Steroid hormones and the brain: Linking “nature” and “nurture”

Contrary to earlier belief, the genetic constitution of each cell of the body (nature) is subject to modulation by environmental factors (nurture) which act throughout the life of the organism to shape the individual characteristics. The nervous system adapts and changes with the environment that the organism experiences through genomic activity controlled by chemical messengers from other nerve cells and from endocrine secretions. The nervous system expresses receptors for a number of circulating hormones, and the location of these hormone receptors has revealed a great deal about the neuroanatomy of neuroendocrine and behavioral control processes. The brain controls the endocrine system through the hypothalamus and pituitary gland, and it responds to circulating hormones throughout each stage of life. These effects begin during early development (eg., sexual differentiation of the brain; effects of maternal or neonatal stress). They continue in adult life in response to cyclic events (eg., season of year; time of day, controlling reproduction and daily activity-sleep rhythms of behavior); and they also include the behavior of other animals which alters hormone output. Hormones also operate during the aging process and under conditions which induce neural damage such as hypoxia and stress. This overview summarizes involvement of steroid hormones of gonads and adrenals in many of these processes and also examines the features of the genomic activity which is modified by these hormones. This area of research is fruitful because it brings together molecular, anatomical, physiological and behavioral approaches in an attempt to understand the longterm plasticity of the nervous system.This overview article, written in recognition of the contributions to neuroscience by Professor Holger Hydén, is based upon a Presidential Special Lecture delivered by the author at the Society for Neuroscience Meeting in Washington, D.C., on November 11, 1986     

Ecosystem integrity and the “fish wars”

The problems of fisheries and aquatic ecosystems in Canada have been analyzed primarily from the standpoint of the conservation of these resources, without much emphasis on the value of aquatic ecosystems for themselves, including their life-support function, vital to all the biota within them. This represents a purely anthropocentric approach, that is flawed from the standpoint of sustainability practically and theoretically (Westra, 1996; Norton, 1995). Without entering in the anthropocentrism debate, the intent of this study is to indicate the apparent conflict between theoretical legislative and regulative aims, and most forms of management principles, even when these are presented in their most enlightened forms. Starting with the examination of a recent Canadian case, the failure of present management practices is outlined, even when these are democratically chosen and support worthwhile social goals. The Canadian fish wars example shows clearly why the ethics of integrity provide better guidelines for public policy, as they alone take as primary biological and ecological objectives.     

Comparative Study of the Absorption,Plasma Levels,and Urinary Excretion of the “New” and the “Old” Lanoxin

A comparative study was performed of the absorption, the plasma level at equilibrium, and the urinary excretion of digoxin using two types of Lanoxin tablets, those produced before and after the 1972 alteration of the tablet manufacture.After a single dose the absorption rate of the new tablets was about twice as great as the old, both in young subjects and in the elderly patients. There were no significant differences in the plasma levels of digoxin for the two tablets 15 hours after the last administration in patients on an equal maintenance dose. The urinary excretion of digoxin increased about 40% when the “old” Lanoxin was replaced by the “new.” In elderly patients a daily dose of 0·125 mg twice daily of the new tablets should be sufficient to reach the therapeutic range. Young people need a higher dosage. If the kidney function is reduced by as much as 50% the dose should be reduced.     

“Neutral theory” and the dynamics of the evolution of “Modern” human morphology

There is a widespread assumption, even among those who reject the Synthetic Theory of Evolution, that the form of “modern”Homo sapiens is somehow superior to that of archaicHomo sapiens (Tattersall 2000). Those who accept the general outlook of evolutionary biology also tend to assume that “modern” form emerged because it was selected for, which also implies that it was better than that which preceded it. However, after years of using craniofacial measurements to compare human populations, I finally came to realize that, with only a few exceptions, the dimensions measured have no relation to differences in adaptation (Brace 1989, 1996, 2000; Brace et al., 1993). Elsewhere the conclusion has been supported that what is shown by craniometrics is selectively neutral on the average (Relethford 2002). With the documentation that approximately 95% of the genome is not functional, molecular genetics has proved to be useful in documenting the length of time of separation of related human populations by investigating the differences that have accumulated in the neutral parts of the genome. Not surprisingly, the picture revealed by the study of genetic differences is very similar to the one revealed by the study of craniometric differences (Brace et al., 2001). For this reason, the logic behind the “neutral theory” in molecular genetics is very similar to that applied to what happens to morphological characteristics when selection ceases (Brace 1963; Kimura 1968). The difference is that random changes in the neutral part of the genome have no other consequences. However, random changes in the genes that produce specific aspects of morphology will be visible even when selection is no longer controlling the particular trait in question. From an assessment of what random changes in genes controlling morphological traits are likely to do, it follows that the most likely change will probably be a reduction in the trait in question, i.e. the Probable Mutation Effect will produce structural reduction. When survival in the temperate zone during the last glaciation dependend on “obligatory cooking”, one of the unintended consequences was a reduction in the selective pressures maintaining a Middle Pleistocene-sized dentition. The result was a gradual reduction in tooth size and a conversion, of a Neanderthal-sized face into one of “modern” dimensions. The manufacture and use of string for snares and nets similarly reduced the selective pressures maintaining post-cranial levels of robustness and muscularity. The reduction in the latter resulted in the emergence of moderm post-cranial robustness out of what had been a Neanderthal level,in situ wherever the technology can be documented and without any need for invasions and replacements.     

