Marc Hauser, "How Humans Evolved a Sense of Self and an Understanding of Their Mortality” - God and Computers: Minds, Machines, and Metaphysics (A.I. Lab Lecture Series)

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PRESENTER: Yeah, welcome to all of you. And thank you for coming to the second lecture of this fall's lecture series, God and Computers, Minds, Machines, and Metaphysics. To start the whole thing, we also have a website. Several people asked for that. I just wrote down the address. So if you want to check the website, if you want to see future speakers, the abstracts and so on, even though I have to warn you, the abstracts usually come only one week before the actual talk, the address is http://www.ai.mit.edu/events/god-and-computers.html.

Last week I forgot, but this week I definitely want to, at first, start this thing by thanking all the organizations which support the series, which is the MIT Electrical Engineering and Computer Science Department, the Artificial Intelligence Lab, the Boston Theological Institute, the Sir John Templeton Foundation, the Center for the Studies of Values and Public Life of Harvard Divinity School, and the Face and Science Exchange in Boston. I thank all these organizations for very generous help, not only financial, but also in terms of organization and stuff. And I also want to mention that the discussion group we have organized at Harvard, which is run by Professor Harvey Cox and me, actually does not take place next Monday. We forgot, it's Columbus Day.

So unfortunately, this thing will not happen. So we will meet the first time on the 27th of October. Outside are brochures, so if you want to have the dates for all three meetings, look in this brochure. But the changes, unfortunately, I'm sorry to say that, but the meeting is not at 1:00 but at 12 o'clock in the refectory in the small dining room at Harvard Divinity School, 45 Francis Avenue. You might find it on any Harvard map, I guess. And it's open for the public, so anyone can come. And for students, it's for noncredit. It's just for the interest of this thing.

And now it is my absolute pleasure to introduce Marc Hauser, the second speaker of this series. Marc is currently associate professor in the departments of anthropology, psychology, and the program in neuroscience at the Harvard University. He's also a member of two interdisciplinary faculties, the Speech and Hearing Science Program of MGH, Harvard and MIT, and the Mind, Brain, and Behavior Program at Harvard.

He has worked with several various monkeys groups on a variety of different problems, like aging, parent, offspring, and gender relationships, sexual behaviors, facial expressions perception, and repeatedly, on language and communication. This last part of Marc's research has led to the 1996 MIT Press book, The Evolution of Communication. And while reviewers all say that this book has a clear potential to become an absolute classic in the field, I like it because it's absolutely fun to read. And so in that sense, I can highly recommend that book for anyone who is interested in that sort of thing.

I first met Marc when we were in our robotics group, dealing with questions of self-awareness. And we had this big problem to understand what that is. And the same time, I lost a bet and so I was forced to dye my hair purple. And so my boss, Rodney Brooks, looked at me and said, well, you know what, there is this guy at Harvard who dyes monkeys' hair blue, and he found out that they have self-awareness that way. And this is how I met Marc. So Marc, I'm very happy that you are here to share your ideas on perception of self and mortality.

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HAUSER: Well, it's been a real pleasure. And I suppose the title, like the one I gave, I should be a little bit humble. So I'll start by telling you a story about my daughter, who has always sort of taught me some interesting things. And when she was about four, I walked into her room and she was sitting on the floor with a book between her legs.

And I noticed the book was upside down. And I said to her, Alexandra, the book's upside down. And she sort of looked at me and looked at the book and said, yeah, but the world's upside down. And I thought, well, I guess it is just a matter of perspective.

And what I want to do with you today is sort of share a perspective that I hold dear to my heart, and that's a perspective that Charles Darwin brought to us. I don't know if we need the lights down a little bit maybe. Can we have the lights down. Yeah, that's probably good.

In one sense, the topic for this series, God and computers, I think Darwin has some interesting things to say. The Darwinian revolution has often been put in opposition to religion, but as many of you know, Darwin himself was quite a religious man. And of course, what Darwin sort of forced us to take seriously is the idea that there is continuity between humans and non-humans. And Darwin could be considered one of the first psychologists, because Darwin took the idea very seriously that not only do we share continuity in terms of what we look like in terms of our morphology, but also in terms of how we felt about the world and how we thought about the world.

Now, we have this extraordinary fascination with our uniqueness. And in fact, we could almost say it's an obsession with our uniqueness, to the point where we have movies trying to put ourselves in opposition to the animals, or having the animals rule us. And we think this is kind of cute. But of course, we know it's not possible.

