Astrobiologists are aware that extraterrestrial life might differ from known life, and considerable thought has been given to possible signatures associated with weird forms of life on other planets. So far, however, very little attention has been paid to the possibility that our own planet might also host communities of weird life. If life arises readily in Earth-like conditions, as many astrobiologists contend, then it may well have formed many times on Earth itself, which raises the question whether one or (...) more shadow biospheres have existed in the past or still exist today. In this paper, we discuss possible signatures of weird life and outline some simple strategies for seeking evidence of a shadow biosphere. Key Words: Weird life—Multiple origins of life—Biogenesis—Biomarkers—Extremophiles—Alternative biochemistry. Astrobiology 9, 241–249. (shrink)

The assumption that all life on Earth today shares the same basic molecular architecture and biochemistry is part of the paradigm of modern biology. This paper argues that there is little theoretical or empirical support for this widely held assumption. Scientists know that life could have been at least modestly different at the molecular level and it is clear that alternative molecular building blocks for life were available on the early Earth. If the emergence of life is, like other natural (...) phenomena, highly probable given the right chemical and physical conditions then it seems likely that the early Earth hosted multiple origins of life, some of which produced chemical variations on life as we know it. While these points are often conceded, it is nevertheless maintained that any primitive alternatives to familiar life would have been eliminated long ago, either amalgamated into a single form of life through lateral gene transfer (LGT) or alternatively out-competed by our putatively more evolutionarily robust form of life. Besides, the argument continues, if such life forms still existed, we surely would have encountered telling signs of them by now. These arguments do not hold up well under close scrutiny. They reflect a host of assumptions that are grounded in our experience with large multicellular organisms and, most importantly, do not apply to microbial forms of life, which cannot be easily studied without the aid of sophisticated technologies. Significantly, the most powerful molecular biology techniques available—polymerase chain reaction (PCR) amplification of rRNA genes augmented by metagenomic analysis—could not detect such microbes if they existed. Given the profound philosophical and scientific importance that such a discovery would represent, a dedicated search for ‘shadow microbes’ (heretofore unrecognized ‘alien’ forms of terran microbial life) seems in order. The best place to start such a search is with puzzling (anomalous) phenomena, such as desert varnish, that resist classification as ‘biological’ or ‘nonbiological’. Ó 2007 Elsevier Ltd.. (shrink)

The assumption that all life on Earth today shares the same basic molecular architecture and biochemistry is part of the paradigm of modern biology. This paper argues that there is little theoretical or empirical support for this widely held assumption. Scientists know that life could have been at least modestly different at the molecular level and it is clear that alternative molecular building blocks for life were available on the early Earth. If the emergence of life is, like other natural (...) phenomena, highly probable given the right chemical and physical conditions then it seems likely that the early Earth hosted multiple origins of life, some of which produced chemical variations on life as we know it. While these points are often conceded, it is nevertheless maintained that any primitive alternatives to familiar life would have been eliminated long ago, either amalgamated into a single form of life through lateral gene transfer or alternatively out-competed by our putatively more evolutionarily robust form of life. Besides, the argument continues, if such life forms still existed, we surely would have encountered telling signs of them by now. These arguments do not hold up well under close scrutiny. They reflect a host of assumptions that are grounded in our experience with large multicellular organisms and, most importantly, do not apply to microbial forms of life, which cannot be easily studied without the aid of sophisticated technologies. Significantly, the most powerful molecular biology techniques available—polymerase chain reaction amplification of rRNA genes augmented by metagenomic analysis—could not detect such microbes if they existed. Given the profound philosophical and scientific importance that such a discovery would represent, a dedicated search for ‘shadow microbes’ seems in order. The best place to start such a search is with puzzling phenomena, such as desert varnish, that resist classification as ‘biological’ or ‘nonbiological’. (shrink)

This study examines the case of community resource mobilization within the context of a farmers market incentive program in Washington D.C., USA to illustrate the ways in which providing opportunities for people impacted by food inequities to develop and lead programming can help to promote food access. Through an analysis of interviews with 36 participants in the Produce Plus program, some of whom also served as paid staff and volunteers with the program, this study examines the ways that group-level social (...) interactions among program participants helped to ensure the program was accessible and accountable to the primarily Black communities that it serves. Specifically, we explore a particular set of social interactions, which we collectively term social solidarity, as a community-level form of social infrastructure that program volunteers and participants mobilized to support access to fresh, local food in their communities. We also examine the elements of the Produce Plus program that contributed to the flow of social solidarity within the program, providing insight into the ways in which the structure of food access programs can serve as a social conduit to facilitate or hinder the mobilization of community cultural resources like social solidarity. (shrink)

