This paper discusses how growth and aging became interrelated phenomena with the creation of gerontology in the United States. I first show that the relation of growth to senescence, which had hardly attracted scientific attention before the twentieth century, started to be investigated by several experimental scientists around the 1900s. Subsequently, research on the connection between the two phenomena entered a new domain through the birth of gerontology as a scientific field comprised of various disciplines, many of which addressed growth. (...) Due to gerontologists’ efforts, the association between aging and growth became stronger and more multifaceted within the discursive and organizational matrix constituting the new science, leading to a broader definition of senescence with an ambiguous connection to chronological age. Furthermore, as gerontologists borrowed the cultural agendas as well as research methods from studies of growth, aging began to be defined as a phenomenon that could be actively controlled and managed in both social arenas and laboratory environments. (shrink)

Diagrams make it possible to present scientific facts in more abstract and generalized form. While some detail is lost, simplified and accessible knowledge is gained. E. B. Wilson's work in cytology provides a case study of changing uses of diagrams and accompanying abstraction. In his early work, Wilson presented his data in photographs, which he saw as coming closest to “fact.” As he gained confidence in his interpretations, and as he sought to provide a generalized textbook account of cell development, (...) he relied on increasingly abstract diagrams. In addition, he came to see that highly abstract and even schematic drawings could provide more than pictures directly from life. (shrink)

Throughout the last quarter of the nineteenth century, researchers became increasingly interested in explaining the ways in which mammalian teeth, especially molars, and their complex arrangements of cusps arose along both developmental and evolutionary timescales. By the 1890s, two theories garnered special prominence; the tritubercular theory and the concrescence theory. The tritubercular theory was proposed by Edward Drinker Cope in 1883, and later expanded by Henry Fairfield Osborn in 1888, while the concrescence theory was developed by Carl Röse in 1892. (...) Reviews concerning the evolution of mammalian molar teeth tended to paint the two theories as occupying opposing sides, and debates arose between their main proponents; however, their tenets do not seem logically incompatible. Throughout this paper, I argue that the conflict that arose was due not to the content of the theories, but to a diverse array of commitments Cope, Osborn, and Röse held, which turned into background assumptions within the setting of these theories. This history traces the context in which Cope, Osborn, and Röse developed the tritubercular and concrescence theories, and the ways in which the assumptions that these investigators held influenced their perceptions of their theories. (shrink)

American biologists in the late nineteenth century pioneered the descriptive-comparative study of all cell divisions from zygote to gastrulation -- the cell lineage. Data from cell lineages were crucial to evolutionary and developmental questions of the day. One of the main questions was the ultimate causation of developmental patterns -- historical or mechanical. E. B. Wilson's groundbreaking lineage work on the polychaete worm Nereis in 1892 set the stage for (1) an attack on Haeckel's phylogenetic-historical notion of recapitulation and (2) (...) support for mechanistic explanations of cleavage patterns. As more lineage work -- especially Lillie's work on "Unio" and Conklin's on "Crepidula" -- became available in the mid-late 1890s, mechanism was tempered with more evolutionary, homology-based views. However, as I show by focusing on three major issues -- homology, body plans and life history -- these views were primarily based on the precocious segregation and prospective significance -- what the cell became not what it was. Even on issues like adaptation, most lineagists argued teleologically from the adult backward. Most cell lineage workers, by 1900, were to varying degrees mechanist/experimentalist and recapitulationist simultaneously. The exception was E. G. Conklin, whose views were more akin to a Darwinian evolutionist than either mechanist or recapitulationist. Lineage work eventually declined and by 1907 published accounts of new lineages had basically stopped. I argue that established workers and younger researchers stopped wanting to take on cell lineage projects because the general patterns were the same for all the spiralians while the specifics showed too much variation. It was hard to theoretically encompass or analyze the minutiae of variation in a recapitulationist or mechanist framework. The only established worker who continued to do comparative lineage studies was E. G. Conklin, perhaps because the variation could best be accommodated by Darwinian evolution. (shrink)

Exact sciences are described as sciences whose theories are formalized. These are contrasted to inexact sciences, whose theories are not formalized. Formalization is described as a broader category than mathematization, involving any form/content distinction allowing forms, e.g., as represented in theoretical models, to be studied independently of the empirical content of a subject-matter domain. Exactness is a practice depending on the use of theories to control subject-matter domains and to align theoretical with empirical models and not merely a state of (...) a science. Inexact biological sciences tolerate a degree of “mismatch” between theoretical and empirical models and concepts. Three illustrations from biological sciences are discussed in which formalization is achieved by various means: Mendelism, Weismannism, and Darwinism. Frege’s idea of a “conceptual notation” is used to further characterize the notion of a form/content distinction. (shrink)

Stem cells did not become a proper research object until the 1960 s. Yet the term and the basic mind-set—namely the conception of single undifferentiated cells, be they embryonic or adult, as the basic units responsible for a directed process of development, differentiation and increasing specialisation—were already in place at the end of the nineteenth century and then transmitted on a non-linear path in the form of tropes and diagrams. Ernst Haeckel and August Weismann played a special role in this (...) story. The first coined the term Stammzelle (stem cell), the second was the author of the first cellular stem-tree diagram. Even today, I shall argue, the understanding of stem cells, especially the popular perception, is to a large extent a Haeckelian–Weismannian one. After having demonstrated this, by analysing the terminology, in this essay I will focus on the use of cytogenetic tree diagrams between 1892 and 1925 and on the tacit understanding of stem cells that they transmit. (shrink)

The technique of nuclear transplantation – popularly known as cloning – has been integrated into several different histories of twentieth century biology. Historians and science scholars have situated nuclear transplantation within narratives of scientific practice, biotechnology, bioethics, biomedicine, and changing views of life. However, nuclear transplantation has never been the focus of analysis. In this article, I examine the development of nuclear transplantation techniques, focusing on the people, motivations, and institutions associated with the first successful nuclear transfer in metazoans in (...) 1952. The conflict between embryologists and geneticists over the mechanisms of differentiation motivated Robert Briggs to pursue nuclear transplantation experiments as a way to resolve the debate. Briggs worked at the Lankenau Hospital Research Institute, a research facility devoted to the study of cancer. The goal of understanding cancer would play a role in the development of the technique, and the story of nuclear transplantation sheds light on the role that biomedical contexts play in biological research in the second half of the twentieth century. (shrink)