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TED2009

Dan Dennett: Cute, sexy, sweet, funny

February 5, 2009

Why are babies cute? Why is cake sweet? Philosopher Dan Dennett has answers you wouldn't expect, as he shares evolution's counterintuitive reasoning on cute, sweet and sexy things (plus a new theory from Matthew Hurley on why jokes are funny).

Dan Dennett - Philosopher, cognitive scientist
Dan Dennett argues that human consciousness and free will are the result of physical processes. His latest book is "Intuition Pumps and Other Tools for Thinking," Full bio

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I’m going around the world giving talks about Darwin,
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and usually what I’m talking about
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is Darwin’s strange inversion of reasoning.
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Now that title, that phrase, comes from a critic, an early critic,
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and this is a passage that I just love, and would like to read for you.
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"In the theory with which we have to deal, Absolute Ignorance is the artificer;
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so that we may enunciate as the fundamental principle of the whole system,
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that, in order to make a perfect and beautiful machine,
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it is not requisite to know how to make it.
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This proposition will be found on careful examination to express,
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in condensed form, the essential purport of the Theory,
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and to express in a few words all Mr. Darwin’s meaning;
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who, by a strange inversion of reasoning,
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seems to think Absolute Ignorance fully qualified
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to take the place of Absolute Wisdom in the achievements of creative skill."
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Exactly. Exactly. And it is a strange inversion.
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A creationist pamphlet has this wonderful page in it:
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"Test Two:
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Do you know of any building that didn’t have a builder? Yes/No.
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Do you know of any painting that didn’t have a painter? Yes/No.
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Do you know of any car that didn’t have a maker? Yes/No.
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If you answered 'Yes' for any of the above, give details."
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A-ha! I mean, it really is a strange inversion of reasoning.
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You would have thought it stands to reason
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that design requires an intelligent designer.
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But Darwin shows that it’s just false.
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Today, though, I’m going to talk about Darwin’s other strange inversion,
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which is equally puzzling at first, but in some ways just as important.
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It stands to reason that we love chocolate cake because it is sweet.
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Guys go for girls like this because they are sexy.
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We adore babies because they’re so cute.
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And, of course, we are amused by jokes because they are funny.
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This is all backwards. It is. And Darwin shows us why.
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Let’s start with sweet. Our sweet tooth is basically an evolved sugar detector,
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because sugar is high energy, and it’s just been wired up to the preferer,
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to put it very crudely, and that’s why we like sugar.
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Honey is sweet because we like it, not "we like it because honey is sweet."
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There’s nothing intrinsically sweet about honey.
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If you looked at glucose molecules till you were blind,
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you wouldn’t see why they tasted sweet.
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You have to look in our brains to understand why they’re sweet.
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So if you think first there was sweetness,
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and then we evolved to like sweetness,
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you’ve got it backwards; that’s just wrong. It’s the other way round.
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Sweetness was born with the wiring which evolved.
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And there’s nothing intrinsically sexy about these young ladies.
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And it’s a good thing that there isn’t, because if there were,
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then Mother Nature would have a problem:
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How on earth do you get chimps to mate?
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Now you might think, ah, there’s a solution: hallucinations.
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That would be one way of doing it, but there’s a quicker way.
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Just wire the chimps up to love that look,
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and apparently they do.
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That’s all there is to it.
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Over six million years, we and the chimps evolved our different ways.
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We became bald-bodied, oddly enough;
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for one reason or another, they didn’t.
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If we hadn’t, then probably this would be the height of sexiness.
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Our sweet tooth is an evolved and instinctual preference for high-energy food.
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It wasn’t designed for chocolate cake.
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Chocolate cake is a supernormal stimulus.
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The term is owed to Niko Tinbergen,
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who did his famous experiments with gulls,
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where he found that that orange spot on the gull’s beak --
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if he made a bigger, oranger spot
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the gull chicks would peck at it even harder.
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It was a hyperstimulus for them, and they loved it.
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What we see with, say, chocolate cake
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is it’s a supernormal stimulus to tweak our design wiring.
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And there are lots of supernormal stimuli; chocolate cake is one.
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There's lots of supernormal stimuli for sexiness.
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And there's even supernormal stimuli for cuteness. Here’s a pretty good example.
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It’s important that we love babies, and that we not be put off by, say, messy diapers.
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So babies have to attract our affection and our nurturing, and they do.
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And, by the way, a recent study shows that mothers
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prefer the smell of the dirty diapers of their own baby.
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So nature works on many levels here.
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But now, if babies didn’t look the way they do -- if babies looked like this,
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that’s what we would find adorable, that’s what we would find --
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we would think, oh my goodness, do I ever want to hug that.
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This is the strange inversion.
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Well now, finally what about funny. My answer is, it’s the same story, the same story.
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This is the hard one, the one that isn’t obvious. That’s why I leave it to the end.
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And I won’t be able to say too much about it.
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But you have to think evolutionarily, you have to think, what hard job that has to be done --
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it’s dirty work, somebody’s got to do it --
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is so important to give us such a powerful, inbuilt reward for it when we succeed.
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Now, I think we've found the answer -- I and a few of my colleagues.
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It’s a neural system that’s wired up to reward the brain
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for doing a grubby clerical job.
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Our bumper sticker for this view is
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that this is the joy of debugging.
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Now I’m not going to have time to spell it all out,
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but I’ll just say that only some kinds of debugging get the reward.
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And what we’re doing is we’re using humor as a sort of neuroscientific probe
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by switching humor on and off, by turning the knob on a joke --
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now it’s not funny ... oh, now it’s funnier ...
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now we’ll turn a little bit more ... now it’s not funny --
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in this way, we can actually learn something
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about the architecture of the brain,
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the functional architecture of the brain.
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Matthew Hurley is the first author of this. We call it the Hurley Model.
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He’s a computer scientist, Reginald Adams a psychologist, and there I am,
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and we’re putting this together into a book.
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Thank you very much.
07:36

