11.進化、情感和理性。情感，第一部分 (11. Evolution, Emotion, and Reason: Emotions, Part I)

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Professor Paul Bloom: On Monday we--I presented an
introduction to evolutionary psychology, the looking at
psychology from an evolutionary perspective, and trying to make
a case and give some examples of how it can help illuminate and
illustrate certain aspects of how the mind works.
One of the advantages of an evolutionary perspective on the
mind is that it forces us to look scientifically at what we
would otherwise take for granted.
There are a lot of aspects of how we are and what we are and
what we do that seem so natural to us.
They come so instinctively and easily it's difficult,
and sort of unnatural, to step back and explore them
scientifically but if we're going to be scientists and look
at the mind from a scientific perspective we have to get a
sort of distance from ourselves and ask questions that other
people would not normally think to ask.
And the clearest case of this arises with the emotions.
And as a starting point there's a lovely quote from the
psychologist and philosopher William James that I want to
begin with. So, he writes:
To the psychologist alone can such questions occur as:
Why do we smile when pleased and not scowl?
Why are we unable to talk to a crowd as we talk to a single
friend? Why does a particular maiden
turn our wits upside down? The common man--[None of you
are the common man.] The common man can only say,
"Of course we smile. Of course our heart palpitates
at the sight of the crowd. Of course we love the maiden.
And so probably does each animal feel about the particular
things it tends to do in the presence of certain objects.
To the lion it is the lioness which is made to be loved;
to the bear the she-bear. To the broody hen,
the notion would probably seem monstrous that there should be a
creature in the world to whom a nestful of eggs was not utterly
fascinating and precious and never to be too-much-sat-upon
object which it is to her. Now, there's a few things to
note about this passage. First, it's incredibly sexist.
It assumes not just merely in reflexive use of phrases.
It assumes that--William James assumes he's talking to males,
male humans who sometimes take the perspective of male bears.
And so, it assumes a male audience.
You wouldn't normally--You wouldn't actually ever write
this way. A second point is it's
beautifully written and you're not--;also, not allowed to write
that way anymore either. It's poetic and lyrical and
if--William James characteristically writes that
way. I think he writes so much
better than his brother, Henry James,
an obscure novelist. [laughter]
Finally though, the point that he makes is a
terrific one, which is yes,
all of these things seem natural to us but the reason why
they seem natural is not because they are in some sense necessary
or logical truths. Rather, they emerge from
contingent aspects of our biological nature.
And so we need to step back. We actually--We need to step
back and ask questions like--and these are questions we're going
to ask--Why does poop smell bad? Avoid the temptation to say,
"Well, poop smells bad because it's so stinky."
The stinkiness of poop is not an irreducible fact about the
universe. Rather, the stinkiness of poop
is a fact about human psychology.
To a dung beetle poop smells just fine.
Why does chocolate taste good? Well, chocolate--The good
tastiness of chocolate isn't some necessary fact about the
world. It's a fact about our minds
that doesn't hold true for many other creatures.
And so, we have to step back and ask why to us do we find
chocolate appealing? Why do we love our children?
Don't say they're lovable. Many of them are not [laughter]
and, as William James points out, every animal,
most animals, many animals love their
children. They think their children are
precious and wonderful. Why?
Why do we get angry when people hit us?
Suppose somebody walked up to you and slapped you in the face?
You'd be afraid. You'd be angry.
Would you get sleepy, feel nostalgic,
suddenly desire some cold soup? [laughter] No.
Those are stupid alternatives. Of course if somebody slapped
us you would--we would get angry or afraid.
Why? Why do we feel good when
someone does us a favor? Why don't we feel angry?
Why don't we feel fearful? What we're going to do
throughout this course is step back and ask these questions.
We're going to ask questions nobody would have otherwise
thought to ask, where the common man wouldn't
address, and this is,
of course, standard in all sciences.
The first step to insight is to ask questions like why do things
fall down and not up? And I imagine the first person
who articulated the question aloud probably met with the
response saying, "What a stupid question.
Of course things fall down." Well, yes, of course things
fall down, but why? Why is our flesh warm?
Why does water turn solid when it gets cold?
These are natural facts about the universe,
but the naturalness needs to be explained and not merely
assumed. In this class we're going to
explore, throughout the course, what seems natural to us and
try to make sense of it. And to that end we have to ask
questions that you wouldn't normally ask.
