by M. Eileen Magnello
© Oxford University Press 2004 All rights reserved
Weldon, Walter Frank Raphael (1860-1906), zoologist and biometrician, was born on 15 March 1860, at Highgate, Middlesex, the second child of the journalist and industrial chemist Walter Weldon (1832-1885) and his wife, Anne Cotton (d. 1881). His father's wealth came from his patents of the manganese regeneration process and the magnesia chlorine process. The family moved so frequently that Weldon's early education was desultory until he was sent to a boarding-school at Caversham, near Reading, in 1873. He spent some months in private study before matriculating at University College, London in the autumn of 1876 with the intention of pursuing a medical career. During his time at University College he acquired a respectable knowledge of mathematics from the Danish mathematician Olaus Henrici, and attended the lectures of the zoologist E. Ray Lankester as well as those of the botanist Daniel Oliver. In the following year he transferred to King's College, London, and stayed for two terms. He was admitted to St John's College, Cambridge, as a bye-term student on 6 April 1878.
Once at Cambridge, Weldon met the zoologist Francis Maitland Balfour and subsequently gave up his medical studies for zoology. Weldon became an exhibitioner in 1879 and a scholar in 1881 (when he also gained a first-class degree in the natural sciences tripos). In the autumn of the latter year he left for the Zoologica Stazione in Naples to begin the first of his studies in marine biological organisms. On returning to Cambridge in September 1882 he became a demonstrator for Adam Sedgwick. Six months later, on 14 March 1883, Weldon married Florence Joy Tebb (d. 1936). In April 1884 he was elected to a fellowship at St John's College and appointed university lecturer in invertebrate morphology. Weldon was one of the founding members of the Marine Biological Station in Plymouth in 1884 along with Lankester, Sedgwick, William Turner Thistleton-Dyer, Michael Foster, and J. Burdon Sanderson. From 1887 until 1891 Weldon lived in Plymouth during June to December, and he stayed in Cambridge in the Lent and May terms.
From 1887 Weldon's work was centred around the development of a fuller understanding of marine biological phenomena and, in particular, the examination of the relationship between various organs of crabs and shrimps to determine selective death rates in relation to the laws of growth. Some of his early work at the Marine Biological Station involved the breeding of the common lobster and the rock lobster or craw fish (Palinurus). In 1887 he started a notebook to study the classification, morphology, and the development of various species of Decapod crustacea (including the Plymouth shore crab, lobsters, shrimp, and prawns). His only work on invertebrate morphology contained an account of the early stage of segmentation and the building of the layers of shrimp. Weldon was both a master of histological techniques and a powerful and accurate draughtsman.
Some time in 1889 Weldon read Francis Galton's Natural Inheritance. In this book Galton had shown that the frequency distributions of the average size of certain organs in man, plants, and moths were normally distributed. Similar investigations had been pursued by the Belgian statistician Adolphe Quetelet whose work was confined to 'civilised man'. Weldon was interested in investigating the variations in organs in a species living in a wild state which were acted upon by natural selection and other influences. His first attempts to find a working hypothesis for variation within Darwin's theories were morphological and embryological. Neither approach enabled him to examine the variation that Darwin emphasized. Galton's Natural Inheritance had, however, suggested to Weldon the possibility of a statistical approach for the analysis of biological variation.
When Galton was writing on heredity in 1889 he predicted that selection would not change the shape of the normal distribution; he expected that the frequency distributions of any given characteristic would remain normally distributed in all cases, whether or not animals were under the action of natural selection. Weldon then began to study the variation of four organs in the common shrimp (Crangon vulgaris) and he collected five samples from waters fairly distant from Plymouth. His statistical analysis published in 1890 confirmed Galton's prediction. Shortly after the paper was published Weldon was elected a fellow of the Royal Society.
In the summer of 1890 Weldon was appointed to succeed E. Ray Lankester in the Jodrell chair of zoology at University College, London. Soon after he took up the post, in 1891, he joined the association for promoting a professorial university of London. It was at this time when he met the biometrician and statistician Karl Pearson (who had been appointed professor of applied mathematics and mechanics at University College in 1884). Weldon, Pearson, and George Carey Foster drafted the scheme of the proposed Association for Promoting a Professorial University for London. The main idea was to unite all the London lecturers so that the separate colleges would then become absorbed. Weldon was a tireless campaigner and his commitment to Pearson marked the beginning of a lifelong friendship. Their relationship could be characterized by an emotional and intellectual intimacy that engendered a symbiotic alliance. It is thus not surprising that one of the most extensive sets of letters in Pearson's archives are those of Weldon and his wife, Florence--consisting of nearly 1000 pieces of correspondence.
