Group selection Group selection was used as a popular explanation for adaptations, especially by V. C. Wynne-Edwards.[1][2] For several decades, however, critiques, particularly by George C. Williams,[3] John Maynard Smith[4] and C.M. Perrins (1964), historically cast serious doubt on group selection as a major mechanism of evolution. Overview[edit] Group selection is possible when the aggregation of individuals into groups with a particular social structure promotes the fitness of group members. More complex forms of group behavior involve individuals sacrificing personal fitness on behalf of other members of the group, as when a sterile soldier termite self-sacrifices to protect the nest. Theoretical models of the 1960s suggested that group selection involving altruism is unlikely to evolve. A variant of group selection theory rooted from the idea of population viscosity (limited offspring dispersal), first proposed by Hamilton (1964), that is widely present in natural populations. rb > c rbk + be > c
Using Neural Networks to Classify Music New work from students at the University of Hong Kong describes a novel use of neural networks, collections of artificial neurons or nodes that can be trained to accomplish a wide variety of tasks, previously used only in image recognition. The students used a convolutional network to “learn” features, such as tempo and harmony, from a database of songs that spread across 10 genres. The result was a set of trained neural networks that could correctly identify the genre of a song, which in computer science is considered a very hard problem, with greater than 87 percent accuracy. What made this feat possible was the depth of the student’s convolutional neural network. In their experiments, the students, led by professor Tom Li, discovered that the optimal number of layers for musical genre recognition was three convolutional (or “thinking”) layers, with the first layer taking in the raw input data and the third layer outputting the genre data.
Eels and groupers hunt better together - life - 05 December 2006 Fish of two different species have been filmed helping each other to hunt. It is the first known instance of two unrelated species hunting cooperatively, except for humans. Like a hunter bringing a dog to flush out rabbits, groupers entice moray eels to hunt with them (movie 1). Groupers are bulky fish that hunt in daytime in the open water off coral reefs. Groupers appear to have worked this out - or at least learned by association that hunting around eels is a good idea. Flushed out Most of the time, the eel responded by following the grouper (movie 4), which repeated the dance more slowly over the crevice where prey was hiding. On average, the researchers reckon both fish were five times more successful at catching prey together than separately. The evolution of this cooperation between mammals is usually prevented because of competition for a single prey. This finding has some bearing on our own species. Journal reference: Public Library of Science (DOI: 10.1371/journal.pbio.0040431)
Advanced Robotic Hand Mimics Human's A European project called Sensopac, made up of 12 groups, came out today with advances in its robot hand. The hand mimics the flexibility and sensitivity of a human hand and is controlled by a neural-network-based program modeled on the cerebellum. Scientists at the German Aerospace Centre (DLR) made a robotic “skin” out of a thin, flexible carbon that changes its resistance depending on pressure. This allows the robot hand to tell the shapes of an object, the amount of force placed upon it, and the direction of that force. Thirty-eight opposing motors control the hand’s joints, giving it a touch that ranges from light to forceful. The researchers modeled the robot hand by utilizing hundreds of MRI images of human hands. As for the robot’s learning ability, the team hopes to improve its understanding of movement and sensation through its neural network.
Top 10: Life's greatest inventions - 09 April 2005 - New Sc Read full article Continue reading page |1|2|3|4|5|6 1. Multicellularity 2. 3. 4. 5. 6. 7. 8. 9. 10. 1. Ponder this one in the bath. Sponges are a key example of multicellular life, an innovation that transformed living things from solitary cells into fantastically complex bodies. Cells have been joining forces for billions of years. Eukaryotes could make this leap because they had already evolved many of the necessary attributes for other purposes. So what started it? Researchers are now trying to reconstruct the biology of the first multicellular creatures by studying the genomes of their nearest living relatives. Yet bigger and more complex isn't necessarily better. Claire Ainsworth. 2. THEY appeared in an evolutionary blink and changed the rules of life forever. The first eyes appeared about 543 million years ago - the very beginning of the Cambrian period - in a group of trilobites called the Redlichia. So what happened in that magic million years? More From New Scientist
Mapping How the Brain Matures Using a new way of analyzing brain-imaging data, scientists have mapped out how the complex networks of connections in the brain evolve as children age. The researchers are now using the technology to examine how brain development in children with specific disorders, such as autism, veers off the norm. Ultimately, researchers aim to use the technology to predict, for example, whether a child at risk for autism will actually develop the disorder, or what treatments might work best for that individual. Previous research by the same team at the Washington University School of Medicine had shown that between age five and 30, the short-range connections in the brain tend to weaken, while longer-range connections get stronger. In the new study, scientists plotted the trajectory for normal brain development and showed for the first time that they could determine a child’s development based on a brain scan.
