Y con tanta ciencia una inútil ansia de tener lástima de algo, de que llueva aquí dentro, de que por fin empiece a llover, a oler a tierra, a cosas vivas, sí, por fin a cosas vivas.
Excerpt:Science is celebrating the 150th anniversary of the publication of Charles Darwin's On the Origin of Species and the 200th anniversary of the author's birth with a variety of news features, scientific reviews and other special content, all collected here.
Editor's Note: This article discusses cultural evolution, and how genes are not sufficient to understand how humanity evolved. Excerpt: Barely a decade after Charles Darwin published On the Origin of Species, he and his long-time correspondent Alfred Russel Wallace were engaged in a fierce debate. Darwin said that natural selection had shaped the human species just like any other. But Wallace disagreed, arguing that selection alone could not account for the exceptional capabilities of the human mind. "How could natural selection, or survival of the fittest in the struggle for existence, at all favour the development of mental powers so entirely removed from the material necessities of savage men?"
Excerpt: Although history is not made entirely, or even mostly, by prominent men and women, two great exceptions to that rule were born exactly 200 years ago today, on 12 February 1809: Charles Darwin and Abraham Lincoln. See Also:Darwin 200 online collection.
Source:Humanity and evolution, Editorial, DOI: 10.1038/457763a, Nature 457, 763-764, 2009/02/12
Big Year For Darwin, But What Would He Make Of The Climate Change Ahead?, ScienceDaily
Excerpts: Charles Darwin may have been born 200 years ago come Feb. 12, but his theory of evolution remains an everyday touchstone for modern biologists. And while the Origin of Species author might not have known the term "global warming," he wouldn't have been surprised that the environment is changing. He would, however, be astonished by the speed at which it's happening today, researchers believe. "Every species is under temporary permanence," says (...). Darwin would have predicted changes in species' habits and even changes in the environment, but the planet's facing changes that are both drastic and unpredictable. (...)
Excerpt: The 200th anniversary of the birth of Charles Robert Darwin falls on 12 February 2009. Darwin was arguably the most influential scientist of modern times. No single researcher has since matched his collective impact on the natural and social sciences; on politics, religions, and philosophy; on art and cultural relations, and in ways that the man himself would never have imagined.
Elysia chlorotica, the solar-powered sea slug, is about 3 cm long (Image: PNAS)
Solar-PoweredSea Slug Harnesses Stolen Plant Genes, New Scientist
Excerpts:
Young E. chlorotica fed with algae for two weeks, could survive for the rest of their year-long lives without eating, Rumpho found in earlier work.
But a mystery remained. Chloroplasts only contain enough DNA to encode about 10% of the proteins needed to keep themselves running. The other necessary genes are found in the algae's nuclear DNA. "So the question has always been, how do they continue to function in an animal cell missing all of these proteins," says Rumpho.
Excerpts: Yet group selection - the idea that evolution can choose between groups, not just the individuals that make them up - has a higher profile today than at any time since its apparent banishment from mainstream evolutionary theory. And it gets better press, too. This is in part owing to the efforts of David Sloan Wilson, of BinghamtonUniversity in New York, who argues that the dismissal of group selection was a major historical error that needs to be rectified. And it does not hurt that he has been joined by Edward O. Wilson, the great naturalist and authority on social insects.
Excerpts: You might think that once evolution has found one way to get something done, it will stick with it. But similar physical forms can hide radically different wiring, (...).
Tunicates - also known as sea squirts - are humans' closest invertebrate cousins. They have tadpole-like larvae that closely resemble miniature vertebrate embryos and so were expected to build their bodies in the same way. But they don't. (..) It's as if you had found a car in which components of the engine were scattered all over the back seat - but the car still worked.
Variation In Evolutionary Patterns Across The Geographic Range Of A Fossil Bivalve, Science
Excerpts: Within a fossil bivalve genus, evolution tended to occur as a random walk at the highest latitudes and to be in stasis mode in deep marine environments.
The fossil record is the only direct source of data for studying modes (patterns) and rates of morphological change over long periods of time. Determining modes and rates is important for understanding macroevolutionary processes, but just how modes and rates vary within a taxon, and why, remain largely unaddressed. We examined patterns of morphological change in the shell of the Mesozoic marine bivalve genus Buchia over its geographic and temporal range.