We've already done this to some extent with domains such as
visual perception, memory, language and
rationality, but now we're going to move to the case where it's
maybe even somewhat more difficult to do this.
Now, we're going to start dealing with the emotions.
We're going to talk about the emotions, why they exist,
what they're there for, and how they work.
I want to start off with the wrong theory of the emotions.
And the wrong theory of the emotions is beautifully
illustrated in the television and movie series Star
Trek. In this alternative fantasy
world, there are characters, Mr.
Spock in the original Star Trek, Data in one of the
spin-offs, who are described as competent,
capable, in fact in many ways, super competent and super
capable people. But they're described as not
having emotions. Spock is described as not
having emotions because he's half Vulcan, from a planet where
they lack emotions. Data is an android who is said
to lack an emotion chip. This lack of emotions on
this--on a TV series does not hurt them much.
They're able to fully function. And in fact,
in a TV series emotions are often seen as a detriment.
You do better off without them. And there are many people in
sort of common sense who might think "Gee, if only I could just
use my rationality, think reasonably and rationally
and not let my emotions guide my behavior I'd be much better
off." It turns out that this is a
notion of how to think about the emotions that is deeply wrong.
And in fact, makes no sense at all.
Using the example of Star Trek, Steven Pinker,
in his book How the Mind Works, nicely illustrates
the problem here. He writes, "Spock must have
been driven by some motives or goals.
Something must have led him to explore strange new worlds,
to seek out new civilizations and to boldly go where no man
had gone before." Presumably, it was intellectual
curiosity that set him to drive and solve problems.
It was solidarity with his allies that led him to be such a
competent and brave officer. What would he have done if
attacked by a predator or an invading Klingon?
Did he do a handstand, solve the four-color map
theorem? Presumably, a part of his brain
quickly mobilized his faculties to scope out how to flee and how
to take steps to avoid a vulnerable predicament in the
future. That is, he had fear.
Spock did not walk around naked around the ship.
Presumably, he felt modesty. He got out of bed.
Presumably, he had some ambitions and drive.
He engaged in conversations. Presumably, he had some
sociable interests. Without emotions to drive us we
would do nothing at all. And you could illustrate this
scientifically. Creatures like Spock and Data
don't exist in the real world but there are unusual and
unfortunate cases where people lose,
to some extent or another, their emotions.
And you could look at these people and see what happens to
them. The classic case,
the most famous case, is that of a man called Phineas
Gage. Phineas Gage is the classic
Intro Psych example – an extremely poor guy,
poor schmuck. In 1848--He was a construction
foreman. In 1848 he was working at a
site with explosives and iron rods.
And due to an explosion, an iron rod passed through his
head like so. Imagine that rod shooting
upwards. It went under his eye and
popped out the top of his head. It landed about one hundred
feet away covered with blood and brains.
The rod itself weighed thirteen pounds.
Amazingly, Gage was not killed. In fact, he was knocked
unconscious only for a short period and then he got up and
his friends surrounded him and asked, "Are you okay?"
And they--And then they took him to the hospital.
On the way to the hospital, they stopped by a tavern and he
had a little pint of cider to drink, sat down and talked to
people. And then he had an infection,
had to have surgery. But when it was all said and
done he wasn't blind, he wasn't deaf,
didn't lose language, didn't become aphasic,
no paralysis, no retardation.
In some sense, what happened was much worse.
He lost his character. Here's a description at the
time of what Gage was like. And this is from Damasio's
excellent book Descartes' Error:
He used to be a really responsible guy,
a family man, very reliable,
very trustworthy. But after the accident he was
fitful, irreverent, indulging at times in the
grossest profanity, manifesting but little
deference for his fellows, impatient of restraint or
advice, a child in his intellectual
capacities and manifestations. He had the animal pleasures of
a strong man. His foul language is so debased
that women are advised not to stay long in his presence.
And he couldn't hold a job. He lost his family,
couldn't hold a job. He ended up in the circus.
He was in the circus going around the country with his big
iron rod telling everybody the story as they surrounded him and
clapped. There are other cases like
Phineas Gage, cases where people have had
damage to that same part of the brain, parts of the frontal
cortex. And what they've lost is they
basically lost a good part of their emotions.
And what this means is they don't really care that much
about things. They can't prioritize.
Damasio tells a case of one of his patients who was under the
pseudonym here of Elliot. And Elliot had a tumor in his
frontal lobe. And the tumor had to be removed
and with it came a lot of Elliot's frontal lobe.