Bacteria discovered 2 miles underground in Researchers have discovered an isolated, self-sustaining, bacterial community living under extreme conditions almost two miles deep beneath the surface in a South African gold mine. It is the first microbial community demonstrated to be exclusively dependent on geologically produced sulfur and hydrogen and one of the few ecosystems found on Earth that does not depend on energy from the Sun in any way. The discovery, appearing in the October 20 issue of Science, raises the possibility that similar bacteria could live beneath the surface of other worlds, such as Mars or Jupiter's moon Europa. "These bacteria are truly unique, in the purest sense of the word," said lead author Li-Hung Lin, now at National Taiwan University, who performed many of the analyses as a doctoral student at Princeton and as a postdoctoral researcher at the Carnegie Institution's Geophysical Laboratory. The international team led by T. C. More information:
Still Waiting on Neural Nets The promise of artificial neural networks is the stuff of sci-fi movies: computers that learn and work much like humans-through experience. In the real world, however, neural networks haven’t begun to live up to their potential. It appears that human nature is at least partially standing in the way-with a failure to communicate fully between two key groups. Researchers gathered to discuss real-world applications of neural networks at a session of the International Joint Conference on Neural Networks held in Washington, DC, in July. But besides research to spur the development of tiny, connected “smart” sensors for use in defense, very little of the discussions had much to do with what anyone outside academia would consider the real world. Instead, researchers outlined the need to better connect neural network technology with current research about how the human brain works. Missing a Core Connection Needed: Neuroinformatics What’s the solution?
Contagious cancer in dogs confirmed; origi See article by Murgia et al. in the August 11, 2006, issue of the journal Cell for details.A new study in the August 11, 2006 issue of the journal Cell provides evidence that a form of cancer afflicting dogs has spread from one individual to another by the transmission of the tumor cells themselves. The disease demonstrates how a cancer cell can become a successful parasite with a worldwide distribution, according to the researchers. The findings may have broad implications for conservation biology and for scientists' understanding of cancer progression, the researchers said. Robin Weiss of University College London and his colleagues traced the origin of so-called canine transmissible venereal tumor (CTVT) to a single clone. "Our results, based on several independent genetic markers in tumor-bearing dogs living on five continents, show that CTVT arose from a common ancestral cancer cell," Weiss said. They quickly found that DNA isolated from the tumor and blood samples were not a match.
Brain waves encode rules for behavior Public release date: 21-Nov-2012 [ Print | E-mail Share ] [ Close Window ] Contact: Sarah McDonnells_mcd@mit.edu 617-253-8923Massachusetts Institute of Technology CAMBRIDGE, MA -- One of the biggest puzzles in neuroscience is how our brains encode thoughts, such as perceptions and memories, at the cellular level. A new study from researchers at MIT and Boston University (BU) sheds light on how neural ensembles form thoughts and support the flexibility to change one's mind. The results suggest that the nature of conscious thought may be rhythmic, according to the researchers, who published their findings in the Nov. 21 issue of Neuron. "As we talk, thoughts float in and out of our heads. Rules for behavior The researchers identified two neural ensembles in the brains of monkeys trained to respond to objects based on either their color or orientation. "Effectively what they're doing is focusing on some parts of information in the world and ignoring others. Oscillation as consciousness
Smelly squirrels fool hungry snakes - life Squirrels are the unlikely inventors of a cloaking device that lets them thwart rattlesnakes by using the snakes' own scent against them. Female California ground squirrels (Spermophilus beecheyi) chew on skins shed by Pacific rattlesnakes (Crotalus oreganus) then lick themselves and their pups, apparently to anoint them with the odour of the enemy. But does this olfactory disguise fool the snakes? To find out, Barbara Clucas of the University of California in Davis captured rattlesnakes and offered them filter paper scented with snake skins, squirrel fur, or both. The snakes were drawn to the squirrel-scented paper, lingering over the spot and flicking out their tongues as they do when they hunt. "The rattlesnakes exhibited much more foraging behaviour to the squirrel scent alone," Clucas says. Clucas reported her findings at the Animal Behavior Society meeting this week in Snowbird, Utah. More From New Scientist Beat temptation with the marshmallow psychologist (New Scientist)