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Life on Earth is classed into three phylogenetic domains: the Archaea, the Bacteria and the Eucarya. Eukaryotic cells are less diverse than prokaryotes metabolically, but have a complex cellular architecture comprising a nucleus, a cytoskeleton (a proteinic network structuring the cytoplasm to facilitate intracellular traffic, endo- and exo-cytosis and amoeboid locomotion; Cavalier-Smith, 2002), an endomembrane system (a system of internal membranes subdivided into several organelles, and used for synthesis, processing, packaging and transport of macromolecules such as lipids and proteins) and organelles such as mitochondria (or derived organelles) and chloroplasts in photosynthetic eukaryotes. Archaea and Bacteria are called prokaryotes because their cells do not contain a nucleus or organelles, and because transcription and translation are coupled, i.e. they do not occur in different cellular compartments. The prokaryotes have diverse and complex metabolisms, but simpler cellular architecture. They possess proteins playing the role of cytoskeleton, but not the motor proteins involved in intracellular transport as in eukaryotes (Moller-Jensen and Lowe, 2005; Cabeen and Jacobs-Wagner, 2005) and some (the planctomycetales) may possess endomembrane systems (e.g. Fuerst, 2005).
The eukaryotic genome is seen as a mosaic of bacterial genes (involved in energy and carbon metabolism) and archaeal genes (related to DNA replication, transcription and translation), but it also contains a core set of genes and proteins unique to eukaryotes (e.g. Kurland et al., 2006), while the membrane lipids are closer to those of the bacteria (Rivera et al., 1998).
The Sun's magnetic activity has steadily declined throughout its main-sequence lifetime. This is an immediate consequence of the declining dynamo as a star spins down by losing angular momentum through its magnetized wind. Along with the decline in magnetic activity, solar radiation ultimately induced by the magnetic fields declined as well, and hence the short-wavelength radiative input into planetary atmospheres diminished with time. (By contrast, solar radiation at visible wavelengths increased with time, as discussed below.) Similarly, the magnetically guided solar wind and high-energy particle fluxes were very likely to be different in the young solar environment compared to present-day conditions. A closer understanding of the magnetic behaviour of the young Sun is therefore pivotal for further modelling of young planetary atmospheres, their chemistry, heating and erosion.
Magnetic activity expresses itself in a variety of features, including dark photospheric, magnetic spots, photospheric faculae and chromospheric plage producing optical and ultraviolet excess radiation, and – most dramatically – magnetically confined coronae containing million-degree plasma that emits extreme-ultraviolet and X-ray emission. Occasional magnetic instabilities (flares) and shocks both in the corona and in interplanetary space accelerate particles to energies much beyond 1 MeV; related electromagnetic radiation (e.g. from collisions) is emitted in the hard X-ray and gamma-ray range (Lin et al., 2002).
By
Robert Pascal, Institut des Biomolécules Max Mousseron, Montpellier, France,
Laurent Boiteau, Institut des Biomolécules Max Mousseron, Montpellier, France
The origin of life, as with any other process of structure formation, should have been accompanied by a loss of entropy. Since the second law of thermodynamics states that the entropy of an isolated system tends to increase, any self-organizing system must exchange free energy (closed system) and/or matter (open system) with its environment in order that the overall entropy increases (Kondepudi and Prigogine, 1998). This simple observation emphasizes the importance of energy transfers in the origin and development of early life. As far as biochemical systems are concerned, energy exchanges mostly involve chemical energy that is brought about by ‘high-energy’ carriers so that energy flows through metabolic pathways from free energy-rich compounds towards low-energy molecules, the difference being released in the environment as heat. When the occurrence of a thermodynamically unfavourable reaction makes it necessary, fresh energy is provided to the system through coupled reactions involving a free-energy carrier such as ATP. The principle that energy is brought about by ‘high-energy’ carriers applies to most metabolic pathways, though some of them do not simply follow this rule. An example is the process of energy collection leading to ATP synthesis, in which ‘chemical’ energy is generated from a ‘physico–chemical’ source: a gradient of concentration between two compartments separated by the plasma–cell membrane (Mitchell, 1961).
The first two thirds of the history of life on Earth are dominated by single-celled microorganisms with prokaryotes characterizing the time period up to at least the Palaeoproterozoic Period (from 2.5 to about 1.8 billion years (Ga) ago). The oldest recognizable eukaryotes appear in the Mesoproterozoic Era (and are dated at between 1.6 to 1.8 Ga (Javaux et al., 2001, 2004; see also review in Knoll et al., 2006). This chapter on early life will concentrate on the traces of life contained in the oldest crustal rocks potentially capable of hosting well-preserved biosignatures, i.e. Early to Mid-Archaean, 3.5 to 3.0 Ga-old sediments and volcanic rocks from greenstone belts in both the Pilbara (NW Australia) and the Barberton (East South Africa) Greenstone Belts. The fossil traces of early microorganisms in these rocks resemble prokaryotes in terms of their morphology, metabolic processes and interactions with the environment. Life is directly influenced by its environment and, reciprocally, it can also influence its immediate environment. On the microbial scale, this influence is in proportion to the size of the microbial colonies, biofilms or mats, which can range from tens of microns to several metres or more (sometimes up to kilometres) for well-developed mats. For instance, if one takes into consideration the probable microbial control on the rise of oxygen in the atmosphere (between 2.4 and 2.0 Ga; Bekker et al., 2004; Canfield, 2005), this influence also reaches the planetary scale.