And again, as a result of this, Elliot was not struck blind or
deaf or retarded, and he didn't become the sort
of profane character that Phineas Gage became,
but he lost the ability to prioritize.
He lost the ability to set goals.
Damasio describes him here:
At his job at an activity he would read and fully
understand the significance of the material [He works in an
office.] but the problem was he was
likely, all of a sudden,
to turn from the task he had initiated to doing something
else and spending an entire day doing that.
He might spend an entire afternoon deliberating on which
principle of categorization he should apply to files.
Should it be the date or the size of the document,
pertinence to the case or another?
He couldn't set his goals. He couldn't--He ended up not
being able to keep a job, not being able to deal with
people. And these are not men who have
lost their emotions. There is no case around where
you could have your emotions entirely blotted out.
But they lost a large part of their emotional capacity and as
a result, their rationality failed.
Emotions set goals and establish priorities.
And without them you wouldn't do anything, you couldn't do
anything. Your desire to come to class to
study, to go out with friends, to read a book,
to raise a family, to be--to do anything are
priorities set by your emotions. Life would be impossible
without those emotions. And so, there's certain themes
we're going to explore here. The first is this,
that emotions are basically mechanisms that set goals and
priorities and we're going to talk a lot about--in this class
and the next class about universals.
We're also going to talk about culture.
It turns out that cultures, different cultures,
including differences between America and Japan and the
American South and the American North,
have somewhat different emotional triggers and emotional
baselines to respond to. But at the same time,
as Darwin well knew, emotions have universal roots
that are shared across all humans and across many animals.
So, the agenda for this class and the next class is going to
go like this. First, I want to talk a little
bit about facial expressions, which are ways in which we
communicate our emotions – not the only way,
but an important way – and look, in particular,
at the case of smiling because it's kind of interesting.
Then I want to look at one case study of a nonsocial emotion,
that of fear. I want to then deal with
feelings towards our kin, people we're genetically
related to, and then--and this will take us
to the next class, feelings towards non kin.
So first, faces. And as an introduction to faces
I have a brief film clip from Paul Ekman, who is one of the
world's great scholars in the study of facial expressions.
In Ekman's work, he presents us with
instructions on how to make different faces and identify
faces. Ekman actually has a sort of
more practical career along with his scientific career.
He trains police and secret service members to try to figure
out cues to honesty and dishonesty.
There's a very interesting New Yorker profile on him
by Malcolm Gladwell a few years ago, something you might be
interested in. But let's do one of his faces.
Please lower your brows and draw them together.
That means even those who aren't making eye contact with
me now.
Tense your lower and upper eyelids.
Don't pop out contact lenses but just tense them.
Stare. Your eyes can bulge somewhat.
[laughter] Okay. Now, the last part is important.
Press your lips together with the corners straight or down.
That's good. You got it.
[laughter] Okay. Just because you are not making
eye contact with me doesn't mean I can't see you.
Okay. . And what face is that?
What emotion does that correspond to?
Anger. There's all sorts of databases
of different faces from around. This guy--I don't know who he
is but he seems to be on a lot of these things [laughter]
but the thing is you don't need to rely on him.
You don't need to rely on Western faces.
Even if you go on line there's, by now, a lot of databases from
faces from all sorts of genders and national origins.
This is from a Japanese women facial expressions.
And there are some subtle and very interesting differences
across countries and across people, but there's also deep
universals. You don't have to work very
hard to figure out what these different facial expressions
mean. I want to give one more face
example because I want to focus on this a little bit.
This one's a little bit easier. Raise the corners of your lips
back and up, please.
[laughter] Raise your cheeks. Raise your lower eyelids if you
can. [laughter] They're smiling.
You're smiling. You can stop [laughter] smiling.
Yale is actually really big on smiling.
We have two of the world's experts on smiling.
This is Angus Trumble, the curator at the British Art
Gallery who wrote this wonderful book,
A Brief History of the Smile looking at the smile
in art. And this is my colleague,
Marianne LaFrance, who is actually not smiling in
that picture but she studies smiling and smiling in adults,
smiling in children, smiling across cultures,
and the different social uses of smiling.
And there are some interesting discoveries people have made
about smiles and about smiles and the emotions.
One--Oh. Well, one is that smiles are
universal. We know, for instance,
that young children smile. This is my son,
Zachary, when he was younger, not that weird-looking kid
[laughs] next to him.
