Are the different hypotheses on the emergence of life as different as they seem?

This paper calls attention to a philosophical presupposition, coined here the continuity thesis which underlies and unites the different, often conflicting, hypotheses in the origin of life field. This presupposition, a necessary condition for any scientific investigation of the origin of life problem, has two components. First, it contends that there is no unbridgeable gap between inorganic matter and life. Second, it regards the emergence of life as a highly probable process. Examining several current origin-of-life theories. I indicate the implicit or explicit role played by the continuity thesis in each of them. In addition, I identify the rivals of the thesis within the scientific community — the almost miracle camp. Though adopting the anti-vitalistic aspect of the continuity thesis, this camp regards the emergence of life as involving highly improbable events. Since it seems that the chemistry of the prebiotic stages and of molecular self-organization processes rules out the possibility that life is the result of a happy accident, I claim that the almost miracle view implies in fact, a creationist position.     

The social and economic origins of genetic determinism: a case history of the American Eugenics Movement, 1900–1940 and its lessons for today

Eugenics, the attempt to improve the genetic quality of the human species by ‘better breeding’, developed as a worldwide movement between 1900 and 1940. It was particularly prominent in the United States, Britain and Germany, and in those countries was based on the then-new science of Mendelian genetics. Eugenicists developed research programs to determine the degree to which traits such as Huntington's chorea, blindness, deafness, mental retardation (feeblemindedness), intelligence, alcoholism, szhiophrenia, manic depression, rebelliousness, nomadism, prostitution and feeble-inhibition were genetically determined. Eugenicists were also active in the political arena, lobbying in the United States for immigration restriction and compulsory sterilization laws for those deemed genetically unfit; in Britain they lobbied for incarceration of genetically unfit and in Germany for sterilization and eventually euthanasia. In all these countries one of the major arguments was that of efficiency: that it was inefficient to allow genetic defects to be multiplied and then have to try and deal with the consequences of state care for the offspring. National Socialists called genetically defective individuals ‘useless eaters’ and argued for sterilization or euthanasia on economic grounds. Similar arguments appeared in the United States and Britain as well. At the present time (1997) much research and publicity is being given to claims about a genetic basis for all the same behaviors (alcoholism, manic depression, etc), again in an economic context – care for people with such diseases is costing too much. There is an important lesson to learn from the past: genetic arguments are put forward to mask the true – social and economic – causes of human behavioral defects. This revised version was published online in August 2006 with corrections to the Cover Date.     

ADAPTATION AND PLASTICITY OF ANIMAL COMMUNICATION IN FLUCTUATING ENVIRONMENTS

Adaptations that facilitate the reception of long‐range signals under challenging conditions are expected to generate signal diversity when species communicate in different habitats. Although we have a general understanding of how individual communicating animals cope with conditions influencing signal detection, the extent to which plasticity and evolutionary changes in signal characteristics contribute to interspecific differences in signaling behavior is unclear. We quantified the visual displays of free‐living lizards and environmental variables known to influence display detection for multiple species from two separate island radiations. We found evidence of both adaptive evolution and adaptive plasticity in display characteristics as a function of environmental conditions, but plasticity accounted for most of the observed differences in display behavior across species. At the same time, prominent differences between the two island radiations existed in aspects of signaling behavior, unrelated to the environment. Past evolutionary events have therefore played an important role in shaping the way lizards adjust their signals to challenges in present‐day environments. In addition to showing how plasticity contributes to interspecific differences in communication signals, our findings suggest the vagaries of evolution can in itself lead to signal variation between species.     

Transmission of acquired adjustments to salinity in Sorghum bicolor

Previous studies showed that exposure of eight-day-old Sorghum bicolor for three weeks to sublethal salinity induces an increase in salinity tolerance, called physiological adaptation (A). During A, plants of a same population differ in reaction and tolerance to salinity. Tolerance levels of the reaction types depend on environmental conditions besides salinity. Reactions observed most frequently in an experiment have generally highest tolerance levels. This phenomenon is defined adaptive determinism (AD). In this study, the relationship between a potential source of the information subjacent to AD and AD itself is analysed in plants first exposed to salt-inducing A. When the reaction types are close variations of one reaction mode, AD is highest. This relationship is inversed in progeny of adapted plants. Results suggest that information relevant to AD is transmitted to the progeny of adapted plants, and that adaptive information is created during A in plants first exposed to adaptation inducing treatment.     

Multi-scale trajectory analysis: powerful conceptual tool for understanding ecological change

The model at the basis of trajectory analysis is conceptually simple. When applied to time series vegetation data, the projectile becomes a surrogate for vegetation state, the trajectory for the evolving vegetation process, and the properties of the trajectory for the true process characteristics. Notwithstanding its simplicity, the model is well-defined under natural circumstances and easily adapted to serial vegetation data, irrespective of source. As a major advantage, compared to other models that isolate the elementary processes and probe vegetation dynamics for informative regularities on the elementary level, the trajectory model allows us to probe for regularities on the level of the highest process integrity. Theories and a data analytical methodology developed around the trajectory model are outlined, including many numerical examples. A rich list of key references and volumes of supplementary information supplied in the Web Only Appendices rounds out the presentation.     

当代基因伦理研究问题探析

基因伦理研究是生命伦理学的一个重要分支。围绕着基因中心文化现象、基因检测技术、生物样本库建设以及基因增强带来的伦理问题,既关注＂我们应该做什么＂的实质伦理学研究,也进行＂我们应该怎样做＂的程序伦理学研究,探讨中国文化背景和社会转型下基因伦理研究的重要工作,为下一步的基因伦理研究提供启示。     

Are Probabilities Necessary For Evolutionary Explanations?

Several philosophers of science have advanced an instrumentalist thesis about the use of probabilities in evolutionary biology. I investigate the consequences of instrumentalism on evolutionary explanations. I take issue with Barbara Horan's (1994) argument that probabilities are unnecessary to explain evolutionary change given the underlying deterministic character of evolutionary processes. First, I question Horan's deterministic assumption. Then, I attempt to undermine her Laplacian argument by demonstrating that whether probabilities are necessary depends upon the sort of questions one is asking.