Galton greeted Darwin's theory of pangenesis with enthusiasm, and tried to test the assumption that the hereditary particles circulate in the blood by transfusion experiments on rabbits. The failure of these experiments led him to reject this assumption, and in the 1870s he developed an alternative theory of heredity, which incorporated those parts of Darwin's theory that did not involve the transportation of hereditary particles throughout the system. He supposed that the fertilized ovum contains a large number of hereditary elements, (...) which he collectively called the "stirp," a few of which are patent, developing into particular cell types, while the rest remain latent; the latent elements can be transmitted to the next generation, while the patent elements, with rare exceptions, cannot since they have developed into cells. The problem with this theory is that it does not explain the similarity between parent and child unless there is a high correlation between latent and patent elements. Galton probably came to realize this problem during his subsequent statistical work on heredity, and he quietly dropped the idea that patent elements are not transmitted in Natural Inheritance (1889). Galton thought that brothers and sisters had identical stirps, and he attributed differences between them to variability in the choice of patent elements from the stirp, that is to say to developmental variability. He attributed the likeness of monozygotic twins to the similarity of their developmental environment. Galton's twin method was to track the life history changes of twins to see whether twins who were similar at birth diverged in dissimilar environments or whether twins who were dissimilar at birth converged in similar environments. It is quite different from the modern twin method of comparing the similarities between monozygotic and dizygotic twins, on the assumption that monozygotic twins are genetically identical whereas dizygotic twins are not. It has been argued that Galton foreshadowed Weismann's theory of the continuity of the germ-plasm, but this is only true in a weak sense. They both believed that the inheritance of acquired characters was either rare or impossible, but Galton did not forestall the essential part of Weismann's theory, that the germ-plasm of the zygote is doubled, with one part being reserved for the formation of the germ-cells. (shrink)

Darwin's ideas on variation, heredity, and development differ significantly from twentieth-century views. First, Darwin held that environmental changes, acting either on the reproductive organs or the body, were necessary to generate variation. Second, heredity was a developmental, not a transmissional, process; variation was a change in the developmental process of change. An analysis of Darwin's elaboration and modification of these two positions from his early notebooks (1836-1844) to the last edition of the /Variation of Animals and Plants Under Domestication/ (1875) (...) complements previous Darwin scholarship on these issues. Included in this analysis is a description of the way Darwin employed the distinction between transmission and development, as well as the conceptual relationship he saw between heredity and variation. This paper is part of a larger project comparing commitments regarding variation during the latter half of the nineteenth century. (shrink)

The publication of Darwin's On the Origin of Species in 1859 ignited a public storm he neither wanted nor enjoyed. Having offered his book as a contribution to science, Darwin discovered to his dismay that it was received as an affront by many scientists and as a sacrilege by clergy and Christian citizens. To answer the criticism that his theory was a theory only, and a wild one at that, he published two volumes in 1868 to demonstrate that evolution was (...) obvious to anyone who cared to look at a bull in a pasture or a dog on a hearth. In response to those who insisted that species were distinct since creation, Darwin pointed to breeders of pigs and pigeons. In reply to those who protested that human intervention is one thing and natural selection another, he argued, "If organic beings had not possessed an inherent tendency to vary, man could have done nothing." To counter those who scorned his descriptions of species in exotic places, he submitted local evidence of cabbages and cauliflower. Based on a wide array of sources, from ancient pictographs to Polish roosters, from skins and from skeletons, from scientific journals and breeding manuals, Darwin assembled a mass of proof--and a hypothesis about species reversion that risked his reputation anew. The Variation of Animals and Plants under Domestication is a two-volume compilation of his thorough and intensive research and the revolutionary conclusions that resulted. The first portion of his work is dedicated to a meticulous analysis of various aspects of plant and animal life, including an inventory of varieties and their physical and behavioral characteristics, investigation of the impact of a species' surrounding environment and the role that both natural and forced changes in this environment have had. Darwin then turns to a richly detailed discussion of the roles of inheritance and crossing in the development of species. A wealth of illustrations further support and enhance his findings. This fascinating, invaluable, and courageous undertaking eventually formed the foundation for our current understanding of evolution. "In science as in politics the victors tend to write the history books. As a result, the record of the past is edited, intentionally or unintentionally, so that it focuses mainly on the precursors of contemporary orthodoxy. Such a focus may accurately represent the genealogy of modern ideas, but it almost inevitably misrepresents the historical experience of their progenitors... Even the powerful, persuasive, and ultimately triumphant theory of evolution by natural selection required not only defense, but repeated buttressing and revision. Variation showed Darwin hard at work on this rearguard action, using the materials he had at hand... His information was gleaned from the observations of fanciers, breeders, and amateur naturalists, as well as from the treatises of those on the cutting edge of zoology and botany. As hindsight narrows the historical spotlight, it imposes its own sense of hierarchy on the preoccupations of the past. But Darwin was interested in all of these topics, valued all of these sources, and belonged, to a greater or lesser extent, to all of these communities."--from the Introduction. (shrink)