[laughter] Thank God. [laughter]
And even blind children, children blind from birth,
will smile. They'll smile appropriately,
making an important point that smiling is not learned by
looking at other people's faces. Smiling is also not uniquely
human. Nonhuman primates smile as well.
Smiles are social signals. You might imagine that people
smile when they're happy. This is actually not the case.
It's not as simple as that. Rather, people smile when they
wish to communicate happiness and we know that from several
studies. There are some studies of
bowlers and the studies are very nice.
What they do is they film bowlers.
So, the bowlers do their bowling and sometimes they knock
down all the pins, which is called a what?
A strike. So a strike--and that's good in
the bowling world. So, they knock down all the
pins but what they don't do, is they don't smile after they
knock down the pins. They are being filmed.
They don't smile. Then they turn around to their
friends and give a big grin. Other studies have looked at
films of people who have just won Olympic gold medals.
Now, not surprisingly, people who have won Olympic
gold medals are very happy. This is good news to win an
Olympic gold medal. But they don't actually stand
on the podium grinning. Rather, they stand there with
their faces in a normal expression.
Then when they stand up and face the crowds,
there's a big smile. You can ask yourself whether
during sex, an activity where many people enjoy,
whether or not people smile during sex.
And you can discover this yourself with [laughter]
a partner or a mirror. [laughter]
So, there are other things we know about smiles.
There are different types of smiles.
There are actually quite a few different types of smiles that
are different in interesting ways.
This is Paul Ekman again.
Which one's a better smile? Who votes for the one on the
right? Who votes for the one on the
left? There are two different sorts
of smiles. The one on the right is a smile
of greeting. It's sometimes known as a "Pan
Am" smile. Pan Am is a now defunct airline
which had at that time--They were--They don't call them
stewardesses anymore but they're--the stewardesses would
come in and they would smile. That was part of their job.
But it was a big, fake smile, the Pan Am smile,
a smile to communicate "hello" and--but it's as opposed to a
smile where the communication is that of genuine happiness.
The difference is around the eyes.
It's not the mouth. It's the eyes.
A real happiness smile, what's known as a Duchenne
smile, after a neurophysiologist who studied it,
involves moving the eyes. What's interesting is about
only one out of every ten people can fake a Duchenne smile.
So, if you smile at somebody, and you just hate their guts
but you want to smile at them, it's--unless you're quite
gifted it's difficult to fake a really good, really happy smile.
You could--It's not difficult to study smiles in the real
world. You could look at politicians,
for instance. Politicians are often in
contexts where they have to smile a lot.
And what they do is they simply give the Pan Am smile.
The mouth moves up, particularly if somebody is
attacking their record or ridiculing them,
and they'll smile and--but it's not a sincere smile.
The eyes don't move. My favorite example of this was
a few years ago when there was a huge battle for the House
majority leader. And a guy named--a Republican
named John Boehner won this position in quite a heated
battle. And they took a picture of the
guy--This is not very nice. They took a picture of the guy,
Roy Blunt, as he stepped out. And he had lost and this was
his expression. [laughter]
And he's not really very happy [laughter]
as opposed to a smile like this, which is a real smile.
So, you have two sorts of smiles: A real happiness smile a
Duchenne smile--called--also known as the Duchenne smile,
and then a Pan Am smile, or greeting smile.
And you'll use each of those smiles at different points in
your day and in your life. It turns out that these
different smiles have real psychological validity.
They seem to sort of reflect deep differences in your mood
and emotions and thoughts. Ten-month-olds,
for instance, give different sorts of smiles.
When their mother approaches there they give a real happiness
smile. Then when a stranger approaches
or someone else approaches there they'll tend to give more of a
greeting smile. John Gottman studied married
couples. And John Gottman does a lot of
work--Well, what he does is he looks at film clips of couples.
And by analyzing the film clips he tries to predict will their
marriages survive. And one of his cues--There's
different cues. Incidentally,
sort of side topic: The death knell for a marriage
for Gottman--This is his big finding.
It's not if they fight a lot. It's not they scream at each
other. It's not even if they hate each
other. The death knell of a marriage
is contempt. And so, if he shows these
clips: I walk in, "Honey, I'm home," and my
spouse has the look of contempt, it's a bad sign.
[laughter] But another clue is the sort of
smiles they give when they see each other when they walk into
the lab. If it's a true happiness smile,
that's actually bodes better for the relationship than a Pan
Am, or greeting smile. Finally, studies have been done
of college yearbook photos looking at people thirty years
later. And it turns out that there's a
correlation, a reliable relationship between how happy
somebody is now and back thirty years ago in their yearbook
photo--what sort of smile they're giving.
