David J Linden – The Accidental Mind

February 06, 2009

David J. Linden, Ph.D., is a Professor in the Department of Neuroscience at the Johns Hopkins University School of Medicine. His laboratory has worked for many years on the cellular substrates of memory storage in the brain, among other topics. He has a longstanding interest in scientific communication and serves as the Chief Editor of the Journal of Neurophysiology.

In this broad discussion with D.J. Grothe, David Linden challenges widespread beliefs about the brain, such as that people only use ten percent of it and that it is amazingly designed, arguing instead that the brain is “accidental.” He talks about why, as a brain scientist, he writes about topics such as love, God and sexual orientation. He describes the downsides of how the brain has evolved by including systems from previous brain “models,” and how this has given rise to those qualities that most profoundly shape our human experience. He discusses the neuron, and how it is a “lousy processor of information,” describing how evolution has nonetheless used it to build “clever us.” He talks about how our brains have constrained us, and may have physically led to the necessity of marriage, family and long childhoods. He surveys various claims regarding the enhancement of our cognitive capacities, such as playing Mozart to babies in utero, vitamins, smart drugs, mental exercises, and physical exercise. He talks about the brain science of homosexuality. And he argues that the brain has evolved to make everyone a “believer,” describing the similarities between belief in science and in religion, that both are similar “branches of the same cognitive stream.”

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This is point of inquiry for Friday, February 6th, 2009. 

Welcome to Point of Inquiry, I’m DJ Grothe growthy point of inquiries, the radio show and the podcast of the Center for Inquiry, a think tank advancing reason, science and secular values in public affairs and at the grass roots. My guest this week is David J. Linden, professor of neuroscience at the Johns Hopkins School of Medicine. He’s the author of The Accidental Mind How Brain Evolution Has Given US Love, Memory, Dreams and God. Professor David Linden, welcome to Point of Inquiry. 

Thanks for having me. 

Professor, your books on the Brain. It’s a topic that inspires lots of folks. You hear people almost preach about how amazing the brain is, how it’s fearfully and wonderfully made. We’re told that it’s so amazing. It’s it’s like engineered and we’re never even really tapping into all of its power. You know, maybe we only use 10 percent of it or something in this book. You take issue with all that stuff. 

I certainly do. I think what is amazing about the brain is that our consciousness can reside in this lump of tissue. And the fact that the mind is in the brain is indeed terrific and and cause for for a lot of excitement. But it doesn’t follow from that that the brain is necessarily well engineered. People imagined that it was designed all at once by a genius inventor on a blank sheet of paper and that it is this impeccable engineering job. And when you lift the hood and look, you find that that isn’t true at all. Mm hmm. 

One thing about your book, I want to talk more about the design of the brain in a bit, but your book isn’t just about that. It’s not just explaining what the brain does. Right. You talk about stuff that some folks argue. Science should stay out of view, touch on God and love and and things that you don’t imagine. Scientists are measuring in labs with their test tubes and beakers and stuff. Why do you focus on these issues? As a neuroscientists and not just on neurons and synapses and how our brain maybe evolved or something? 

Well, I think these things are intertwined. I think if we want to understand those things that are most central to our humanity. And you mentioned a number of them, love and memory and dreams and human predisposition for religious feeling. Really explaining that requires considering brain function and brain evolution because it’s only in light of brain function and brain evolution that these phenomena make any sense. 

Mm hmm. So the title of your book, The Accidental Mind, you kind of touched on this minute ago. But I’d like you to put a finer point on it, if you don’t mind. You’re suggesting that our minds, since they are accidental, they evolved. They were kind of cobbled together from previous models that they certainly aren’t on purpose. They’re on accidents. The title of your book suggests that you don’t see intelligent design in the development of the brain. Here it is, the most complex thing that scientists say we could study in the universe. And you don’t see any purpose there? 

Well, I wouldn’t want to say that I see no purpose. There is purpose that can be driven evolutionarily, but that purpose is just evolution, sole purpose to pass our genes along to the next generation. 

So not grand design, right? 

I don’t see anything beyond that. When I look at the brain, I see something that has taken a very particular historical turn. In other words, there have been some choices, evolutionary choices that have been made hundreds of millions of years ago that have locked the brain into certain routes of development and that have forced certain subsequent evolutionary pathways. 

And it’s not like at any point in evolution, you just wipe the slate clean and start over with the new design. It’s sort of like if if someone said to you, OK, I’ve got a great project for you, you’re going to design the latest new car. 

