Darwin and Mendel: who was the pioneer of genetics?

Although Mendel is now widely recognized as the founder of genetics, historical studies have shown that he did not in fact propose the modern concept of paired characters linked to genes, nor did he formulate the two "Mendelian laws" in the form now given. Furthermore, Mendel was accused of falsifying his data, and Mendelism has been met with scepticism because of its failure to provide scientific explanation for evolution, to furnish a basis for the process of genetic assimilation and to explain the inheritance of acquired characters, graft hybridization and many other facts. Darwin was the first to clearly describe almost all genetical phenomena of fundamental importance, and was the first to present a developmental theory of heredity--Pangenesis, which not only greatly influenced many subsequent theories of inheritance, particularly those of de Vries, Galton, Brooks and Weismann, but also tied all aspects of variation, heredity and development together, provided a mechanism for most of the observable facts, and is supported by increasing evidence. It has also been indicated that Darwin's influence on Mendel, primarily from The Origin, is evident. The word "gene" was derived from "pangen", itself a derivative of "Pangenesis" which Darwin had coined. It seems that Darwin should have been regarded as the pioneer, if not of transmissional genetics, of developmental genetics and molecular genetics.     

Role of de Vries in the rediscovery of Mendel's paper. II. Did de Vries really understand Mendel's paper?

In this paper, we discuss briefly three of the several lines of evidence that we believe demonstrate de Vries's lack of understanding of Mendel's paper. In our view, at least part of de Vries's failure of understanding derives from the fact that he appears to have viewed Mendel's paper as being mainly about the inheritance of characters that was his own interest. Therefore, he looked at it to see whether Mendel had found any laws of inheritance. Mendel had done his research for another purpose, to find the laws describing the formation of hybrids and the development of their offspring. Thus, de Vries started his examination of Mendel's paper with a very fundamental misunderstanding of what it was about.     

Mendel, the empiricist

In contemporary texts in biology and genetics, Mendel is frequently portrayed as a theorist who was the father of classical genetics. According to some authors, he created his theory of inheritance to explain the results of his experimental hybridizations of peas. Others have proposed that he designed and carried out his experiments to demonstrate the correctness of a theory of inheritance he had already developed. We disagree strongly with these views of Mendel. Instead, we have come to regard him as an empirical investigator trying to discover the empirical natural laws describing the formation of hybrid peas and the development of their offspring over several generations. We have supported our view with an analysis of portions of Mendel's paper and his letters to Carl N ageli.     

L. H. Bailey's citations to Gregor Mendel

L. H. Bailey cited Mendel's 1865 and 1869 papers in the bibliography that accompanied his 1892 paper, Cross-Breeding and Hybridizing, and Mendel is mentioned once in the 1895 edition of Bailey's "Plant-Breeding." Bailey claimed to have copied his 1892 references to Mendel from Focke. It seems, however, that while he may have first encountered references to Mendel's work in Focke, he actually copied them from the Royal Society "Catalogue of Scientific Papers." Bailey also saw a reference to Mendel's 1865 paper in Jackson's "Guide to the Literature of Botany." Bailey's 1895 mention of Mendel occurs in a passage he translated from Focke's "Die Pflanzen-Mischlinge."     

Role of de Vries in the recovery of Mendel's work. I. Was de Vries really an independent discoverer of Mendel?

Recently, doubt has been cast on the view that de Vries developed the idea of disjunction independently of Mendel. Arguments are based on de Vries' own writings that showed the F2 data of his numerous crosses are reported as 3:1 ratios only after 1900. They also show that his theory of inheritance becomes quasi Mendelian only after 1900. The authors of this review paper cannot but agree with de Vries' critics that he did not develop his law of disjunction independently of Mendel. They also raise some questions that, hopefully, will lead to a reanalysis of de Vries' theory of inheritance in 1900.     

The real objective of Mendel's paper: A response to Monaghan and Corcos

Mendel's work in hybridization is ipso facto a study in inheritance. He is explicit in his interest to formulate universal generalizations, and at least in the case of the independent segregation of traits, he formulated his conclusions in the form of a law. Mendel did not discern, however, the inheritance of traits from that of the potential for traits. Choosing to study discrete non-overlapping traits, this did not hamper his efforts.     

