viernes, 12 de septiembre de 2008

Selección del Complexity Digest - Septiembre

New Ant Species Found, Science News

Excerpts:

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 Arizona State University 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." (...)

Source: Anthropologists Develop New Approach To Explain Religious Behavior, ScienceDaily & University of Missouri-Columbia, 2008/09/10


Biologists Identify Genes Controlling Rhythmic Plant Growth, ScienceDaily

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 Uppsala University 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.


Biological Theory: Postmodern Evolution?, Nature

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.

Big Data: Wikiomics, Nature

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,(...)."

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