But this obsession, I think, blurs what are really the important questions about thinking about our evolution. That in one sense, all animals come into the world with special features, things that make them special and unique. So the claim that we're unique really just begs the question, unique in what way? And what I hope to reveal to you today is some of the ways in which we are special, but also some of the ways in which we share common ground with many other animals.

Now, how can we study the evolution of something so complicated as our minds? The fossil record, of course, is in some sense quiet on this problem, because they're not around to tell their tale. But on the other hand, there are some lively things that are left in the past that we can use to understand what was going on. Artifacts, for example, are really traces of a mind from the past. And archeologists and paleoanthropologists have done some extraordinary work working out the details of things like artifacts. When fire came into existence, when artifacts, tools, art, religion, began to come around.

Well, I want to sort of push this further back than those guys, and I want to deal with a creature for the moment that is very, very different from us. And I want to bring up this creature for a very particular reason. And it's because in the area of philosophy, and in particular philosophy of mind, people such as Thomas Nagel have thrown out the question, what is it like to be a bat? Or what is it like to be any type of creature other than ourselves?

And his answer, and answer that many people have given, is that there is no such thing that it's like to be another animal because our sensory world, our perceptual world, is so critically different from that of another animal. Surely, it's different from a bat, who sees the world, so to speak, with its ears. They send out a biosonar pulse. The biosonar pulse hits objects in the world, and this gives them a menu of possible objects that are in their environment. So how could we possibly understand what their beliefs, their thoughts, their emotions are like if their whole sensory system is so different?

Well, if you don't want to buy that bats are a good model for our thinking, well, then I think that primates should probably be a little bit more digestible to you because they're a little bit more closely related. This is the comparison group that I want to talk about today. My daughter, when I showed her this slide, asked me why that one was over there rather than somewhere down here. She's gotten quite sophisticated with her phylogenetic thinking.

And I want to, in fact, talk to you today in particular about three species, the three species that I've been working on for the last 15 years, and their representatives, although by no means "the" representatives of their taxonomic groups. And that's the chimpanzees, who are great apes, closely relate to the gorillas and orangutans. An old world monkey, in particular, the rhesus monkey, very closely related to species like baboons and vervet monkeys that you may be familiar with, and a new world monkey, the cotton-top tamarin.

Now, unlike some of the people that you'll be hearing in this series who work in labs with robots and so forth, I work in a variety of places. And this sort of informs how I go about thinking about my work. So I want to share a little bit of that with you right now.

The chimpanzees that I study live in a forest in Uganda. It's a tropical rain forest. And the chimpanzees have become very habituated to the presence of humans, so we can watch in detail their behavior. And I'll be telling you a little bit about that at the last part of the talk.

Rhesus monkeys, these guys here, the ones I study, they're actually from India, but they were imported in the 1930s to a small island off the coast of Puerto Rico known as Cayo Santiago. And for those of you who think that field research is tough, this is the place that we work on. It's not tough at all. In fact, the pina coladas are somewhere over here. And then lastly, the cotton-top tamarin that we study at our lab at Harvard University.

Okay, so those are the cast of characters. The outline for my talk today is going to be sort of like a version of Sesame Street, but with, hopefully, a little bit more content for you. And it's going to be broken into approximately four parts. In the first part, I want to touch upon an issue which [? Ana ?] mentioned at the beginning of today's talk, which is the notion of self, And to try to work out how we could understand whether other creatures have a kind of a self. And if so, whether it's different from ours. And if it's different, in what ways might it be different? And if it's the same, wouldn't that be interesting?

The second part is to say if they do have some understanding of self, can they apply the knowledge that they have to make predictions about the minds of others? Can they mind read in the way that all of you are capable of mind reading every single day? You are constantly making predictions about other people without any experience of what they're doing.

You see somebody, they say to you, I have the following religious affiliation. You say, aha, I bet you believe the following, okay? You merely jumped to that conclusion. Do animals have such capacities?

Part three will be to focus on the notion of death. Do animals have any understanding of their mortality? And then lastly, taking all three of these together, I will touch briefly upon the notion of morality to see whether or not animals could possibly be moral creatures in the way that we think we're moral creatures.