From “Periodical Observations” to “Anthochronology” and “Phenology” – the scientific debate between Adolphe Quetelet and Charles Morren on the origin of the word “Phenology”

Mankind has observed and documented life cycle stages of plants and animals for a long time. However, it was comparatively recently that the newly emerging science was given its name. The name of Charles Morren and the year 1853 are being cited, although not frequently. Exact information is hardly known among present-day phenologists, yet new evidence shows that the term “phenology” was already in use in 1849. In the early 1840s, physicist and astronomer Adolphe Quetelet set up an observational network named "Observations of periodical Phenomena of the Animal and Vegetable Kingdom” and issued instructions for it. Even though biologist Charles Morren welcomed Quetelet's initiative, differences between Morren and Quentlet regarding the instructions for the observations and the potential results soon arose and a debate started, which lasted for nearly 10 years. In the wake of these disagreements, Morren was compelled to create a new term to denote his ideas on “periodical phenomena”. At first, he temporally used the word anthochronology, but in the end he coined the word phenology. The term was first used in a public lecture at the Académie royale des Sciences, des Lettres et des Beaux-Arts de Belgique’ in Brussels on 16 December 1849, and simultaneously in the December 1849 issue of volume V of the Annales de la Société royale d’Agriculture et de Botanique de Gand. One had to wait until 1853 before the new name appeared in the title of one of Morren’s publications. Based on evidence from archives and original publications, we trace the 10-year-long scientific debate between Morren and Quetelet. Morren states his biologist’s view on the subject and extends the more climate-related definition of Quetelet of “periodical phenomena”.     

Biosociality,biocitizenship and the new regime of hope and despair: interpreting “Portraits of Hope” and the “Mehmet Case”

The concepts of biocitizenship and biosociality, in many ways developed as a reaction to the former critique of genetification and fears of a return of eugenics, have gained a stronghold in much of the current debates on the social effects of modern-day genetics. In contrast to claims of a return to eugenics, the literature on biocitizenship highlights the new choice-enhancing possibilities involved in present-day biomedicine, underlining the break with past forms of biopower. In this analysis, hope becomes a life-inducing and vitalizing force, opening new avenues of civic participation and engagement. Most critics of this analysis have attacked the claims to novelty attributed to these concepts, arguing that more traditional forms of biopower remain as important as ever. In contrast, we argue that the biocitizenship literature underestimates the radical nature of this break with the past, ending up with a too narrow and one-sided interpretation of the ramifications of the new discourse of hope. On the basis of two different case stories, the “Portraits of Hope” campaign from California, USA and the “Mehmet Case” from Norway, we indicate an alternative “darker” reading of the new discourse of hope, arguing that its driving force is not so much future possibilities as present despair.     

The history of the homology concept and the “Phylogenetisches Symposium”

The homology concept has had a long and varied history, starting out as a geometrical term in ancient Greece. Here we describe briefly how a typological use of homology to designate organs and body parts in the same position anatomically in different organisms was changed by Darwin’s theory of evolution into a phylogenetic concept. We try to indicate the diversity of opinions on how to define and test for homology that has prevailed historically, before the important books by Hennig (1950. Grundzüge einer Theorie der Phylogenetischen Systematik. Deutscher Zentralverlag, Berlin) and Remane (1952. Die Grundlagen des Natürlichen Systems, der Vergleichenden Anatomie und der Phylogenetik. Geest & Portig, Leipzig) brought more rigor into both the debate on homology and into the usage of the term homology among systematists. Homology as a theme has recurred repeatedly throughout the history of the “Phylogenetisches Symposium” and we give a very brief overview of the different aspects of homology that have been discussed at specific symposia over the last 48 years. We also honour the fact that the 2004 symposium was held in Jena by pointing to the roles played by biologists active in Jena, such as Ernst Haeckel and Carl Gegenbaur, in starting the development towards a homology concept concordant with an evolutionary world view. As historians of biology, we emphasize the importance of major treatises on homology and its history that may be little read by systematists active today, and have sometimes also received less attention by historians of biology than they deserve. Prominent among these are the works of Dietrich Starck, who also happened to be both a student, and later a benefactor, of systematics at Jena University.     