There is some evidence for a third sort of smile.
This is known as a coy smile or an appeasement smile.
This is sort of a very specialized sort of smile.
This is a smile of embarrassment or stress.
You give it when you want people to like you,
you want to join in; you want to make people feel
positive about you. But you're in,
sort of, a high-stress situation often with some sort
of risk. And what you do is you sort of
you turn away. There's no eye contact.
You turn away and kind of give this-- And this actually shows
up in other primates. Here's a nice picture.
[laughter] So, the rhesus monkey bites her
own infant, and the infant gives a scream and then the
submissive, coy smile. And it also shows up in human
infants. Here's a nice clip of a coy
baby smile. I'll walk you through it.
The baby is being approached, [laughter]
goes like this , smiles like this ,
and then the aversion . Yeah.
Babies are cute. [laughter]
Any questions at this point about smiling?
What are your smiling questions? [laughter] Yeah.
Student: Do nonhuman primates' smiles [inaudible]
Professor Paul Bloom: That's a good question.
I don't know. There's evidence that the coy
smile shows up in non--The question was,
"Do nonhuman primates give the same smiles that humans do?"
such as a distinction between the Pan Am smile,
a greeting smile, versus a genuine smile of
happiness? I don't know.
I'll find out for you for next class though.
That's a good question. Yeah.
Student: How come some people's smiles are better than
other people's smiles? Professor Paul Bloom:
How come some people's smiles are better than other people's
smiles? The non-interesting
psychological answer, some people are better looking
and there's more thing-- [laughter]
but the deeper answer is some people are better able to smile.
Some people are better able to use the cues to express true
happiness. There's something else about
smiles which is going to come up, which your question raises,
I think, which is going to come up in--when we talk about
emotional contagion and actually,
some issues of morality. Smiles are extremely contagious.
So, what I'd like people to do--If you're sitting next to
somebody, please turn around and find someone next to you and
look at them. Don't do anything.
Just look at them. Whoever is being looked at,
look back. [laughter]
This is not-- [laughter] Please arbitrarily decide.
Okay. Please arbitrarily decide on
the smiler. That will be--No,
not at me, at each other, [laughter]
and that will be the person--If you are unable to resolve this
dispute--yes, you two, please--if you are
unable to resolve this dispute, the person to the right of me
will be the smiler. So, look at each other
expressionless. [laughter]
Now, the person who is the mandated smiler,
[laughter] on three, please smile.
One, two, three. [laughter] Okay.
[laughter] Worst class demo ever
[laughter] but if one could imagine more
restrained circumstances, it is actually extremely
difficult to be facing somebody who's really smiling at you and
not smile. This is true,
by the way, for virtually every other emotion.
The phenomena is known as "emotional contagion," where if
you're facing somebody, for instance,
and they're--they look at you in a face of absolute rage,
it is very difficult to just sit there without your own face
molding in accord to their own. And the reasons why this
happens and how that works is something we'll talk about later
on. So that's--One more question.
Yes. Student: [inaudible]
Professor Paul Bloom: I don't know if that's--The
question is, "Is there a difference between
smiling with your teeth versus just your lips closed?"
There probably is. That's not a main smile
difference but my bet is that there probably is a difference.
And my bet also is that that sort of distinction,
how much teeth you show when you smile,
is the sort of thing that would show regional and country by
country differences. For instance,
there's been research finding that people in England smile
different from people in the United States.
And I think that those are the sort of contrasts that you would
expect to find in cross-cultural differences.
Every culture is going to have Pan Am smiles,
happiness smiles, coy smiles, but the variation
of that sort is something which will vary as a result of how
you're raised and the people around you.
I want to deal with a few emotions in this class and next
and the first case study of an emotion I want to deal with is
the emotion of fear. And I want to deal with fear
for different reasons. One reason is it's a basic
emotion, it's universal. All humans have it.
Many nonhumans, probably most nonhuman,
species have it too. And it also brings us back to
the lecture on behaviorism where we talked about classical
conditioning and different theories of what people are
afraid of. It's a nonsocial emotion.
What I mean by this is it's possible, of course,
to be afraid of a person, but unlike an emotion like
gratitude, it's not intrinsically social.
You could be afraid of falling off a cliff or something.
It has a distinctive facial expression again.
