animals, we are led to conclude that they have been alike produced from a similar living filament." 26 "Many features in the anatomy of man point to a former quadrupedal position, and indicate that he is not yet fully adapted to the erect position; that, further, man may have arisen from a single family of monkeys, in which, accidentally, the opposing muscle brought the thumb against the tips of the fingers, and that this muscle gradually increased in size by use in successive generations." 27 The theory of natural selection is almost the sole thing in which Erasmus Darwin failed to anticipate his more famous grand son. Though there is no evidence that Lamarck (1744–1829) knew of the work of Erasmus there is a striking similarity in the ideas of the two. Lamarck became a botanist and was closely associated with Buffon. At the At the age of fortynine he changed to zoology and was placed in charge of the invertebrates at the Jardins des Plantes in Paris. Up to this time he believed in the fixity of species. In 1802 he suggests the word biology as the title of natural science and sketches an evolution theory which involved the mutability of species and changes, caused not directly by the environment, as Buffon taught, but indirectly through influence upon the nervous system. His "Philosophie Zoologique" (1809) presents his ideas in complete form. He states four laws: 1. Life by its own properties constantly tends to in crease the volume of every organism and to enlarge its parts up to the limits which it itself fixes. 2. The production of a new organ in an animal body results from a new need which continues to make 26 CLODD, E. o. c., p. 112. 27 Ibid., p. 113. itself felt and from a new movement which this need starts and continues. 3. The development of the organs and their power of action is constant because of the use of these organs. 4. Everything which has been acquired, or changed in the individual during its life is preserved in the process of reproduction and transmitted to the new individuals which come from those that have undergone the changes. Lamarck's general conception is simple. The creator endowed matter and life with its qualities. Nature is always creating the lower types. The simplest forms appear first and thenceforth there is a slow, continuous evolution which has taken enormous periods of time. All species shade into each other. The gaps are merely places where we have lost the intermediate forms. The changes are not caused by any scheme or design in nature. They result from the reaction to the environment. "Circumstances influence the forms of animals. But I must not be taken literally, for environment can effect no direct changes whatever upon the organization of animals." Yet on plants he thought direct environmental was effective and he was not entirely consistent with regard to animals. "But great changes in environment bring about changes in the habits of animals. Changes in their wants necessarily bring about parallel changes in their habits. If new wants become constant or very lasting, they form new habits, the new habits involve the use of new parts, or a different use of old parts, which results finally in the production of new organs and the modification of old " 28 ones. 28 OSBORN, H. F. o. c., p. 168. higher species which were seen to bear striking resemblance to the existing chain of life from the lowest to the highest forms. There came also a revival of interest in the theories of the Greeks which led the philosophers who were by no means ignorant of the significance of the newer scientific discoveries into a new field of speculation. The last factor was the growth of anatomical knowledge which raised many questions as to the assumed perfection of organisms and indicated that many parts were useless survivals. Thus the way was cleared for a new viewpoint. The first observer to sense the new order was Buffon (1707-1788). In early life he shared, as did Linnæus, the common viewpoint. Later he changed his views markedly. "The pig does not appear to have been formed upon an original, special and perfect plan, since it is a compound of other animals; it has evidently useless parts, or rather parts of which it cannot make any use, toes all the bones of which are perfectly formed, and which, nevertheless, are of no service to it. Nature is far from subjecting herself to final causes in the formation of her creatures." 24 Or In middle life he emphasized the rapid variation of species. "One is surprised at the rapidity with which species vary, and the facility with which they lose their primitive characteristics in assuming new forms." 25 again: "How many species being perfected or degenerated by the great changes in land and sea, by the favors or disfavors of nature, by food, by the prolonged influences of climate, contrary or favorable, are no longer what they formerly were." 25 Buffon saw the changes caused by domestication of animals. He noted the high birth rate, the struggle for 24 OSBORN, H. F. o. c., p. 132. 25 Ibid, p. 133. existence and the elimination of many individuals. He hints at the common ancestry of ass and horse, of man and ape. He thought the environment modified animals and urged that present changes be studied that older changes might be understood. It is hard to judge Buffon. He is frequently contradictory. He recants his opinions when attacked on theological grounds by the Sorbonne. When expressing himself on some moot points he suggests that inasmuch as the Bible teaches the contrary this view cannot be true. He had less influence than Linnæus largely because he was ahead of his time- but he greatly stimulated research. Erasmus Darwin (1731-1802) squarely broke away from the idea of special creation. He thought that life originated in water: Hence without parents, by spontaneous birth, In unmistakable language he pictures the evolution of life from its simplest forms to man himself. "When we revolve in our minds the metamorphosis of animals, as from the tadpole to the frog; secondly, the changes produced by artificial cultivation, as in the breeds of horses, dogs and sheep; thirdly, the changes produced by conditions of climate and of season, as in the sheep of warm climates being covered with hair instead of wool, and the hares and partridges of northern climates becoming white in winter; when, further, we observe the changes of structure produced by habit, as seen especially by men of different occupations; or the changes produced by artificial mutilation and prenatal influences, as in the crossing of species and production of monsters; fourth, when we observe the essential unity of plan in all warm-blooded animals, we are led to conclude that they have been alike produced from a similar living filament." 26 "Many features in the anatomy of man point to a former quadrupedal position, and indicate that he is not yet fully adapted to the erect position; that, further, man may have arisen from a single family of monkeys, in which, accidentally, the opposing muscle brought the thumb against the tips of the fingers, and that this muscle gradually increased in size by use in successive generations." 27 The theory of natural selection is almost the sole thing in which Erasmus Darwin failed to anticipate his more famous grand son. Though there is no evidence that Lamarck (1744-1829) knew of the work of Erasmus there is a striking similarity in the ideas of the two. Lamarck became a botanist and was closely associated with Buffon. At the age of fortynine he changed to zoology and was placed in charge of the invertebrates at the Jardins des Plantes in Paris. Up to this time he believed in the fixity of species. In 1802 he suggests the word biology as the title of natural science and sketches an evolution theory which involved the mutability of species and changes, caused not directly by the environment, as Buffon taught, but indirectly through influence upon the nervous system. His "Philosophie Zoologique" (1809) presents his ideas in complete form. He states four laws: 1. Life by its own properties constantly tends to in crease the volume of every organism and to enlarge its parts up to the limits which it itself fixes. 2. The production of a new organ in an animal body results from a new need which continues to make 26 CLODD, E. o. c., p. 112. 27 Ibid., p. 113. |