This was based on what little normative science could be carried out through crossing different animals. It was an accepted fact to many in the animal husbandry business. The first creative breakthrough occurred in 1868 when a young Swiss physician, Freiderich Meischer, isolated something that had not been seen before. This creative scientist isolated nucleic acid, a compound found in both DNA and RNA (Fredholm). This discovery sparked a quest to understand more about nucleic acid and its connection to Mendel's pea experiments just two years earlier. Mendel believed that the traits seen in peas were passed on through "packages" that contained the information (Fredholm). These packages later turned out to be DNA.
These discoveries led to the normal science processes and a quest to learn more about DNA and its connections to selective breeding. However, in mainstream practice, many had not heard of DNA yet, it had not reached the household term status that is has today. In practice, farmers and others in the animal husbandry business continued to produce better animals that same way that they had been doing it for thousands of years. The information and discoveries of Mendel and Miescher had not reached the level of common knowledge. It was not until the late 1940s that normal science began to explore DNA and its connection to life in earnest (Fredholm).
When the concept of DNA and its connection to life were first introduced in the late 1940s, many scientists refused to accept it, simply because it seemed too simple to explain the complexities of life on earth (Fredholm). However, this did not discover creative scientists such as Watson and Crick, who set out to solve the problem of the structure of DNA (Fredholm). They used stick and ball models to explore the double helix structure that is now so common that everyone immediately recognizes it. The normal science process continued with experiments that attempted to use X-rays to see through DNA (Fredholm).
In 1954, Pauling won a Nobel Prize for his work with chemical bonds and the structure of molecules and crystals (Fredholm). This work complimented the work done by Watson and Crick, providing another piece to the puzzle. The normative science portion of the paradigm shift then reached a frenzy, with work going on everywhere to try to understand the processes that were behind the secrets of life itself. However, these concepts, still were not household words.
Knowledge continued to build in regards to our understanding of how chemical bonds formed and combined in DNA to create life. In 1973, Herbert Boyer and Stanley Cohen used enzymes to cut bacteria and insert a strand of DNA in the gap (Fredholm). This was the first attempt at gene splicing. By this time, the concept of DNA was accepted as the new paradigm in bioengineering. The doubters of the late 1940s were gone and had been completely replaced by the acceptance of DNA as the basis for life. However, it turned out that it is not as "simple" as early critics of the new paradigm claimed.
By the early 1970s, anyone who openly doubted that DNA was the substance of life would be ridiculed and dismissed as a fool. The new paradigm had completely replaced the old one. This supports Kuhn's concept of incommensurability of the old and new paradigm. The old idea that DNA was not the source of life and the concept that DNA was the source of life could not exist at the same time. Since that time, normal science continues to unlock the genetic code. We now understand how specific DNA chains contribute to disease and the body's natural ability to heal.
Through an examination of the progression of thought about DNA and its connection to life, one can seen that Kuhn's concepts about scientific revolution apply. The field of bioengineering is a prime example of Kuhn's concepts in action. One can pinpoint the key paradigm shift regarding DNA to sometime between the late 1940s and the early 1970s. Considering that the concept of selective breeding has been around for thousands of years, this is relatively short time span for a complete reversal of old ideas. By the late 1990s, these concepts had become imbedded in the average American household and the public school system for mass dissemination.
One of the key cautions that must be mentioned regarding Kuhn's concepts is that it is retrospective and is not predictive. No one can predict in advance, where paths in the field of science may lead. However, Kuhn's theories can provide clues as to where we are in the process. We can describe the current state of a new field as being in its early normal science stage, or mature. As a new branch of science matures, it can be observed that the information moves from general to specific. This was seen in our example of bioengineering. During the late 1940s, the concepts being presented were general in nature. Now, the information available is highly specialized. Specialization is a function of the processes described by Kuhn. As a new field matures through normal science, it begins to split into specialties. This concept was not discussed by Kuhn, but it is the next logical step in the argument.
Perhaps eventually, the paradigms that we now have about DNA will be replaced by new paradigms. An examination of the history of thought in genetics and bioengineering support Kuhn's ideas about DNA and life on earth. Despite the critics of his theory, it is easy to see that the basic concepts of his theories can be supported by an examination of many field of science. Science is an ever-changing area where old ideas are continually being replaced by new ones. Kuhn's theory provides a map that can be used to follow these changes. This map can serve as a guide in many branches of the sciences.
Fredholm, L. The Discovery of the Molecular Structure of DNA - The Double Helix. 2003.