On the origins of the Mendelian laws

The two laws usually attributed to Mendel were not considered as laws by him. The first law, the law of independent segregation occurs in Mendel's paper as an assumption or hypothesis. Hugo de Vries refers to this as a law discovered by Mendel. This appears to be the first use of an expression equivalent to Mendel's law. In his paper de Vries did not associate the observable characters with structures having a causitive role. That was done by Correns, who transformed the law of segregation of characters into a law of the segregation of anlagen. The second law, the law of independent assortment, is present in embryonic form in Mendel's paper. Here the independent assortment of characters appears as a secondary conclusion to a series of experiments involving several pairs of traits. Mendel repeats the primary conclusion later in the paper but not the secondary one. This leads us to believe that he considered the secondary conclusion as of lesser importance. We note in this context that the 9:3:3:1 ratio commonly associated with the idea of independent assortment, and attributed to Mendel, also does not occur in his paper. A careful reading of the papers of his discoverers shows it was Correns who first drew attention to this ratio. However, he did not formulate the second Mendelian law even though it was clearly implied. Neither was it stated by de Vries. Indeed, the first clear separation of the two laws and the naming of the second law was by T. H. Morgan some 13 years later.     

What about R.A. Fisher's statement of the "too good" data of J.G. Mendel's Pisum paper?

Mendel was accused by Fisher that his observed data, which corresponded to expectations, were too good to be true, and, further, that Mendel, growing only 10 plants per offspring, disregarded in his genotypical analysis the loss of recessives by assuming a ratio of 1:2 instead of 1.1126:1.8874. In contrast, it is proposed here that all chi-square statistics of genetic segregations fall short because the variance of genetic segregations is smaller and not of a binomial type as assumed. Furthermore, this variance and the corresponding chi-square statistics are not homogeneous in different segregation types. Consequently, it is not possible to summarize the different chi-square statistics as Fisher did. It is only in this way that he was able to obtain his unrealistic result (a probability of "seven times in 100,000 cases"). Regarding Fisher's second accusation, it should be taken into account that Mendel selected his 10 plants from offspring with a finite and not an infinite number of entities. Although this number is different from offspring to offspring, the average number is about 30. This means that the loss of recessives must be calculated by using a hypergeometric and not a binomial model as Fisher did. Consequently, the real deviation from the 1:2 ratio can be disregarded.     

Mendel's experiments: A reinterpretation

Conclusion My conclusion is that Mendel deliberately, though without any real falsification, tried to suggest to his audience and readers an unlikely and substantially wrong reconstruction of the first and most important phase of his research. In my book I offer many reasons for this strange and surprising behavior,⁵³ but the main argument rests on the fact of linkage. Mendelian genetics cannot account for linkage because it was based on the idea of applying probability theory to the problem of species evolution. Central to the theory is the law of probability according to which the chance occurrence of a combination of independent events is the product of their separate probabilities. This is the common basis of Mendel's first and second laws, but this is why Mendel's second law on independent assortment is enunciated in too general a way. From Morgan's work we now know that characters may not always be independent if their genes are located very close one to the other on the same chromosome. And this was also the basis of Mendel's personal drama: he surely observed the effects of linkage, but he had no theoretical tools with which to explain it. So he presented his results in a logical structure consistent with the central idea of his theory. Had he described the real course of his experiments he would have had to admit that his law worked for only a few of the hundreds of Pisum characters — and it would thus have been considered more of an exception than a rule. This is why he insisted on the necessity of testing the law on other plants, and this is why in his second letter to Carl Nägeli he admits that the publication of his data was untimely and dangerous.⁵⁴.We can argue that already in 1866 Mendel was less confident that his so-called second law had the same general validity as the first — and that later he lost his confidence altogether. Contemporary testimony indicates that in the end he became as skeptical as all his contemporaries as to the scientific relevance of his theory.⁵⁵ But he was wrong. His research is in no way the fruit of methodological mistakes or forgery, and it remains a landmark in the history of science. He was only the victim of a strange destiny in which the use of probability theory was responsible, at the same time, for the strength and for the weakness of his theory. We must still consider him the father and founder of genetics.     

An undignified bioethics: there is no method in this madness

In a recent article, Alasdair Cochrane argues for the need to have an undignified bioethics. His is not, of course, a call to transform bioethics into an inelegant, pathetic discipline, or one failing to meet appropriate disciplinary standards. His is a call to simply eliminate the concept of human dignity from bioethical discourse. Here I argue that he fails to make his case. I first show that several of the flaws that Cochrane identifies are not flaws of the conceptions of dignity he discusses but rather flaws of his, often problematic, understanding of such conceptions. Second, I argue that Cochrane's case against the concept of human dignity goes too far. I thus show that were one to agree that these are indeed flaws that require that we discard our ethical concepts, then following Cochrane's recommendations would commit us not only to an undignified bioethics, i.e. a bioethics without dignity, but to a bioethics without much ethics at all.     

