Nature and Human Nature
Nature and Human Nature :
Lamarck's Influence on The Development of Darwin's Theory of Evolution
There have been many ideas on the theory of evolution. Some simply take our existence for granted. Others prefer to explain all evolution in terms of the bible and the presence of a God. However, there are those who have researched the topic of evolution and have offered an explanation as to where a species comes from and how they evolved in the manner that they did. This type of science has been studied for a very, very long time and one of the most famous minds in the field of evolution was a man named Charles Darwin. Darwin was not the first one to offer theories on evolution. There have been many scientists who preceded him. These earlier evolutionists came up with models of evolution that were unfortunately unworkable. One of these early pioneers was Jean-Baptiste Lamarck. Lamarck believed in deism and advocated natural religion based on human reason. He believed in the harmony and rationality of the world. And although flawed, the work of Lamarck did not go unnoticed, however. Darwin also believed in the harmony of the world, and it was Darwin himself who said that Lamarck was the first man whose conclusions on evolution brought about excitement and attention. He was the one who showed law in organic and inorganic species evolution. As it turned out, the work of Lamarck was quite influential on Darwin.
Lamarck's views on inheritance of characteristics can be seen in Darwin's accounts of natural selection. When Lamarck wrote of transmutation, Darwin followed with his beliefs of the mutability of species. As well, Darwin had used Lamarck's ideas on use and disuse of organs. Lamarck was not the greatest of influences on Darwin, but he was an important one. One of the most important arguments in Darwin's theories was the idea of natural selection. It is generally thought that the world first heard of this idea in the form of Lamarck's inheritance of acquired traits theory. Lamarck's work showed that organisms improve themselves on their own. Then these new advantages for the environment would be passed on to the species offspring on the genetic level. This idea of self-improvement detailed how, through hard work of the organism, the path of evolution was continuous, always improving to the point of perfection. Lamarck had said that organisms must first be faced with a different mode of environment that would trigger some sort of pressure for an altered gene, to be inherited in the next generation. This process has come to be known as Lamarckism. (Gould, 1980) Darwin did not deny any of this. He regarded it as support for natural selection as an evolutionary mechanism.
Darwin's theory was more complex then Lamarck's, but the basic structure was there. Darwin had rooted his theory on the concept of adaptation, just as Lamarck had previously done. Adaptation is the notion of organisms responding to changing environments by evolving either a form or function of the body that would better suite it in the environment. Lamarck had explained that the method of transfer of information was directly to the organism. The animal would perceive the change and simply respond in the necessary way so that their offspring can be better adapted. Darwin's answer to what the mechanism is was much different. Darwin spoke of there being two components, variation and direction. (Gould, 1980) Darwin had taken into account that the species did indeed create offspring that were better suited for the environment, just as Lamarck had said. Darwin proposed that instead of direct transfer of environmental change, those that vary by good fortune are better suited for the environment and leave more surviving offspring. A species would have this beneficial trait through random variation. Then, the characteristic would help the animal survive, while the others died off.
This ensured that the beneficial trait would get passed on. This explanation is similar to Lamarkism, with obvious adjustments. Darwin simply showed that natural selection is, above all, a theory about the struggle of individual survival and reproduction. Lamarck's theory on inheritance of acquired characteristics is not that much different, in fact. Lamarckism has occasionally been mistaken for Darwinism. Darwin did indeed take Lamarck's inheritance of characteristics theory and modify it so that he improved upon it. This shows how Lamarck influenced Darwin to create the natural selection theory. It did not stop there, though. Lamarck also influenced Darwin with the idea of transmutation, and prompted Darwin to theorize on that aspect of evolution as well.
Transmutation was an idea resulting in the problem that Lamarck faced when dealing with the apparent extinction of a species. To Lamarck, extinction was not a possibility. Lamarck believed that extinction could not occur because then it would mean that God created an imperfect being, which was not a possibility for Lamarck. One purpose for the theory of transmutation was to offer an explanation for the apparent 'disappearance' of a species. The theory was that out of inherited characteristics, a species would undergo change. Each generation would continue to change because inheritance of traits would always occur.
Eventually, over a very gradual amount of time, the species would evolve so dramatically, that the new adaptations would bear little or no resemblance to the original species. (Ospovat, 1981) Darwin, who incorporated this idea, modified it slightly. To Darwin, extinction was very much a reality. He had stated in his Origin of Species that only few species in a particular genus would ever undergo a change.
