The tree, the network, and the species

To enrich the Hennigian internodal conception of species, a new formalization of the definition of the species concept is proposed. This rigorous definition allows for considerable unification of the various, and sometimes conflicting, techniques of species delimitation used in practice. First, the domain of such a definition is set out, namely, the set of all organisms on Earth, past, present, and future. Next, the focus is on the genealogical relationship among organisms, which provides the key to analysing the giant or global genealogical network (GGN) connecting all these organisms. This leads to the construction of an algorithm revealing the topological structure of the GGN, from families to lineages, ending up with a definition of species as equivalence classes of organisms corresponding to branches of the 'tree of life'. Such a theoretical definition of the species concept must be accompanied by various recognition criteria to be operational. These criteria are, for example, the ill-named 'biological species concepts', 'phylogenetic species concepts', etc., usually, but wrongly, presented as definitions of the species concept. Besides clarifying this disputed point, the definition in the present study displays the huge diversity of the scales (time-scale and population size) involved in actual species, thus explaining away the classical problems raised by previous attempts at defining the species concept (uniparental reproduction, temporal depth of species, and hybridization).  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 509–521.     

Causality, randomness, intelligibility, and the epistemology of the cell

Because the basic unit of biology is the cell, biological knowledge is rooted in the epistemology of the cell, and because life is the salient characteristic of the cell, its epistemology must be centered on its livingness, not its constituent components. The organization and regulation of these components in the pursuit of life constitute the fundamental nature of the cell. Thus, regulation sits at the heart of biological knowledge of the cell and the extraordinary complexity of this regulation conditions the kind of knowledge that can be obtained, in particular, the representation and intelligibility of that knowledge. This paper is essentially split into two parts. The first part discusses the inadequacy of everyday intelligibility and intuition in science and the consequent need for scientific theories to be expressed mathematically without appeal to commonsense categories of understanding, such as causality. Having set the backdrop, the second part addresses biological knowledge. It briefly reviews modern scientific epistemology from a general perspective and then turns to the epistemology of the cell. In analogy with a multi-faceted factory, the cell utilizes a highly parallel distributed control system to maintain its organization and regulate its dynamical operation in the face of both internal and external changes. Hence, scientific knowledge is constituted by the mathematics of stochastic dynamical systems, which model the overall relational structure of the cell and how these structures evolve over time, stochasticity being a consequence of the need to ignore a large number of factors while modeling relatively few in an extremely complex environment.     

Bioethics,children, and the environment

Queer perspectives have typically emerged from sexual minorities as a way of repudiating flawed views of sexuality, mischaracterized relationships, and objectionable social treatment of people with atypical sexuality or gender expression. In this vein, one commentator offers a queer critique of the conceptualization of children in regard to their value for people's identities and relationships. According to this account, children are morally problematic given the values that make them desirable, their displacement of other beings and things entitled to moral protection, not to mention the damaging environmental effects that follow in the wake of population growth. Objectionable views of children are said even to have colonized the view of lesbian, gay, bisexual, and trans (LGBT) people who – with the enthusiastic endorsement of bioethics – increasingly turn to assisted reproductive treatments to have children. In the face of these outcomes, it is better – according to this account – that people reconsider their interest in children. This account is not, however, ultimately strong enough to override people's interest in having children, relative to the benefits they confer and relative to the benefits conferred on children themselves. It is certainly not strong enough to justify differential treatment of LGBT people in matters of assisted reproductive treatments. Environmental threats in the wake of population growth might be managed in ways other than devaluing children as such. Moreover, this account ultimately damages the interests of LGBT people in matters of access, equity, and children, which outcome is paradoxical, given the origins of queer perspectives as efforts to assert and defend the social interests of sexual and gender minorities.     

Health, justice, and the environment

In this article, we argue that the scope of bioethical debate concerning justice in health should expand beyond the topic of access to health care and cover such issues as occupational hazards, safe housing, air pollution, water quality, food and drug safety, pest control, public health, childhood nutrition, disaster preparedness, literacy, and many other environmental factors that can cause differences in health. Since society does not have sufficient resources to address all of these environmental factors at one time, it is important to set priorities for bioethical theorizing and policy formation. Two considerations should be used to set these priorities: (1) the impact of the environmental factor on health inequality, and (2) the practicality of addressing the factor.     

Darwin,the amphibians,and the natural selection

A critical review of Darwin's publications shows that he did not dissert much about amphibians, in comparison with the other tetrapods. However, in “A Naturalist's Voyage round the World”, Darwin described for the first time several amphibian species and was surprised by their peculiar way of life, terrestrial or euryhaline. These amphibian observations around the world led Darwin to discuss evolutionnary notions, like developmental heterochronies or evolving convergences, and later to illustrate his famous natural selection theory. This is confirmed, for example, by the publication of “On the Origin of Species” where Darwin ironically questioned creation theory, trying to explain the absence of amphibians on oceanic islands. Lamarck also considered amphibians as relevant material to illustrate his theory of acquired character heredity. These historical uses of lissamphibians as evolutionary models have been mostly realized before any amphibian fossil discovery, i.e. out of a palaeontological context.     

Estrogen, exercise, and the skeleton

Patterns of variation in bone size and shape provide crucial data for reconstructing hominin paleobiology, including ecogeographic adaptation, life history, and functional morphology. Measures of bone strength, including robusticity (diaphyseal thickness relative to length) and cross-sectional geometric properties such as moments of area, are particularly useful for inferring behavior because bone tissue adapts to its mechanical environment. Particularly during skeletal growth, exercise-induced strains can stimulate periosteal modeling so that, to some extent, bone thickness reflects individual behavior. Thus, patterns of skeletal robusticity have been used to identify gender-based activity differences, temporal shifts in mobility, and changing subsistence strategies. Although there is no doubt that mechanical loading leaves its mark on the skeleton, less is known about whether individuals differ in their skeletal responses to exercise. For example, the potential effects of hormones or growth factors on bone-strain interactions are largely unexplored. If the hormonal background can increase or decrease the effects of exercise on skeletal robusticity, then the same mechanical loads might cause different degrees of bone response in different individuals. Here I focus on the role of the hormone estrogen in modulating exercise-induced changes in human bone thickness.