Okay, so self. This is Tigger from Winnie the Pooh. And Tigger-- I won't read through the whole thing-- but is surprised to see himself in front of a mirror, because he thought that he was the only tigger in the world. So the mirror, for Tigger, is a reflection of another. He doesn't get what the mirror should be telling him.

Now, is there anything natural about this situation for animals in the wild? Well, yes, there is. Animals often might see themselves in a mirror reflection, and that's water. So there are situations where animals, like these fowl, might have the opportunity to get information about themselves.

And it's this kind of reflection that might tell an animal that it is a unique individual. And this might be the beginning stages of the development or the emergence of a sense of self. But how can we get further on this problem?

Let me tell you about what I think of as one of the most ingenious experiments I think to ever come out of the field of animal behavior, because it's so very simple. It actually started with Charles Darwin. In The Expressions of Emotions in Man and Animals, Charles Darwin thought to himself, I wonder if animals have a sense of self. And the thought, let's see. Let's put up a mirror in front of an orangutan, which is exactly what he did.

And what he found was the orangutans were interested. They went up, they looked in the mirror. They often looked behind the mirror. And they displayed at the mirror.

And Darwin thought, well, based on this aggressive kind of display, it seems that orangs do not have a sense of self. They think that the mirror reflection is somebody else, in the same way that Tigger did. But it's also possible, which Darwin did acknowledge, that they were trying out their displays, acting aggressively, seeing what they looked like. Boy, don't I look good in that mirror?

We can't distinguish that. So along comes Gordon Gallup, a comparative psychologist in the 1970s, who decides that we need to test this a little more formally. So he presented the chimpanzees a mirror, a full standing mirror, and let them watch. And he watched what they did. And they did the same things that the orangs did.

They touched the mirror. They inspected it. They looked at themselves and so forth. And after exposure to the mirror, he anesthetized the chimpanzees, knocked them out with a drug, and while they were sleeping, he placed a red mark above one eyebrow and a red mark above the opposite ear.

And when they woke up, he put the mirror in front of them. And what he found was the chimpanzees directly touched those marks on their eyebrow and the mark on their ear. And not the opposite ones. And from this kind of observation and others, such as the following, chimpanzees now beginning to use the mirror to find good things, like picking their noses, flipping their lips up and seeing what they look like, all these body parts they've never seen before. What a revelation, right?

Gordon Gallup concluded that not only do chimpanzees recognize themselves in the mirror, in other words, they know that that's me, but they have something much more profound, which is a sense of self-awareness. Now, maybe in the questions we can come back to this issue, but it suggests a pretty profound difference that to recognize oneself in the mirror seems, to me at least, quite a different type of claim than the claim that they are aware of themselves. That they are aware, in some sense, of what they believe, and that they know that those beliefs, in some sense, are different from the beliefs of others.

Well, if you work on a species which has been tested in the same type of design and fails, you feel like you've got a really dumb species. So you worry about it a lot. And the one species that we work on, the tamarin, which I mentioned before-- this is a little of focus, sorry-- was a species that had been tested on the Gallup test, with these marks on the eyebrow, and they basically fail.

And we thought, well look, why might they fail this test? And if they fail, does it really tell us they lack a sense of self? So we worried about this quite a lot, and we thought, look, why might a tamarin fail?

Well, one reason why a tamarin might fail is because, maybe because they have a black face, the red mark isn't really that distinctive. They might not notice it. The other thing is tamarins, like all other monkeys, and in contrast with the apes, like chimpanzees, find looking at somebody else to be aversive. Staring is not good. Staring is a threat.

And if staring is a threat and your first implication that you draw from seeing the mirror is that it's somebody else, then the mirror is aversive. So you might never pick up the details of what a mirror gives you, which is something about real time coordination between your emotion and something else. So we thought, look, we've got to do something really dramatic that will make them pay attention. And that's what we did.

We dyed their hair, as [? Ana ?] told you. And to do this required some very delicate equipment. It requires going to Hubba Hubba, which I'm very sorry to say no longer exists in Central Square, to buy Manic Panic. And we dyed our monkeys with this Manic Panic. Different colors, as you can see here. Some have green, some have purple, some have blue and pink and so forth. And we ran exactly Gallup's test.

