Discover Interview What Makes You Uniquely "You"?
Nobel laureate Gerald Edelman, your brain is one-of-a-kind in the history of the universe.
published online January 16, 2009
Some of the most profound questions in science are also the least tangible. What does it mean to be sentient? What is the self? When issues become imponderable, many researchers demur, but neuroscientist Gerald Edelman dives right in.
A physician and cell biologist who won a 1972 Nobel Prize for his work describing the structure of antibodies, Edelman is now obsessed with the enigma of human consciousness—except that he does not see it as an enigma. In Edelman’s grand theory of the mind, consciousness is a biological phenomenon and the brain develops through a process similar to natural selection. Neurons proliferate and form connections in infancy; then experience weeds out the useless from the useful, molding the adult brain in sync with its environment.
Edelman first put this model on paper in the Zurich airport in 1977 as he was killing time waiting for a flight. Since then he has written eight books on the subject, the most recent being Second Nature: Brain Science and Human Knowledge. He is chairman of neurobiology at the Scripps Research Institute in San Diego and the founder and director of the Neurosciences Institute, a research center in La Jolla, California, dedicated to unconventional “high risk, high payoff” science.
In his conversation with DISCOVER contributing editor Susan Kruglinski, Edelman delves deep into this untamed territory, exploring the evolution of consciousness, the narrative power of memory, and his goal of building a humanlike artificial mind.
This year marks the 150th anniversary of The Origin of Species, and many people are talking about modern interpretations of Charles Darwin’s ideas. You have one of your own, which you call Neural Darwinism. What is it?
Many cognitive psychologists see the brain as a computer. But every single brain is absolutely individual, both in its development and in the way it encounters the world. Your brain develops depending on your individual history. What has gone on in your own brain and its consciousness over your lifetime is not repeatable, ever—not with identical twins, not even with conjoined twins. Each brain is exposed to different circumstances. It’s very likely that your brain is unique in the history of the universe. Neural Darwinism looks at this enormous variation in the brain at every level, from biochemistry to anatomy to behavior.How does this connect to Darwin’s idea of natural selection?
If you have a vast population of animals and each one differs, then under competition certain variants will be fitter than others. Those variants will be selected, and their genes will go into the population at a higher rate. An analogous process happens in the brain. As the brain forms, starting in the early embryo, neurons that fire together wire together. So for any individual, the microconnections from neuron to neuron within the brain depend on the environmental cues that provoke the firing. We have the extraordinary variance of the brain reacting to the extraordinary variance of the environment; all of it contributes to making that baby’s brain change. And when you figure the numbers—at least 30 billion neurons in the cortex alone, a million billion connections—you have to use a selective system to maintain the connections that are needed most. The strength of the connections or the synapses can vary depending on experience. Instead of variant animals, you have variant microcircuits in the brain.What has gone on in your own brain and its consciousness over your lifetime is not repeatable, ever—not with identical twins, not even with conjoined twins.Before talking about how this relates to consciousness, I’d like to know how you define consciousness. It’s hard to get scientists even to agree on what it is.
William James, the great psychologist and philosopher, said consciousness has the following properties: It is a process, and it involves awareness. It’s what you lose when you fall into a deep, dreamless slumber and what you regain when you wake up. It is continuous and changing. Finally, consciousness is modulated or modified by attention, so it’s not exhaustive. Some people argue about qualia, which is a term referring to the qualitative feel of consciousness. What is it like to be a bat? Or what is it like to be you or me? That’s the problem that people have argued about endlessly, because they say, “How can it be that you can get that process—the feeling of being yourself experiencing the world—from a set of squishy neurons?”What is the evolutionary advantage of consciousness?
The evolutionary advantage is quite clear. Consciousness allows you the capacity to plan. Let’s take a lioness ready to attack an antelope. She crouches down. She sees the prey. She’s forming an image of the size of the prey and its speed, and of course she’s planning a jump. Now suppose I have two animals: One, like our lioness, has that thing we call consciousness; the other only gets the signals. It’s just about dusk, and all of a sudden the wind shifts and there’s a whooshing sound of the sort a tiger might make when moving through the grass, and the conscious animal runs like hell but the other one doesn’t. Well, guess why? Because the animal that’s conscious has integrated the image of a tiger. The ability to consider alternative images in an explicit way is definitely evolutionarily advantageous.I’m always surprised when neuroscientists question whether an animal like a lion or a dog is conscious.
There is every indirect indication that a dog is conscious—its anatomy and its nervous system organization are very similar to ours. It sleeps and its eyelids flutter during REM sleep. It acts as if it’s conscious, right? But there are two states of consciousness, and the one I call primary consciousness is what animals have. It’s the experience of a unitary scene in a period of seconds, at most, which I call the remembered present. If you have primary consciousness right now, your butt is feeling the seat, you’re hearing my voice, you’re smelling the air. Yet there’s no consciousness of consciousness, nor any narrative history of the past or projected future plans.
Saturday, January 31, 2009
Discover Interview - What Makes You Uniquely "You"?
Cool interview. Gerald Edelman is an excellent author and thinker, and I highly recommend his recent book, Second Nature: Brain Science and Human Knowledge. While I may not always agree with him (consciousness, to me, is more than a biological function), he is fascinating, insightful, and makes me think about issues of consciousness and being human in new ways.
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