| EVOLUTION, CREATION AND WORLDVIEWS As individuals we are bound by time and space. On average we will live about 70 years and many of us will spend our entire lives within a radius of a few hundred miles. Our mental processes, however, can transcend these physical limits and provide us with the knowledge of time and space needed to understand the present, which is the result of the past and the launching pad to the future. Given our limited personal perspective, it is not surprising that most of us fail to intuit the extent of change that has characterized the history of this planet. We observe change all about us but dismiss it as irrelevant. Night follows day and the seasons of the year return with predictable regularity. For all practical purposes our world is static and constant. The continents seem permanently fixed in location, the mountains everlasting, and the species living with us unchanged for the five thousand or so years of recorded history. Only technological achievement, a distinctly human artifact, and occasional species extinction, e.g., the dodo bird and the passenger pigeon, suggest change in an otherwise static universe. This static view of nature to which our personal experience attests was formally described by the ancient Greek natural philosophers and has dominated our cultural traditions ever since. Only recently has science begun to challenge this view by producing an alternative paradigm for understanding the universe. This course will explore the evidence for this new paradigm and suggest some of the many ramifications which follow from viewing the universe as a dynamic, evolving entity. Change in Biological Systems Essential to the concept of evolution is the notion of change, but not all change in biological systems constitutes evolutionary change. Life is a dynamic process which involves change over time; our bodies are in a constant state of flux. Cells die and are replaced. The macromolecules (e.g., proteins) that comprise our cells are replaced over relatively short time spans and even our bones which appear to be inert are constantly being remodeled. Yet, despite continual cellular and biochemical change, we appear to be unchanging. Over longer time periods, however, we do change in appearance due to the developmental processes of growth and ageing. Even our behavior changes as we assimilate information and learn to cope with our environment. Beyond the level of individual organisms there exists change in the species composition of any particular geographic area. This change, called ecological succession, involves hundreds of years. If left undisturbed, a grassy plot will be transformed into a plot of shrub growth which will later give way to a forest. The species composition of the forest will eventually change as shade-tolerant species, e.g., oak and maple, eliminate those, e.g., birch and poplar, which are not shade-tolerant. Should the forest be destroyed, this sequence of species replacement will start again. Over even longer time periods, thousands rather than hundreds of years, the chemicals which sustain life shift their locations in a process known as biogeochemical cycling. For example, excess carbon dioxide in the atmosphere, which can increase global temperature through the green- house effect, is assimilated by the oceans and stored as carbonate salts in the sediment of the ocean floor only to be later returned to the atmosphere through volcanic explosion. Thus, many processes involving life on this planet result in change, but none of the changes mentioned above constitutes an example of evolutionary change. Evolutionary Change What type of change does constitute evolutionary change? Only heritable change in populations between successive generations (microevolution) or in entire species over thousands of generations (macroevolution) constitutes evolutionary change. The key word is heritable which means a change in the genetic composition of a population or species. Thus, evolution is essentially a genetic phenomenon which results in directional, not cyclical, change. The examples of change mentioned above were nonevolutionary because they were not genetic. This course deals with the mechanisms and implications of directional, genetic change. Creation vs Evolution Creation and evolution are contrasting explanations for the origin of existing species diversity. The ongoing creation vs evolution debate involves one simple question: do species change over time to produce different species through either lineage splitting (speciation) or long term transformation (phyletic evolution), or are species essentially static entities whose origin is the result of a single, creative act? Since no human has ever witnessed the origin of any contemporary species, this issue cannot be resolved by direct observation; hence the controversy. Science vs religion The term "creation" undoubtedly has a religious connotation because it implies a creator, commonly interpreted as a divine being with supernatural powers. Hence, the use of the term "creation" in the context of the origin of species refers to their origin by means of a supernatural act. While it might appear that the creation/evolution debate is a conflict between religion (which seeks ultimate meaning guided by revelation) and science (which attempts to explain nature through natural process), this is not the case. Most denominations in the Judaic- Christian tradition view the creation story as myth, not as an historical fact, and so allow for an evolutionary interpretation of species origin. Theodosius Dobzhansky, a population geneticist and pioneer in developing modern evolutionary thought, related to two processes by noting that the mechanism of creation was evolution. Further- more, evolutionists vary in religious views from atheism and agnosticism to devout theism; hence, there exists no correlation whatsoever between religious belief and evolutionary thinking. If this is so, why all the fuss between creationists and evolutionists? Static vs dynamic worldviews Far from