This is a famous picture of Lee Harvey Oswald who was being
assassinated by Jack Ruby. And this is the detective's
face standing there, a mixture of fear and anger –
the face being drawn back in a universal expression that every
human everywhere would be able to recognize.
So, the basic question to ask is "What are we afraid of?"
And the answer's a little bit interesting.
We're afraid of spiders, snakes, heights,
storms, large animals, darkness, blood,
strangers, humiliation, deep water, and leaving home
alone. We are afraid of other things
too but those are big things to be afraid of.
I'm not even going to ask. If there's somebody who--in
this room, who's not afraid of any of those things?
You're a tougher person than I am.
These are universal fear elicitors.
Why? What do they have in common?
Why would you be afraid of those things?
And the answer is--And why would--why are there so few
people afraid of guns, cars, and electrical outlets?
The answer is not particularly surprising.
These are things that--something's ticking over
there. These are things that are scary
in our ancestral environment. More particularly,
these are things that through the course of human evolution
have been dangerous to us. And so, we are afraid of these
things and not so afraid of these things;
similarly for nonhuman primates. So, chimpanzees are afraid of
certain things and they can often develop phobias for
certain things, but the phobias they develop,
the fears they develop, are things like spiders and
snakes. There was a nice study done in
urban Chicago, in the inner city of Chicago.
And they asked children raised in the inner city,
"What are you most afraid of?" And you might think they would
say, "I'm afraid of being shot. I'm afraid of guns.
I'm afraid of being killed by somebody or being harmed by
somebody. I'm afraid of being run over by
a car." The two biggest fears of
children in urban Chicago are that , snakes and spiders,
even though many of these children have probably never
seen a snake outside of a zoo in their lives.
These are natural fears. There is some research done by
the psychologist Judy DeLoache at University of Virginia where
she's studying babies' fears of spiders and snakes,
babies obviously who, since their parents are normal,
have not yet seen spiders and snakes.
There are various ethical reasons why you can't show
babies--you can't try to construct phobias in babies of
spiders and snakes but the research she's finding using
more indirect methods finds, as one would expect,
these are what psychologists would call "pre-potent stimuli";
that is, these are things that naturally elicit fear and
concern. And that's all I have to say
about fear. I want to turn for the rest of
this lecture and for next lecture next week to the social
emotions. And the social emotions can be
broken down into two categories. Bless you, bless you.
Those emotions you feel towards your kin, towards your genetic
relatives, and those emotions that you feel towards the people
you're not related to but interact with.
And I want to focus particularly on emotions that
generate kind or altruistic behavior.
"Altruism" is the biologists' term meaning kindness,
generosity, and evolutionary biologists have worked really
hard to explain why animals might evolve to be kind.
A very old, very wrong view of evolution is that evolution has
shaped animals such that they're merely survival machines.
If so, then from an evolutionary standpoint any
kindness towards an animal--that an animal shows towards another
animal--is a mystery. If evolution wired us up simply
to survive, then it's a puzzle why animals would relate
positively to other animals. But of course, that's not true.
Here's a simple example showing it's not true.
Imagine two genes, two sorts of animals each
containing their own gene. Gene "A" makes an animal care
for its offspring. Gene "B" makes an animal care
only for itself. Imagine what will happen in the
next generation. Plainly, Gene "A" will win out.
It's a very simple case. An animal who has evolved a
brain that says, "Take care of your offspring"
will do much better from a natural selection point of view
from an animal who has evolved a brain that says,
"Eat your offspring." The animal that eats its
offspring, those genes are a biological dead end.
What matters then is not survival, per se.
What matters is reproduction. And so, that simple fact is why
we would expect animals to care for their children,
because children are the means through which genes replicate.
But it gets a little bit richer than that.
And this is one of the major revolutions in evolutionary
biology over the last half century.
Forget about the animal a bit and take another perspective.
Take a perspective of the cold virus.
People have been sneezing in the front row.
Now, you're coughing. Thank you.
Why do you sneeze when you get a cold?
Here's not a-- Point made. Here is--Here's not a bad
answer. You sneeze because you've got
all these germs inside you and your body wants to get the germs
out, so you sneeze. It's not that it's totally
wrong, but it's not bad. The real answer is a little bit
more interesting. Don't look at it from the
person's perspective. If you have a cold,
try to get away from your own selfish perspective,
"I have a cold." Look at it from the perspective
of the cold virus. The cold virus has evolved just
as much as you evolved. And it's evolved due to
survival and reproduction. What the cold virus does is
evolve different strategies to cause it to reproduce.
