2011/10/17 by D. J. Galton · 1 citation
Agricultural and Biological Sciences · #Plant and animal studies
paper · pdf · doi:10.1093/qjmed/hcr195
openalex publication_date 2011/10/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
In 1936 Professor R. A. Fisher (1890–1962) published a 26-page article1 criticizing Mendel's publication of 1866 entitled Versuche uber Pflazen-Hybriden2 (Experiments in Plant-Hybridization). He accuses Mendel (1822–84) of falsifying his data. Fisher had worked through most of Mendel's results over the 8-year period of experiments to calculate the deviations of expected numbers of different progeny types from those actually observed, based on the relevant sample sizes. For example, he calculated from the F2 hybridization experiments of the year 1858 that 258 plants gave 8023 seeds of which 6022 were yellow compared with 2001 that were green. Fisher states that the deviation (that is 0.009) from the expected ratio of 3:1 is less than the standard error of random sampling; therefore there may have been manipulation of the data sets by someone. Nor did Mendel test the significance of the deviations from the expected ratio of 3:1 but states it as 3.009:1 without giving any probable error, either absolute or relative. Fisher points out that tests of significance of deviations from expectations in a binomial series were familiar to mathematicians since the middle of the 18th century. (Incidentally Fisher's article failed to comment on a paper by Tschermak3 of 1900 where the difference between observed and expected ratios was even smaller than Mendel's, the observed ratio being 3.008:1 giving a difference of 0.008 from expected4). As a result of Fisher's calculations, and without access to Mendel's laboratory notebooks, he directs a stream of pejorative remarks at Mendel's work. To give a verbatim sample of these: … it can be shown that Mendel left unaccounted, or at least unpublished far more material than appears in his paper … this course would seem to imply as much foreknowledge of the outcome as if he had deliberately chosen unifactorial crosses … … this would be intellible if the ‘experiments’ reported in the paper were fictitious being in reality themselves summaries … of aggregate frequencies from different experiments. … he [Mendel] is taking, as redacteur, excessive and unnecessary liberties with the facts. ; if his facts have suffered much manipulation the style of his report must be judged as disingenuous. There can be no doubt that the data from later years of the experiments have been biased strongly in the direction of agreement with expectation. This bias seems to pervade the whole data … . … , it remains a possibility, among others, that Mendel was deceived by some assistant who knew too well what was expected. This possibility is supported by independent evidence that the data of most, if not all, of the experiments have been falsified so as to agree closely with Mendel's expectations. Fisher makes it sound as though Mendel has committed some sort of crime against science to have imagined how inheritance works; and then to publish some data, even if partial, to support his ideas. Without the original laboratory note-books it is impossible to know if any data sets were discarded, perhaps because of stunted growth of the hybrids, attack by parasites or even because of too small a progeny. If such data sets were discarded, were steps taken to adjust for introducing bias by discarding data sets that supported expectations? If so, this would not be counted by many as falsification; and without the laboratory note books, destroyed after Mendel's death, it is impossible to know what was done. A balance has to be maintained between ideas and facts; but without insight, facts can be a meaningless jumble of measurements. Intuition (not meaning idée fixe) is perhaps the greatest gift a scientist can have if he wants to present a new viewpoint; how can it be done by the data alone? Mendel, a contempory of Darwin (1809–82), probably pondered on this famous scene described in Origin of Species:5 It is interesting to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complete a manner, have all been produced by laws acting around us. These laws taken in the largest sense, being Growth with Reproduction; Inheritance which is implied by reproduction… . Mendel did more than contemplate this tangled scene. Out of its complexity he abstracted the key elements that explain some basic aspects of reproductive inheritance; he disentangled some of the first principles of heredity and gave us a glimpse into a new aspect of the truth that would open up a whole new field of endeavour. It is remarkable that such a simple algebraic formulation, resembling a binomial expansion, could be found to describe so accurately such a complex set of relationships as the formation of gametes, pollination, fertilization of the ovum and transmission of certain characters to the progeny. In the paper of 1866, Mendel2 published the right hand side of the equation showing the distribution of hereditary factors (the word gene had not been coined as yet) to the progeny. But he described the left hand side of the equation in a diagram; namely that hereditary factors come in pairs, one from each parent and that the hereditary factors randomly segregate into the gametes. This was done at a time before chromosomes had been discovered, before the concept of gene had been formulated; and there was no knowledge of meiotic division of germ cells into gametes. The ability to isolate the critical elements of a complex problem and to see the numerical relationships between these elements and the observable phenomena is one of the highest gifts a scientist can hope to have. Mendel showed a supreme effort of abstraction, imagination and concentration to pursue his 8 years of experimentation in solitude; sadly after which he was elected Abbot of his Augustinian monastery when the experiments were discontinued as he took up his administrative duties. There is no logical path to the principles he uncovered, they arise by intuition framing the right concepts based on a sympathetic interpretation of the experimental results. The ability to foresee these invariant relationships amidst a welter of apparently unrelated facts and to express them mathematically is more than equal to the creative works of any of our greatest artists. Before Fisher attacked the results of Mendel's paper of 1866 perhaps he should have turned his critical attention to Newton's First Law of Motion. This states: Every body continues in its state of rest or of uniform motion in a straight line, unless it is compelled to change that state by forces impressed upon it.6 This Law should perhaps be blazoned above the entrance of every serious research laboratory as it demonstrates the needs for both data and intuition. Newton (1642–1727) had data supporting the first part of the Law; but not a shred of experimental evidence for the second part, that is uniform motion in a straight line; which he based primarily on observing the passage of comets across the night sky. He just imagined it must be true. And he was correct; hence our ability to send spacecrafts to Mars. Equally we know that Mendel was correct. Both might then, on occasion, have agreed with the sentiments of William Blake (1757–1827) that ‘I will not reason and compare; my business is to create’.7 Grateful thanks are due to Professor John Beardmore and Professor John Walker-Smith for helpful criticisms.