being simply a conflict between science and religion, the creation/evolution debate is a contest between two completely different views of the world. Creationism is based on a static worldview which sees change as insignificant and posits that species are eternal and immutable. This position is articulated in the Bible's Book of Genesis which attributes species origin to an unknowable and instantaneous creative act of God. The prayer, ".... as it was in the beginning, is now, and ever shall be ..." summarizes the worldview of creationists. Evolution, on the other hand, holds to a dynamic worldview which sees change as the inevitable consequence of natural processes that are continuous over time. Hence, existing species diversity is the product of change in ancestral species which existed in the past. The creation/evolution debate is actually a modern version of a much older debate involving two different paradigms originally proposed by the Greek philosophers, Heraclitus (544- 484 BC) and Parmenides (540-470 BC). Heraclitus believed that reality was constantly changing as revealed by our senses, while Parmenides believed that reality was immutable and fixed as comprehended by our intellect and that sense knowledge was misleading and illusory. Being vs becoming Heraclitus held that our senses accurately portray physical reality which exists in a constant state of flux. Although nature might appear to the mind to be static, actually it is changing. As Heraclitus noted, a river appears to be static, but the water which wets your foot one minute is not the same water which wets it a minute later. By emphasizing change, Heraclitus developed a philosophy of becoming and so departed from most other influential Greek philosophers who held to a philosophy of being: "To be or not to be", that was their question. Parmenides stated that change could not be grasped by the intellect and so was unknowable. If our senses reveal change, they are wrong. The intellect recognizes only two states: being and nonbeing. Nothing can become (change) because everything either is or is not. To say that something which becomes already was is as absurd as saying that something comes from nothing. Since (according to Parmenides) nothing comes from nothing, everything which exists must be eternal and immutable. Our intellect corrects the error of our senses. The static world of Plato and Aristotle This problem of change was addressed by a number of later Greek philosophers, most notable of whom were Plato (428-348 BC) and his pupil, Aristotle (384-322 BC). Plato reconciled the positions of Heraclitus and Parmenides by positing two worlds: the suprasensual world of form understood by our intellect and the ephemeral world detected by our senses. The real world of forms was perfect, eternal and immutable and contained the essence of being; the world perceived through the senses was imperfect and only represented the changeless world of forms in vague fashion, thus giving the illusion of variation and change. For example, our eyes reveal horses as existing in different sizes, shapes and colors and changeable to a limited extent during their lifetime. But these varied appearances are but imperfect representations of the pure form of horse which alone is real. The intellect (mind) can recognize these different objects revealed by our senses as horses only because it can grasp the form of a horse through a process of abstraction. Plato adopted the dualism of body and soul (matter and mind, or sense and intellect) to explain nature. Only the intellect is capable of true knowledge because it participates in the ideal world of forms. The senses suggest change and variation only because they perceive shadows of this real world. Plato thus sided with Parmenides in viewing nature as static, fixed and eternal. Aristotle rejected Plato's ideal world of forms existing apart from the world perceived by the senses and suggested that form resided within beings. Form causes an object to be what it is. He constructed a new dualism of matter and form (or act and potency) which provided him with a somewhat different solution to the problem of change. Aristotle conceived of an intermediate state between being and nonbeing, i.e., being in potency. Beings have the potential for change because their forms are capable of change. A seed is a seed because of its form, but this form can change to give rise to a tree. Thus, Aristotle's philosophy of being allowed for change - but only limited developmental, not evolutionary, change. Aristotle believed that the Cosmos was without beginning or end and so agreed with Plato that species were eternal and immutable. Although as a biologist Aristotle recognized change in living beings, his concept of change was nonevolutionary (see change in biological systems discussed above) and so consistent with a static worldview which denies essential change in nature. Unfortunately, Aristotle had a tremendous impact on western intellectual thought (particularly through the scholastic philosophy of St. Thomas Aquinas which dominated Church thinking) and so the concept of species evolution was unthinkable until his influence waned and science was reborn in the 17th century. The "Cosmos" of Greek philosophy was a small universe in which the Earth was centrally located. In 2 AD Ptolemy described mathematically the Aristotelian view of circular motion of the sun and planets around a stationary Earth. The expression, "the sun rises and sets", is based on this model as is the view that humans occupy the top rung in the scale of nature (Scala Naturae) in a geocentric universe. During the 16th and 17th centuries, however, this concept of the universe began to unravel. In 1543 Nicolaus Copernicus suggested that the Earth was not the center of the universe but revolved around the sun. Bruno proclaimed in 1584 that the universe was infinitely large and contained many solar systems; he was burned at the stake for this heretical insight. In 1609 Kepler replaced the circular orbits of planetary motion