And then after you sign on the dotted line, they say, well, actually, we didn’t tell you everything. We’re gonna give you a Model T Ford. And in making the best new car, the only thing you can do is add things to it. You can’t take anything away. And that’s more or less how the brain has proceeded. It is evolved in an unglamorous to manner, meaning it’s never been totally redesigned. 

And when we add new functions, as the brand evolves, we just put new stuff on top of the old right. 

You use the metaphore of an ice cream cone kind of building an ice cream cone to argue that the design is inelegant. It’s all been kind of clumsily put together. 

Well, very much so. So, for example, in our brain, we have two visual systems and two auditory system. We have an evolutionarily ancient one that we share with, for example, lizards and fish, and then we have an evolutionarily modern one that has come along in the mammalian lineage. And these two things operate side by side. It’s as if your iPod had to have a eight track tape player attached to it at all times. 

So our brains were built by evolution from these older parts, kind of from previous species. This is where we get our, you know, fight or flight reflexes. You know, people talk about the reptilian brain. But the point remains that that’s not all we’re left with. We have the front part of our brain, the top part of our brain, the top of the ice cream cone, so to speak. And it gives us this capacity to have love. And you talk about, you know, maybe this where belief stems from. Is that where all of it comes from? That kind of reduces all this great human stuff to just brain you sloshing around in our noggins? 

Well, I would say it’s not so much that it all can be reduced to that, but I would say there are certain cross cultural universals. I mean, things like love get socio culturally elaborative and all kinds of different ways. You go around and look at different individuals and different cultures around the world. But there are some things that are common. And I guess what I would say is that I would start from the very, very beginning. And it goes something like this. The basic component of our brain is the nerve cell. The neuron and the nerve cell is a very lousy processor of information. It’s slow, it’s unreliable, at least signals to its neighbor. 

Right. If the brain were designed, you’d fired the designer because the neurons are not very elegant. 

The neuron is terrible. And then so you have the problem. Well, how do you build clever us out of such crummy parts? And the answer is that in order to build clever us out of such crummy parts, you need to use an enormous number of neurons and have them very massively interconnected. So you may have heard some of these famous numbers where there are something on the order of a half a trillion connections in the brain, and that’s a synapse. 

You know, neurons connecting dots, right? 

That’s a synapse, which is the name for a place where neurons send chemical messages to other neurons. 

But the only way this inelegant neuron can do its job is if it’s three dimensional. It’s this glop of stuff in our cranium and it’s connected in three dimensions and all over the place. And that’s what gives this inelegant thing in Iran, the capacity to give us consciousness and love and belief and all that stuff. 

Well, I think in some way it’s what gives us. And in some ways, we’ve been constrained in these things through odd bits of history. So if we want to build clever us, we need a big fat brain. So our brain, our human brain in the adult stages of that. Twelve hundred cubic centimeters, which is about threefold larger than an adult chimpanzee brain. Now, a newborn’s brain is also. Is about a newborn human is about the size of an adult chimpanzee. And so you’ve got this big problem, right? You’ve got this big fat brain that barely fits through the birth canal of the human body. As it is, humans are the only species that where there’s death during childbirth. Actually, with the exception of hyenas, which give birth to a pseudo phallus. But if you discount that odd situation, they’re the only species. 

And that’s because of the big brain. 

And that’s because of the big brain. But even that brain isn’t big enough that for 400 brain. 

And so what you have to have you have to have that brain growing massively from birth. It grows at an enormous rate up until age five and then at a much slower rate, up until about age 20. And the brain isn’t mature until about age 20. And what this means is that humans, because of this very long period of brain maturation, have the longest childhoods by far of any animal. And having that long childhood means that unlike almost any other any animal, females have a difficult time raising their offspring by themselves. They really need male help in a way that an orangutan female does not, or a chimpanzee or a bamboo female does not. And as a result, they have mating systems where the male scampers off, doesn’t recognize its offspring, doesn’t contribute to raising. And we have marriage of a dominant cross cultural institution everywhere. Every culture you go to around the globe has heterosexual marriage. I mean, they have a bunch of other things, too. But I would claim that ultimately heterosexual marriage. This this, you know, our. 

Love, if you will, derive ultimately from the fact that neurons are chromate process. 

You’re drawing a direct line from the evolution of the brain. And what it makes necessary for kind of raising offspring. So pair bonding is a function of our big craniums in more ways than one. 

Right. We wouldn’t need to have our very particular mating system, which is extremely odd. And the mammalian world. I mean, most mammalian species don’t form lefton pair of bombs. Most of them don’t mate throughout the females modulatory cycle. They have. We have a very a typical and unusual mating system. And it’s driven by the fact that we have these absurdly long childhoods, derived from the fact that we need to grow these very large rabbits. 

