Matt: Why can’t I tickle myself? Anybody else can tickle me, but when I try it, nothing happens. — Anonymous, via email

Somehow this was also a burning question in Swedish academic circles. Maybe something to do with those itchy wool sweaters. At any rate, some Swedes took pictures of the brains of tickle-ees when set upon by others and then themselves. The brain maps of the surprise tickles lit up like Vegas. Electrons zapping all over the place. And the self-tickle response? A ghost town. Hmmm... What does it all mean? they mused. Tickles and laughs are so complicated.

Photo by Rick Geary

What the Swedes did was compare the anticipation of a tickle with the actual tickleation activity itself. Darned if the brain maps didn’t look similar. Even in the brains of self-ticklers. It seems our brains can anticipate what it’s going to feel like to be tickled and will respond accordingly. The Brits ran some tests and opined that the self-tickling reaction may be related to our brains’ ability to anticipate the effects of our own movement on our own bodies. Anyway, it’s this ability to anticipate what’s coming that makes self-tickling such a flop. The out-of-control, can’t-tell-when-it’s-coming other-person tickle works beautifully.

So, why should we laugh when tickled or in anticipation of a tickle? Laugh? Most of the time, what you really want to do is sock the tickler in the nose to get him to stop. Anyway, more science brains suspect that tickle laughter is somehow linked to our basic panic response because of the brain centers that are involved. But on the up side, looking at ape, monkey, and human activity, they also think laughter is a group bonding experience and an indication to the group that danger has passed. Truth is, apes’ and monkeys’ equivalent of laughter is panting. They don’t really chuckle or anything.

Hard to believe it, but the laughter brain circuit, say, in response to a good joke, goes from the left side of the cerebral cortex to the frontal lobe, back to the cerebral cortex (except on the right side this time), straight to the sensory area of the occipital lobe. This covers brain areas involved in word analysis, emotional responses, intellectual analysis, visual processing, and physical responses. So, laughter is a real workout.

Anyway, laughter is such serious business, there is even an International Society for Humor Studies. And UCSD developed its own automatic tickling machine for research studies. Would like to have read the grant proposal for that one.

Matthew: How did the tune “Turkey in the Straw” become the perennial favorite for ice cream trucks? — Summertime Dreamer, La Mesa

To be fair, “The Entertainer” by Scott Joplin and “Pop Goes the Weasel” are equally ubiquitous, nationwide. The elves flagged down an engineer with Magic Box in Jacksonville, Florida, who offered them some Popsicles left over from 1963 and the answer to your question.

Once upon a time, Beals Music Inc. was the only manufacturer of loudspeaker systems for ice cream trucks. For many years, if you wanted one, you had to buy theirs. They started out with mechanical chimes, then graduated to a loudspeaker system using guitar pickups, then took to digitizing analog recordings of an attractive tune. Attractive and cheap. “Turkey in the Straw” et al. are in the public domain, so Beals didn’t have to pay royalties every time a truck rolled down the street. Beals is now out of biz, replaced by two companies that make the “music boxes,” as they’re known in the trade. Magic Box now offers about 60 different songs in the form of a digital chip and can customize your system if you’d like to broadcast dogs howling the Notre Dame fight song or your kid playing “Lady of Spain” on the accordion. But “Turkey/Pop/Entertainer” are still the best sellers. Tradition. Inertia. Cheapness. Standard output used to be 16 watts, but Magic Box has reduced theirs to 8 watts to appease the irritated multitudes.

Matt: Why do avocados have such big seeds? Sometimes they’re all seed, no guac. — GuacamoleGirl, South Bay

The pit’s designed to reproduce the parent tree, not to please you. The wild avocado grows in subtropical jungles, so the new sprout has to get several feet tall before it can share sunlight (to make food) with its neighbors. Until it grows out of their shadows, it relies on nutrients in the seed, so it better be big.