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CREATING THE FUTURE
Perspectives on Educational Change
Compiled and Edited by Dee Dickinson
EXPANDING LIFESPAN LEARNING
Paul D. MacLean, M.D.
With the celebration of the tenth Anniversary of New Horizons for Learning, it will be one and a half years since New Horizons' memorable Conference on Lifespan Learning at George Mason University. Until being asked to be one of the speakers, I had frankly not thought in terms of lifespan learning. In contemplating this assignment, my first association was to Shakespeare's As You Like It and Jaques' lines beginning, "All the world's a stage," and then depicting life's seven ages, or, as one might say, stages. Certainly, Shakespeare's pictures of the last two stages would not qualify as an advertisement for lifespan learning and would not give one iota of support for Browning's exhortation, "Grow old along with me, The best is yet to be, The last of life, for which the first was made!" More about that in a moment.
Since all life's experiences and actions are staged in the brain, I decided to choose as the title of my talk "All the Brain's a Stage." But then in terms of lifespan learning, I began to have second thoughts because of the gnawing question of what to say about Shakespeare's last two ages. I was dissatisfied with the prospect of avoiding the question by focusing on what I considered to be the two most important stages (and in many respects the most neglected) in human learning -- namely, the first two stages. That would be a natural focus for me because the latest phase of my research has been concerned with the localization of brain mechanisms accounting for three forms of family-related behavior that characterize the evolutionary transition from reptiles to mammals -- namely, 1) maternal nursing and care, 2) audiovocal communication for maintaining maternal-offspring contact, and 3) play. Indeed, one could say that the 180-million-year history of evolution of mammals is the history of the evolution of the family. The very name for mammals is attributable to their possession of mammary glands for nursing. In contrast to reptilian hatchlings, baby mammals could not survive without the nourishment and attentions of a nursing mother. The maternal compulsion to answer to these needs might be regarded as representing the germ of responsibility that in human beings generalizes to become what we call conscience.
In sampling mammalian populations, Calhoun found that the number of members in family groups generally did not exceed twelve, a figure doubtless owing to the number of young that a mother can deliver and sustain. In sampling a large number of mammalian species, one finds that the number of nipples averages about six, and seldom exceeds twelve. Since learning and play have their incipience in the nest, it is evident how early experiences carrying over into childhood and adolescence might influence all of subsequent lifespan learning. The noted paleontologist Alfred Romer once commented that it would be no exaggeration "to say that our modern educational systems all stem from the initiation of nursing by ancestral mammals." Such considerations invite discussion about such educational matters as the role of intimacy in teaching and smaller classrooms.
But what positive thing could one possibly say about the timeworn question of why nature puts people out of commission just about when, through experience and learning, they would be better equipped than ever to provide solutions to life's problems? A recent forecast by the World Health Organization has presented a gloomier outlook than ever for people in Shakespeare's last two stages. At the present time more than 10% of the population over sixty years of age suffer from some form of dementia. Based on current statistics, the number of people over sixty will have increased to over one billion by the year 2025. This means that if the present rate of population growth continues, the number of people with senile dementia, Alzheimer's disease, or other cerebral disease will be staggering.
In the past it has been tacitly assumed that because of genetic and other factors not much can be done to alter the aging process. Consequently, society has the expectation that when a person reaches a certain age, he or she becomes suddenly incompetent and, like a dog, is supposed to roll over and make room for a younger individual. No wonder there is so often shriveling depression and a drying-up of the brain's energizing sap! One might say, therefore, that old age is in no small part a sociogenic disease.
Until modern times it would seem that nature has never had to deal extensively with human aging. But since 1920 the average life expectancy has increased from fifty-four years to seventy-five. More and more, it is beginning to look as though a number of presumed aging processes are attributable to such causes as slow viral infections, environmental toxins, and dietary factors. The suspicion is growing, for example, that Parkinson's disease, now affecting younger age groups, may be owing to some environmental toxin. Despite the natural blood brain barrier, there are several ways that viruses and toxic agents can get through it to affect the brain.
As mentioned, dietary factors may be involved. It has been recognized that fatty products containing cholesterol may build up in the walls of blood vessels and decrease the blood supply to vital organs. But it is only now being realized that an oversupply of fat in any form may be damaging. This is of particular interest because of the longtime recognition that cellular accumulation of a fatty pigment called lipofuscin (literally, dusky fat) is the most common sign of aging. Lipofuscin is so resistant to analysis that it is still not known how it is formed or exactly what it is made of. Nerve cells are particularly prone to its accumulation because of having no means of getting rid of it. Somewhat analogous to the pileup of plastic bags of garbage in New York during a strike, packets of lipofuscin may gradually fill up nerve cells until they burst open like seed pods.
Granted that the role of dietary fat in the formation of lipofuscin is not known, the thought suggests itself that one of the reasons the Chinese are valued in old age is because they have a preserved intellect for communication. This recalls that the Chinese diet contains only 15% fat, as opposed to a Western diet of 40% fat. Experimentally, it has long been known that rats raised on a barely subsistent diet may have an increased life expectancy of 30 to 35%. This would mean that if a like outcome could be achieved in human beings, life expectancy could increase to 100 years.
Some pundits would claim that in the past, when there was a relatively short life expectancy, we were victimized by young people who believed they had to do or die before the age of forty or fifty. Hence, with current life-expectancy, if aging might bring the learning experience and wisdom for more meaningful survival of humanity and the rest of earthly life, there would exist an urgent need to proceed with all haste to learn how the brain could better protect itself and cleanse itself of injurious substances. Such knowledge might prove to be a crucial next step in evolution.
About: Paul D. MacLean, M.D.
Dr. Paul MacLean, Senior Research Scientist at the National Institute of Mental Health, has made significant contributions to the understanding the human brain. His work has profound implications for teaching and learning throughout the lifespan, as the following article indicates.
His Triune Brain Theory, based on an evolutionary model of the brain, proposes the idea that the human brain is really three brains in one. The R-Complex is similar to the brain of reptiles, in that it controls basic, instinctive survival thinking and behavior. The limbic system, which is similar to that of lower mammals, seems to be the source of emotions, some aspects of personal identity, and some critically important memory functions. The third and outer formation of the brain, called the neocortex, like the brain of higher mammals, is devoted to higher order thinking skills, reason, linguistic expression, and verbal memory.
MacLean's research suggests that most behaviors are the results of a complex cooperation among these three formations (and systems) of the brain. Of particular significance to educational planning and practice is his finding that when basic needs are not met or there is a negative, threatening emotional context for learning, the brain may literally downshift to basic, survival thinking.
In 1952, he published his first paper on the "visceral brain" and coined the term "limbic system." During an appointment in physiology and psychiatry at Yale he continued to investigate brain mechanisms of emotion, and in 1957 he joined the Laboratory of Neurophysiology at the National Institute of Mental Health, heading a new section on the limbic system. In 1971 he became Chief of the NIMH Laboratory of Brain Evolution and Behavior. An extensive synthesis of his work appears in his book, The Triune Brain in Evolution, published in 1990.
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