The evolutionary ideas of F. M. (Ladimir) Klacel, teacher of Gregor Mendel

Abstract: A philosopher and teacher, F. M. (Ladimir) Klacel (1808-1882), educated in what is now the Czech Republic, developed his own explanation for the origin and interaction of living organisms. Klácel, a member of the Augustinian Monastery in Brno, influenced his younger colleague, Friar Gregor Mendel, who went on to formulate concepts in heredity that are still recognized for their profound insight. A mutual interest in the natural sciences of these two friends provided a basis for their discussions of the relationship between religion, evolution, and society. Klacel's outspoken defense of his proposals caused him to lose favor with both the Church and the authorities, and he immigrated to America in 1869. His failing health and inability to communicate with the English-speaking populace, unfortunately, limited his influence in his new environs. In this paper we trace the roots of Klacel's philosophy and elucidate his incorporation of ideas from Hegel, Darwin, and others. An investigation of Klacel's recipe for a successful society reveals his belief in the universality of life and his optimistic hope for human achievement.     

Chi-square and Mendel's experiments: where's the bias?

Mendel has been accused of "cooking" his data to meet a particular hypothesis. The earliest time he could have formulated an hypothesis in the course of his experiments was at the end of the second year of experiments 1 and 2. If he knew what to expect as the result of his first two pea-seed experiments, one might expect the chi-square values of subsequent experiments to exhibit a trend toward smaller values. However, when the individual experiments are, each in turn, subjected to a chi-square test, there is no evidence of the expected trend. With few exceptions, the data show no systematic variation in a particular direction. In our view, the suggestion of bias is not supported.     

‘Further Development’ of Mendel’s legacy? Erich von Tschermak-Seysenegg in the context of Mendelian–biometry controversy, 1901–1906

The contribution of Erich von Tschermak-Seysenegg (1871?C1962) to the beginning of classical genetics is a matter of dispute. The aim of this study is to analyse, based on newly accessible archive materials, the relevance of his positions and theoretical views in a debate between advocates of early Mendelian explanation of heredity and proponents of biometry, which took place in England around 1901?C1906. We challenge not only his role of an ??external consultant??, which at the time de facto confirmed his status of ??rediscoverer?? of Mendel??s work but also analyse his ambivalent positions which are to be seen as a part of ??further development?? (Weiterführung), a development of Mendel??s legacy as he understood it. Second, there is an interesting aspect of establishing connections within an ??experimental culture?? along the Mendel??s lines of thought that was parallel to the first step of institutionalizing the new discipline of Genetics after 1905/06. Part of the study is also the analysis of contribution of his older brother Armin von Tschermak-Seysenegg (1870?C1952) who??much like in the case of ??rediscovery?? of 1900?C1901??was for his younger brother an important source of theoretical knowledge. In this particular case, it regarded Bateson??s ??Defence?? of Mendel from 1902.     

Lorenz Hiltner, a pioneer in rhizosphere microbial ecology and soil bacteriology research

Lorenz Hiltner is recognized as the first scientist to coin the term “rhizosphere” in 1904. His scientific career and achievements are summarized in this essay. Most of his research he performed in the Bavarian Agriculture–Botanical Institute (later named the “Bavarian Institute of Plant Growth and Plant Protection”) in Munich, where he was the director from 1902 to 1923. Beginning with intensive and thorough investigations on the germination and growth of different crop plants (legumes and non-legumes) Hiltner became convinced, that root exudates of different plants support the development of different bacterial communities. His definition of the “rhizosphere” in the year 1904 centered on the idea, that plant nutrition is considerably influenced by the microbial composition of the rhizosphere. Hiltner observed bacterial cells even inside the rhizodermis of healthy roots. In analogy with fungal root symbionts, Hiltner named the bacterial community that is closely associated with roots “bacteriorhiza.” In his rhizosphere concept, Hiltner also envisioned, that beneficial bacteria are not only attracted by the root exudates but that there are also “uninvited guests,” that adjust to the specific root exudates. Based on his observations he hypothesized that “the resistance of plants towards pathogenesis is dependent on the composition of the rhizosphere microflora.” He even had the idea, that the quality of plant products may be dependent on the composition of the root microflora. In addition to his scientific achievements, Hiltner was very dedicated to applied work. Together with F. Nobbe he had the first patent on Rhizobium inoculants (Nitragin). He continuously improved formulations and the effectivity of the Rhizobium preparations and he also initiated seed dressing with sublimate for plant protection of seedlings. Thus, Hiltner tightly linked breakthroughs in basic research to improved rhizosphere management practices. In addition, he wrote a pioneering monograph on plant protection for everybody’s practical use. His emphasis on understanding microbes in the context of their micro-habitat, the rhizosphere, made him a pioneer in microbial ecology. Even now, in the era of genome and postgenome analysis with our better understanding of plant nutrition and soil bacteriology, his ideas and contributions are as fresh as they were more than 100 years ago.     

