast: What?
    Arthur: Best laid plans of mice and men.
    Slartibartfast: Oh. No, I don't think men had much to do with it.

  • ... that if they played stupid, people would stop screwing electrodes into their skulls.

    "Hey you humans. There's a mouse over there. He's really smart. Why don't you fuck with him for a change?" Its the same logic I use when the wife asks me to do something around the house. Mess up a couple of times and she stops asking.

  • I don't think any proper scientists has thought in terms of a hierarchy of intelligence since we discovered that quantifying intelligence was harder than we thought (about a century ago).

    But I could certainly see journalists thinking in those terms.

  • Just for grins, I looked up the difference between mice and rats on Google. It turns out, rats can play the saxophone! Who knew? https://www.google.com/#q=mous... [google.com]
  • OK, who thought of this song first upon reading the summary?

    http://en.wikipedia.org/wiki/A... [wikipedia.org]

    (I have no idea which of the versions listed I've heard.. maybe the Muppet show.. but it's one of those songs where I definitely haven't seen the _original_, or at least not in its entirety, but still know the song.)

  • It totally screws up the Secret of Nymh. :_(

    Buuuut... They were genetically enhanced rats, so it still works.

    It's ok everybody CRISIS AVERTED!!

  • When they see a mouse, they say "Oh look, a baby rat!" (based on actual experience)

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