And to our great surprise, when the tamarins saw themselves in the mirror, they also touched their hair. But they did something which, to us, was far more interesting. And that's shown in one of the few data slides I'm going to have in a moment, which is that unlike what they did before their hair was dyed, the tamarins with their hair dyed now looked at themselves in the mirror for a very long time.

So this is what happened to those animals before their hair was dyed, and this is what happens to them after their hair is dyed. They sat in front of the mirror, peacefully, without vocalizing, without aggressively displaying, just looking in the mirror. Some would put their hands in front of the mirror and watch the reflection as they moved it round and round. Others would go up in front and check out their backsides.

They began to use the mirror in this subtle kind of way. Now, it wasn't as dramatic as the chimpanzees, but it suggests a similar kind of phenomenon, that minimally, perhaps, the tamarins perceive themselves in the mirror as themselves. We think, however, this experiment is completely silent when it comes to revealing anything about what they think about in terms of themselves, what they believe, whether they really have self-awareness.

Now, I want to share with you a videotape of something that we recently saw on the island of Cayo Santiago with the rhesus monkeys. This is a population of about 900 monkeys living on an island. No people live there at all. And to our knowledge, they really have not been exposed to any kind of mirror.

Well, a few weeks ago-- sorry, a few months ago, when I was down on the island of Cayo Santiago, a film crew was there from the BBC. And they were interested in what rhesus would do in front of a mirror. Sadly enough, the mirror broke, so they never got any footage. But we were able to get some, because four females picked up these fragments of mirrors and carried them around everywhere.

[LAUGHTER]

Okay, why aren't we going here? We're having technical difficulties here. I'm hitting all the right buttons, but it's not moving. Yeah, it's on A, because that lit up the blue screen. It's the machine which is not going rather than the-- well,

AUDIENCE: [INAUDIBLE]

HAUSER: That's a good point. Thank you.

[LAUGHTER]

Talk about human technology. Why does it do it? I'm not from MIT. See, it's the problem.

AUDIENCE: It's making itself aware.

HAUSER: Okay. This is natural footage of the animals. And this animal's never seen itself in the mirror. And unlike all the claims in the literature, this rhesus is grabbing this fragment of mirror and staring at itself at extremely close range while looking in the mirror.

Now, this is fascinating for the following reason. First of all, only females did this. Hmm. Secondly, and more importantly, why, in all the previous reports where rhesus monkeys have been tested, do they continue to act aggressively? In this case, they don't.

Here's one possible explanation. All the other tests are done with full standing mirrors. This is a mirror you can grab around with you. How could you possibly carrying around another rhesus monkey inside? Impossible. The physics rules out the alternative explanation for that.

So we think what's possibly going on here is that the ability to carry around with you your reflection rules out the competing interpretation in the other situations, giving themselves the information that seems to be needed to identify it as themselves. So what we have here is not only what seems to be absolute fascination with their own reflection, but pretty much the first demonstration of a naturally occurring evidence that the animals are interested in themselves in this particular way. And although we can't say with absolute certainty, what seems to be clear sex differences.

In this population, like in all monkey populations, males dominate females. There would be no problem for a male coming over and grabbing the mirror from her and taking it. Never have seen this happen. It's not that it's not possible for it to happen, but we did not see it.

So what I'd like to argue from this first part of my talk is the following, that if we're interested in understanding how certain kinds of capacities have evolved, which I certainly am and I hope some of you are, then what we need to do is to develop certain kinds of tools, certain kinds of experiments, certain kinds of observations that tell us what's going on. There have been, of course, infinite numbers of pop psychological books written on the mental lives of dogs, the mental lives of animals, speculating on what's going on.

And these speculations are interesting because they give us the groundwork upon which we can make more progress. But we have now a set of tools in our hands, such as these, where we can begin to explore in more detail what is actually going on. My conclusion from this part of the talk is the following, that these experiments seem to tell us that the animals do recognize themselves in the mirror. They leave wide open the question of what is going on in their head in terms of their own beliefs.

And it's with that claim that I want to turn to the second part of the talk, which is, what is going on in their heads and how can we find out? In Magritte's painting here, it's interesting, of course, because we know what's going on in the mirror. And he's sort of flipping the mirror image around. And we can understand it because we can form a representation in our own minds, in our own mind's eye, about what the reflection should look like.

