As a scientist and a believer in human progress, I have been concerned about how well the established process of teshuvah (repentance) has worked. Yom Kippur after Yom Kippur - in fact, since the 11th century - we have recited the same confessional prayer, "Al Chet." If we were any good at repentance, shouldn't the list have changed in 1,000 years? Even if we don't want to change the ancient formula, shouldn't we be able to feel that we had eliminated or reduced at least a few on the list? Yet the list of sins remains the same, as does the ritual for expunging them. Why haven't we improved?
Perhaps we are genetically stuck. The newspapers and scientific journals are full of genetic determinism. Human geneticists, aided by the massive investment in the human genome project, have identified hundreds of genes in which specific alterations cause conditions that range from mental retardation to dyslexia. Mouse geneticists have created models not only of human disease, but also of mating and mental processing. One recent headline concerned genetically engineered male mice that spent more or less time grooming their mates, according to which piece of regulatory DNA they received. Other transgenic mice were better than their sibs in learning to find an underwater platform.
Or maybe we are stuck with the particular wiring of our brains. A person who suffers a stroke that affects one region of the brain cannot hear; another person can hear but cannot recognize words; another can recognize words but cannot identify a photograph of the President; another can recognize the President but cannot identify the function of a hammer or a screwdriver. Similarly, a range of neurological and neuropsychiatric disorders - many of which have genetic components - affect thought, memory, mood, and even religious experience.
In the face of such powerful biological constraints, can we really hope to change ourselves or our community? The answer is certainly yes.
It is true that genes determine the basic wiring of the brain and therefore the basic processing pathways for external information and internal feelings. But the brain is nothing if not a learning machine.
Neuroscientists talk about the brain's plasticity, meaning that the brain can not only change but that it can also maintain those changes over time. Genes certainly influence many aspects of the brain's structure and operations, but - as our everyday experience attests - genes alone do not determine who we are or what decisions we will make about our lives.
Evolution has produced a genetically programmed brain, adapted for plasticity. Humans may be hardwired to learn language, just as a songbird is hardwired to learn a song, but the particular language and the particular song depend on experience. We can also learn to pedal a bicycle, play a piano or putt a golf ball. While we learn these skills best during childhood, we maintain plasticity as adults.
In every case, learning changes the physical state of the brain. Even people who have suffered strokes or spinal cord injury can often recover lost functions during rehabilitation by practicing strategies that employ and strengthen alternate neural routes. Similarly, psychoanalysis and psychotherapy may well work by selectively entraining alternate neural pathways.
In the last few years, neuroscientists have been working hard to understand the nature of these changes, in humans and other primates, in mice and rats, even in fruit flies and sea hares. Several lessons have emerged. First, even without changing their circuitry, nerve cells can change the intensity of their communication with one another so that a particular circuit works more or less easily as a result of experience; a sea hare escapes more rapidly from noxious stimulus after several encounters, just as practice modifies our facility on a bicycle or a dance floor.
A particularly exciting recent discovery has been that, contrary to our previous understanding, some nerve-cell precursors preserve their capacity to divide even into adult life. These progenitors can generate new nerve cells in response to environmental stimulation. Putting young rats into an enriched environment (for example, by placing toys and other objects into their normally bleak cages) stimulates the proliferation of these cells, suggesting a cellular basis for the well-known benefits of a rich environment in early childhood. In the not too distant future, these neural progenitor cells may provide a means for repairing brains and spinal cords damaged by disease or injury.
Even without dividing, however, nerve cells can alter their shape and their connections as a result of environment and experience. Some of the most extraordinary such changes occur during the recovery from brain or spinal cord injury. Nerve cells - in both the brain and spinal cord - sprout new connections and make new signaling molecules. More heavily used neural pathways sometimes even take over from unused circuits, for example, in those pathways once connected to a now-amputated limb.
One well-known case involves an impressive man named Craig Dobkin, who was badly hurt in a climbing accident, severing his lower spinal cord so that he lost conscious control of his legs. Craig had some good fortune, however, in that his brother is Dr. Bruce Dobkin, Director of Neurorehabilitation at UCLA, a man who has pioneered new methods for retraining the brain and spinal cord after stroke and spinal cord injury. As a result of this retraining, Craig's spinal cord has learned to pattern his leg movements even though it no longer communicates directly with the brain. The important result is that Craig can move on crutches, rather than only in a wheel chair.
Since his accident, Craig Dobkin has founded an organization called Play for Peace, which brings children from conflicting cultures together through cooperative play. The goal of Play for Peace is to promote positive relationships among people who have a history of intercultural tension, starting in Jerusalem with Israeli and Palestinian youngsters. By bringing children with unique backgrounds, values, and beliefs together through the seemingly simple act of play, Play for Peace sows seeds of compassion. It is as if Craig Dobkin has adapted his brother Bruce's method of fostering spinal cord plasticity to the fostering of moral plasticity.
Our capacity for teshuvah is, I believe, a reflection of our neural plasticity. The limitations of our teshuvah do not reflect genetic programs, but the more basic problem of the nature of sin itself. Indeed, many of the sins listed in the "Al Chet" confessional seem to be rather subtle distortions of activities and thoughts that are positive: sinful meditations do not occur in an uncontemplative person; nor does contentiousness or scoffing arise in someone who has separated from the community; and sinful confession of the lips can only happen in someone who is moved to confession in the first place. Our problem then is to unravel the good from the evil. We need to increase our capacity to discern.
How can we take advantage of neural plasticity in making such important distinctions? To the extent that we can choose our experiences - internal and external - we can consciously change the workings of our brains, just as Craig Dobkin can consciously - if indirectly - change the workings of his legs. Just as we gradually learn to discriminate between creativity and cliché in literature, art, movies and music, we must train ourselves to discriminate morally between expansiveness and aggressivity, between involvement and voyeurism, between helpfulness and presumption. In our teshuvah, we must train ourselves to become connoisseurs of our own actions. The bad news is that this task is highly complex; the good news is that our brains are on our side - intellectually and emotionally. The meaning of the annual repetition of the same sins may be that our tradition recognizes that this struggle inevitably must continue from year to year.
For more information about Play for Peace, visit www.playforpeace.org