Where does "brain freeze" come from? Or, why we get ice cream headaches.

A site called io9 explains that brain freeze is an evolutionary tactic.

Blood rushing through the extremities cools down, and when it comes back to the body, it cools the rest of the system. The body has negotiate a way to keep blood flowing to the fingers, toes, and nose, while protecting itself.

....

Ice cream headaches don't usually happen in cold weather, but they are bound up with the body's response to it. When people eat ice cream, it chills the area around the head, and the blood vessels constrict. This constriction is painful - it's the same thing that causes intense and debilitating migraines.

But fear not:

It doesn't do damage and lasts only a few minutes. Still, people don't like discomfort with their desserts, and they've found a few ways to avoid it. One is to, yes, eat more slowly.

I always know it's &%$#@!ing cold out when I laugh and get brain freeze from the cold touching my teeth.  It's about that temperature right now in New York.  And speaking of laughing, you know what is really not funny?  The whole Gaddafi family and how they are massacring their own citizens.

Brainfreeze does not cause long-term brain damage

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Did you really think it did?  I've never heard that before.  Luckily a writer at Popular Science has cleared all of this up for us with this helpful post, in which he first describes the two theories of how and why one gets brainfreeze (or an "ice-cream headache"):

"First, let’s get one thing straight. “This condition is referred to as an ‘ice-cream headache,’ ” says Stacey Gray, a sinus surgeon at the Massachusetts Eye and Ear Infirmary in Boston. “It’s a very technical term.” Although there’s no published paper saying as much, a milkshake slurped too quickly probably does not actually lower brain temperature. Besides, Gray says, the temporary pain can’t do any harm because it has nothing to do with the brain.

There are two schools of thought on what causes the ice-cream headache. The drink may chill the air in your sinuses and cause the blood vessels in the nasal cavity near your forehead to constrict, creating pain similar to a migraine. Or perhaps it touches off a branch of the trigeminal nerve in your mouth, triggering a pain response in the nerve that’s responsible for facial sensation."

Later he quotes a doctor explaining why lowering brain temperature temporarily is not a big deal:

"“Even if the patient wasn’t anesthetized, at that temperature they would be in a noninteractive state, unable to sense stimuli or produce a response,” Tamargo says. “But once you warm the brain up, it picks right up from where it left off. It’s not harmful at all.” So whether your brain is frozen or not, if you can handle a little pain, slurp away."

Have you ever heard of this before?  Long-term brain damage?  Seriously?