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How hiccups, yawns and giggles make us human

In his new book, "Curious Behavior: Yawning, Laughing, Hiccupping, and Beyond," Robert R. Provine takes us on a tour of those all-too-common quirks that make us sometimes hide our heads in shame. But Provine, an electrophysiologist and professor of psychology and neuroscience at the University of Maryland, Baltimore County, contends that these behaviors can yield important clues as to what makes us not only uniquely human but also “beasts of the herd.”

Q: You refer to your research as “small science.” What does that mean?
A: We’re all familiar with “big science,” like the Mars Rover or the Large Hadron Collider. These are huge collaborative projects that cost billions of dollars and require new technologies. Small science is different. Anyone can do it with minimal resources, not cutting-edge technologies. There are amazing things all around us. You just need to know where to look and how to see. Some of the topics I pursue in my book, such as laughing and hiccupping and so on, have been a source of concern from Plato to the present.

Q: You devoted an entire chapter to yawning. It’s not that it bored me, but when I read it I did start to yawn.
A: You’re going to start yawning if you’re just thinking about yawning. We yawn when we see other people yawn or when we read about it. Actually, anything that has to do with yawning will make us yawn.

Q: Why does that interest you?
A: It’s extraordinary. It‘s a reminder that we humans, who find ourselves to be conscious and rational, are also beasts of the herd. You don’t think about it (yawning), you just do it. But we also laugh when we hear other people laugh. We scratch if we see other people scratch. These are ancient, instinctive pre-wired actions.

Q: What about tearing, or crying, when we see someone else cry?
A: Other animals produce tears, but we are the only ones that produce emotional tears. It’s uniquely human, and synchronizes our behavior with that of another person. Plus, only humans have  “whites of the eyes,” the sclera. If you’re sad and you tear up, the eyes also become red. So by looking at the eyes of a human you get two sources of information (about emotion) that are not available to other animals. But the instinctive behaviors chosen (for the book) are not all contagious.

Q: Such as what?
A: Sneezing isn’t contagious. And neither is farting or belching, unless you are a boy.

Q: That, of course, begs the question: Why study farting?
A: We have another perspective, which is why do we talk through our mouth instead of our butts. The starting point is that human speech is an evolutionary accident whereby a valve that’s used to keep food and drink out of the vocal chords was set into vibration. Basically, when we exhale we are setting up vibrations in the vocal folds. So this valve that’s designed to keep foods out of the airways was put to use for speech. But passing air through the rectum sets up vibrations in the membranes and valves of the anus. That actually could have been another contender in the vocal sweepstakes, but it was more limited. We evolved to speak through our mouth. The vocal airway was more flexible than Option B, the unmentionable one. But I think considering other options is a useful tool in understanding evolutionary processes.

Q: Most of us view tickling either as an annoyance or a lot of fun, depending on who is doing the tickling. But you are looking at tickling from a broader perspective, why?
A: The observation that you can’t tickle yourself, except maybe mildly, shows that a tickle requires another person. It’s not a knee-jerk reflex. By defining the stimulus for tickle, we understand not only what constitutes personhood, but also the idea of other.

Q: So what are the implications?
A: It seems trivial, but it winds up being an important issue. If we understand the neuromechanism, we could program robots to be ticklish.

Q: Ticklish robots?
A: 
On several levels that would be an important development. Having a robot that’s programmed with a sense of ticklishness would mean we would have a robot that isn’t constantly startling itself. It would understand (the difference) between it bumping into something and something bumping into it. In other words, it would have a sense of self.

Q: Why are any of these behaviors important in terms of a scientific agenda?
A:
"Curious Behavior" describes a research agenda that’s not a finished product, including ticklish robots. We talk about the social breakthrough of emotional tearing and humans. But what is the neurological transformation that allows us to tear and other animals not? We can learn about pathologies of behaviors, too. Do individuals that don’t (exhibit) contagious laughing or contagious yawning, lack empathy? Do they show symptoms of autism or schizophrenia? So by describing these behaviors, we (may also) develop diagnostic tools that allow us to discover previous unanticipated pathologies.

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