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Dan Dennett - Philosopher, cognitive scientist
Dan Dennett argues that human consciousness and free will are the result of physical processes. His latest book is "Intuition Pumps and Other Tools for Thinking,"

Why you should listen

One of our most important living philosophers, Dan Dennett is best known for his provocative and controversial arguments that human consciousness and free will are the result of physical processes in the brain. He argues that the brain's computational circuitry fools us into thinking we know more than we do, and that what we call consciousness — isn't. His 2003 book "Freedom Evolves" explores how our brains evolved to give us -- and only us -- the kind of freedom that matters, while 2006's "Breaking the Spell" examines belief through the lens of biology.

This mind-shifting perspective on the mind itself has distinguished Dennett's career as a philosopher and cognitive scientist. And while the philosophy community has never quite known what to make of Dennett (he defies easy categorization, and refuses to affiliate himself with accepted schools of thought), his computational approach to understanding the brain has made him, as Edge's John Brockman writes, “the philosopher of choice of the AI community.”

“It's tempting to say that Dennett has never met a robot he didn't like, and that what he likes most about them is that they are philosophical experiments,” Harry Blume wrote in the Atlantic Monthly in 1998. “To the question of whether machines can attain high-order intelligence, Dennett makes this provocative answer: ‘The best reason for believing that robots might some day become conscious is that we human beings are conscious, and we are a sort of robot ourselves.'"

In recent years, Dennett has become outspoken in his atheism, and his 2006 book Breaking the Spell calls for religion to be studied through the scientific lens of evolutionary biology. Dennett regards religion as a natural -- rather than supernatural -- phenomenon, and urges schools to break the taboo against empirical examination of religion. He argues that religion's influence over human behavior is precisely what makes gaining a rational understanding of it so necessary: “If we don't understand religion, we're going to miss our chance to improve the world in the 21st century.”

Dennett's landmark books include The Mind's I, co-edited with Douglas Hofstaedter, Consciousness Explained, and Darwin's Dangerous Idea. Read an excerpt from his 2013 book, Intuition Pumps, in the Guardian >>

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