DNA Chunks, Chimps And Humans: Marks Of Differences Between Human And Chimp Genomes, Innovations-report
Excerpts: Researchers have carried out the largest study of differences between human and chimpanzee genomes, identifying regions that have been duplicated or lost during evolution of the two lineages. (...) "By looking at only one 'reference' sequence for human or chimpanzee, as has been done previously, it is not possible to tell which differences occur only among individual chimpanzees or humans and which are differences between the two species. (...) Rather than examining single-letter differences in the genomes (so-called SNPs), the researchers looked at copy number variation (CNV) - the gain or loss of regions of DNA. (...)
Human Genes Are Multitaskers - Up To 94% Of Human Genes Can Generate Different Products., Nature
Excerpts: Most genes are made from sections of DNA found at different locations along a strand. The data encoded in these fragments are joined together into a functional messenger RNA (mRNA) molecule that can be used as a template to generate proteins.
But researchers have found that the same gene can be assembled in different ways, sometimes leaving out a piece, for example, or including a bit of the intervening DNA sequence.
(...)
This process, called alternative splicing, can produce mRNA molecules and proteins with dramatically different functions, despite being formed from the same gene.
Being Human: Language: A Social History Of Words, Nature
Excerpts: The evolution of language probably occurred in concert with the evolution of many of the other traits we associate with being human, such as the ability to fashion tools or a strong propensity to learn. If this is true, it suggests that we shouldn't be trying to understand one characteristically human trait in isolation from the others. Moreover, instead of the brain being a collection of separate modules, each dedicated to a specific trait or capacity, humans are likely to have a complex cognitive architecture that is highly interconnected on multiple levels.
Excerpts: Is religion a product of our evolution? The very question makes many people, religious or otherwise, cringe, although for different reasons. Some people of faith fear that an understanding of the processes underlying belief could undermine it. Others worry that what is shown to be part of our evolutionary heritage will be interpreted as good, true, necessary or inevitable. Still others, many scientists included, simply dismiss the whole issue, seeing religion as childish, dangerous nonsense.
How Evolution Learns From Past Environments To Adapt To New Environments, ScienceDaily
Excerpts: The evolution of novel characteristics within organisms can be enhanced when environments change in a systematic manner, according to a new study (...) suggest that in environments that vary over time in a non-random way, evolution can learn the rules of the environment and develop organisms that can readily generate novel useful traits with only a few mutations. (...) The ability to generate novelty is one of the main mysteries in evolutionary theory. (...) began with the observation that environments in nature seemingly vary according to common rules or regularities. They proposed that organisms can learn how previous environments changed, and then use this information (...).
Excerpts: How does an animal conceal itself from visual detection by other animals? This review paper seeks to identify general principles that may apply in this broad area. It considers mechanisms of visual encoding, of grouping and object encoding, and of search. In most cases, the evidence base comes from studies of humans or species whose vision approximates to that of humans. The effort is hampered by a relatively sparse literature on visual function in natural environments and with complex foraging tasks. (...) Finally, the paper considers how we may understand the processes of search for complex targets in complex scenes. (...)
Source:Review. Camouflage And Visual Perception, T. Troscianko, C. P. Benton, P. G. Lovell, D. J. Tolhurst, Z. Pizlo, DOI: 10.1098/rstb.2008.0218, Philosophical Transactions: Biological Sciences, 2008/11/06
Excerpts: Genetic tests showed that cheaters, although closely related to their nest-mates, are genetically distinct. They also revealed the same cheater lineage in more than one nest, suggesting that it can spread between colonies, and leading the researchers to describe the cheats as a transmissible 'social cancer' that has evolved to exploit the cooperative behaviour of the majority.
Visions Of Evolution: Self-Organization Proposes What Natural Selection Disposes, Biol. Theor.
Excerpts: This article reviews the seven "visions" of evolution (...) concluding that each posited relationship between natural selection and self-organization has suited different aims and approaches. (...) we show that these seven viewpoints may be collapsed into three fundamentally different ones: (1) natural selection drives evolution; (2) self-organization drives evolution; and (3) natural selection and self-organization are complementary aspects of the evolutionary process. We then argue that these three approaches are not mutually exclusive, since each may apply to different stages of development of different systems. What emerges from our discussion is a more encompassing view: that self-organization proposes what natural selection disposes.