I want to switch gears a bit and talk about a few things that you’re skeptical of in the book. Not only like we spoke initially regarding these celebrations of the brain and you know how amazing it is. You’re skeptical of that. You explained why. But I want to ask if you’re skeptical of some other neurologist’s claims, maybe pop psychology. Brain scientists then argue not only can different parts of the brain be mapped for different kinds of functions or maybe even different behaviors like the basal ganglia might be involved in, you know, obsessive compulsive stuff or that side or smelling starts in the cortex. But some of these guys go further. And I want your take. They say that with certain diets or mental exercises or playing brain age on my B.S. light, that it can actually change brain anatomy to improve these functions. Do you buy all that? 

Well, a little, yes. A little no. So if we step back a bit and we ask the more general question, is it true that our experience in the world can change the very fine scale anatomy of our brain that can kind of make certain connections between neurons? These synapses you mentioned earlier are weaker and stronger and thereby encode information in our brain? The answer is yes, absolutely. That’s how we store memories in our brain. That’s the way our experience can mold our brain. 

And we know that stress hormones can change the brain physically or that is absolutely true. 

Stress hormones can. Sex hormones can. The obligatory cycle changes the brain physically. All of these things can happen. Exercise. 

Physical exercise can have enormous effects on the fine structure of the brain as well. 

Vitamins, blueberries, stuff like that. 

Well, vitamins. Probably not there. I would start to get a little skeptical. 

Generally speaking, most of the work on vitamins unhealth and vitamins on brain function have shown that if you have a basically healthy diet, if you’re living in an affluent society and not just eating crap all the time, you’re getting all the nutrients you need. And the indications are that vitamin pills, you know, are a scam. They don’t do anything for you at all. And I don’t see any indication that they do anything for your brain either. Now, that said, I think there are actually very good indications that there are some things that can improve brain function. One of them is eating a heart healthy diet. So if you have a healthy cardiovascular system, that means that you have better function in delivering blood to your brain and particularly as you age. It seems that people who eat heart healthy diets age more successfully have less loss of cognitive power, less senile dementia. Mm hmm. It also seems like staff drugs that people take to slow deposition of fatty deposits in the cardiovascular system also have benefit for the agent brand as well. 

And exercise has an enormous benefit. Physical exercise has an enormous benefit. But some of the things that I don’t think work are, for example, Mozart seeds to be played to your newborn or to be played in utero. 

This is the claim that parents can create enriched environments to aid their children’s brain development. You know, like playing music in utero, as you mentioned, did it actually rewires the brain can make your kids smarter. 

I think that’s the really hasn’t been supported by the science at all. I think if you look at the extreme, if you say, all right, well, let’s say if you if you take a newborn and sensory deprived it, then, yeah, you can impair you can impair activity dependent brain development. And one of the interesting things is that in utero and then following them, that first five years of life, the brain develops not just according to a genetic program, but it’s guided by. Variance and so experience is crucially important. But if you live in kind of a normal situation where you’re having, you know, a lot of experiences, you don’t have a deficit. It’s not like your brain is going to develop better. If you’re being bombarded with expensive, mopey old and poise and Mozart citizen does, if you’re just kind of a regular kid in a regular place, you know, playing and interacting and doing what kids do or when the trial’s older playing one of the, you know, like brain age or something that purports to raise your IQ through mental exercises. Well, I mean, the thing is, IQ is a funny thing. Right. People say, well, you can’t study to improve on an IQ test. Well, that’s wrong. Right. So there are certain classes. There are certain classes of tasks you can improve on in that way through practice. And there are some indications that certain kinds of computer software can produce very small effects and things like improving reaction time among the elderly and improving cognitive capacity. But those effects are very, very small, and they pale in comparison to the effects of, say, doing a Robak exercise for 45 minutes a day. That effect on your cognitive capacity when you’re 60 years old is much larger than the effect of buying the software that’s offered by a number of these companies for this purpose. That great expense. 

I didn’t invite you on the show to talk about improving cognitive capacity and all that. But just one more question on that point. What do you think about the smart drugs? It’s maybe it’s fringe science. I would hesitate to call it pseudoscience, but it’s on the borderlands of science. The arguments coming out of psychopharmacology that, you know, certain drugs can increase your cognitive performance. And I’m not just talking about the amphetamine type drugs, you know, but drugs that give you better memory, you know, just like steroids for the brain. 

