Comets and the formation of biochemical compounds on the primitive Earth--a review.

Thirty years ago it was suggested that comets impacting on the primitive Earth may have represented a significant source of terrestrial volatiles, including some important precursors for prebiotic synthesis (Oró, 1961, Nature 190: 389). This possibility is strongly supported not only by models of the collisional history of the early Earth, but also by astronomical evidence that suggests that frequent collisions of comet-like bodies from the circumstellar disk around the star beta Pictoris are taking place. Although a significant fraction of the complex organic compounds that appear to be present in cometary nuclei were probably destroyed during impact, it is argued that cometary collisions with the primitive Earth represented an important source of both free-energy and volatiles, and may have created transient, gaseous environments in which prebiotic synthesis may have taken place.     

A Scientific Look at Spaghetti

The United States is currently experiencing its worst man-made environmental disaster, the BP Deepwater Horizon oil leak. The Gulf of Mexico oil spill is severe in its impact, but it is only one of several global oil spill disasters in history. Students can utilize the technology of Google Earth to explore the spatial and temporal distribution of oil spills. In addition to increasing content knowledge of oil spills, Google Earth assists in developing student geographic and technologic literacy. Designed for a middle school science class, this activity may also be used in English, history, math, art, and poster-making.     

Comets and the formation of biochemical compounds on the primitive Earth – A review

Thirty years ago it was suggested that comets impacting on the primitive Earth may have represented a significant source of terrestrial volatiles, including some important precursors for prebiotic synthesis (Oró, 1961,Nature 190: 389). This possibility is strongly supported not only by models of the collisional history of the early Earth, but also by astronomical evidence that suggests that frequent collisions of comet-like bodies from the circumstellar disk around the star Pictoris are taking place. Although a significant fraction of the complex organic compounds that appear to be present in cometary nuclei were probably destroyed during impact, it is argued that cometary collisions with the primitive Earth represented an important source of both free-energy and volatiles, and may have created transient, gaseous environments in which prebiotic synthesis may have taken place.     

Unlocking the potential of Google Earth as a tool in invasion science

Distribution data are central to many invasion science applications. The shortage of good information on the distribution of alien species and their spatial dynamics is largely attributable to the cost, effort and expertise required to monitor these species over large areas. Virtual globes, particularly Google Earth, are free and user-friendly software which provide high-resolution aerial imagery for the entire globe. We suggest this has enormous potential for invasion science. We provide suggestions and tools for gathering data on the distribution and abundance of invasive alien trees using visual interpretation of Google Earth imagery, and propose how these data may be used for a number of purposes, including calculating useful metrics of invasions, prioritising species or areas for management and predicting potential distributions of species. We also suggest various practical uses of Google Earth, such as providing a tool for early detection of emerging invasions, monitoring invasions over time, and to help researchers and managers identify suitable field study sites. Virtual globes such as Google Earth are not without limitations and we provide guidance on how some of these can be overcome, or when imagery from Google Earth may not be fit for invasion science purposes. Because of Google Earth’s huge popularity and ease of use, we also highlight possibilities for awareness-raising and information sharing that it provides. Finally, we provide the foundations and guidelines for a virtual global network of sentinel sites for early detection, monitoring and data gathering of invasive alien trees, which we propose should be developed as part of a “citizen science” effort. There has been limited use of virtual globes by invasion scientists and managers; it is our hope that this paper will stimulate their greater use, both within the field of invasion science and within ecology generally.     

Radiation: microbial evolution, ecology, and relevance to mars missions

Ultraviolet (UV) radiation has been an important environmental parameter during the evolution of life on Earth, both in its role as a mutagen and as a selective agent. This was probably especially true during the time from 3.8 to 2.5 billion years ago, when atmospheric ozone levels were less than 1% of present levels. Early Mars may not have had an "ozone shield" either, and it never developed a significant one. Even though Mars is farther away from the Sun than the Earth, a substantial surficial UV flux is present on Mars today. But organisms respond to dose rate, and on Mars, like on Earth, organisms would be exposed to diurnal variations in UV flux. Here we present data on the effect of diurnal patterns of UV flux on microbial ecosystems in nature, with an emphasis on photosynthesis and DNA synthesis effects. These results indicate that diurnal patterns of metabolism occur in nature with a dip in photosynthesis and DNA synthesis in the afternoon, in part regulated by UV flux. Thus, diurnal patterns must be studied in order to understand the effect of UV radiation in nature. The results of this work are significant to the success of human missions to Mars for several reasons. For example, human missions must include photosynthetic organisms for food production and likely oxygen production. An evolutionary approach suggests which organisms might be best suited for high UV fluxes. The diurnal aspect of these studies is critical. Terraforming is a potential goal of Mars exploration, and it will require studies of the effect of Martian UV fluxes, including their diurnal changes, on terrestrial organisms. Such studies may suggest that diurnal changes in UV only require mitigation at some times of day or year.     