The capacity that we have that I referred to in the beginning my talk, which was the capacity for mind reading, is an incredible tool. We can sit here and embed intentionality and embed beliefs at an extraordinary level. Little Charlie here can have a thought Z, and little Susie can have a thought about Charlie having a thought Z, and little Bill can have a thought about Susie having a thought about Charlie having a thought Z. And we can go on forever like that almost.

And this capacity allows us to navigate in the social world in a way which is extraordinary. And what's so interesting about this is it seems that certain parts of our brains are really responsible for this. And we know this from a number of different avenues, but one in particular which is so telling is something like autism, which is a complete breakdown, in many cases, of this capacity. Of this capacity to realize that others have minds and others have beliefs that are often very distinctive from our own.

What about non-human animals? And how can we find out? We don't have language. We can't ask them with language. So how can we tell?

Let they tell you about a very simple but elegant experiment that's been run on a large number of normal children, and also run on autistics, and then tell you about our version of this experiment that we run in our lab at Harvard with the cotton-top tamarins. It's a test which tries to ask whether an animal or whether a human animal can understand the notion of a false belief. This is critical, because when things happen that we don't witness, we have a belief that may be very, very different because of a transaction that happened in our absence.

Here is the experiment. A child watches a puppet show between two puppets, Sally and Ann. Sally in blue, Ann with the polka dots. And they're playing with a ball. And Sally puts the ball into the blue box and says, I'm going to go outside and get something. When I come back in, let's keep playing.

So she splits. While she's gone, Ann takes the ball out of the blue box and places in the green box. And now Sally comes back, and you ask the child, where will Sally look for the ball? Now, if you understand what's going on, you understand that Sally can't possibly know that it's been switched. Your prediction should be Sally's going to look in the blue box.

But if you think your world view is shared by everyone, your prediction will be that she's going to look in the green box. That's wrong. That means that you don't understand the notion of false beliefs.

Three-year-old children say that Sally will look in the green box. Four-year-olds say the blue box. Autistics say the green box. There's something going on here developmentally and neurologically.

But here is a fascinating twist in the story which gives us our in to this experimental procedure. You asked the three-year-old, where is Sally going to look for the ball? The three-year-old looks at the blue box and says the green box. The three-year-old seems to be predicting accurately with its eyes, but something goes wrong when language comes in.

The authors of this work, Clemmensen Perner, suggest that the reason why something goes wrong is because without language, they're making an implicit or covert representation of what's going on. But language forces them to entertain the two hypotheses for where Sally might go explicitly. They must make a concrete representation in their mind about what the alternatives are. And somehow, language is screwing things up.

Now, hold that sort of possibility in your mind for the moment. But now just think about this. The eyes are telling us something about what's going on in the child's head. And if that's true, then the eyes of an animal should be equally telling. Okay, so we used the eyes of our tamarins to tell us something about false belief. And we borrowed a technique which was developed within developmental psychology.

And the technique used a little bit of magic. And the idea is this. Why is magic so interesting to us? Magic is interesting, and special effects are interesting, because we're constantly being faced with violations of the way the world works. Physical principles are being violated. Bodies sawed in half, bodies levitating, people's faces being stretched all over the place. Whatever it is, it's a violation. It's interesting.

Now, infants don't necessarily come into the world with an understanding of that, but if they do, then they should be as surprised and should look as long at those violations when they're contrasted with things that are consistent in the world. That's the logic behind the experiment I'm going to tell you right now.

Here is our version of the Sally Ann experiment. An actor would come into a room while a tamarin was seated in that little transparent box. And an experimenter stood on one side of the table. The actor came in chewing some apple, placed the apple on the table and gave the tamarin some, shared some apple, and then placed the apple in one of the opaque boxes, let's say box number 2.

And then the actor in the first condition we tell you about leaves the room. Now, in this first condition, the boxes are transparent. You can see where the apple is. And now the actor comes back in. But before he does, the experimenter moves the apple from the box number 2 into box number 1.

Now, the actor should be thinking coming in, the apple was in Box 2, that's where I left it. But now he should search in Box 1 on the left because he can see it. So the violation in this situation is searching in Box 2 if the tamarins think the actor wants the apple.

But now we run the controls for this procedure in the next two situations. In the next one, now the boxes are opaque. And now when the actor leaves the room and the apple is moved, now looking in Box 1 is a violation, whereas looking in Box 2 is consistent.