There’s no question that the amphetamine type drugs can improve people’s focus and they can improve your function in a lot of ways. They work. So it’s not you don’t have to have a have ADHD to benefit from Ritalin. Everybody does better on Ritalin. 

Everybody does better on Adderall. It helps you to focus. It doesn’t improve your memory. It doesn’t improve your cognitive function, per say. But it does help you to focus on the task at hand. And in that sense, it is a cognitive enhancer. But in terms of drugs that actually improve, for example, the storage of memory as opposed to just one’s ability to focus. There’s been a lot of efforts on this, both in sort of the fringe, in people offering, you know, herbal drink some, you know, smart cocktails, which, you know, are mostly non sounds. And some biotech startup company is there’s a place called Memory Pharmaceuticals, for example. But basically very, very little has come out of that to date. I’m willing to believe that it is possible to develop drugs that actually directly improve memory function. But so far, there’s very little there. 

I was interested that in this book I mentioned it’s breath. You touch a little on sexual orientation. You argue that being gay is due at least somewhat to what’s going on physically in the brain. 

Well, I would say I would step back a bit and say, you know, for a lot of complex human behaviors, whether it’s something like a general intelligence or sexual orientation or even childhood, China, when you do analysis of family and you look at the heritability and you look at adopted twins studies, which are sort of the gold standard for this, what you find is that for all of these things, there is a genetic component and there is a non genetic component. And that in the mom’s genetic component, there are socio cultural aspects. And then there are biological factors that are not genetic. An example of one of those would be, for example, if your mother has the flu while she’s pregnant with you, your chance of becoming schizophrenic is about five times higher than it is otherwise. That’s not something genetic, but it is biological. So to get to sexual orientation, if you just look at the genetics to start with and you say, well, if you look at the siblings of straight folks and gay folks and look out the probability of being straight or gay as a consequence of this, it’s totally clear that there is a degree of heritability to sexual orientation. And so if you look at twin three. 

Sample monozygotic, so-called identical twins have a much higher incidence of coordinated sexual orientation than do fraternal twins. 

Even if they have been raised within the same family. So the evidence for some degree of genetic basis for sexual orientation is very strong. Now, what that will turn out to be and putting a number to it. I would say is unclear. Maybe it’s going to turn out to be 25 percent. Maybe it’s going to turn out to be 80 percent. And we don’t yet know and we don’t yet actually have particular genes that are associated with sexual orientation. Now, to move on to the brain. We know that there are certain structural features of the brain, particularly regions of a very low brain structure called the hypothalamus. 

Right. Levey’s work years ago or something. There’s a difference in the hypothalamus between men and women, maybe between gay men and straight. Right. 

Basically, what Levey claims was that this particular little bit of the hypothalamus. That’s difference between men and women, that gay men have that region that have a size that looks more like straight women. Mm hmm. And this work has been replicated now. And there are a number of other regions of the brain where there has also been found, both sexually dimorphic, brain structures and also differences with sexual orientation. I think the thing to realize that it’s very early days on this. In other words, what people are looking at now is the growth structure, like the five little whole clump of cells in the brain. And that can tell you some things. But a lot of what’s going on in neurons are very fine, microscopic things or biochemical things. In other words, what may really be important is, you know, the density of a particular neurotransmitter receptor in a particular place in the brain. 

But it’s not like we’ve found the gay part of the brain. 

We have not found the gay gene, nor have we found a gay brain region. What we have found is a place in the brain that at least in gay men on average, is smaller than it is in straight men. There are tath lies and hints, but it’s very early days on the science there. 

I’d like to let our listeners know that you can get a copy of The Accidental Mind How Brain Evolution has Given US Love, Memory, Dreams and God through our website point of inquiry dot org. Professor Linden, I want to finish up where you kind of finish up in the book. And that’s talking about religion, how the design of the brain might lead to the religious impulse. You say that our brains evolved to make us all believers. 

Yes, I think that that’s true. I think that one thing that has become clear in recent years, an analysis of the brain, is that our brains are build’s to have us create narratives, create stories that make sense out of disparate sensory experiences or facts. We try to take fragments of information and weave them together into a story. And we do this both consciously and subconsciously. And what I hold is that this cognitive process is narrative creation is the base of not just of religious faith, which is something that you find in every culture across the world, but is also the basis of scientific thought. So, for example, when John Brockman edge word, which is something I’m sure a number of your listeners go to on the Web, it’s a terrific resource. Posed a question to a lot of prominent scientists. And he said, what do you believe that you cannot prove? Now, none of those people said, well, I’m a hard headed, rational atheist and there’s nothing that I can prove. 

