Natural Behavior. Burton A. Weiss
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small population compared to phenomena in the physical universe. The ball that rolled down the incline contains more molecules than the total population of all of life’s individuals on this Earth. Thus, life scientists investigating small populations, and often individuals, must frequently employ statistical techniques.
In addition to small populations, life sciences must also explain the high degree of complexity and organization of life. Physical parameters like size do not help. Measuring species size does not cope with the differences among 100 foot whales, 300 foot tall sequoias, and three-micron wide microsporidian spores. To understand the complexity and organization of life, life scientists must know the history of life. They need to comprehend life’s origins and evolution to its present state, or how life came to be the way it is. Evolution provides the historical analysis and deterministic mechanism, in natural selection, that unveil the phenomena of life. Thus, evolution is the fundamental underlying principle of all the life sciences.
History of Evolutionary Theory
The concept of evolution involves the change of species through time. A comprehensive review of the history of evolutionary theory would fill volumes. However, a synopsis, of some of the major steps in the history of evolutionary theory, serves to illustrate the creative and dynamic effort of many great thinkers in formulating modern evolutionary theory, and to clarify past errors.
Among the earliest theories proposing change of species was Aristotle’s linear hierarchy, already noted on the first page of the chapter. In this system each level was more perfect than the level below. Thus, in the version of Aquinas, God represented absolute perfection followed by angels, who were less perfect than God, but still too perfect to commit sin. The next rank, at the top of the real world, was humans. Humans were less perfect than angels, in that people were rational and could choose to commit sin. Heaven was reserved only for those who did not sin. After humans were animals. Animals were viewed as even less perfect because they could not reason, but only react with instinct. Finally, came plants, which were at the bottom in perfection because they merely vegetated. In addition, those in each level strove to be more like the level above. The level of understanding of life for most people, even today, reflects the idea that humans are rational, but animals respond only by instinct. The Hindu concept of the scheme of life inherent in reincarnation, also includes a similar ordering of life. It contains the idea of transmigration that includes all life in a pursuit of perfection and heaven, or nirvana.
Galileo developed a theory of impetus which held that objects maintain momentum unless stopped. The theory was influential because it avoided causal or animistic explanations for movements. Momentum kept the planets in orbit, not some unknown invisible gear system that had to be cranked. Change, not stability, was the natural state of the universe. Coupled with other later discoveries, like calculus by Leibnitz and Newton, Galileo’s ideas triggered a 17th century revolution in thought, which emphasized mechanism and scientific determinism. The revolution led to great progress in the physical sciences and caused abandonment of the teleological view that the complex organization and design of the world called for the existence of a designer. Darwin was later to forsake the same teleological, no-clock-without-a-clock-maker, approach in his explanation of the origin of species. However, the teleological idea is still influential in theology.
Life science, in awe of the progress of the physical sciences, began to emulate them. Led by Linnaeus (Karl von Linne) in the 18th century, life scientists developed a complex classification system, categorizing species by anatomical and functional similarities. The rationale was that classifying would reveal organization and permit induction of laws concerning life. But, species were considered immutable entities.
Hegel originated the technique of using history as an analytic tool, rather than merely as a description of past events. He was interested in the origin of social institutions and structures. His thought had tremendous impact on the social disciplines of history, anthropology, economics, sociology, and social psychology. Hegel’s new analytic approach also began a 19th century revolution in other sciences. Astronomy and physics began using Hegel’s approach to explain the origin of the universe and to conceive astrophysics. Lyell employed the analytic approach in geology by using the history contained in rocks to explain the formation of the Earth. His work heretically replaced the story of Noah and the flood to explain the origin of the Earth’s structures. Lyell’s thought influenced the closely related field of paleontology and a young student at the time, Charles Darwin.
New ideas were accumulating rapidly in the life sciences. Buffon, in 1760, had destroyed the purposive explanation of organs, like eyes are for seeing. He observed that two of the five digits on each of a pig’s feet did not touch the ground. Therefore, toes could not be for walking. The pig’s vestigial digits led Buffon to explain all quadrupeds as degradation from fourteen primary types. Animals, instead of being direct divine creations, were now viewed as imperfect descendants of originally divine creations. The theory cracked the ground of life science for later seeds of historical analysis of life’s origins.
By 1803 Lamarck, Buffon’s student, had formulated the first theory attempting to explain life as progressive and adaptive change. Life diverged from a primal type, rather than degraded from divine forms. Lamarck’s theory held that acquired characteristics, like large muscles, affected the (at that time unknown) genetic material and were inherited. Thus, a right-handed blacksmith’s son should have a muscular right arm. Many a blacksmith’s son did have a large arm, but not because of his father’s acquired characteristics. Only in rare instances, like alteration of the sex cells by drugs or radiation, can acquired changes be inherited. Lamarckian theory could not explain how a blacksmith, who lost an arm, could subsequently have offspring with complete arms. Lamarck also used the old Aristotelian notion of striving toward perfection. He contended that the striving toward perfection of organisms led to the acquisition, through use, of improved characteristics, that were, in turn, inherited. Disuse would result in the loss of characteristics and the subsequent reduction of those characteristics in future progeny. Although such concepts mediated Lamarck’s impact among life scientists, his influence was still immense. Indeed, there are even recent Lamarckians, like Lysenko (Morton, 1951), the former President of the Lenin Academy of Agricultural Sciences. Lamarckian theory adapted readily to the milieu of socialist realism in which Lysenko worked. Against the advice of knowledgeable experts like N. I. Vavilov, who was later purged and died in detention, over 3000 biologists, who disagreed with Lysenko, were dismissed, imprisoned, or executed. Lysenko made decisions affecting grain breeding in Russia. Lysenko’s influence, destroyed progress in Soviet genetics and crop production. Russian influenced countries like Czechoslovakia, Poland, China and others were also affected by Lysenkoism. After Stalin’s death Lysenko lost his position, and Soviet genetics again flourished. Khrushchev reinstated Lysenko, but on February 4, 1965, Lysenko followed Khrushchev in being ousted. Lysenko died in Kiev on November 20, 1976.
Lysenko illustrates the periodic resurgence of Lamarckian ideas. Historically, however, Lamarck’s theory experienced difficulty from the beginning. St. Hilare, Lamarck’s student, debated Cuvier in the French Academy of Science in 1830. Cuvier favored the idea that the world reached its current condition as the result of a series of catastrophic changes. Each change gave major reorganization to life forms. No mechanism for gradual accumulation of alterations was included. St. Hilare supported Lamarck’s position, but used evidence linking the independent and unrelated, though similar, eyes of vertebrates and cephalopods, like the octopus. Cuvier, being knowledgeable in anatomy, caught St. Hilare’s error and won the contest. The debate was extremely influential and served to suppress ideas on evolution for the next three decades. At the time, the poet Goethe was reportedly more interested in reading the result of the debate than in seeing a critical review of his own poetry. Darwin was a college student at the time. In addition to the debate and the work of Lyell, Darwin also pondered the ideas of Malthus. Malthus contended that the rapid reproduction and subsequent increase in the population of organisms would outstrip food supply, unless there were checks on the population. The next year, 1831, following graduation, Darwin joined the H. M. S. Beagle as ship’s naturalist for a five-year voyage around the world to survey, record, and collect plant and animal specimens.
In 1859 Charles Darwin published his book, The Origin of Species. The book was the culmination of his observations on the Beagle journey and of his subsequent