And then the final control for this is that now the actor stays in the room with the opaque boxes and he witnesses the apple's movement from Box 2 to Box 1. Now you reverse again the expectation. Now, looking in Box 2 is bizarre. Looking in Box 1 is appropriate because he saw it move there.

So in each case, the actor's action is exactly the same. The only thing that differs is what the actor should or should not know. And all I'm going to show you now in the next slide, it's the last data slide, which is what the tamarins do in terms of how long they look.

And here's what we find. This is the amount of time they spent looking. These are the three conditions-- transparent box actor leaves, opaque box actor leaves, opaque box actor stays. No difference at all in the transparent box condition.

Now, for some of you, you may think of this as a failure. And it's possible that it is a failure. But another way of thinking about this is as follows. The tamarins love apples. Apples are fascinating. And they are particularly fascinating in this situation because the actor gives them some.

So certainly, reaching for the box where the apple now is and they can see it is interesting because it's likely that they're going to have some apple. But for some reason, they find it equally interesting when the actor searches in the box with nothing. And more importantly, in some cases, some animals, they would look at the actor opening this transparent box and then look back at the apple, desiringly perhaps, and then come back to the transparent box.

So this was equally interesting, but we couldn't pull apart the difference. Where we can pull apart the difference is in these two conditions. And this is critical, because it suggests the possibility that what the tamarins are doing is representing what the actor must believe.

Here, looking in the box where the apple now is is unexpected, because the actor can't know it's there. Here, looking in the box where the apple now isn't is bizarre, because they saw it moved. So the looking time of these animal seems to be telling us something, at some level, about what they know. And it suggests the possibility, a first possibility, that tamarins have some notion of a false belief.

What's unclear is whether it's the same kind of understanding that a three-year-old has, which is implicit, covert, they're not quite aware of what it is, or whether it really is a form of explicit knowledge. We just can't tell. But this is the beginning.

And this is an area of research which is extremely in its infancy. We know very, very little about what animals believe, what they know. So what I want to do is I'm going leave you at this point of the talk with a suggestion, a hint, that non-human primates may have some understanding of beliefs. They may have, in the words of Dave Premack, a theory of mind. They may have some capacity to mind read.

Let me now turn to the third part of the talk. Death is something that is on most people's minds at some point in time in their life. It takes on all sorts of different configurations and properties in terms of what people believe about death. Whether you believe in the afterlife. Whether you believe that certain things should be done Following on the death of somebody.

In Uganda, for example, a place that I work, when somebody dies, there's a three-day ceremony. The first day is a day of mourning. People come from all over-- relatives, friends-- to the ceremony. It's a full day of mourning.

And then after that, it's two full days of parties. And the reason why, in part, there's this change from morning to partying, is because many of the people that have come to the funeral they haven't seen for a long time. In fact, they may not see them for a very, very long time after everybody leaves.

So they both want to think about the person who's just died, but they also want to enjoy the people who've come. So beliefs change all over the place depending upon people's cultural values, depending upon one's beliefs, and so forth. And this is very flexible.

But what people can agree upon at some level is that when somebody dies, there are certain things that happen that are very different from when someone was alive. Do animals have any understanding of this? Would they be able to make a distinction between somebody in a trance, like this who, in some senses, lacked the key vital signs, and someone who truly is dead?

If I'm walking down the street and I see one of you and I say hi, we're good friends, and so if I say hi, and then five minutes later I find you flat out on the floor, check your breathing, don't detect anything. You're not really breathing at all. I can't smell anything form your nose.

Call the ambulance, they say sorry, she's dead. I'm terribly sorry. Then five minutes later I see you in the street again, I'm going to go, whew, wait a minute. I say, I though before you were just like dead. And say, well, no, I'm actually not. So I'm fine.

And then a few minutes later I find you, again, laid out. Now, my second encounter, I'm not going to trust what I thought the first time. And I think, this person is just, something's happening here.

And my beliefs are going to change. And they're going to change in important ways. And they're going to change in important ways because our conceptual apparatus is built in such a way that we can take on new experience and modify what we believe.

Let me give you a complete opposite situation. Ed Wilson at Harvard, who many of you, I think, have come to know through his work on sociobiology, but is also one of the world's experts in the study of ants. And Ed Wilson discovered something very important a long time ago, in the '70s, that when ants die they are dragged out of their colony. And what he wanted to know is, well, what is the mechanism by which they recognize dead ants from living ants?