Everybody had something right. All right. 

So some of us believe in science and some of us believe in religion, Sulman. Both, but it’s not always based on evidence. Yuson. 

Well, what I’m saying is that the first act of science and the first act of religion are the same act. In both cases, you are making a hypothesis. He was saying, I have an incomplete set of information. And based on that, a complete set of information, I believe X to be true. Now, if this is the scientific faith, you are then saying, all right. And this could be falsified by such and such experiments or such and such observation. And if this is the basis of religious faith, then you say no. That’s my story. And I’m sticking to it. That’s my faith. And I’m not going to subjected to those particular. Modes of inquiry. But the initial act of scientific hypothesis, making and creating a religious narrative is the same at science and religion are two branches of the same cognitive stream, both derived from our brains. 

Narrative creation circuitry that’s gonna strike some hard know scientists counterintuitive. You know, you’re saying the inclination to be religious stems from the same brain processes that we get our drive to be scientific. But you’re saying, you know, it all comes from narrative that our brains are made up so that we connect the dots, we tell stories about what we experience. But the question is, what about the truth, value of the stories that we experience? And our brain structure, our capacities, our intellectual capacities kind of enter into that. It’s true that we all believe things that can’t be proven or maybe our brains evolved to make us all believers. But wouldn’t you say that the scientist, too, does that second step you mentioned you where you falsify that that initial hypothesis that the scientist believes things on the whole that are true as opposed to being mostly just based on faith? 

Well, you know, I would say that I agree with that because obviously I’m studying my life being a scientist. But that doesn’t invalidate the notion about where the urge to do science comes from. 

Right. What you’re teaching about the brain isn’t just stories that your brain evolved to tell you to believe. They’re the best idea of how we think the brain works based on the evidence that seems to be. Maybe I’m revealing my bias here, but different than the way people try to explain the universe when they’re coming at it from a religious point of view. 

A lot of times those things are different, but I think there’s been a lot of arrogance on both sides. You know, science and religion have been at war for a long time, particularly in the United States, more than in other countries. And I think there has been a lot of arrogance on both sides. 

I think there are a lot of people of faith who say, well, you know, without these moral rules from God or whatever, that you can’t live a moral life. 

And I think that sounds and there are a lot of scientists who say, well, if I can disprove some particular fact in your religious texts, say that Genesis creation story from the Judeo-Christian tradition, I can prove that the you know, the Earth isn’t really 6000 years old them. Therefore, I am going to throw out all aspects of your faith, including those things that I don’t have the ability to disprove. And that’s what good science. 

Last question on that point, Professor Linden. If you use brain science to explain the religious impulse where it’s coming from, this narrative in this narrative process, more hard wired to tell stories, to explain stuff by connecting the dots. Well, if you explain religion that way, is that also explaining it away? In other words, you’re saying it’s happening in the brain and it’s not happening out there in the real world? 

Yeah, in a sense I am. But I’m saying the same thing for science. In other words, you know, both both science and religion are both inside us and outside us in the sense that there are things outside of the world that we try to fashion explanations for. And the way we fashioned them is determined by the hardware we have in our head. And of course, we’re not even those of us, you know, who take us solely scientific world view are not purely rational beings. We like to think we are. But the brain is wired such that sensation and emotion are are intertwined at the very earliest steps of perception. And we’re incredibly bad at a lot of things. Our brains are really awful at things like being an eye witness, for example, and picking things out of our distant memory and recalling them accurately. We’re really lousy at those things. So even when we try to be as as rational and scientific as possible. 

A lot of times we’re rather bad at it. 

Thank you very much for joining me on Point of Inquiry, Professor David Linden. 

Thanks for having me. A lot of fun. 

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Point of inquiry is produced by Thomas Donnelly and recorded from St. Louis, Missouri. Executive producer is Paul Kurtz. Point of Inquiry’s music is composed for us by Emmy Award winning Michael Playlet. Contributors to today’s show included Sarah Jordan and Debbie Goddard. I’m your host DJ Grothe. 

DJ Grothe

D.J. Grothe is on the Board of Directors for the Institute for Science and Human Values, and is a speaker on various topics that touch on the intersection of education, science and belief. He was once the president of the James Randi Educational Foundation and was former Director of Outreach Programs for the Center for Inquiry and associate editor of Free Inquiry magazine. He previously hosted the weekly radio show and podcast Point of Inquiry, exploring the implications of the scientific outlook with leading thinkers.