Gerald Maurice Edelman
(1929 - 2014)
Gerald Maurice Edelman was born on July 1, 1929, in New York City. In 1950, Edelman received the B.S. degree from Ursinus College in Pennsylvannia. He then attended the University of Pennsylvannia and obtained his M.D. degree from the Medical School in 1954. A year later, he joined the U.S. Army and became a Captain in the Medical Corps and practiced in a Station Hospital in Paris, France. In 1957, he became a graduate student at the Rockefeller Institute, receiving his Ph.D. in 1960. Following graduation, he was appointed Assistant Dean of Graduate Studies at the Rockefeller Institute. From 1963 to 1966, Edelman became the Associate Dean of Graduate Studies. Since 1966, he has been a professor at the Rockefeller University.
Edelman won the Nobel Prize in Physiology or Medicine in 1972 for his work on the immune system. He is noted for his theory of mind, published in a trilogy of technical books. His work Topobiology contains a theory of how the original neuronal network of a newborn's brain is established during development of the embryo. Neural Darwinism contains a theory of memory that is built around the idea of plasticity in the neural network in response to the environment. The Remembered Present contains a theory of consciousness.
Edelman has asked whether we should attempt to construct models of functioning minds or models of brains which, through interactions with their surroundings, can develop minds? Edelman's answer is that we should make model brains and pay attention to how they interact with their environment. Edelman accepts the existence of qualia and incorporates them into his brain-based theory of mind. His concept of qualia avoids the pitfalls of the idea of special qualia with non-functional properties, which was criticized by Daniel Dennett.
Edelman expounds a biological theory of consciousness, which he explicitly locates within Darwin's Theory of Natural Selection and Darwinian theories of population dynamics. He rejects dualism and also dismisses newer hypotheses such as the so-called 'computational' model of consciousness, which liken the brain's functions to the operations of a computer.
Edelman argues that the mind and consciousness are wholly material and purely biological phenomena, occurring as highly complex cellular processes within the brain, and that the development of consciousness and intelligence can be satisfactorally explained by Darwinian theory.
Gerald Edelman is the founder and director of The Neurosciences Institute, a nonprofit research centre in San Diego that studies the biological basis of higher brain function in humans.
The following press release from the Royal Swedish Academy of Sciences describes Edelman's work
“Antibodies is the collective name of a group of blood proteins that play an important part in the defense against infections and in the development of several different diseases. Up to the year 1959 our knowledge of their nature and mode of function was very vague and incomplete, in spite of a century of research. This year, however, Edelman and Porter independently presented the first results of investigations that within a few years were to lead to a practically complete clarification of the most essential questions concerning the nature of these substances.
Antibodies form giant molecules and for this reason a study of them is difficult. In order as far as possible to facilitate their task both scientists looked for methods to split the large molecules into well defined fragments that, it was hoped, would prove to be more easily handled.
Porter aimed at separation of those parts of the molecule that are responsible for the capacity of the antibody to react specifically and combine with that foreign substance, that antigen to which it is specifically fitted. He found that this indeed could be done with the aid of the protein splitting enzyme papain. For several reasons it had earlier been assured that the most common type of antibody would carry two identical combining sites. Porter in fact found that the molecule split into three fragments, two smaller very similar ones, both with capacity of combining with the antigen, and one larger one lacking this capacity.
Edelman's point of departure was the assumption that the antibody like most biologically active proteins might be composed of a number of chain structures, held together by cross-links of some kind, most probably sulfur bonds. Therefore he tested methods that might cause breaks of such cross-links and he succeeded in dividing the molecule into several separate chains. None of these fragments had retained the specific reactivity of the antibody.
Later both Porter and Edelman could show that the antibody molecule is composed of two pairs of chains, two so-called "light" ones and two about twice as long "heavy" chains. Porter was then able to build a model of the molecule which has since been generally accepted and successively fitted with additional details. According to Porter the antibody molecule is shaped like the letter Y. The two branches are formed each by one light and the fore part of a heavy chain; in the stem the remainder of the heavy chains are to be found. The various chains run side to side, held together by a number of sulfur links. Thus the capacity of specific combination, which is associated with the structure of the tips of the branches, rests on a co-operation between the free ends of the light and the heavy chain, each one by itself inactive.
There exist several main classes of antibodies with different functions and characteristics. All of them carry principally the same kind of light chains, whereas the heavy ones are characteristic of each class. The hind parts of the heavy chains in the stem of the Y determine certain features of the antibodies' behavioral patterns, i.e. the capacity of activating the so-called complement system which for instance can dissolve and destroy cells or microorganisms with which the antibody has reacted. In this region, furthermore, those chemical groups are located which determine whether the antibody will be able to penetrate certain membranes, e. g. through the placenta from mother to fetus.
The impact of Edelman's and Porter's discoveries is explained by the fact that they provided a clear picture of the structure and mode of action of a group of biologically particulary important substances. By this they laid a firm foundation for truly rational research, something that was previously largely lacking in immunology. Their discoveries represent clearly a break-through that immediately incited a fervent research activity the whole world over, in all fields of immunological science, yielding results of practical value for clinical diagnostics and therapy.”
Sources: Nobelprize.org, Wikipedia, Nobel Prize Biography