Familiarity with Charles Darwin's treatise on evolution is essential to every well-educated individual. One of the most important books ever published--and a continuing source of controversy, a century and a half later--this classic of science is reproduced in a facsimile of the critically acclaimed first edition.

In The Origin of Species (1859) Darwin challenged many of the most deeply-held beliefs of the Western world. Arguing for a material, not divine, origin of species, he showed that new species are achieved by "natural selection." The Origin communicates the enthusiasm of original thinking in an open, descriptive style, and Darwin's emphasis on the value of diversity speaks more strongly now than ever. As well as a stimulating introduction and detailed notes, this edition offers a register of the many (...) writers referred to by Darwin in the text. (shrink)

Explores the development of the ideas of evolutionary biology, particularly as affected by the increasing understanding of genetics and of the chemical basis of inheritance.

This paper argues that our modern concept of biological heredity was first clearly introduced in a theoretical and practical setting by the generation of French physicians that were active between 1810 and 1830. It describes how from a traditional focus on hereditary transmission of disease, influential French medical men like Esquirol, Fodéré, Piorry, Lévy, moved towards considering heredity a central concept for the conception of the human bodily frame, and its set of physical and moral dispositions. The notion of heredity (...) as a natural force, with a wide ranging capabilities of transmitting differentially both fundamental and accidental characters was generalized by that generation of physicians with the help of contemporary naturalists and physiologists. By 1830 the term hérédité was widespread, and it shared the explanatory and semantic qualities of traditional medical concepts like constitution and temperament. An analysis is given of the main developments that led to the conception of biological (including human) bodies as consisting of a layered, hierarchical organization of characters, differentially affected by the laws of conservation (Heredity) and change (Inneity, Variation). The mid-century work of the French physician Prosper Lucas, Traité Philosophique et Physiologique de L'Hérédité Naturelle, is shown to be the culmination of the efforts of several generations of French physicians towards having a feasible, complexly structured notion of how heredity works. (shrink)

In 1875 Francis Galton was the first to study twins as a test of the relative strength of heredity and environment. This paper examines Galton's work on twins, using his surviving working papers. It shows that his enquiry was larger and more systematic than previously realized. Galton issued several hundred questionnaires to parents of twins, with the aim of establishing how far the similarities and differences between twins were affected by their life experiences. The paper also discusses Galton's study in (...) relation to his understanding of the physiology of twinning and his theory of heredity. The modern concept of monozygotic twins had not yet been established, and the similarity between Galton's work and modern twin studies should not be overstated. While Galton's work was important as a pioneering study, in some respects his conclusions went beyond his evidence. The paper finally examines whether Galton's twin studies influenced his position on the links between social class, heredity and social mobility, and surveys the evidence for his views on these issues. (shrink)