Well, it turns out that when an ant dies, it emits a chemical called oleic acid. And if you take oleic acid and you put it on a live ant, they are dragged out of the colony kicking and screaming. For an ant, therefore, dead equals oleic acid. It's very simple. It's a lock and key system. It can't be modified.

They don't seem to learn at all from this kind of experience, or from the person ahead of him saying, excuse me, I'm still alive. That's a different kind of concept of death [INAUDIBLE] what we have, even though we can have hopes of people coming back, even though we can think that there may be all sorts of things that will change. Let me tell you now about a couple more cases of animals responding to death, which will now build a picture which is, perhaps, a little more complicated than we see in ants.

Now here, is this a recognition of death? Monkey hear no evil, see no evil, speak no evil. Clearly recognizing something's going on that's difference, something that's wrong. Animals certainly age. On the island of Cayo Santiago, we have many, many old animals that change, that become lethargic, arthritic, lose a lot of their sensibilities. Presumably they're coming to the end of their lives.

Is there a change in the way they think about their current lives? Do they reflect upon their past? Do they wonder what it would be like not to be around anymore?

In elephants, there are stories, some of them true, about what elephants do when another individual has died. This is a slide taken from an animal, a young individual, that I took when I was living in Kenya, who was not going to make it. In fact, the infant died at the end of this day.

This is a slide of its mother trying to basically pick it up and move it so it will walk. It was this sort of get up, stumble down, and fall over. And the mother, with its trunk, and as you can see here was like, would sort of kick it and try to get it to go. And it wouldn't work. And eventually, the infant died.

And what's been reported in the literature over and over again is that elephants will come back to the dead individual over and over again. In fact, will come back to their dead bones, their bones, pick up the bones in their trunks, manipulate them, come back, sit very solemnly, very quietly, and looking at the pile of bones. What is going on in their heads?

We can invent all sorts of stories, but it's really not clear what is going on in their heads. And if you're interested in what's going on in their heads, then we take these observations much further. Let me tell you one example of this.

These are the vervet monkeys that I was studying in Kenya. The vervets-- this doesn't seem to focus at all, so sorry about that. Any case, the vervet monkeys are a small, [INAUDIBLE] monkey, closely related to the rhesus monkeys.

And in this population, the following experiment was done to see whether mothers could recognize the voices of their infants. They played back a vocalization that infants give when they're distressed and separated from their mothers. And they played back this call through a speaker to a mother and two adult females.

And when the call was played back, the mother looked to the speaker and the two females looked to the mother, suggesting the possibility that the females understand the relationship, that that is that mother's kid. What is she going to do about it?

The point I'm making here that I want to anchor is that the infant's call has a kind of a signature. Well, during the two years that I was in Amboseli working on these vervet monkeys, seven infants died whose vocalization, that particular vocalization, I recorded before their death. And I played it back to mothers 24 hours to 48 hours after the infant's death.

Now, for some of you probably think, god, what a bastard. What a terrible experiment to do. But think about it. Think of the assumptions you've just made in criticizing me. See, I preempted it already.

We don't know what they think. Here is the result. Seven females, play back their call. Nobody responds. Zippo. Nothing. Nothing was going on at the time I played the call back. The females were all resting, sitting peacefully, quietly, eating in a tree.

Call went off. Not even a detectable flinch. Now, what's the mechanism here? Is it out of sight, out of mind? Possibly. This is 24 hours later. In the life of a vervet infant, infants are never away from their mothers for more than about two hours.

So 24 hours, it's gone. And predation in this population is massive. 70% of the kids never make it to their first birthdays. So it's very likely that a mechanism would have evolved in this species for out of sight is out of mind.

So maybe we're a little bit closer. At least we've got one possible mechanism going on that would make them respond to death in certain kinds of ways. But maybe it's no different than what the ant does. What would happen if we brought the infant back and then played the trick again, like in our discussion of walking through town and seeing somebody who was passed twice in a row. Would they change their minds? We don't know.

But now let me show you another videotape from a species where there's a little bit more compelling, possibly, evidence. It's in part because it's a documentary and has music behind it, but I want you just to watch the response of this female chimpanzee.

[VIDEO PLAYBACK]

- --what this female called [INAUDIBLE] understands about her own tragedy. Her infant is mortally ill. Since her baby's too feeble to cling to her, she resorts to carrying it with her foot as she climbs in search of the food she needs to survive.

