Poor would-be senator Christine O’Donnell has been ridiculed for her comment about mice with human brains:
O’DONNELL: … these groups admitted that the report that said, “Hey, yay, we cloned a monkey. Now we’re using this to start cloning humans.” We have to keep…
O’REILLY: Let them admit anything they want. But they won’t do that here in the United States unless all craziness is going on.
O’DONNELL: They are — they are doing that here in the United States. American scientific companies are cross-breeding humans and animals and coming up with mice with fully functioning human brains. So they’re already into this experiment.
From transcript of O’Reilly show, Friday, November 16, 2007.
Why would Ms. O’Donnell (or someone who informed her) believe this?
Reports of mouse-brain research have been greatly exaggerated
It doesn’t take much to find some of the “evidence” that may have convinced her or her informant. As others have noted, there have been experiments in which human cells were injected into embryo mice, and became part of their brains. A bit different than “cross-breeding humans and animals and coming up with mice with fully functioning human brains”, but all rumors have to start somewhere.
Bad reporting may be to blame: here’s the headline and first line of the 2005 article on the National Geographic site:

From nationalgeographic.com.
In case that last line is too small to read, it says “Researchers in California have created living mice with functioning human stem cells in their brains.”
Earlier that same year (2005) another article on the NatGeo site briefly referred to the same research (before it had occurred) this way “And at Stanford University in California an experiment might be done later this year to create mice with human brains.” The title of this misleading article was Animal-Human Hybrids Spark Controversy. Yes, plenty of controversy, but in the article no hybridization is being talked about, only the use of stem cells to demonstrate their potential to be re-purposed. In biology, a hybrid is the offspring of two plants or animals of different species or varieties, such as a mule (a hybrid of a donkey and a horse), and that is the popular understanding as well. Few would consider a mouse with a few cells of human origin, all functioning as mouse cells, to be a hybrid.

Christine, you need a smart friend; meet Clyven the mouse
But wait, it’s not all down to irresponsible journalism; perhaps Ms. O’Donnell got her information from this page, on the site of the prestigious RYT Hospital, about “Clyven: The World’s First Transgenic Mouse with Human Intelligence” :

Here’s the explanatory text from that page.
Margaret A. Keyes, M.D., Ph.D., is a researcher in genetic medicine and Professor of Cell Biology and Genetics at RYT Hospital-Dwayne Medical Center. She is exploring the use of embryonic stem cells as a means to cure neurological conditions such as Alzheimer’s Disease and Creutzfeldt-Jakob Disease.
By implanting human brain cells (grown from a human embryo’s stem cells) into a mouse engineered to have Alzheimer’s, Dr. Keyes inadvertently made a remarkable and startling discovery: she not only cured the mouse’s Alzheimer’s Disease, but the animal soon developed the relative intelligence of a human being.
After extensive consideration by RYT Hospital’s Institutional Review Board (IRB) and Institutional Animal Care and Use Committee (IACUC), it was decided that this mouse would be placed under a new study led by Dr. Keyes’ lab.
As part of this new facility (pictured to the right), Clyven is placed inside a light-sensitive box with electrodes attached to him. He is able to communicate and interact with people via this neuro interface. He is able to communicate and interact with people via this neuro interface. [sic] To hear a live audio feed of Clyven inside his box, please click here.
© RYT Hospital-Dwayne Medical Center
Source.
Evidently RYT Hospital has a very understanding Ethics Committee; they approve of confining an animal with a human brain in a little box and punching his head full of electrodes. But Clyven is not bored—in fact, you are invited to chat with him or play a game against him.

Unfortunately, Clyven’s conversation is limited and repetitious—maybe he himself wrote that quoted passage above, that has the repeated sentence. My best conversation with him was this one,
ME: Hi Clyven.
MOUSE: Yo.
ME: Do you know that a tea party candidate is talking about you?
MOUSE: That’s pretty silly.
ME: Yes.
MOUSE: Tell me more.
ME: I don’t want you to know how dumb people can get.
MOUSE: I’m sorry. I hope to get smarter as time goes on. Please be patient with me. I will be receiving additional neurological treatments next week.
On the other hand, don’t let him persuade you to bet money on that CheezeMaze contest, he’ll beat you paws down.
It’s surprising we haven’t heard more about this RYT Hospital, with the amazingly advanced and useful research that is being done there. Elsewhere on the site, you can read about a new drug, Revitalex

about successful gene therapy for back pain, and about “NanoDocs”, nanobots that circulate throughout the body repairing tissues.

