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Speaker 1: Welcome to brain Stuff from How Stuff Works, Hey, brain Stuff,

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Speaker 1: Lauren vogelbam here. If you've ever had the distinct pleasure

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Speaker 1: of sourcing stock photos for any reason, you've likely come

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Speaker 1: across a whole lot of laughing women eating salads alone.

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Speaker 1: But you've also probably stumbled upon a truckload of people

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Speaker 1: scratching their heads to symbolize confusion, deep thought, or perhaps

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Speaker 1: a bad case of dandruff scalp dryness. Aside, how exactly

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Speaker 1: did the head scratch come to symbolize intellectual processes? Some

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Speaker 1: people believe that certain automatic gestures are simply natural, expressive

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Speaker 1: motions that are caveman predecessors passed down to us. San

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Speaker 1: Diego reader columnist Matthew Alice wrote this about it. One

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Speaker 1: popular explanation for any hand to head movements is that

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Speaker 1: their frustrated aggression a reversion to the natural movements of

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Speaker 1: our rock throwing ancestors. If you watch a small child

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Speaker 1: strike at something, he'll raise an arm over his head

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Speaker 1: and bring it forward in an arc. It's an natural,

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Speaker 1: unstudied movement, not much finesse, but for a caveman it

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Speaker 1: got the job done. Alice also pointed to a possible

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Speaker 1: anthropological explanation for head scratching. He wrote, when we're wrestling

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Speaker 1: with some knotty problem, we experience feelings of frustration, perhaps

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Speaker 1: some anger, and before we know it, our hand flies

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Speaker 1: up in the air. But hold it. In these modern times,

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Speaker 1: it's not polite to bash the guy who asked the question,

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Speaker 1: so instead we deflect attention from the movement and scratch

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Speaker 1: or rub our head or chin or neck. In a

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Speaker 1: two thousand nine article for Psychology Today, author and former

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Speaker 1: FBI counter intelligence agent Joe Navarro wrote, when we are

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Speaker 1: under stress, our brain requires a certain amount of hand

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Speaker 1: to body touching, handwringing, forehead rubbing, temple massaging, lip touching, etcetera.

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Speaker 1: These pacifiers serve to soothe the individual when there is

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Speaker 1: negative limbic arousal, fear, stress, etcetera. Recent research seems to

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Speaker 1: back up this stress theory and add another unexpected layer

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Speaker 1: to the story. In a two thousand and seventeen study

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Speaker 1: which was published in the journal Scientific Reports, scientists who

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Speaker 1: observed forty five recent monkeys found that scratching was more

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Speaker 1: likely to occur in times of heightened stress, like standing

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Speaker 1: in the presence of a high ranking or unfamiliar monkey.

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Speaker 1: It turns out monkeys who scratched were significantly less likely

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Speaker 1: to be attacked by those threatening strangers. Lead author Jamie

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Speaker 1: Whitehouse said in the study, as scratching can be a

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Speaker 1: sign of social stress, potential attackers might be avoiding attacking

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Speaker 1: obviously stressed individuals because such individuals could behave unpredictably or

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Speaker 1: be weakened by their stress, meaning an attack could be

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Speaker 1: either risky or unnecessary. And meanwhile, itching is still a

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Speaker 1: pretty mysterious phenomenon to scientists, but recent research suggests the

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Speaker 1: tickly sensation isn't necessarily a mild form of pain, but

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Speaker 1: its own distinct occurrence caused by a molecule that sends

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Speaker 1: a message from the heart to the spinal cord. So

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Speaker 1: while there's no single explanation for this head scratcher, you

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Speaker 1: know what was coming. It appears that acting out your

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Speaker 1: anxiousness with this stereotypical tick could keep you in the

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Speaker 1: good graces of others. Today's episode was written by Michelle

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Speaker 1: Konstantinovski and produced by Tyler Clang. If you love our

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Speaker 1: show and want to wear your heart on your sleeve,

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Speaker 1: check out our new shop te public dot com. Slash

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Speaker 1: brain Stuff for shirts and other merchandise, and of course,

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Speaker 1: for more on this and lots of other topics that

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Speaker 1: will scratch your itch for knowledge, visit our home planet,

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Speaker 1: how stuff Works dot com