Some Ancient-Greek Ideas on Evolution

Abstract

THE theory of evolution explains the development of organisms from ancestral types over a long period of time. For most students the theory had its origin in the last century. This is a reflection of coverage of the topic in textbooks; in which, quite correctly, the work of Charles Darwin and Alfred Russel Wallace is emphasized. Contrary to much popular belief, Darwin and Wallace did not bring into existence the idea of biological evolution. Textbooks generally point out this fact and note that earlier in the 19th century Lamarck had strongly advocated evolution of organisms. The mechanism of evolution propounded by Lamarck was quickly recognized as being unlikely, whereas that put forth by Darwin and Wallace was plausible. In addition, Darwin and Wallace presented much more evidence to support their explanation of evolution than Lamarck did. Consequently, Darwin and Wallace are considered to be the founders of the modern theory of evolution. Furthermore, although other explanations of the mechanism of evolution have since been proposed; that of Darwin and Wallace, based on natural selection of variants of a species, has best stood the test of time. Actually the concept of evolution goes back to before the 19th century. For example, in the 18th century Erasmus Darwin, the grandfather of Charles Darwin, wrote that he did not believe that species of animals living on Earth at that time had remained unchanged since the time of their creation. He argued that species would change over long stretches of time. His views on the subject were published in his Zoonomia, or the Laws of Organic Life. There is enormous diversity in the biological and nonbiological world. Be that as it may, all things, whether living or nonliving, are made up of the same chemical elements. The theory of chemical evolution was proposed in the 1920s by a Russian biochemist named Oparin and by Haldane, a British biologist. According to their theory, life developed from nonliving sources by a series of spontaneous chemical reactions in the atmosphere and oceans early in the Earth's history. These reactions do not occur under chemical and physical conditions found on Earth today, but it was postulated that they could have done so under the kinds of conditions that existed on Earth billions of years ago. Two American scientists, Miller and Urey, provided the first experimental evidence in support of chemical evolution. In 1953, they subjected certain chemical elements and simple inorganic compounds that existed in great abundance on the primitive Earth to energy from simulated lightning, and found that amino acids and some other organic compounds were formed. Subsequently, other investigators confirmed and expanded these studies. Among the others is Melvin Calvin, best known for his Nobel prize-winning research on photosynthesis, but who has also made major contributions to chemical evolution. All known human cultures, primitive as well as advanced, have developed explanations for the origin of the world, human beings and other organisms. Virtually all of the explanations are based on supernatural phenomena. This reflects the great difficulty posed by trying to explain a natural origin for the Earth and its numerous forms of life. Like other cultures, the ancient Greeks gave their attention to the origin of the world and life. It was generally believed that supernatural beings created everything that existed. For example, Prometheus created man from clay. Then Prometheus stole fire from heaven and gave it to man to make life easier for him. Zeus, the supreme god, punished Prometheus for giving man fire. Since fire would greatly benefit man, Zeus counterbalanced it by bringing about the creation of woman to trouble man (Harvey 1966). The foregoing notwithstanding, some ancient Greeks tried to explain the origin of human beings and other forms of life as a consequence of natural happenings. Although he had no concept of chemical elements as we know them today, Thales (ca. 640-546 B.C.) proposed that all things, living as well as nonliving, were ultimately made up of just one basic substance. The writings of Thales have not survived, but it is known from Aristotle that Thales believed water was the fundamental building block of matter (Aristotle 4th century B.C.). There was a reason for that belief, since Thales knew that water could exist in more than one form. For example, when heated, liquid water changes into steam, the gaseous form of water. Concerning organisms and the basic substance, water was known to be essential for all forms of life, a good reason to believe that it was the elemental substance of living things. Thales asserted that water was not David Bardell is Professor of Biology at Kean College of New Jersey, Union, NJ 07083-9982.