In my response to the paper by Jagers op Akkerhuis, I object against giving definitions of life, since they bias anything that follows. As we don’t know how life originated, authors characterise life using criteria derived from present-day properties, thus emphasising widely different ones, which gives bias to their further analysis. This makes their results dependent on their initial suppositions, which introduces circularity in their reasoning.

This paper analyses the broad methodological structure of population-biological theorising. In it, I show that the distinction between initial exploratory, hypothesis-generating research and the subsequent process-reconstructing, hypothesis-testing type of research is not being made. Rather, the hypotheses generated in population biology are elaborated in such detail that students confound the initial research phase with the subsequent hypotheses-testing phase of research. In this context, I therefore analyse some testing procedures within the exploration phase and show that, as an extreme form of (...) confusion, statistical null-models are mistakenly given the status of causal population-biological theory. (shrink)

This paper compares two approaches that attempt to explain the origin of life, or biogenesis. The more established approach is one based on chemical principles, whereas a new, yet not widely known approach begins from a physical perspective. According to the first approach, life would have begun with—often organic—compounds. After having developed to a certain level of complexity and mutual dependence within a non-compartmentalised organic soup, they would have assembled into a functioning cell. In contrast, the second, physical type of (...) approach has life developing within tiny compartments from the beginning. It emphasises the importance of redox reactions between inorganic elements and compounds found on two sides of a compartmental boundary. Without this boundary, “life” would not have begun, nor have been maintained; this boundary—and the complex cell membrane that evolved from it—forms the essence of life. (shrink)

This paper distinguishes four recognisably different geographical processes in principle causing species to die out. One of these processes, the one we dub “range eclipse”, holds that one range expands at the expense of another one, thereby usurping it. Channell and Lomolino (2000a, Journal of Biogeography 27: 169–179; 2000b, Nature 403: 84–87; see also Lomolino and Channell, 1995, Journal of Mammalogy 76: 335–347) measured the course of this process in terms of the proportion of the total range remaining in its (...) original centre, thereby essentially assuming a homogeneous distribution of animals over the range. However, part of their measure seems mistaken. By giving a general, analytical formulation of eclipsing ranges, we estimate the exact course of this process. Also, our formulation does not partition a range into two spatially equal parts, its core and its edge, but it assumes continuity. For applying this model to data on the time evolution of species, individual time series should be available for each of them. For practical purposes we give an alternative way of plotting and interpreting such time series. Our approach, being more sensitive than Channell and Lomolino’s, gives a less optimistic indication of range eclipses than theirs once these have started. (shrink)