This book consists of notes of lectures given by G. E. Moore at Cambridge during the three terms of 1934-35. They were compiled by the editor, Alice Ambrose, who was then Student of Newnham College, and the late Margaret Macdonald, who was then Fellow of Girton College. The lectures contain discussions of some material on which Moore published little or nothing, for example, types and tokens, propositional functions and their relation to common properties and relations, and the objects of false (...) judgements. They also include detailed examinations of the views of a number of Moore's contemporaries, including C. D. Broad, Bertrand Russell, F. P. Ramsey, W. E. Johnson, and John Wisdom. Moreover, the lectures do a nice job of illustrating Moore's general approach to the philosophical enterprise, highlighting his emphasis upon ordinary language and revealing the high standards of clarity and precision that he demanded of himself and others. It is clear, however, that Moore is not so much concerned with formulating philosophical positions as with exploring philosophical problems. This lends a certain lack of focus to the lectures and makes them a bit confusing at times. Nevertheless, the lectures provide valuable insight into the evolution of Moore's later thought about a number of important philosophical problems. (shrink)

Education is so strongly emphasized in the Chinese culture that academic success is widely regarded as the only indicator of success, while too much physical activity is often discouraged because it drains energy and affects academic concentration. This study investigated the relations among academic achievement, self?esteem, school conduct and physical activity level. The participants were 333 Chinese pre?adolescents (aged 8?12) in Hong Kong. Examination results and conduct grades were obtained from the school records. Global self?esteem was measured with the Physical (...) self?description questionnaire (PSDQ), while physical activity patterns of the children were assessed with the Physical activity questionnaire for children (PAQ?C). Results showed that high academic achievers consistently attained better school conduct marks. However, physical activity level was quite an independent entity that was related neither to academic achievement nor school conduct. Furthermore, regression analyses showed that only academically high?achieving boys and physically active boys had higher self?esteem. (shrink)

Sir Richard Phillips was a London-born author and publisher of educational textbooks who used a vast array of pseudonyms, including that of Reverend C. C. Clarke. Phillips' marketing techniques - the systematic borrowing of famous authors' names for his textbooks, along with the multiplication of easy to produce related educational products - were key to his success. No doubt meant as an accessible encyclopaedia, this 40th edition of 1834 - attributed to Phillips himself - is a surprisingly vast and heterogeneous (...) survey, which compiles natural and man-made curiosities across the world. The Himalayas and Mont Blanc share a chapter with the Peak of Derbyshire; famous rivers lead to mysterious subterranean forests; and Stonehenge is closely followed by St Paul's cathedral. Halfway between reference book and textbook, this richly illustrated volume is a fascinating catalogue of the world's wonders as perceived in the early nineteenth century. (shrink)

Lazare Carnot was the unique example in the history of science of someone who inadvertently owed the scientific recognition he eventually achieved to earlier political prominence. He and his son Sadi produced work that derived from their training as engineers and went largely unnoticed by physicists for a generation or more, even though their respective work introduced concepts that proved fundamental when taken up later by other hands. There was, moreover, a filial as well as substantive relation between the work (...) of father and son. Sadi applied to the functioning of heat engines the analysis that his father had developed in his study of the operation of ordinary machines. Specifically, Sadi's idea of a reversible process originated in the use his father made of geometric motions in the analysis of machines in general. (shrink)

It is shown that the usual procedures of obtaining the macroscopic Maxwell equations from the microscopic Maxwell-Lorentz equations by performing averages contain an arbitrary choice of gauge. By a suitable different choice of the gauge the so-obtained Maxwell equations can be cast back to the form of the starting Maxwell-Lorentz equations. Therefore one cannot consider the Maxwell equations to be obtainable from the Maxwell-Lorentz equations by simply performing averages. The implication of this result is that besides the electromagnetic fields produced (...) by the moving electric charges, as given by the Maxwell-Lorentz equations, there may be some other agents that cannot be identified as some kind of motion of the electric charges and that participate in the production of the electromagnetic fields. (shrink)

It is shown that the Maxwell-Lorentz equations can be deduced from the law of Biot-Savart by simply performing some theoretical experimentations.