Development Puts An End To Evolution Of Endless Forms, ScienceDaily
Excerpts: Researchers have put forward a simple model of development and gene regulation that is capable of explaining patterns observed in the distribution of morphologies and body plans (or, more generally, phenotypes). (...) Nature truly displays a bewildering variety of shapes and forms. Yet, with all its magnificence, this diversity still represents only a tiny fraction of the endless 'space' of possibilities, and observed phenotypes actually occupy only small, dense patches in the abstract phenotypic space. Borenstein and Krakauer demonstrate that the sparseness of variety in nature can be attributed to the interactions between multiple genes and genetic controls involved in the development of organisms (...).
The Relevance Of Brain Evolution For The Biomedical Sciences, Biol. Lett.
Excerpt: Most biomedical neuroscientists realize the importance of the study of brain evolution to help them understand the differences and similarities between their animal model of choice and the human brains in which they are ultimately interested. Many think of evolution as a linear process, going from simpler brains, as those of rats, to more complex ones, as those of humans. However, in reality, every extant species' brain has undergone as long a period of evolution as has the human brain, and each brain has its own species-specific adaptations. By understanding the variety of existing brain types, we can more accurately reconstruct the brains (...).
Excerpt: Much of human DNA is the genetic equivalent of e-mail spam: short repeated sequences that have no obvious function other than making more of themselves. After starting out in our primate ancestors 65 million years ago, one type of repetitive DNA called an Alu retrotransposon now takes up 10 percent of our genome, with about one million copies. Roughly every 20th newborn baby has a new Alu retrotransposon somewhere in its DNA, scientists have estimated. As mutations gradually blur the features of older Alu elements, some become unable to make copies of themselves. (...)
Excerpts: Technological revolutions rocked our world long before the information age. Between 80,000 and 60,000 years ago, it was spurts of innovative toolmaking, rather than extreme climate changes, in southern Africa's Stone Age cultures that heralded a human exodus out of Africa, a new investigation suggests.
Environmental changes in southern Africa, including those brought on by a massive volcanic eruption in Sumatra around 74,000 years ago, played a secondary role at best in instigating ancient cultural advances and intercontinental migrations, (...). Other researchers regard ancient climate fluctuations as key motivators of human movement out of Africa.
Ages For The Middle Stone Age Of Southern Africa: Implications For Human Behavior And Dispersal, Science
Excerpts: Dating of the first use of symbols and jewelry in South Africa shows that the emergence of modern human behavior was not influenced by just environmental factors.
The expansion of modern human populations in Africa 80,000 to 60,000 years ago and their initial exodus out of Africa have been tentatively linked to two phases of technological and behavioral innovation within the Middle Stone Age of southern Africa¡Xthe Still Bay and Howieson's Poort industries¡Xthat are associated with early evidence for symbols and personal ornaments. Establishing the correct sequence of events, however, has been hampered by inadequate chronologies.
The Iceman's Mysterious Genetic Past, Science News
Excerpts: Further genetic studies of modern Europeans might identify some who belong to what Rollo's group has dubbed "Oetzi's branch."
"Through the analysis of a complete mitochondrial genome in a particularly well-preserved body, we have obtained evidence of a significant genetic difference between present-day Europeans and a prehistoric human, despite the fact that the Iceman is only about 5,000 years old," Rollo says.
No Evidence For An Evolutionary Trade-Off Between Learning And Immunity In A Social Insect, Biol. Lett.
Excerpt: The immune response affects learning and memory in insects. Given this and the known fitness costs of both the immune system and learning, does an evolutionary trade-off exist between these two systems? We tested this by measuring the learning ability of 12 bumble-bee (...). We then tested their immune response using the zone of inhibition assay. We found a positive relationship between colony learning performance and immune response, that is, fast-learning colonies also show high levels of antimicrobial activity. We conclude that there is no a priori reason to demand an evolutionary relationship between two traits that are linked physiologically.