And what it does is--one way to reproduce is to occupy other
animals and manipulate their bodies so as to expel it.
From this point of view then, the reason why you sneeze when
you have a cold is that your cold--the cold virus is using
your body as a tool to replicate itself.
From this person--this perspective, a person is just a
germ's way of making other germs.
And there's tons of other examples of this.
There's a parasite known as toxoplasmosis that lives in the
bodies of rats. But it gets passed on when the
rats get eaten by cats. And then it ends up in the
cats' feces and then it ends up back in rats.
If you are a rat and you have toxoplasmosis,
you are perfectly healthy except for one thing.
The toxoplasmosis rewires your brain and it makes you less
afraid of cats. Now, again, this is not some
sort of bizarre quirk of a humorous god.
Rather, it's because this is a perfectly--this is the adaptive
strategy of the toxoplasmosis virus.
In fact, a real powerful virus would skip the respiratory
system altogether, even better than a cold virus.
What it would do is it would take over the brain and it will
make people want to run around and have sex with other people
and kiss them on the mouth. And in fact,
there is some evidence that this happens.
There's some evidence, for instance,
that one of the effects of sexually transmitted diseases
like syphilis is it arouses the libido,
makes people more sexually engaged, because this is part of
the strategy through which these viruses replicate themselves.
Imagine a virus, for instance,
that captured an animal's brain and then modified the animal's
brain such that the animal would run out and bite other animals
so as to pass on the virus. And then, of course,
you would call that virus "rabies."
Along these lines, the evolutionary biologist
Richard Dawkins took the general step of suggesting that animals
are the vehicles through which genes exploit to reproduce.
From this perspective, an animal is just the
person's--is just the gene's way of creating another animal.
Well, as psychologists, what benefit does that--does
this way of analysis give us? It actually can help us explain
altruism. So, which genes are going to
survive? Well, the genes that survive
are going to be the ones that make the most copies of
themselves. Animals are vehicles through
which genes reproduce. An animal's merely the gene's
way of making another gene. Hence, selfish genes will lead
to altruistic animals because, to the extent that evolution
operates at the level of the genes,
there's no hard and fast distinction between your own
body and someone else's body. And here's an illustration by
the biologist Haldane. So, Haldane was once asked,
"Would you lay down your life for your brother?"
And he responded, "No, but I would gladly give my
life for three brothers or five nephews or nine first cousins."
Now, he's joking. You don't actually do the math
if you're normal. But what he's capturing is the
logic, the ultimate causation of our feelings towards our kin.
Our genes have wired us up--our brains up to love our children
and love our kin because, in this way,
our genes manage to replicate themselves.
And in fact, you get his calculations by
looking at genetic relatedness. The genetic relatedness,
from an evolutionary standpoint, affects how much you
care for other people. From the standpoint of your
genes, you dying for the life of three brothers is an excellent
compromise because the genes replicate by fifty percent more.
If you imagined--;So, here is his calculations.
If you imagined a choice between this one gene that makes
the animal choose to die and the other gene that makes an animal
choose for its brothers to die, the gene that sacrifices the
body it belongs to will make more copies in the future.
And there's an interesting irony to this.
The selfish gene theory is often seen as sort of a
cold-blooded evolutionary analysis,
but it provides a scientific basis for real,
genuine altruism, for really arguing that,
from the standpoint of the genes, there really is no hard
and fast difference between yourself and another person.
From this perspective, we can start to answer some
interesting questions at least about nonhumans.
When a new male lion takes over a pride what he does is kill all
the remaining cubs and any lionesses undergo spontaneous
abortions. This all might seem very cruel
but from a genetic standpoint it makes sense.
The other cubs are genetic competition for him.
They do not have his genes. Moreover, only once they're out
of the way can he reproduce and copulate with the females.
The females do their spontaneous abortions because
that's a reliable adaptive trick.
These cubs are not going to survive once they are born so
the female's best strategy is to get rid of them and start anew.
From a psychological point then, animals have evolved to be
nice to their kin, particularly their children,
and particularly in birds and mammals.
Birds and mammals invest in quality and not quantity,
as opposed to fish and reptiles.
For birds and mammals, we don't have many kids but--so
we devote a huge amount of psychological energy to
protecting the ones that we have.