Global change ecology

Ecology has expanded from its traditional focus on organisms to include studies of the Earth as an integrated ecosystem. Aided by satellite technologies and computer models of the climate of the Earth, global change ecology now records basic parameters of our planet, including its net primary productivity, biogeochemical cycling and effects of humans on it. As I discuss here, this new perspective shows us what must be done to transform human behaviors to enable the persistence of life on Earth under human stewardship.     

Role and regulation of sigma S in general resistance conferred by low-shear simulated microgravity in Escherichia coli

Life on Earth evolved in the presence of gravity, and thus it is of interest from the perspective of space exploration to determine if diminished gravity affects biological processes. Cultivation of Escherichia coli under low-shear simulated microgravity (SMG) conditions resulted in enhanced stress resistance in both exponential- and stationary-phase cells, making the latter superresistant. Given that microgravity of space and SMG also compromise human immune response, this phenomenon constitutes a potential threat to astronauts. As low-shear environments are encountered by pathogens on Earth as well, SMG-conferred resistance is also relevant to controlling infectious disease on this planet. The SMG effect resembles the general stress response on Earth, which makes bacteria resistant to multiple stresses; this response is sigma s dependent, irrespective of the growth phase. However, SMG-induced increased resistance was dependent on sigma s only in stationary phase, being independent of this sigma factor in exponential phase. sigma s concentration was some 30% lower in exponential-phase SMG cells than in normal gravity cells but was twofold higher in stationary-phase SMG cells. While SMG affected sigma s synthesis at all levels of control, the main reasons for the differential effect of this gravity condition on sigma s levels were that it rendered the sigma protein less stable in exponential phase and increased rpoS mRNA translational efficiency. Since sigma s regulatory processes are influenced by mRNA and protein-folding patterns, the data suggest that SMG may affect these configurations.     

The evolutionary geometry of human anatomy: Discovering our inner fly

The human body is one still frame in a very long evolutionary movie. Anthropologists focus on the last few scenes, whereas geneticists try to trace the screenplay back as far as possible. Despite their divergent time scales (millions versus billions of years), both disciplines share a reliance on a third field of study whose scope spans only a matter of days to months, depending on the organism. Embryology is crucial for understanding both the pliability of anatomy and the modularity of gene circuitry. The relevance of human embryology to anthropology is obvious. What is not so obvious is the notion that equally useful clues about human anatomy can be gleaned by studying the development of the fruit fly, an animal as different from us structurally as it is distant from us evolutionarily. The underlying kinship between ourselves and flies has only become apparent recently, thanks to revelations from the nascent field of evolutionary developmental biology, or evo‐devo. All bilaterally symmetric animals, it turns out, share a common matrix of body axes, a common lexicon of intercellular signals, and a common arsenal of genetic gadgetry that evolution has tweaked in different ways in different lineages to produce a dazzling spectrum of shapes and patterns. Anthropologists can exploit this deep commonality to search our genome more profitably for the mutations that steered us so far astray from our fellow apes.     

Prebiotic Chemistry: What We Know,What We Don't

How life on Earth began remains an unexplained scientific problem. This problem is nuanced in its practical details and the way attempted explanations feedback with questions and developments in other areas of science, including astronomy, biology, and planetary science. Prebiotic chemistry attempts to address this issue theoretically, experimentally, and observationally. The ease of formation of bioorganic compounds under plausible prebiotic conditions suggests that these molecules were present in the primitive terrestrial environment. In addition to synthesis in the Earth's primordial atmosphere and oceans, it is likely that the infall of comets, meteorites, and interplanetary dust particles, as well as submarine hydrothermal vent synthesis, may have contributed to prebiotic organic evolution. The primordial organic soup may have been quite complex, but it did not likely include all of the compounds found in modern organisms. Regardless of their origin, organic compounds would need to be concentrated and complexified by environmental mechanisms. While this review is by no means exhaustive, many of the issues central to the state of the art of prebiotic chemistry are reviewed here.     

The Role of Intuitive Ontologies in Scientific Understanding – the Case of Human Evolution

Psychological evidence suggests that laypeople understand the world around them in terms of intuitive ontologies which describe broad categories of objects in the world, such as ‘person’, ‘artefact’ and ‘animal’. However, because intuitive ontologies are the result of natural selection, they only need to be adaptive; this does not guarantee that the knowledge they provide is a genuine reflection of causal mechanisms in the world. As a result, science has parted ways with intuitive ontologies. Nevertheless, since the brain is evolved to understand objects in the world according to these categories, we can expect that they continue to play a role in scientific understanding. Taking the case of human evolution, we explore relationships between intuitive ontological and scientific understanding. We show that intuitive ontologies not only shape intuitions on human evolution, but also guide the direction and topics of interest in its research programmes. Elucidating the relationships between intuitive ontologies and science may help us gain a clearer insight into scientific understanding.     