In a paper entitled ‘The prospect of alien life in exotic forms on other worlds’ published in 2006, the authors write:
The nature of life on Earth provides a singular example of carbon-based, water-borne, photosynthesis-driven biology. Within our understanding of chemistry and the physical laws governing the universe, however, lies the possibility that alien life could be based on different chemistries, solvents, and energy sources from the one example provided by Terran biology.
(Schulze-Makuch and Irwin, 2006)
Similar comments can be found in several papers (Bains, 2004).
We are not planning to address the possibility of an alien life, but wish to focus on the issue of the solvent in order to try to demonstrate that water is an essential component of all living systems. Living systems are complex both at the molecular and supra-molecular levels (Schulze-Makuch and Irwin, 2006). Water plays, at both these levels, a role which is crucial for the structure, the stability and the biological function of all molecules that are essential for life, a role that cannot be played by any other solvent or any other molecule.
A solvent is never an inert medium and always interacts with the solute molecules. These interactions affect not only the solute but also the solvent. Water is a unique solvent because solute-induced modifications are very important in this medium.
The class in Archaeoastronomy at the University of Wales Trinity Saint David is taught as part of the MA in Cultural Astronomy and Astrology, within the University's School of Archaeology, History and Anthropology. This paper will present and review some of the postgraduate work produced in the course, reporting on its findings as examples of the level of work that may be expected on a taught MA course at a UK University.
In the favored correlation between the Mayan and Gregorian calendars, a time period of a little over 5125 solar years will be completed on the winter solstice of 2012. While numerous Classic Maya hieroglyphic texts feature the previous closing of this era in 3114 BCE, only one text—Monument Six of Tortuguero, Tabasco, Mexico—mentions the future event. The portion of the monument describing the event is damaged, and previous attempts to decipher this part of the text have been inconclusive. These have inadvertently led to popular and far-flung millenniarian speculations about ancient esoteric knowledge. The whole of Tortuguero Monument Six—an exquisite piece of Classic sculpture and literature—addresses the fundamental relationship between royal charter, warfare, captive sacrifice, appeasement of the gods, the ordering of time, and the stability of society for posterity. The author and her colleagues—employing high-resolution photos and great attention to script detail—have brought to light a more accurate interpretation of the damaged text. The results of this effort suggest a distant future ceremony of investiture for a deity of deep-time transitions whose reflexes can be seen in indigenous community celebrations of highland Guatemala.
Since the 1980s, the entrances of a certain form of monumental Neolithic enclosure (Kreisgrabenanlage, KGA) have been discussed in relation to solstice or lunistice directions. In our current project we analyze astronomical orientations in more than 30 KGAs in Lower Austria, and combine virtual reconstructions based on previous magnetic surveys with horizon surveys and astronomical simulation software.
The authors have shown previously that, as viewed from an evident observing point to the west, and a plausible observing point to the east, the Thirteen Towers of Chankillo formed an artificial ‘toothed’ horizon that spanned the annual rising and setting arcs of the sun and provided a means to identify each day in the seasonal year by observing the position of sunrise or sunset against them. The Thirteen Towers thus constitute a unique solar observation device that is still functioning, and a remarkable example of a native form of landscape timekeeping that preceded similar facilities in imperial Cusco by almost two millennia. Yet the social, political, and ritual contexts in which Chankillo's astronomical alignments operated deserve further exploration. In this paper, we present new archaeoastronomical evidence that not only clarifies some aspects of the solar observation device but suggests a wider range of alignments visible from more publicly accessible parts of the ceremonial complex, and also suggests a possible interest in marking lunar alignments as well as solar ones. We also bring together archaeological evidence to suggest that the society that built Chankillo was differentiated. The Thirteen Towers may have served to regulate the calendar, solar and ritual, while the solar cult centred on them may have lent legitimacy and authority to a rising warrior elite through ceremony in an impressive sacred setting that brought society together while reproducing its growing inequality.
As there are so many Australian Aboriginal and Torres Strait astronomies and cosmologies, commonalities are unusual. However one of the ‘things belonging to the sky’ that seems common to all groups across the continent is the open star cluster of the Pleiades. Yet interpretations of this cluster vary. So far I have tentatively identified four different cultural areas, the first being most of mainland Australia; the second being the islands south of mainland Australia known as Tasmania; the third being the cultural area of north-eastern Arnhem Land; and the fourth being the cultural area of the Torres Strait Islands. Within these areas, versions of the stories vary as contemporary circumstances change.
