Note: Where available, the PDF/Word icon below is provided to view the complete and fully formatted document
Disclaimer: The Parliamentary Library does not warrant or accept liability for the accuracy or usefulness of the transcripts. These are copied directly from the broadcaster's website.
Soul Dust: Big brains, consciousness, and lon -

View in ParlViewView other Segments

HideRobyn Williams: Let's start with Soul Dust, the title of the book by that aristocrat of consciousness in Cambridge, Nick Humphrey, who even thinks he knows why our brains are so big when they needn't be. But why 'soul dust'?

Nicholas Humphrey: What I'm saying is that out of the dust of physical matter we've created some extraordinary phenomenon within each of our own heads, and that's our own experience of consciousness. But it is that experience of consciousness which feeds into the cultural concept of the soul. Almost every culture believes deeply in the human soul, and I think that that's a direct consequence of the way nature has set up our minds to experience ourselves and the world around us.

Robyn Williams: How do you actually bridge that between the way we've got a cultural conception of soul and awareness and what science actually comes up with?

Nicholas Humphrey: Well, science is beginning to come up with an account of what it's like to be a human being living in the presence of one's own consciousness. I begin in my book with the simple experience of waking up to the sounds and sights and the smells that we are all so familiar with, and as we regain consciousness our mind becomes full, it's like a lake of sensation. Of course it's a very magical phenomenon. It's been very hard for physics and chemistry or computing science for that matter to have even begun to suggest what kind of experience this is, and I think it's because it is in fact a contrived illusion.

Nature has been very cunning in the way in which it has set up our minds, it has given us the impression that we are living outside of ordinary time and space and physics. And of course physical science does find it very hard to account for the illusion of a non-physical experience, to create just that kind of much more deeper, more magical impression that we are living in a kind of time outside of time, a space outside of space, experiencing qualities which couldn't conceivably be conjured up out of physical matter.

Robyn Williams: But science can actually use drugs to give us completely different experiences, and it can also show how the brain being damaged behaves in a clear and obvious and dramatically different way.

Nicholas Humphrey: First on the question of drugs, I agree and have experienced that you can have the quality of your sensory consciousness changed by drugs, but let's not underestimate the extent to which we are all, in a way, on drugs all the time. It's not as if being high on cannabis, for example, completely gives you a new experience. It can just enlarge and make it even grander the experience that you have. And I think it's true that there are huge individual differences in this. A lot of people are there already when they go out and walk in the fields or the mountains or whatever it is, they are already on a high.

So let's not imagine that you have to have drugs in order to have these magical experiences, I think we all have them all the time, unless actually we are in a very poor condition, under deep depression and so on when what I call the thick moment of consciousness begins to shrink almost to the instant of physical time, and that's a terrible state to be in. But of course we are mostly on a high from the moment we wake up.

Yes, brain damage can create changes in the way the mind works and the way in which people experience our self and so on, it can. So far though there is very little in the way of brain damage which can abolish sensory consciousness. You don't find (except in one case I'll mention in a moment) that a lesion in the brain can abolish this sense of living in the present moment of sensation. But there is one, and it's one which I've worked on myself many years ago back in the 1960s, I studied the effect of brain lesions at the back of the brain in Rhesus monkeys, and the lesion had cut out the so-called primary visual cortex. An operation had been done by my supervisor in Cambridge, Larry Weiskrantz, and I was a humble research student, but I had access to his monkeys and I took advantage of that to try to coax out of them something about their experience which nobody had even imagined before.

These monkeys that appeared to be blind, it's what you'd expect after you take out the primary visual cortex. I demonstrated that they weren't blind, drawing them out in ways no one had tried to before. I showed that in one particular monkey I worked with for seven years, she actually had almost complete physical capacity, she could run around a room picking up peanuts, she could catch flies, climb trees and hold my hand and walk with me through the park and so on. But there was something very strange about her vision, and what it was I guessed at but we didn't prove until Weiskrantz went on to use some of the same tests and techniques I'd used with human patients.

She had what we now call 'blind sight'. That's vision without sensation, and to the human patient and I imagine to the monkey herself, it's a very strange and almost alarming way of experiencing the world. Patients will say they're blind, they believe they are blind but if you say, 'Yes, of course I know what it must be likely you, but supposing you weren't blind, just imagine that you could see and, for example, now can you see this pencil which I'm holding up in front of you, could you reach out and touch it?' And sometimes the patient will say, 'No Doctor, you're kidding me, stop teasing me like that,' but if you can persuade the patient he (they are almost all men, by the way) will say, 'Okay, I'm going to try,' and will reach out and touch the pencil directly. You can say, 'What orientation is it?' And they'll say whether it's horizontal or vertical. You can ask them what colour it might be, and he said, 'Well, I'm only guessing but I suppose it might be red.'

This is an astonishing phenomenon; vision without sensation. And to come back to your original question about whether brain lesions have shown us something about primary consciousness, I think this is the only example we have of that yet.

Robyn Williams: Isn't that interesting, because you describe a couple of things to do with animal brains there that would remind us...there's some people, for instance Susan Greenfield, who have suggested that consciousness is something that has evolved, that you have degrees of consciousness going up through the different species. Would you accept that as a description or would you say that the magic in humans is of a different scale altogether?

Nicholas Humphrey: Well, of course consciousness has evolved. It's obviously a designed aspect of the human brain, and design doesn't exist without natural selection having got to work to produce it, and that means of course it must have been an advantage to our ancestors who first developed consciousness. How far it goes back we don't know at the moment, we don't have the right tests. My guess is that it began to emerge with the mammalian brain, but maybe birds, I'm not sure, let's put it back at least to vertebrates.