Okay, so it’s not a real site but the project of an artist named Virgil Wong. He’s a painter, film-maker, and head of web design for two real hospitals.
Still, can’t you see how anybody might be taken in by the slick style, and accept that there really is a mouse with human intelligence, and nanobots that can tidy up your blood vessels?
No? You say anyone beyond the stage of believing in the Tooth Fairy should have seen through this? and through the distorted reports of growing human brains in mice?
I think so too.
Wherever Christine O’Donnell may have gotten her “information” about mice with human brains, the real problem is minds like hers that are unprepared to question things that most of us would find outlandish. They also believe that Obama is Hitler, Stalin, and a Kenyan anti-colonialist, all at the same time! which would explain why, as I have heard on good authority, Obama has three heads, a fact cleverly concealed by camera angles and good tailoring.

Eastern Newt (Notophthalmus viridescens), Red Eft Stage. Etymological note: Notophthalamus from the Greek noto (a mark) and ophthalmus (eye), presumably in reference to the eye spots on the sides and back; viridescens from the Latin, (slightly green) referring to the greenish color of the adults. Source.
One born every minute? or are they made?
Where do these credulous people come from? I don’t mean people like Newt Gingrich, who will repeat anything—no matter how preposterous—if it seems advantageous. No, demagogues use untruths consciously, with calculated intent. The power of the demagogue depends upon there being enough people who cannot distinguish between the likely, the possible, and the absurd, and therefore won’t laugh him off his soapbox. And where do they come from?
The beginning preparation for most credulous people of otherwise normal intelligence is, I think, being raised with a huge area of life and thought which is categorically excluded from rational examination. Now, every culture and sub-culture has some areas like that, because they are essential as part of the group’s self-definition. In this Land of the Unquestioned reside things like appropriate behavior (manners), kinship rules, dress codes, what we eat and how we cook it, all that sort of thing. That’s why our way of life seems so logical and natural, and other groups’ ways seem bizarre and senseless.
No problem when it’s a question of the relative merits of haggis or corn on the cob, but in the area of exclusion there are more significant topics also, such as attitudes to the “Other” (women, outsiders, those in your own group who don’t conform), and toward violence. That’s the cultural “Don’t think about these things” list. Then there’s religion and its list.
Religion is the really big no-fly zone for human reason. It covers a much wider area of life than ordinary cultural indoctrination, often upon a foundation of dogmatic zeal which asserts sole possession of truth, and enforces details of the dogma with extreme fervor.
Totalitarianism and extremist religions share two fundamental principles: there is only one true way, and everyone must be forced to acknowledge it. It is not enough for the non-believer to refrain from critical expression and deviant action: he or she must be made to believe. Hence the show trials held by the Soviets, the Chinese Cultural Revolution, and the Inquisition, in which tortured inmates confess their nonexistent sins; hence the death penalty for apostasy in Islam, and the roasting alive of unrepentant Christians by the Romans and doggedly heathen Native Americans by the Christians. The Other must be brought within the fold or die, and it should be done in a public and painful way to present a compelling example to everyone else.
Children are born enquirers (non-believers), and about the age of three they start to ask “Why?” about everything, with irritating persistence. Give an answer and they ask for more details or ask “Why?” again. (Offer a non-answer like “I don’t know” or “Be quiet” and they repeat the original question or say nothing; curiosity discouraged begins to shut down.) Their brains are making and pruning connexions, they’re constructing an internal model of the world, and they want and need to know more and to discuss their own thoughts. They are also learning how to learn, how to figure things out.
A child who gets yelled at for asking about talking snakes, or smacked for asking why the God of Love is such a bloody-handed war-approving tyrant in the Old Testament (see note 1), will learn to accept what he or she is told and not think about it. The lesson is to avoid questioning—especially the things in life that seem illogical, cruel, unfair, out of sync with reality. And that “respect for authority” (actually, it is only respect for power and avoidance of punishment) carries over into other parts of life. The more intensely the “No Questions Zone” is defended, the more timid the young mind’s reason becomes.
Curiosity is inborn, but logic is learned. When children are exposed to illogical conclusions, such as “You got a cold right after you ate that ice cream, so no more ice cream” or “I know the Bible is the Word of God because the preacher says so and the Bible says to follow what the preacher says” they won’t learn the basic rules of logic that help humans sort true from false, as well as “probably true” from “probably false”. Ignorance of logic is of course a good thing for those enforcing a monolithic belief system.