Eastern Polynesian astronomy was practiced by navigators and astronomer-priests who were in charge of adjusting the lunar calendar and their annual ritual cycle of activities known as ‘The Work of the Gods’. The festivity known in Polynesia as Matariki, Matali'i or Matari'i was related to the heliacal and acronical rising and setting of the Pleiades. A study of 75 marae on the island of Raivavae, Austral Islands and of 7 marae in the island of Raiatea, Society Islands shows that there are alignments towards important star positions associated with this ritual cycle. Their use as observatories has not been documented and therefore these alignments could have served solely ritual purposes. On Easter Island all information regarding the Matariki festival coincides with the arrival of a Spanish expedition in 1770.
Sky observation in sub-tropical Andean areas, part of ancient Collasuyu, during the Inca empire (ca. 1470 A.D.) was characterized by the combined use of geographical, social, psychological and natural elements of the entorno (environment or landscape). From a phenomenological perspective, it would be understood as: the place (point of observation), the path (line or relation), the horizon (calendrical marker) and the zenith/anti-zenith (vertical projection) as an expression of ‘dwelling or living in the world’. I present results obtained from a spatio-temporal analysis of mountain worship which took place at the Atacama Indian community of Socaire, northern Chile (23° 35′ 28″S, 67° 52′ 36″W, 3274m AMSL). These indicate the existence of an animistic relationship between astronomical observations, the worship of mountains, and agricultural practices. The psychological phenomena of pareidolia, apophenia and hierophany also contribute to explain the mimetolith of the ‘Hand of God’ (formed by the Tumisa, Lausa, Chiliques, Ipira and Miñiques mountains) and the social categories of space and time in Socaire: ‘above, here, and down’; ‘right and left’; ‘female and male’; ‘noon and midnight’; ‘north and south’; and ‘visible and invisible’ (as complementary opposites or yanantin).
Human beings have recognized and interpreted celestial objects and events since time immemorial. The sky, our common and universal heritage, forms an integral part of all human cultures around the world. The Ancient Skies Project aims to collect, verify and publish available information about various human cultures and their astronomical knowledge in one single web-accessible knowledgebase.
The overall vision for the project is
In this paper we describe the basic tenets of the project, discuss the design of the knowledgebase, and compare the project to other similar projects.
Following the Starlight meeting held in La Palma in November 2009, members of the IAU Working Group on Astronomy and World Heritage and the Starlight Initative are working together, with the approval of the UNESCO World Heritage Centre, to produce a new integrated web site for the UNESCO–IAU Astronomy and World Heritage Initiative that will act as a Portal to the Heritage of Astronomy. As such, the portal will be the bridge between the Initiative, the scientific community, National Commissions and experts, and the general public.
This essay draws on the skeptical opinions that some historians of science have of archaeoastronomy, on historians' changing interpretations of proper historical method, and on their varied understandings of the nature of science to discuss how these methodological issues apply to archaeoastronomy. The essay argues that archaeoastronomical research should bear as much attention to the external context of early astronomies as it does to their internal content, suggesting specifically that insights into the origins of science can be gained by paying greater attention to the practitioners of early astronomies—to the skywatchers.
In this paper we discuss the contemporary production of cosmological discourse, especially that concerning celestial space, among the aboriginal Toba and Mocoví communities of the Argentinian Chaco. Cosmology remains essential for Tobas and Mocovís at the present time. However, we shall demonstrate the importance of the emergence of new producers of cosmological discourse related to new actors in the struggle over leadership. We will also take into account the present contexts of discourse—the new interlocutors and communications technologies. Our goal is to understand cosmological terms in the context of the complex relations resulting from the structural subordination of these groups to national society.
The Ryukyu (Okinawa) Islands are situated in sub-tropical zone between the Japanese Archipelago and Taiwan. Although Okinawan people have a rich tradition of star lore, few studies have been undertaken on its relevance to subsistence, religion and the socio-political system. This paper is a first attempt to explore a systematic relationship between star lore (e.g. relating to the Pleiades) with agriculture, fishing, navigation and religious practice. This paper also considers the possibility of interpreting the nature of prehistoric and historical stone structures from the viewpoint of archaeoastronomy. This kind of analysis is likely to be fruitful, since the kingship of the Ryukyu Islands was strongly associated with sun worship.
We present some methodological reflections based upon twelve years' experience working in South American ethnoastronomy. The aim is to propose a basis for a possible development plan for ethnoastronomy in this region. Taking as axiomatic that ethnoastronomy is a social science, we discuss issues such as the process of development of an academic discipline, the links between ethno- and archaeoastronomy, the idea of ‘otherness’, ethnographic methodology, the relevance of logics of practice, the relationship between orality and writing, and the dialectic relationship between change and continuity. In addition, we discuss possible ways to achieve the institutionalization of ethnoastronomy. We conclude by considering the importance of regional and international academic exchange.
Examining Ancient Maya notions about prophecies and their calendar cycles, we find that they predicted no ‘end of the Maya calendar’. Indeed, surviving texts and art indicate that they seem to have expected no change in the status quo whatever, for at least 4000 years into the future. This search also turned up evidence that different local schools of calendar-priests differed significantly from each other; it is entirely possible that priests in one city expected the End of the World, while their peers elsewhere believed the opposite.