The other species of the same genus would go extinct and leave no modified offspring. Only the ones that have apparently gone through some sort of mutation would produce offspring. This theory shows a direct link to Lamarck's because Darwin believed in transmutation also. On his voyage to the Galapagos Islands, Darwin found birds that seemed to be similar, but were each distinct. These birds came to be known as Darwin's finches, and Darwin discovered that each variety shared a common ancestry that grew out of the mainland. Although his method for scientific analysis was poor, Darwin concluded that when the same species of birds had migrated to the different islands of the Galapagos, they found that their competition for survival had decimated. The finches would then evolve to fit the new feeding environment and take over the roles of the previous birds. (Gould, 1980) This idea was influenced by Lamarck's principal that each newly established evolutionary line would gradually move up the ladder. In Lamarckism, transmutation and inherited characteristics went hand in hand. Transmutation occurred out of the willingness of the organism to adapt to the environment. Although Darwin's theory of mutated animals is a bit different, again the influence of Lamarck is apparent.
To Darwin, transmutation was not the achievement of higher levels of organization, but rather the production of new forms better suited for life in the external environment. Although this seems the opposite to Lamarck, Darwin merely tried to show the scientific fact behind transmutation, he needed to involve extinction, Lamarck did not, it was necessary to prove the notion of mutation and transmutation because it was not regarded at the time due to the fact that the steps in-between were not visible. Darwin saw the difficulty in Lamarck's view and was influenced by the evolutionist to come up with an idea that supported the topic as a whole, not necessarily Lamarck's view. Darwin proceeded to try and improve upon Lamarck's theory when the idea of use and disuse became of interest to him.
The idea that an organism would have parts of their body disappear due to the fact that the particular part was of no function over many generations and had no use, was presented to Darwin by Lamarck. It was Lamarck who had said that if he were to put a patch over the left eye of two children, one male and one female and the patch be kept there throughout their lifetime, and then in turn, their children would also be given a patch to wear, that gradually over many generations, the right eye would adapt so that the left eye would no longer be needed. Lamarck was confident that distant generations would not even have a left eye and that further down the road. The right eye would start to move towards the center. (Corsi, 1988) Obviously there would be no proof on this particular hypothesis. Lamarck did not stop there, though. He also stated that the giraffe's long neck was the result of continuous stretching for food atop the highest trees. The will power of the giraffe changed the structure of its neck so that future offspring would be able to reach for the best leaves. (Corsi, 1988) The idea of use and disuse is connected with the idea of inherited characteristics as well. To Darwin, this idea showed him the correlation between the environment and natural selection. He had stated that through the natural selection of beneficial traits, the inheritance of use and disuse would help in evolving a species to adapt to the surrounding conditions. Lamarck's theory on use and disuse of structures within the organism is clearly shown here in Darwin's work of the same manner, once again showing influence of Lamarck's inheritance of traits on Darwin's theory of natural selection.
The idea of use and disuse is directly the result of natural conditions in the environment. If an organism is better suited for the environment and has no use for a particular appendage, for instance, that appendage would eventually get weaker and weaker. Over time, that appendage would most likely start to become less and less apparent, maybe to the point that it may start to shrink. This idea, which Darwin advocated, was a theory of Lamarck.
When people talk of evolution, Darwin is usually a name that is mentioned most often. He was arguably the most popular mind in the field of evolution. However, he was not the only one, not by any stretch. Many scientists who specialized in evolution preceded him. Darwin's work was influenced by theses earlier evolutionists, and one of the most important people who directly influenced Darwin was Lamarck. Lamarck however, was not always entirely correct when it came to his theories on where a species came from, and how it got there. Using the work of Lamarck, Darwin was able to improve upon theories that had the right idea, but was curved by biblical belief or information unknown at the time, such as the possibility of a species going extinct. Lamarck's theories on inheritance of characteristics, transmutation and the use and disuse of internal structures can be seen in the preliminary ground work of Darwin's theory of natural selection, mutation of species and use and disuse of an organisms body parts. Darwin had revolutionized the belief in evolution and in doing so. He had brought back some theories that were not all that popular when they were first introduced. Great minds like Lamarck had influenced Darwin to show the world where it originated and how it progressed through the ages.
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