Sercarzian immunology--In memoriam. Eli E. Sercarz, 1934-2009

During his long career as a principal investigator and educator, Eli Sercarz trained over 100 scientists. He is best known for developing hen egg white lysozyme (HEL) as a model antigen for immunologic studies. Working in his model system Eli furthered our understanding of antigen processing and immunologic tolerance. His work established important concepts of how the immune system recognizes antigenic determinants processed from whole protein antigens; specifically he developed the concepts of immunodominance and crypticity. Later in his career he focused more on autoimmunity using a variety of established animal models to develop theories on how T cells can circumvent tolerance induction and how an autoreactive immune response can evolve over time. His theory of "determinant spreading" is one of the cornerstones of our modern understanding of autoimmunity. This review covers Eli's entire scientific career outlining his many seminal discoveries.     

A tribute to Thomas Roosevelt Punnett, Jr. (1926-2008)

We honor here Thomas (Tom) Roosevelt Punnett, Jr. (May 25, 1926–July 4, 2008), who was a pioneer of Biology, particularly of biochemistry of plants and algae, having specialized in photosynthesis under Robert Emerson of the University of Illinois at Urbana-Champaign. He did exciting work on regulation and control of various metabolic reactions. He was an innovator and raconteur par excellence, and he prized critical thinking. His enthusiasm for basic science questions was matched by his grasp of their “real-world” implications. His last project was a patent for anaerobic sewage treatment that he hoped would lead to solution of waste disposal and energy creation world wide, including the clean-up of Lake Erie, where he had sailed as a boy. On the personal side, he had a strong sense of morality and a great wit and humor.     

From the laboratory to the patient and back--an interview with Marc Mareel. Interview by Marc E. Bracke

The career of Marc Mareel is a synthesis of scientific research and clinical activity. During his medical studies, he already made his first enthusiastic steps in research via experimental work on avian developmental biology. Later, during his training as a radiotherapist, he founded his own laboratory for experimental cancer research. There he built up his international reputation as a pioneer in invasion research. Although invasion is the hallmark of tumor malignancy, he also kept an open mind about invasion in non-cancer conditions, such as in placental behavior, developmental biology, immunology and parasitology. His contribution to our understanding of invasion mechanisms has been both technical and conceptual. A number of assays have been developed in his lab, such as the embryonic chick heart and collagen gel invasion models, that have been (and still are) useful for many other research teams. He also contributed to the discovery of a number of key elements in the process of invasion, such as the stromal influence (including its extracellular matrix) and the cadherin family of cell-cell adhesion molecules. Concerning metastasis formation, he developed the original concept that a number of interacting eco-systems are implicated, such as the primary tumor, regional lymph nodes, the bone marrow and the (pre)metastatic niches in distant organs. Since his retirement, Marc Mareel has continued to integrate clinical practice with research creativity. He favours the idea of translational research bringing the results of laboratory findings to medical applications, and exploiting the feedback to the laboratory. The team in the Laboratory of Experimental Cancer Research at Ghent University currently consists of about 25 collaborators, who continue to appreciate his inspiring ideas and suggestions.     

George I. Finch and his pioneering use of oxygen for climbing at extreme altitudes.

George Ingle Finch (1888-1970) was the first person to prove the great value of supplementary oxygen for climbing at extreme altitudes. He did this during the 1922 Everest expedition when he and his companion, Geoffrey Bruce, reached an altitude of 8,320 m, higher than any human had climbed before. Finch was well qualified to develop the oxygen equipment because he was an eminent physical chemist. Many of the features of the 1922 design are still used in modern oxygen equipment. Finch also demonstrated an extraordinary tolerance to severe acute hypoxia in a low-pressure chamber experiment. Remarkably, despite Finch's desire to participate in the first three Everest expeditions in 1921-1924, he was only allowed to be a member of one. His rejection from the 1921 expedition was based on medical reports that were apparently politically biased. Then, following his record ascent in 1922, he was refused participation in the 1924 expedition for complex reasons related to his Australian origin, his forthright and unconventional views, and the fact that some people in the climbing establishment in Britain saw Finch as an undesirable outsider.