During the Easter vacation of 1892 Weldon and his wife went to Malta and the Bay of Naples to collect 23 measurements from 1000 adult female shore crabs (Carcinus moenas). Over the course of the summer they calculated crab measurements at the biological station in Naples. Weldon discovered that all but one of the 23 characters he measured in the Naples group were normally distributed: he found that the frontal breadth of the carapace was instead a double humped (bi-modal) curve. His first attempt to interpret the data involved breaking up the curve into two normal distributions as Galton had advocated. Weldon then approached Pearson for assistance with interpreting his data. At that time, Pearson was teaching applied mathematics to engineering students at University College and was also giving geometry lectures at Gresham College.
By the end of 1892 Pearson began to devise a probability system of curve fitting for Weldon's data, and he used this material in his Gresham lectures in the following year. Weldon's attempt to break up his double humped curve into two normal components seems to have been derived from Galton's belief that all biological characteristics should be normally distributed. Weldon also seems to have been exploring Galton's claims that a new species could be established only by a 'hopeful monster' or saltation (sudden evolutionary change) producing a new type (that is, instantaneous speciation). Up until the middle of the nineteenth century species were defined in terms of types or essences by a consistent majority of naturalists. Weldon and Pearson developed a more gradualistic approach to understanding the process of species divergence than that of Galton and a number of other biologists. When they first examined the double humped curve, they were trying to detect two curves produced by the intermingling of populations corresponding to parent and saltated form. Weldon's finding of the double humped curve in the distribution of the forehead of the carapace of the Plymouth shore crab led to his first project for the evolution committee of the Royal Society in 1894 when he hoped to have found dimorphism in herring as well. After Weldon discovered that his measurement from his herring data did not indicate that all the characters of the herring were dimorphic, neither he nor Pearson pursued any further work on speciation.
Charles Darwin's recognition that species comprised different sets of statistical populations, rather than types or essences, prompted a reconceptualization of statistical populations by Pearson and Weldon. Moreover, this required the use of new statistical methods, and, largely owing to Weldon's influence, Pearson founded biometrics (though some of the statistical work of John Venn and Francis Ysidro Edgeworth played a role in Pearson's early work on probability). Weldon's influence in the emergence and development of Pearsonian statistics was paramount; he also offered continual moral support and promulgated the Pearsonian corpus of statistics throughout the 1890s and until his death in 1906. From the joint biometrical projects they undertook Pearson went on to develop the modern theory of mathematical statistics.
Weldon's most fruitful venture with Pearson came about when he demonstrated empirical evidence of natural selection in the forehead of the carapace of the shore crab at Plymouth Sound. In 1894 the primary source of evidence of natural selection acting upon biological variation had been established by Henry Bates with his work on mimicry. In the same year Weldon was drawn to looking at changes in the shore crab because Plymouth Sound had undergone environmental changes after a breakwater had been built in the middle of the nineteenth century. When the fine china clay which came down from Dartmoor in rainy weather was carried into the sea, the breakwater increased the amount of clay that settled into the sound. Moreover, the great dockyard in Devonport was expanded, which led to an increase in the size of the population; subsequently, the sound became polluted from the sewage that spilled into the sea. In the summer of 1895 Weldon collected 600 female shore crabs and measured the frontal breadth of these crabs and he found that the fine china clay was a selective agent. The mortality rate was greatest for crabs whose frontal breadth was narrower. The process by which natural selection was affected was thought to be largely associated with the way in which crabs filtered the waters entering their gill chambers. A narrow frontal breadth seems to have made one part of the process of filtration of water more efficient than in crabs with larger frontal breadths. Five years later Weldon undertook further research on the structure of the whorls in snails Clausilia laminata (Montagu) which has been considered to be some of his most convincing work in pointing to empirical evidence of natural selection.
In his presidential address to the zoological section of the British Association in 1898, Weldon introduced the corpus of Pearsonian statistics to a group of zoologists. He demonstrated two statistical innovations: the first involved using the standard deviation as a statistical method to express the full range of organic variation for a variety of biological characteristics. Second, he emphasized the necessity for using the relative frequency approach to probability by showing how probability could be used for curve fitting. Weldon then urged all zoologists who professed to have a genuine interest in animal evolution to use the statistical machinery devised by Pearson. Weldon also introduced the idea of a negative correlation when Pearson was working out the mathematical properties of simple correlation and regression in 1896. (Galton had used positive correlations only.)