described by Ptolemy and Copernicus with elliptical ones and in so doing obtained a more precise description of the heliocentric solar system. This mathematical description was confirmed by the observations of Galileo a year later. The discovery of the law of gravity by Newton (1687) provided a mechanical explanation for planetary motion and capped the paradigmatic shift in thinking about the universe called the Copernican Revolution. Later investigation confirmed that the Earth is far from being the center of the universe, situated as it is at the periphery of the Milky Way - one of over 50 billion galaxies that populate the modern cosmos. The dynamic worldview of Darwin The advances in physical science described above certainly changed our view of the universe but did not impact on the static world of the ancient Greeks. Planetary motion was cyclical, not directional, and so did not promote transformation of the basic units of nature. That all changed with Charles Darwin's publication in 1859 of his seminal work, On the Origin of Species by Means of Natural Selection. Darwin produced a mountain of evidence supportive of species change, a notion suspected in intellectual circles even before his day. In supporting evolution, Darwin opened the door to a new dynamic worldview which challenged the prevailing static concept that had persisted since the days of Plato and Aristotle. Although he was aware of the implications of his publication, few came to grips with its full ramifications, perhaps because his theory of evolutionary mechanism, natural selection, was not immediately accepted. Today, the Darwinian Revolution is upon us and its implications for directional change are being extended to other sciences as well, as seen in the new concepts of an expanding universe in astronomy and plate tectonics theory in geology. Paradigmatic change is most exciting as one worldview replaces another. We all interpret reality through paradigms and one of the purposes of liberal education is to make us realize the paradigms which guide our thinking. One immediate effect of the Darwinian Revolution was to change our thinking about ourselves. If all species existing today are the transformed survivors of previously existing species, then no species is more important than any other. The Darwinian evolutionary tree or bush with many terminal twigs (existing species) has replaced the ladder of life view of diversity and in so doing has denied any privileged status to Homo sapiens. In this regard the Darwinian Revolution completed the Copernican Revolution's displacement of humans from our position of central importance in a static, heliocentric and anthropo- centric universe designed by God. Is Nature an Objective or Subjective Reality? Over the history of western intellectual thought our view of nature and the universe has changed. Early on our ancestors viewed the forces of nature as supernatural gods who often vied with one another, e.g., the god of the wind fighting with the god of the sea to produce storms. We mere mortals were caught up in this conflict as poetically portrayed in Greek mythology. The natural, pre-Socratic philosophers of ancient Greece, who introduced science before Plato shifted emphasis from physics to metaphysics, departed from their forebears by viewing nature as orderly and governed by laws which were knowable. No longer did we have to resort to the whim of gods to explain the forces of nature. Nevertheless, their view of nature was quite different from ours. For the ancient Greeks all of nature was animated - even rocks had some form of soul. Thus, their problem was explaining death. Today, we see the Earth as an island of life in a cold, dead universe and ask, "Why life?" In a world that is basically static, change is the problem to be investigated; but for a dynamic universe in which change over long periods of time is inevitable, why things remain stable for short periods might be the significant question. What constitutes an important question to be investigated depends upon one's view of the world and we are just beginning to explore the view of the world thrust upon us by Darwin and studied by modern scientists. The world of Newtonian physics suggested that nature was an objective reality that could be described by precise laws which were universal and eternal. The role of science was to unlock the secrets of nature in search of absolute truth and the divine plan of creation. For Newton, Kepler and Galileo there was no real conflict between science and religion. Today, the theory of relativity has come to dominate physics and we know from the history of science that scientific views of the world in large measure replace rather than build upon one another. We are not progressively coming closer to a fuller understanding of some objective reality with the passage of time; rather, our view of the world changes as we invent new paradigms for explaining and interpreting empirical evidence. Our view of the universe, consequently, is very subjective and changes radically with each paradigmatic shift. Scientific knowledge is uncertain, quite relative to the current paradigms in place and is subject to future change. For some biblical creationists, e.g., scientific creationists, this unsure, dynamic view of the world is quite disturbing because it lacks the level of certitude found in the Book of Genesis. God created the world in orderly fashion with an overall purpose in mind. Science is suppose to reinforce religion by gradually revealing the divine plan and supporting the truth of the creation story, thus lending authenticity to the Bible's religious truths. For these fundamentalists, faith (religion) and reason (science) must go hand in hand and cannot contradict one another. We shall return to the topic of evolution and religion near the end of the course, but for our next topic we will take a close look at the nature of science to understand why scientific truth is relative rather than absolute. | |
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