Phosphorus in prebiotic chemistry

The prebiotic synthesis of phosphorus-containing compounds-such as nucleotides and polynucleotides-would require both a geologically plausible source of the element and pathways for its incorporation into chemical systems on the primitive Earth. The mineral apatite, which is the only significant source of phosphate on Earth, has long been thought to be problematical in this respect due to its low solubility and reactivity. However, in the last decade or so, at least two pathways have been demonstrated which would circumvent these perceived problems. In addition, recent results would seem to suggest an additional, extraterrestrial source of reactive phosphorus. It appears that the 'phosphorus problem' is no longer the stumbling block which it was once thought to be.     

The macroecology of sustainability

The discipline of sustainability science has emerged in response to concerns of natural and social scientists, policymakers, and lay people about whether the Earth can continue to support human population growth and economic prosperity. Yet, sustainability science has developed largely independently from and with little reference to key ecological principles that govern life on Earth. A macroecological perspective highlights three principles that should be integral to sustainability science: 1) physical conservation laws govern the flows of energy and materials between human systems and the environment, 2) smaller systems are connected by these flows to larger systems in which they are embedded, and 3) global constraints ultimately limit flows at smaller scales. Over the past few decades, decreasing per capita rates of consumption of petroleum, phosphate, agricultural land, fresh water, fish, and wood indicate that the growing human population has surpassed the capacity of the Earth to supply enough of these essential resources to sustain even the current population and level of socioeconomic development.     

Study of the anatomy of the living human heart using echocardiography

For studying anatomy of the alive human heart, a new method of ultrasonic echography has been used. With its assistance it is possible to see all the cardiac chambers, interventricular and interatrial septa, tricuspidal and mitral valves, their chordae, papillary muscles, myocardium and pericardium. Not only their statics, but also their dynamics are investigated, when the heart contracts and its valves make movements. Owing to this, possibilities for studying cardiac anatomy in the alive people.     

Man and the Sea--The Ecological Challenge

Cultural "revolutions" are characterized by increased utilizationof natural resources, resulting in increased carrying capacityfor the human species. We are witnessing the Marine Revolution,which challenges us to develop unifying, ecosystem-based approachesto the science and use of the sea. Knowing (i.e., science) marineprocessesshould form the fundamental basis for doing (i.e., conservationand management), within a global human ecological framework. The issues of human ecology are about the same by land or sea,but these subdivisions of Earth are fundamentally different.The sea must be understood in its own right, rather than bedriven by terrestrially-derived models. For example, animaldiversity is on a species level by land; marine diversity isat higher taxonomic levels and, if viewed functionally, is greaterthan the land's. This has important implications in the designof protected areas. Another example concerns the roles of largeorganisms in ocean processes; fishery ecology has been neglected,but a total ecosystem viewpoint is essential towards placingfisheries on a sustainable basis. New perspectives toward the sea are rapidly emerging. Satelliteshave the potential for revolutionizing oceanography. Ecotoxicologyis in the process of addressing pollution on an ecosystem basis.A unified scientific perspective of "oceanology" is requiredto help meet problems of human ecology during the Marine Revolution.     

Evaluating changes in land cover and their importance for global change

During recent years, much progress has been made in integrating traditional natural science disciplines and in the developmnet of multidisciplinary models. This is crucial for an increased understanding of the dynamics of the Earth system. The domination of human activities in altering these dynamics is still increasing. However, few research projects have focused directly on understanding the motives for such intensification. It has only recently been acknowledged that improved understanding of human driving forces of global change is required to enable meaningful projections of plausible future states of the Earth system.     