Moreover, the kids we have are vulnerable for long periods of
time and require our resources. So, there's various
psychological mechanisms that this gives rise to.
One is how parents or how adults in general respond to
children. Another one is how children
respond to parents. And I'll briefly talk about a
few of these phenomena.
Small animals make distress calls.
They chirp, they mew, they bleat or they cry.
The governing of a distress call is actually an extremely
delicate high-wire act for any young organism from an
evolutionary point of view. It has to on the one hand be
annoying enough to actually generate help,
to get people to help you, to feed you,
to pick you up, to take you and put them next
to you. On the other hand,
it can't be so annoying that the people around you kill you
[laughter] and so it's complicated.
But, from your point of view, you're wired up to respond to
them. That sound is,
at very minimum, extremely annoying.
And it's more--it's not annoying because of its volume
or pitch. It's annoying because your
brains are wired up so that that baby cry is going to drive you
up the wall. On the more positive side,
babies are cute. I got this from Google Images,
typing in "cute baby," [laughter]
getting rid of the porn and [laughter]
coming on to that. No, no, Playboy,
but anyway it was over that. [laughter]
And do not be tempted to say, "Isn't it wonderful that the
way nature works is that babies are cute?
Otherwise we would have killed them."
[laughter] That's not the right story.
If--Babies are not--Human babies are not,
sort of, metaphysically cute. If Martians came down they
wouldn't say, "Oh, cute baby."
Rather, they're cute because of how our brains are wired up.
They're cute because there are certain cues that correspond to
the way our brains work. And in fact,
this is how it works for all mammals.
So, babies have these big, protruding foreheads,
an upturned little nose, chubby cheeks and big eyes.
Those are the ingredients for cute.
Stephen Jay Gould has a wonderful essay where he
discussed this, looking at the evolution of
Mickey Mouse from the Walt Disney character.
Mickey Mouse starts off as an ugly, little rodent.
[laughter] Over time he gets cuter and
cuter and cuter as the artist converged on more and more
baby-like features. Studies of adults show what's
known as a baby-face bias. This is not unique to the
United States. The same studies have been done
in Asia. You find a baby face in an
adult, Leonardo DiCaprio, to be particularly naive,
helpless, kind and warm. And in mock trials,
people with baby faces are more likely to be found innocent than
people like Ben Affleck, [laughter]
who do not have baby faces. [laughter]
Now, one question which is going to come up for an entire
lecture later on is "who is sexier, the baby faced man or
Testosterone Man?" here .
[laughter] And I am going to ask actually
for a vote because I'm going to return to this.
I do not--I only want the men to vote, please.
Who would go for--And forget the fact that he looks sort of
unhappy. Who would go for Ben Affleck
here? Okay.
[laughter] Who would go for Leonardo?
Okay. [laughter]
Well, the women votes would actually be more complicated.
We will discuss when we get the lecture on sex.
Your choice will depend on where you are in the menstrual
cycle. [laughter]
Now, so far, we're talking about how babies
respond to--We're talking about our responses to babies.
What about babies' responses to us?
Well, there's a very old theory known as the "Cupboard Theory"
proposed by the behaviorist B.F. Skinner which argues that
babies' attachment to their parents is because the parent
provides food, characteristically breast milk,
but it could be food from a bottle or whatever.
And because of operant conditioning,
the baby is driven towards the adult.
An alternative theory is that of Bowlby, which is that they're
drawn to their mother for comfort and social interaction
as well as fear of strangers. To test this,
the psychologist Harlow performed a series of ingenious
experiments with nonhuman primates distinguishing between
what he called "wire mothers" and "cloth mothers."
And you'll see illustrations of this to follow.
Wire mothers are mothers that are built that they give food.
They have a little nipple attached and you can drink from
it and give food to the baby. And that's the baby's source of
food. Cloth mothers don't give any
food but they give warmth and comfort.
There was a while in the psychology department where one
professor was known to be extremely supportive to his
students but didn't really provide much warmth.
And he was known as the cloth mother.
And another one was very productive and everything but
provided no love. And she was known as the wire
mother. But anyway, I'll show you the
movies. I have to warn you this third
and final movie is an example of why this research is not
currently done, but it illustrates an important
scientific point. Oh.
Now him-- I think I'm-- They're just more Google Images.
[laughter] I think I'll--I want to begin
next class by wrapping up and explaining the Harlow studies in
more detail and what they tell us.
And then we'll move towards altruism, towards non kin.
I'll see you next week.