Our country’s culture has an equivocal position on learning. Along with its tradition of independence and individualism, the US also has a strong anti-intellectual tradition, because of its religious foundations and the pragmatic demands of survival on successive frontiers from New England to the Pacific coast. When book-larnin’ is seen as irrelevant, perhaps un-masculine, some will make a positive virtue of ignorance. Also, study is hard, ignorance is effortless. Entropy prevails.
Logic and critical thinking are not enough. In order to winnow the wheat from the chaff reliably, it’s necessary to have some actual knowledge. When a statement is made, the hearers check it against their relevant knowledge base. This process is usually instant and automatic. The new information may directly conflict with existing knowledge, or it may just appear quite unlikely based on what is already known. A certain stock of knowledge, reliable because it has been tested or was provided by a trusted authority, is needed to get through life. Yet even some of this knowledge may be false—blondes are dumb, bankers are trustworthy, a barking dog never bites—and individuals must also possess the willingness to re-examine beliefs based on new experience. Except in the No Thinking Zone, where the only safe course is to agree with authority and otherwise keep your mouth shut.
When politics is the subject, then history must have special prominence among relevant areas of knowledge. Just like more workaday fields of endeavor, political systems embody responses to real needs and problems. If I were re-designing the internal combustion engine, I would first need to know why each part had been designed as it was; what earlier mechanisms were tried for mixing the fuel or timing the ignition, and what were their flaws?
It is history which answers these questions in politics, and must be consulted before tinkering or throwing away parts. For example, decades of controversy about the constitutional provision in the First Amendment usually referred to as “separation of church and state” have distorted public understanding of the law’s intent by framing it as a dispute between agnostics or atheists, vs. religious people. In fact it was enacted to defend all religions from government, and from a preference being shown for a single church, as well as to protect government (or non-religious persons) from religion. And the history of state-established religions illustrates the many repressions and disenfranchisements which are imposed upon members of the non-official religions, even including banishment and death. Only modern ignorance permits the discussion of this subject to be framed entirely as a conflict between religion and irreligion. [Christine O’Donnell, in a recent debate, was ignorant of the provision entirely. After the phrase “Government shall make no law respecting establishment of religion” was quoted to her, she asked “That is in the First Amendment?” Yes, it is, though the exact words are “Congress shall make no…”.]
Logic, general knowledge, critical thinking, history: how is the American public doing on these?
37% of Americans believe that houses can be haunted, and 25% believe in astrology, i.e. that the position of the stars and planets can affect people’s lives.
Fewer than a third can identify DNA as a key to heredity, only about 10% know what radiation is, and 20% think the Sun revolves around the Earth, an idea science abandoned by the 17th century.
50% of our fellow citizens believe in alien abductions, though happily only 7% say they or someone they know has been abducted.
39% of Americans could not name any of the freedoms in the First Amendment.
14 percent of Americans say President Barack Obama may be the Antichrist (24 percent of Republicans believe this). Almost 20% believe he is a Muslim. Does that add up to 34% or is there some overlap?
Two-thirds of 1,000 American adults polled couldn’t name a single current justice of the Supreme Court. In the same survey, more than a third did not know the century in which the American Revolution took place, and half of respondents believed that either the Civil War, the Emancipation Proclamation or the War of 1812 occurred before the American Revolution.
And 21% believe in witchcraft, so O’Donnell’s “I’m not a witch” ad did have its audience.
When you look through these and other poll results it seems that at least 10% to 25% of Americans believe in just about any unproven concept you can imagine. A larger percentage is very ignorant of history and public affairs.
If you’re reading this, and have been apathetic about getting to the polls, you better think again.
One final poll result: in 2009, 19% percent of Americans agreed that the First Amendment goes too far in the rights it guarantees, and 39% said the press has too much freedom.

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NOTE 1: I cite only two examples, both from the same holy book, for the sake of brevity, but every religion seems to have its own set of magical events and unquestioned cruelties which must be accepted in order to belong. Belong, get along, go along.