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Matt: I have this friend who decided that burglars should learn to use their feet instead of their hands when they steal things so they won’t leave any fingerprints behind. I think he was kidding at the time, but when we checked our feet we saw that they had patterns just like fingerprints on them. My friend might be crazy, but I think my question is real. Are toeprints individual, like fingerprints? And how do fingerprints get to be individual, since identical twins don’t have identical fingerprints. At least I don’t think they do. — Another Matt, San Diego

Good thing your friend has you hanging with him or he might fall into a manhole or wander off down some dark street. He’s the dreamer; you’re Mr. Practical. And you’re right about fingerprints. No two are identical. Ditto for footprints. More than one burglar has been identified by bare footprints left at a crime scene. There’s some degree of genetic determination in the basic pattern of a finger- or footprint — the way the whorls and ridges go. But when you get down to a microscopic level, there are a lot of differences. Prints are matched according to the little breaks and forks in the bigger ridges in the pattern. It’s here that the innocent is separated from the guilty. And identical twins might have what look like identical fingerprints, but close examination will expose the differences. The differences in the breaks and branches are developed in utero, by the difference in position of each fetus, what fingers and toes rub against, and how their positions change. That also accounts for any bigger physical differences between identical twins, who don’t always look like eerie Xeroxed images of one another.

Hello Matt: Just wondering, is there any scientific explanation for déjà vu? — Just wondering

Hey, Grandma, haven’t we answered this question before? Sounds familiar.

“No. And I told you that the last time you asked. Didn’t you ask me that yesterday? Just answer the question, Matthew.”

Okay, déjà vu vs. science. What have we got here? Well, we’ve got many definitions. Many theories. Not so much research since it’s sort of hard to get someone to have a déjà vu experience on demand. Déjà vu is an aberration of memory that different scientists explain in slightly different ways. Neurologists recognize it as a frequent accompaniment to temporal lobe seizures — electrical misfirings in a particular part of the brain. Psychiatrists see it in schizophrenic patients. And almost all of us experience it at one time or another, unrelated to any medical or psychiatric diagnosis. Some research suggests that people suffering anxiety or fatigue are more prone to the eerie feeling.

Most explanations of garden-variety déjà vu propose that although we think we’ve never been in this place or been through this experience, there are enough common emotional links between our present situation and some dim past event that we muddle the two and call it déjà vu. The situations aren’t identical, but close enough that we conflate the two. One of the problems with the phenomenon is that it likely involves three parts of our brains: the amygdala, hippocampus, and temporal lobe, all of which participate in memory and emotion. Science is just beginning to map out that complicated territory.

The science guys are working on several different theories of memory, which affects their views of déjà vu. One theory says we store conscious recollections, things that we can call into memory in some detail. And we have a second type of memory based on familiarity — the kind of memory that makes you say, “Yeah, I think I’ve seen her somewhere before.” Connecting the two might produce that creepy déjà vu. But there’s so much research left to do to map memory in the brain then follow the connections, it may be a while before we can pin down déjà vu.

Three Questions: 1. Is it true that you are actually a woman? 2. Why do farts smell so good to those that cut them? 3. Why do you always include some snide, condescending “why don’t you get a life” type remark in every response? — Fernando Castro, Chula Vista

  1. Where did you get that bonehead idea?
  2. Where did you get that bonehead idea?
  3. Where did you get that bonehead idea?
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