Bernard Norton's friends in the history of science have had many reasons for commemorating, with admiration and affection, not only his research and teaching but no less his conversation and his company. One of his most estimable traits was his refusal to beat about the bush in raising the questions he thought worthwhile pursuing. I still remember discoursing at Pittsburgh on Darwin's route to his theory of natural selection, and being asked at the end by Bernard what were Darwin's views (...) on heredity. I answered with the conventional waffle to the effect that the theory concerned the populational fate rather than the individual production and transmission of heritable variation, so that whatever views Darwin had on heredity had only a subsidiary place in his theorizing. Bernard was not fooled. ‘I would have thought’, he said, ‘that in order to understand anyone's theorising about evolution it would be necessary to look at his views on heredity’. (shrink)

While Wallace disagreed with Darwin that domesticates provided a great deal of useful information on wild populations,71 Darwin continued to draw on his domesticated animals and plants to inform him on the workings of his theory. Unlike Wallace, his exposure to natural populations was extremely limited after his return from the Beagle voyage. By the 1850s, he had settled into a life at Down House and was becoming more and more withdrawn from London scientific circles. He turned to his network (...) of informants, visits from colleagues such as Hooker and T. H. Huxley, subscriptions to various journals, and his own experimental studies at Down.This work on domesticates was clearly related to other natural history studies conducted by Darwin and others during the same period. For example, during the 1850s when Darwin worked on domesticates, he was also engaged in questions of geographic distribution. To study the dispersal and subsequent viability of introduced seeds, he soaked various seeds in a tub filled with seawater and counted which of the seeds floated after a given period; later he planted the seeds in the yard at Down to look for potential viability. There was no attempt at controlled, replicated experiments in these studies, or in his work with domesticates, nor should there have been. To Darwin the results of one experiment represented a potential truth of nature, and he was quick to seize upon these results as supporting evidence for his theory.I have suggested in this paper that his work on domesticates was not simply meant to provide an analogy for natural selection but rather became a research program to investigate other aspects of his natural selection theory, especially inheritance and variability; these subjects were integral parts of his theory of natural selection, but by 1859 he had not found a mechanism to account for them. The experiments brought home the difficult problems of inheritance, and Darwin specifically formulated pangenesis to account for these problems. Pangenesis was not an afterthought but an integration of several decades of thinking on inheritance. It was a unified theory to explain the complicated results he witnessed in his own experiments.Much of the Darwin scholarship has focused on Darwin's path toward the discovery of natural selection. Natural selection per se was a major interest, but not the only area of interest to Darwin. Inheritance was an area of serious concern for him both before and after he had formulated natural selection. His experimentation with domesticates was an attempt to look beyond natural selection and to concentrate on the difficult subject of inheritance. He found inheritance especially troublesome, requiring a “provisional hypothesis” to account for it. To see domesticates, as they are described in the Origin, as merely an analogy for natural selection, does not account for the importance Darwin placed on them. For him they were not man's monstrous productions, but worthy experimental subjects providing him with crucial information on inheritance. (shrink)

In Darwinism's Struggle for Survival Jean Gayon offers a philosophical interpretation of the history of theoretical Darwinism. He begins by examining the different forms taken by the hypothesis of natural selection in the nineteenth century and the major difficulties which it encountered, particularly with regard to its compatibility with the theory of heredity. He then shows how these difficulties were overcome during the seventy years which followed the publication of Darwin's Origin of Species, and he concludes by analysing the major (...) features of the genetic theory of natural selection, as it developed from 1920 to 1960. This rich and wide-ranging study will appeal to philosophers and historians of science and to evolutionary biologists. (shrink)

In Darwinism's Struggle for Survival Jean Gayon offers a philosophical interpretation of the history of theoretical Darwinism. He begins by examining the different forms taken by the hypothesis of natural selection in the nineteenth century and the major difficulties which it encountered, particularly with regard to its compatibility with the theory of heredity. He then shows how these difficulties were overcome during the seventy years which followed the publication of Darwin's Origin of Species, and he concludes by analysing the major (...) features of the genetic theory of natural selection, as it developed from 1920 to 1960. This rich and wide-ranging study will appeal to philosophers and historians of science and to evolutionary biologists. (shrink)