Modulation of proliferation of peripheral blood lymphocytes after irradiation of volunteers with polychromatic visible and infrared light

Effects on human immune system of visible and infrared (IR) radiation, the dominating types of solar light on Earth, still remain poorly studied. In the present work, a small area of the volunteers' body surface was irradiated with polychromatic visible + IR polarized (VIP) light, whose spectral range is close to the natural one (400-3400 nm, 12 J/cm2), and spontaneous and phytohemagglutinin (PHA)-induced DNA syntheses were studied by radiometric method in lymphocytes (Lym) of peripheral blood. This Irradiation stimulated both spontaneous and PHA-induced DNA synthesis in Lym but only in volunteers with initially decreased parameters of synthesis (on average, by 2.5 and 2.7 times, respectively), which was recorded 24 h after irradiation of volunteers, and after a 72 h cultivation of separated mononuclears. In the parallel experiments, blood of each volunteer was irradiated in vitro. Besides, by modeling situation in vivo, when a small amount of transcutaneously photomodified blood contacts its much larger circulating volume, the irradiated and non-irradiated samples of autologous blood were mixed at a 1:10 volume ratio. In Lym with the initially decreased synthesis level, the spontaneous synthesis elevated by 2 and 3 times, respectively, whereas stimulation of PHA-synthesis was observed only after addition of the irradiated blood to the intact one (by 2.2 and 1.6 times, respectively). A high degree of positive correlation in changing the studied parameters is revealed in irradiation of blood in vivo and in vitro. This makes it possible to associate the light-stimulating effect on Lym of the entire circulating blood with transcutaneous photomodification of its small amounts, and with action of such blood on the rest of blood. A similarity in the direction and additivity of mitogenic effects of VIP light and PHA was revealed. The obtained data enable us to suggest that therapy employing polychromatic visible and IR light would promote presumably an increase in the number of Lym in peripheral blood and an enhancement of their response to antigenic stimulus.     

Mammal extinctions and the increasing isolation of humans on the tree of life

A sixth great mass extinction is ongoing due to the direct and indirect effects of human pressures. However, not all lineages are affected equally. From an anthropocentric perspective, it is often purported that humans hold a unique place on Earth. Here, we show that our current impacts on the natural world risk realizing that expectation. We simulated species loss on the mammalian phylogenetic tree, informed by species current extinction risks. We explored how Homo sapiens could become isolated in the tree if species currently threatened with extinction disappeared. We analyzed correlates of mammal extinctions risks that may drive this isolation pattern. We show that, within mammals, and more particularly within primates, extinction risks increase with the number of known threat types, and decrease with geographic range size. Extinctions increase with species body mass, trophic level, and the median longitudinal extent of each species range in mammals but not within primates. The risks of extinction are frequently high among H. sapiens close relatives. Pruning threatened primates, including apes (Hominidae, Hylobatidae), from the tree of life will lead to our species being among those with the fewest close relatives. If no action is taken, we will thus not only lose crucial biodiversity for the preservation of Earth ecosystems, but also a key living reference to what makes us human.     

Layers of symbiosis--visualizing the termite hindgut microbial community

Jared Leadbetter takes us for a nature walk through the diversity of life resident in the termite hindgut--a microenvironment containing 250 different species found nowhere else on Earth. Jared reveals that the symbiosis exhibited by this system is multi-layered and involves not only a relationship between the termite and its gut inhabitants, but also involves a complex web of symbiosis among the gut microbes themselves.     

Milestones and rates of growth in the development of biology.

An attempt has been made to examine the exponetial rate of increase of the great discoveries, the "milestones," in the rise of biology from the beginning of the seventeenth century, and particularly in the rise of genetics from the beginning of the twentieth century. The biological sciences in general, during the three centuries named, exhibit a doubling of the number of great discoveries in each fifty years. Genetics, in the twentieth century, has risen much faster. Its doubling time for the most significant discoveries has been about twenty-two and a half years. Either of these rates is of course far slower than the exponential rise in the total output of biological science, the number of scientists, or the cost of science, which have been generally reported to double about every ten years or less. It follows that, as time passes, and until these exponetial rates become considerably altered, a relationship of diminishing returns is quite evident. As time passes, even though the most significant discoveries continue to increase exponetially, it takes a greater total output, a greater number of (assisting?) scientists, and greater amounts of money to yield a set quantity of major new findings. The rapid rise of the life sciences cannot continue its present course into the twenty-first century without meeting ineluctable limits to expansion. It may be argued that as in other human spheres of activity, so too in natural science there are limits to growth which we are rapidly approaching. From the predictable asymptote only unpredictable breakthroughs might deliver us.     

On the Evolutionary Foundations of Language

New data on the cognitive capacities of other primates requires a reevaluation of our position on the nature of human language and the factors that led to its development. Pressures on the limited display system of the social primates may have made changes in the vocal tract anatomy of man associated with the development of upright posture of great selective importance. Human vocal tract anatomy may be at least as important as brain capacity in accounting for the origins of human language. An apparent upper age limit on efficient language acquisition in man leads to the "foreign accent" phenomenon. This may have been adoptively significant as a device which helped in the maintenance of a population structure in which rapid genetic change was possible. Embedding in language may represent a cognitive ability that is also reflected in the capacity for cultural variation, and may be extremely important in maintaining efficient population structure and in selecting for increasing intelligence.