Early 20th-century research at the interfaces of genetics, development, and evolution: Reflections on progress and dead ends

AbstractThree early 20th-century attempts at unifying separate areas of biology, in particular development, genetics, physiology, and evolution, are compared in regard to their success and fruitfulness for further research: Jacques Loeb's reductionist project of unifying approaches by physico-chemical explanations; Richard Goldschmidt's anti-reductionist attempts to unify by integration; and Sewall Wright's combination of reductionist research and vision of hierarchical genetic systems. Loeb's program, demanding that all aspects of biology, including evolution, be studied by the methods of the experimental sciences, proved highly successful and indispensible for higher level investigations, even though evolutionary change and properties of biological systems up to now cannot be fully explained on the molecular level alone. Goldschmidt has been appraised as pioneer of physiological and developmental genetics and of a new evolutionary synthesis which transcended neo-Darwinism. However, this study concludes that his anti-reductionist attempts to integrate genetics, development and evolution have to be regarded as failures or dead ends. His grand speculations were based on the one hand on concepts and experimental systems that were too vague in order to stimulate further research, and on the other on experiments which in their core parts turned out not to be reproducible. In contrast, Sewall Wright, apart from being one of the architects of the neo-Darwinian synthesis of the 1930s, opened up new paths of testable quantitative developmental genetic investigations. He placed his research within a framework of logical reasoning, which resulted in the farsighted speculation that examinations of biological systems should be related to the regulation of hierarchical genetic subsystems, possibly providing a mechanism for development and evolution. I argue that his suggestion of basing the study of systems on clearly defined properties of the components has proved superior to Goldschmidt's approach of studying systems as a whole, and that attempts to integrate different fields at a too early stage may prove futile or worse

Interview with Eric Davidson

1. MBL Woods Hole, U. Penn, Rockefeller Institute-Becoming a molecular biologist of early development Ute: I want to start at the very beginning of your scientific biography. I have read that as a high-school pupil you spent some time at Woods Hole Marine Biological Laboratory. Eric: I went to a very primitive high school, nothing that today would be regarded as acceptable science teaching whatsoever. But there was one wonderful woman whose name was Miss Krum; she probably was educated around 1910. I went to high school in 1950, and I graduated in'54. Miss Krum taught the biology class, which was in 10th grade. So that was 1951. She was an elderly lady with grey hair. When I came in on the first day of class, I said, “Miss Krum, I'll make an arrangement with you. I'll make all the laboratory preparations for the whole class, for the whole year, if I don't have to take any examinations except the final.” She looked at me and said, “Do you know how to use a microscope, young man?” I said, “Yes, ma'am.” Because one of my father's friends had given me that for a Christmas present a few years earlier, I knew a little bit about using a microscope. So she said, “Well, you go home and make some preparations and show them to me tomorrow morning.” I took some Paramecium and other stuff and stained them with permanganate, and she said, “Very well, young man.” The result of that was that I became completely fascinated with biology, looking at all of these wonderful things that we had to show the class the whole year

SCIENCE AND POLITICAL IDEOLOGY The example of Nazi Germany

Although in their basic framework Nazi anti-Semitic and racist ideology and policies were not grounded in science, scientists not only supported them in various ways, but also took advantage of them, for example by using the new possibilities of unethical experimentation in humans that these ideologies provided. Scientists' complicity with Nazi ideology and politics does, however, not mean that all sciences in Nazi Germany were ideologically tainted. I argue, rather, that despite the fact that some areas of science continued at high levels, science in Nazi Germany was most negatively affected not by the imposition of Nazi ideology on the conduct of science but by the enactment of legal measures that ensured the expulsion of Jewish scientists. The anti-Semitism of young faculty and students was particularly virulent. Moreover, I show that scientists supported Nazi ideologies and policies not only through so-called reductionist science such as eugenics and race-hygiene, but also by promoting organicist and holistic ideologies of the racial state

Self-Organization and Genomic Causality in Models of Morphogenesis

The debate about what causes the generation of form and structure in embryological development goes back to antiquity. Most recently, it has focused on the divergent views as to whether the generation of patterns and form in development is a largely self-organized process or is mainly determined by the genome, in particular, complex developmental gene regulatory processes. This paper presents and analyzes pertinent models of pattern formation and form generation in a developing organism in the past and the present, with a special emphasis on Alan Turing’s 1952 reaction–diffusion model. I first draw attention to the fact that Turing’s paper remained, at first, without a noticeable impact on the community of biologists because purely physical–chemical models were unable to explain embryological development and often also simple repetitive patterns. I then show that from the year 2000 and onwards, Turing’s 1952 paper was increasingly cited also by biologists. The model was updated to include gene products and now seemed able to account for the generation of biological patterns, though discrepancies between models and biological reality remained. I then point out Eric Davidson’s successful theory of early embryogenesis based on gene-regulatory network analysis and its mathematical modeling that not only was able to provide a mechanistic and causal explanation for gene regulatory events controlling developmental cell fate specification but, unlike reaction–diffusion models, also addressed the effects of evolution and organisms’ longstanding developmental and species stability. The paper concludes with an outlook on further developments of the gene regulatory network model

Ute Deichmann to Viktor Hamburger, March 30, 1991

Request for information about the history of experimental embryology and neuroembryology in Germany and the United StatesCorrespondenc

Ute Deichmann to Viktor Hamburger, March 12, 1991

Follow-up questions for Hamburger after his initial responses about his experiences in experimental embryology and neuroembryology in Germany and the United StatesHamburger's initial responses attachedCorrespondenc