Individualized social niches in animals: Theoretical clarifications and processes of niche change.

What are social niches, and how do they arise and change? Our first goal in the present article is to clarify the concept of an individualized social niche and to distinguish it from related concepts, such as a social environment and a social role. We argue that focal individuals are integral parts of individualized social niches and that social interactions with conspecifics are further core elements of social niches. Our second goal in the present article is to characterize three types of processes-social niche construction, conformance, and choice (social NC3 processes)-that explain how individualized social niches originate and change. Our approach brings together studies of behavior, ecology, and evolution and integrates social niches into the broader concept of an individualized ecological niche. We show how clarifying the concept of a social niche and recognizing the differences between the three social NC3 processes enhance and stimulate empirical research.

Health-Oriented Environmental Categories, Individual Health Environments, and the Concept of Environment in Public Health.

The term 'environment' is not uniformly defined in the public health sciences, which causes crucial inconsistencies in research, health policy, and practice. As we shall indicate, this is somewhat entangled with diverging pathogenic and salutogenic perspectives (research and policy priorities) concerning environmental health. We emphasise two distinct concepts of environment in use by the World Health Organisation. One significant way these concepts differ concerns whether the social environment is included. Divergence on this matter has profound consequences for the understanding of health and disease, for measures derived from that understanding targeting health promotion and disease prevention, and consequently, for epistemic structures and concept development in scientific practice. We hope to improve the given situation in public health by uncovering these differences and by developing a fruitful way of thinking about environment. Firstly, we side with the salutogenic conception of environment as a health resource (as well as a source of health risks). Secondly, we subdivide the concept of environment into four health-oriented environmental categories (viz., natural, built-material, socio-cultural, and psychosocial) and we link these with other theoretical notions proposed in the health sciences literature. Thirdly, we propose that in public health 'environment' should be understood as consisting of all extrinsic factors that influence or are influenced by the health, well-being, and development of an individual. Consequently, none of the four categories should be excluded from the concept of environment. We point out the practical relevance and fruitfulness of the conception of environment as a health source and frame this in causal terms, representing individual health environments as causal networks. Throughout, we side with the view that for the design of human health-promoting settings, increased attention and consideration of environmental resources of salutogenic potential is particularly pressing.

How Individualized Niches Arise: Defining Mechanisms of Niche Construction, Niche Choice, and Niche Conformance.

Organisms interact with their environments in various ways. We present a conceptual framework that distinguishes three mechanisms of organism-environment interaction. We call these NC3 mechanisms: niche construction, in which individuals make changes to the environment; niche choice, in which individuals select an environment; and niche conformance, in which individuals adjust their phenotypes in response to the environment. Each of these individual-level mechanisms affects an individual's phenotype-environment match, its fitness, and its individualized niche, defined in terms of the environmental conditions under which the individual can survive and reproduce. Our framework identifies how individuals alter the selective regimes that they and other organisms experience. It also places clear emphasis on individual differences and construes niche construction and other processes as evolved mechanisms. The NC3 mechanism framework therefore helps to integrate population-level and individual-level research.

ENCODE and the parts of the human genome.

This paper examines a specific kind of part-whole relations that exist in the molecular genetic domain. The central question is under which conditions a particular molecule, such as a DNA sequence, is a biological part of the human genome. I address this question by analyzing how biologists in fact partition the human genome into parts. This paper thus presents a case study in the metaphysics of biological practice. I develop a metaphysical account of genomic parthood by analyzing the investigative and reasoning practices in the ENCODE (ENCyclopedia Of DNA Elements) project. My account reveals two conditions that determine whether a molecule is a part of the human genome (i.e., a genomic part). First, genomic parts must possess a causal role function in the genome as a whole, that is, their functions must contribute to the genome directing the overall functioning of the cell. Second, genomic parts must have a specific chemical structure and be actual segments of the DNA sequence of the genome.

The limits of reductionism in the life sciences.

In the contemporary life sciences more and more researchers emphasize the "limits of reductionism" (e.g. Ahn et al. 2006a, 709; Mazzocchi 2008, 10) or they call for a move "beyond reductionism" (Gallagher/Appenzeller 1999, 79). However, it is far from clear what exactly they argue for and what the envisioned limits of reductionism are. In this paper I claim that the current discussions about reductionism in the life sciences, which focus on methodological and explanatory issues, leave the concepts of a reductive method and a reductive explanation too unspecified. In order to fill this gap and to clarify what the limits of reductionism are I identify three reductive methods that are crucial in the current practice of the life sciences: decomposition, focusing on internal factors, and studying parts in isolation. Furthermore, I argue that reductive explanations in the life sciences exhibit three characteristics: first, they refer only to factors at a lower level than the phenomenon at issue, second, they focus on internal factors and thus ignore or simplify the environment of a system, and, third, they cite only the parts of a system in isolation.