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

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."

5 of 154 comments (clear)

  1. I thought lawyers were the preferred replacement by Crashmarik · · Score: 4, Funny

    Because there are some things rats just wont do.

  2. List of Animals by number of Neurons by volvox_voxel · · Score: 4, Interesting

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

    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....

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

    1. Re:List of Animals by number of Neurons by ShanghaiBill · · Score: 4, Informative

      Does body mass tend to scale linearly with brain mass?

      No, it does not. Humans have a brain:body ratio of about 1:40. Small ants are 1:7. The highest among mammals is a shrew at about 1:10. Small birds are about 1:14. Elephants are 1:560. Hippos are 1:2500.

  3. Re:Intelligence isn't that important by tomhath · · Score: 4, Funny

    experiments that depend on measuring problem solving and it's interaction with the brain have never really been better from smarter creatures

    Citation needed. We gave our dog an intelligence test - put a treat under a paper cup and see if he's smart enough to move the cup and get the treat. Dog looked at me waiting for a signal, as soon as I said "OK" he knocked the cup over with his paw and grabbed the treat. Tried the test with our goldfish; he just flopped around on the floor.

  4. Re: So don't use mice or rats for experiments. by camperdave · · Score: 4, Funny

    That's nothing. I trained my scientist to think that mice are as smart as rats. Can you believe it? Mice! So anyway, now they're doing all the gene/intelligence research on them instead.

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