Evolutionary Biology: Small Regulatory RNAs Pitch In, Nature
Excerpts: How did organismal complexity evolve at a cellular level, and how does a genome encode it? The answer might lie in differences, not in the number of genes an organism has, but rather in the regulation of gene expression.
It is commonly believed that complex organisms arose from simple ones. Yet analyses of genomes and of their transcribed genes in various organisms reveal that, as far as protein-coding genes are concerned, the repertoire of a sea anemone - a rather simple, evolutionarily basal animal - is almost as complex as that of a human.
Experimental Evidence For Spatial Self-Organization And Its Emergent Effects In Mussel Bed Ecosystems, Science
Excerpts: Spatial self-organization is the main theoretical explanation for the global occurrence of regular or otherwise coherent spatial patterns in ecosystems. Using mussel beds as a model ecosystem, we provide an experimental demonstration of spatial self-organization. Under homogeneous laboratory conditions, mussels developed regular patterns, similar to those in the field. An individual-based model derived from our experiments showed that interactions between individuals explained the observed patterns.
"Mauro le compraba Neurofosfato Escay lo que era una idiotez, y también Hierro Quina Bisleri, cosas que se leen en las revistas y se les toma confianza"
Recuerdo las reconstrucciones de los hombres de Neanderthal que disfrutaba en mi infancia. El cavernícola tosco, bestial y enteramente instintivo en su comportamiento. Era muy difícil concebir una convivencia o un trato con este tipo de personas. Con el paso del tiempo, las idiosincracias y el reconocimiento de algunas subjetividades (sapiens, no neanderthales) la comunidad científica ahora piensa que este grupo de humanos pudo haber sido mucho mas parecido al nuestro, por lo menos en algunos refinamientos congnitivo-culturales. Raul Alzogaray me acercó este vínculo a una nota de National Geographic Magazine revisando un poco los últimos días de los Neanderthales es su distribución mas occidental, la península ibérica.
Foto: Ama de casa neanderthal (probablemente) desesperada
One weird ant suggests lost world of ancient ants living underground. (...)
Its DNA may be even more interesting. Genetic analysis puts the new ant so far from other species that it deserves its own subfamily, Martialinae, (...).
This newly discovered ant species, with mouthparts like forceps and no eyes, may come from the most ancient known lineage of living ants. Credit: Rabeling and M. Verhaagh
Paleoanthropology: Brainy Babies And Risky Births For Neandertals, Science
Excerpts: As adults, the extinct Neandertals had brains and bodies larger than those of living people. But little has been known about their early brain development because few fossils have been found of Neandertal newborns or female pelves. A 1990 study of 10 Neandertal fossils between the ages of 2 and 10 found that their brain volumes were as large as those of modern humans. But the new study uses "amazing specimens" to provide the first data on infants, (...).
Evolution: Dynamics Of Body Size Evolution, Science
Excerpts: Is bigger better? Does climate affect size? The processes controlling body size evolution remain unclear.
Body size is one of the simplest organismic traits one can measure, yet it correlates with almost every aspect of the biology of a species, from physiology and life history to ecology. So, not surprisingly, biologists have long been interested in understanding how body size evolves. Two things are obvious when one looks at the distribution of body sizes of species within large groups: The sizes span multiple orders of magnitude, and species are not distributed uniformly within this range.
The Evolution Of Superstitious And Superstition-Like Behaviour, Proc. Biol. Sc.
Excerpts: Superstitious behaviours, which arise through the incorrect assignment of cause and effect, receive considerable attention in psychology and popular culture. Perhaps owing to their seeming irrationality, however, they receive little attention in evolutionary biology. Here we develop a simple model to define the condition under which natural selection will favour assigning causality between two events. This leads to an intuitive inequality (...) that shows that natural selection can favour strategies that lead to frequent errors in assessment (...). (...) We conclude that behaviours which are, or appear, superstitious are an inevitable feature of adaptive behaviour in all organisms, including ourselves.