Whether it has changed in quality since the early days, whether a mouse has similar consciousness to us, my hunch is the answer is yes because, and in particular, that it has changed with the advent of human beings. I think humans now use consciousness, they enjoy it, they make of consciousness something which our animal ancestors never did. And that has almost certainly meant because we are connoisseurs of consciousness in a way our animal ancestors weren't, it means that natural selection has had reason to make consciousness even more magical, even more mysterious, even more a gift from the gods than it ever would have been for animals who wouldn't have had the uses for consciousness that we all do today.

Robyn Williams: How much are you impressed by the new research that has gone on, for instance in Oxford on birds, you mentioned birds before, Betty the Crow, the toolmaking, the planning, the insight, the intention. And the other day I saw the bonobo Kanzi who was sitting there making tools that seemed to be almost the same as our forebears did in ancient Stone Age times, using them in the predictable way. I mean, that's pretty impressive stuff.

Nicholas Humphrey: Robyn, be careful, I don't think brain power, intelligence, cleverness is equal to consciousness. I think we must distinguish that the possibility of artificial intelligence which could do many of the things which we prize as aspects of human intelligence without involving sensory consciousness of the kind we ourselves possess…of course amazed by the new discoveries, particularly with birds. I don't just say Oxford, in fact some of the best work has gone on here, Nicky Clayton's group here in Cambridge. Birds seem to be...Nicky has called them feathered chimpanzees, and they have astonishing mental powers given that they have 1 cc of a brain compared with the 400 cc of a chimp or the 1,500 cc of ourselves. The bird brains are clearly wired up in a very different way from human or mammalian brains, but they've been wired to certainly achieve some of the intellectual feats which we thought were only possible with the big mammalian brain.

Whether they are conscious in the way we are, I'm not sure. I want to reserve judgement on that. Some of the evidence we have of birds playing, revelling in what looks like just revelling in the present moment of rich sensation, is very suggestive. There's a wonderful piece mentioned rooks, there's a piece on YouTube of a rook playing a game with a tin lid which it draws up to the top of a snowy roof, sits on, slides down with a huge grin on its face, if a bird can grin. It turns around, goes up to the top and does it again and again. That's the kind of evidence which does impress me about the possibility of sensory consciousness in birds. In humans, what consciousness does, it gives us joy in living which we wouldn't otherwise have. If it exists in other animals, and especially in other non-mammalian animals, that's the kind of evidence I would look for.

Robyn Williams: Yes, having fun, of course. Well, when you look at the way the mammalian brain has got bigger and our own size, which is an order of...well, a couple of orders of magnitude larger, that's one hell of a commitment physiologically, something like a fifth or more of the energy that we consume, and making that investment implies that our ancestors' bodies kind of knew where they were going, because making that commitment on the hope that it might come off is a hell of a risk.

Nicholas Humphrey: The human brain is much too big, it is a very surprising and paradoxical phenomenon. I say it is much too big because we know that human beings can actually do almost everything we would expect of a human being with a brain half the size, in other words the size of our Homo erectus ancestors two million years ago. We know that because it has been found post-mortem after death that humans who have not failed in any department of life—they've been married, they've been to university, they've had PhDs, they've been socially successful—at death it has been discovered they only had one hemisphere. Human beings can get by with only half the brain size that we have. And, as you've said, that's very odd because the brain is a very expensive organ to maintain.

It has been argued, particularly by Robin Dunbar, that we need all this extra brain in order to manage our social relationships. I just don't buy into that. I think we can manage social fact we evidently can with a much smaller brain, albeit perhaps a larger one than a chimpanzee. So what's going on, why has the human brain doubled in size?

Well, if you want to know my thought about it, I think it allows us to live longer. In fact we know it allows us to live longer. If you look at the incidence of Alzheimer's and early stroke, for example, in humans, it directly correlates with brain size. If you have a brain in the bottom quarter range of human brain size, you have five times the chance of developing Alzheimer's disease. Why would it matter to protect us from Alzheimer's and early death from strokes and so on? It matters because we're humans and grandparents have become essential to human culture and to human child rearing.

About...we can only begin to guess, let's say half a million years ago, it became a real advantage to have older members of the community still alive, still contributing their skills and their knowledge and so on, and to do that they had to have something which would prevent them from dying at the age of 40 from brain disease. The brain doubled in size in order I think to give it reserve capacity, and it has now become actually a very interesting area of research, the reserve capacity of the brain and how it protects us from Alzheimer's disease. But I think that indeed it was exactly that role which the very large and expensive brain began to perform for our ancestors half a million years ago.

Robyn Williams: Because our children are so vulnerable for so long and, as we know these days in modern times, having a nuclear family is kind of not sufficient with all the commitment you need to bring up babe, all those years, decades even. But a final question, what kind of research can be done by science to tease out this nature of consciousness? What would you look for as evidence?

Nicholas Humphrey: I have argued that actually it is not in the lab that we are going to find the answer, that what we need is a new kind of natural history of consciousness. We need in fact to just look around us at the world we live in and see what kind of difference consciousness, and I mean sensory consciousness, the magical but spiritual experience which we all take for granted of what it is like to be ourselves, let's see what difference that is making to the way in which we relate to each other, we relate to the world. Just imagine that human beings were zombies without that kind of consciousness, if it were true, how would that be affecting the kinds of ways in which we live out there in nature and out there in our communities. And it's through that, through getting direct evidence from anthropology and sociology of the role of let's call it the human soul in our lives that we begin to get evidence that nature has done an amazing job in providing us with the brain mechanisms which trick us into believing in the human soul.

Robyn Williams: Soul dust. The mesmerising Nick Humphrey. Read about it in his book, called Soul Dust. Professor Nicholas Humphrey in Cambridge is linked to Maynard Keynes, the Waddingtons, and Susannah York, the late film star.