Hugo de Vries and the reception of the “mutation theory”

Conclusion De Vries' mutation theory has not stood the test of time. The supposed mutations of Oenothera were in reality complex recombination phenomena, ultimately explicable in Mendelian terms, while instances of large-scale mutations were found wanting in other species. By 1915 the mutation theory had begun to lose its grip on the biological community; by de Vries' death in 1935 it was almost completely abandoned. Yet, as we have seen, during the first decade of the present century it achieved an enormous popularity. As this paper has tried to suggest, one of the principal reasons for this was that de Vries' theory served as a banner around which a whole crowd of disaffected Darwinians or anti-Darwinians could rally. However, not all of those who favored de Vries did so for quite the same reasons. Underlying the multitude of views ran several common threads: a dissatisfaction with current Darwinian theory born out of misunderstanding natural selection, a general misunderstanding of the nature of species, and a prejudice against speculative, nontestable theories in biology.Supporters of de Vries were not the only opponents of Darwinism, nor was the mutation theory the only alternative to natural selection. In the early twentieth century a number of theories had been proposed to explain away the problems which Darwin had left unsolved. There was the idea of orthogenesis, championed by the American paleontologists Cope, Osborn and others; organic selection (or orthoplasy) was championed by M. M. Baldwin and C. Lloyd Morgan; there were the concepts of convergent evolution proposed by Hermann Friedmann, the theory of physiological selection by John George Romanes, and the concepts of reproductive divergence by H. M. Vernon. Virtually none of these men either accepted or were strong supporters of the de Vriesian theory, for each had his own particular ism to advocate as the major factor in evolution. The existence of a large number of such theories, each purporting to be the explanation, was characteristic of evolutionary theory at the turn of the century. It is to a large extent the emphasis on such fragmentary concepts that retarded development of the comprehensive theory of evolution which emerged in the 1920's and 1930's. For the historian, however, a study of these alternative theories is instructive in trying to understand the inherent difficulties which Dawwinian theory posed to biologists at the time. De Vries' mutation theory serves historically as a mirror to reflect the critical mood of a generation hostile to the theory of natural selection.It has often been claimed that it was impossible to understand the mechanism of natural selection until it could be placed in genetic and mathematical terms. It is certainly true that great strides have been made in population genetics and the treatment of evolutionary concepts with mathematical tools in the last forty years. But the very people who developed the genetical and mathematical approach to evolution were already convinced of the essential correctness of Darwinian theory before they started. Advances in an understanding of Mendelian heredity aided greatly in solving one important issue for evolutionists: the origin of variations. And the rigor with which selection acted could best be studied by observing changes in gene frequencies (calculated mathematically) over a number of generations. But as this paper has shown, two of the basic problems which biologists faced in evaluating Darwinian theory at the turn of the century-the nature of species, and the criteria of what constituted an acceptable explanation in biological science-could not be answered directly by mathematics. What mathematical and genetical theory did do was to help convince the skeptics of the validity of the Darwinian proposition.The change in explanatory criteria which many hailed as de Vries' most important contribution to evolutionary theory seems to have been part of a general emergence of twentieth-century biology from the domination of theorizers in the nineteenth. It also marked the emergence of America from the domination of biological, and particularly evolutionary, influence of Europeans. The change occurred in three areas: in the kinds of questions asked: testable versus non-testable; in the kind of data sought: quantitative versus qualitative; and in the kinds of theories proposed: analytical and reductive—the attempt to see complex processes in terms of simpler components-as opposed to synthetic and speculative. Although ultimately wrong in his idea, de Vries and his theories rode high on the wave of experimentalism which was the harbinger of a new era in evolutionary theory.Preparation of this paper has been aided by a grant from National Science Foundation (GS 1832).     

On the Unnecessary and Misleading Taxon “Cetartiodactyla”

Journal of Mammalian Evolution - The name “Cetartiodactyla” was proposed in 1997 to reflect the molecular data that suggested that Cetacea is closely related to Artiodactyla. Since...