[MUSIC PLAYING]

Still the baby clings to life.

- How do we really realize that somebody's dead? How would we realize if we didn't have all the science and other things? So I think while they certainly know that something special is happening, that they would like to fight against it, but that they can't. And they realize it after a while.

- Finally, the emaciated form of her infant lies deathly still. Then with a gesture so human it's painful to watch, she seems to bid her baby farewell with a kiss.

[MUSIC PLAYING]

If chimps share with us the--

[END PLAYBACK]

HAUSER: I probably should be handing out handkerchiefs or something, probably. So the point I like to make here in this juncture of the talk is that we have these fascinating observations, these observations that are so compelling to us, but they're compelling to us to a large extent because we are unavoidably empathetic creatures. We can't turn it off.

We see somebody that even looks close to what it means to be human and we immediately jump to the conclusion that it must be feeling or experiencing the kinds of things that we do. And it may be true that what the chimpanzee is feeling at the moment when it experiences its own dead child, that the experience is very much like what we experience. And certainly, given the close evolutionary proximity between humans and chimpanzees, it seems like a reasonable interpretation. But the problem is that behavior can often be a very misleading guide to what's going on in the heart and what's going on in the head.

So what I would like to do now is turn to the last part of the talk and talk for a moment about emotions, and talk about emotions as being the central core to our thinking about morality and its evolution. Let's take something that is a very late developing emotion in the child, embarrassment. Embarrassment is a critical emotion if you are going to be a moral creature, because it suggests the possibility that if you feel embarrassed, you have some feeling of guilt that you've done something wrong, or that you're embarrassed by your action.

It wasn't quite appropriate. It wasn't quite right. We see cross-culturally that the expression of embarrassment comes in very similar forms. There's a covering up of the face. There's a hiding, deflecting the eyes, and so forth.

Do animals show embarrassment? And how do we know? Is this rat embarrassed?

[LAUGHTER]

Now, we don't think of the rat as embarrassed, but how would we find out? Behavior could be very, very misleading. Let's take somebody that looks a little bit more like what we do. When chimpanzees are attacked, and when other non-human primates are attacked, they often scream.

They scream very loud. They retract their faces. They retract their lips. And they show what we call a fear grimace. It's a very characteristic sign. It's very dramatic and exaggerated.

But what happens in some primate species, and in not very many non-primate species, is that following a fight, animals reconcile. They make up for what's going on. They make up in very interesting and very human-like ways.

This is that same individual here who now comes over to the dominant who just pummeled it and offers its hand to its mouth as a gesture. And this is a sign of trust. I could bite you, but I'm not going to. The fight's over, let's get back to business.

Males will come over, who have just been beaten, a low ranking male will come over to the higher ranking animal and offer their testicles to the male, who will hold onto them, gently.

[LAUGHTER]

This is trust, as the word comes from, test-a-ment. That This is trust. And it's done to keep levels of aggression down. It is a mechanism that keeps peace within a society. And we see it in spades within the chimpanzees. We see it in lesser degrees within other non-human species.

So these are the kinds of things, these are the kinds of emotion and kinds of ways of dealing with emotion that would seem to be at the root of our moral status. Without these kinds of emotions, it seems impossible to evolve a moral society.

Now, what I want to show you is the last clip, and then the last bit of discussion, is a fantastic case recently that many of you I'm sure have heard about but you probably haven't seen the footage from. And it's a fascinating case of a boy who fell into a gorilla enclosure at the Chicago Zoo. And it's the response that the female gorilla shown here, Binti, did when it discovered this young boy. This was taken by a person who was just at the zoo.

[VIDEO PLAYBACK]

- Chicago's Brookfield Zoo. A three-year-old boy fall into the gorillas' enclosure, knocking himself unconscious. Amazingly, a female gorilla gently picks up the injured child, cradles him, and brings him to the cage door.

- And here we see Binti [INAUDIBLE] the boy was unconscious when she picked him up. She transported him very gently from the [INAUDIBLE] to an area where people could get access to the boy. And so she was considered rescuing that child [INAUDIBLE]. And the boy survived afterwards.

- She's carrying the boy to where humans could reach him quickly. Binti also prevented the other six gorillas from hurting the child. But did she really intend to save him, or did she pick him up because he was a curious new object? And it's the subject of much debate.