When Weldon moved to Oxford in 1899 to take up the Linacre chair of comparative anatomy he carried on the biometric tradition by gathering a number of students who began to look for empirical evidence of natural selection acting upon various animals and plants. Despite Weldon's move he made arrangements to be with Pearson every year during the Easter and Christmas vacations and throughout the summer months. During the summer, they spent most weekends in Oxfordshire or in London near Pearson's home in Hampstead. They continued their collaborative work investigating biometrical problems such as natural selection, inheritance and, in particular, Mendelian inheritance. Following a much heated debate initiated by William Bateson on one of Pearson's papers on inheritance at the Royal Society on 15 November 1900, Weldon suggested to Pearson that they start their own journal for papers dealing with matters of statistical biology. Galton acted in consultation and Pearson named the new journal Biometrika.
In October 1900 Weldon began to analyse Gregor Mendel's results of three of the seven sets of discrete characters of the common sweet pea (Pissum sativum) on the assumption of phenotypic dominance and independent assortment. He did not challenge Mendel's integrity or the results, but only the interpretation and universality of the findings. He also regarded Galton's ancestry as an essential component to Mendelism. Weldon's statistical interpretation of Mendel's data led Bateson to publish his fiercely polemical 100-page chapter to 'defend Mendel from Professor Weldon' (W. Bateson, Mendel's Principles of Heredity. A Defence, 1902, viii). Bateson's criticisms seem actively to have discouraged Weldon from adopting virtually any aspect of Bateson's work. Nevertheless Weldon continued to work on determining the relationship between Mendel and Galton's ancestral theory of inheritance for the rest of his life.
Weldon's last project was on the inheritance of coat colour in horses. By November 1905 he was spending nine hours a day on this project and he continued this work throughout the winter of 1905 and into the early spring of 1906. During the Easter vacation of 1906 the Pearsons were in Berkshire, where they took a cottage at Longcott House, a mile from the Weldons, who were staying at the little inn at Woolstone, at the foot of the White Horse Hill. On Sunday 8 April Weldon and Pearson cycled into Oxford. When Pearson saw Weldon on the Tuesday afternoon, he found him in bed suffering from what appeared to be an attack of influenza. By evening his health had worsened and he was taken to a nursing home. He died of double pneumonia on Easter Monday, 13 April 1906, at 3 Nottingham Place, Marylebone, London. A service was held in the chapel at Merton College, Oxford, on 18 April and he was buried at Holywell cemetery, Oxford.
Shortly after the funeral Pearson approached Henry Richard Hope-Pinker to sculpt a marble bust of Weldon. The bust remained in Pearson's office until his retirement in 1933 when it was moved to the University Museum at Oxford. Pearson also established the Weldon memorial prize in 1907 in Oxford to be awarded once every three years to contributions to biometry. Weldon's widow left the residue of her estate to found the Weldon chair of biometry in October 1936 and J. B. S. Haldane became the first holder.
M. EILEEN MAGNELLO
Sources
DNB
R. S. Cowan, 'Weldon, Walter Frank Raphael', DSB, 14.251-2
M. E. Magnello, 'Karl Pearson: evolutionary biology and the emergence of a modern theory of statistics', DPhil diss., U. Oxf., 1993
M. E. Magnello, 'Karl Pearson's Gresham lectures: W. F. R. Weldon, speciation and the origins of Pearsonian statistics', British Journal for the History of Science, 29 (1996), 43-63
M. E. Magnello, 'Karl Pearson's mathematization of inheritance: from ancestral heredity to Mendelian genetics (1895-1909)', Annals of Science, 55 (1998), 35-94
K. Pearson, 'Walter Frank Raphael Weldon, 1860-1906', Biometrika, 5 (1906), 1-52; repr. in E. S. Pearson and M. G. Kendall, eds., Studies in the history of statistics and probability, 1 (1970)
K. Pearson, The life, letters and labours of Francis Galton, 3 vols. in 4 (1914-30), vol. 3a
LUL, Karl Pearson MSS
CGPLA Eng. & Wales (1906)
DNB
Archives
Marine Biological Association of the United Kingdom, Plymouth, notebook relating to decapod crustacea of Plymouth area
RS
U. Oxf., department of zoology, papers
UCL, corresp. and papers
UCL, papers
Likenesses
R. H. Hope-Pinker, marble bust, 1908, Oxf. U. Mus. NH
photograph, UCL [see illus.]
Wealth at death
£28,988 0s. 11d.: administration with will, 12 May 1906, CGPLA Eng. & Wales
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