Anthropologists Develop New Approach To Explain Religious Behavior, ScienceDaily
Excerpts: Without a way to measure religious beliefs, anthropologists have had difficulty studying religion. Now, two anthropologists from the University of Missouri and ArizonaStateUniversity have developed a new approach to study religion by focusing on verbal communication, an identifiable behavior, instead of speculating about alleged beliefs in the supernatural that cannot actually be identified. (...) "We noticed that communicating acceptance of a supernatural claim tends to promote cooperative social relationships. This communication demonstrates a willingness to accept, without skepticism, the influence of the speaker in a way similar to a child's acceptance of the influence of a parent." (...)
Excerpts: A team of biologists (...) has identified the genes that enable plants to undergo bursts of rhythmic growth at night and allow them to compete when their leaves are shaded by other plants. The researchers report (...) that these genes control the complex interplay of plant growth hormones, plant light sensors and circadian rhythms that permit plants to undergo rhythmic growth spurts at specific times of the day or year in response to varying levels of light and other environmental conditions. Their discovery (...) could eventually allow scientists to design crops that can grow substantially faster and produce more food than the most productive varieties today. (...)
Primordial Fish Had Rudimentary Fingers, PhysOrg.com
Excerpts: Tetrapods, the first four-legged land animals, are regarded as the first organisms that had fingers and toes. Now researchers at UppsalaUniversity can show that this is wrong. Using medical x-rays, they found rudiments of fingers in the fins in fossil Panderichthys, the "transitional animal," which indicates that rudimentary fingers developed considerably earlier than was previously thought.
Our fish ancestors evolved into the first four-legged animals, tetrapods, 380 million years ago. They are the forerunners of all birds, mammals, crustaceans, and batrachians. Since limbs and their fingers are so important to evolution, researchers have long wondered whether they appeared for the first time in tetrapods, or whether they had evolved from elements that already existed in their fish ancestors.
Excerpts: Over dinner at the meeting's end, Pigliucci expresses his hope of "moving from a gene-centric view of causality in evolution to a pluralist, multilevel causality". Postmodernists in the humanities call this 'decentering', and they are all for it. Over the course of the meeting, it's fairly clear that the means to this pluralist end are being sought through mixing and matching neglected ideas and old problems from biology's past with the latest experimental and analytical techniques.
Network Scaling Reveals Consistent Fractal Pattern In Hierarchical Mammalian Societies, Biol. Lett.
Excerpt: Recent studies have demonstrated that human societies are hierarchically structured with a consistent scaling ratio across successive layers of the social network; each layer of the network is between three and four times the size of the preceding (smaller) grouping level. Here we show that similar relationships hold for four mammalian taxa living in multi-level social systems. For elephant (Loxodonta africana), gelada (Theropithecus gelada) and hamadryas (Papio hamadryas hamadryas) baboon, successive layers of social organization have a scaling ratio of almost exactly 3, indicating that such branching ratios may be a consistent feature of all hierarchically structured societies. (...)
Scientists Develop New Computational Method To Investigate Origin Of Life, ScienceDaily
Excerpts: Scientists at Penn State have developed a new computational method that they say will help them to understand how life began on Earth. The team's method has the potential to trace the evolutionary histories of proteins all the way back to either cells or viruses, thus settling the debate once and for all over which of these life forms came first. "We have just begun to tap the potential power of this method," said (...). "We believe, if it is possible at all, that it is within our grasp to determine whether viruses evolved from cells or vice-versa." (...)
Multimodal Warning Signals For A Multiple Predator World, Nature
Excerpts: During spring, when birds are active and bats less so, we found that tiger moths did not produce ultrasonic clicks. Throughout both spring and summer, tiger moths most active during the day were visually conspicuous. Those species emerging later in the season produced ultrasonic clicks; those that were most nocturnal were visually cryptic. Our results indicate that selective pressures from multiple predator classes have distinct roles in the evolution of multimodal warning displays now effective against a single predator class.
Excerpts: Pioneering biologists are trying to use wiki-type web pages to manage and interpret data, reports Mitch Waldrop. But will the wider research community go along with the experiment? (...)
Scientists write review articles and textbooks to make sense of it all. But it's still not enough.
Hence the proliferation of wikis, which have the potential to vastly multiply the number of annotators and bring in the most interested expertise: "The best people to do annotation are the researchers in the laboratories, the people who are producing this knowledge in the first place,(...)."
yahoo.co.in
