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Mutation as an "intentional" strategySequencing of those hundreds of Arabidopsis thaliana plants revealed more than 1 million mutations. Within those mutations a nonrandom pattern was revealed, counter to what was expected. "At first glance, what we found seemed to contradict established theory that initial mutations are entirely random and that only natural selection determines which mutations are observed in organisms," said Detlef Weigel, scientific director at Max Planck Institute and senior author on the study. Instead of randomness they found patches of the genome with low mutation rates. In those patches, they were surprised to discover an over-representation of essential genes, such as those involved in cell growth and gene expression. "These are the really important regions of the genome," Monroe said. "The areas that are the most biologically important are the ones being protected from mutation." The areas are also sensitive to the harmful effects of new mutations. "DNA damage repair seems therefore to be particularly effective in these regions," Weigel added.
What sponges can tell us about the evolution of the brain -- ScienceDailySponges use their digestive chambers to filter out food from the water and interact with environmental microbes. To understand what the cells expressing synaptic genes do, the Arendt group joined forces with six EMBL teams as well as collaborators in Europe and worldwide. Working with EMBL's Electron Microscopy Core Facility, Yannick Schwab's team and Thomas Schneider's group operating synchrotron beamlines at EMBL Hamburg the researchers developed a new correlative imaging approach. "By combining electron microscopy with X-ray imaging on a synchrotron beamline we were able to visualize the stunning behaviour of these cells," Dr Schwab explained. The scientists captured three-dimensional snapshots of cells crawling throughout the digestive chamber to clear out bacterial invaders and sending out long arms that enwrap the feeding apparatus of specific digestive cells. This behaviour creates an interface for targeted cell-cell communication, as it also happens across synapses between neuronal cells in our brains.
Ant Colonies Retain Memories That Outlast the Lifespans of Individuals | Science | SmithsonianFrom day to day, the colony’s behavior changes, and what happens on one day affects the next. I conducted a series of perturbation experiments. I put out toothpicks that the workers had to move away, or blocked the trails so that foragers had to work harder, or created a disturbance that the patrollers tried to repel. Each experiment affected only one group of workers directly, but the activity of other groups of workers changed, because workers of one task decide whether to be active depending on their rate of brief encounters with workers of other tasks. After just a few days repeating the experiment, the colonies continued to behave as they did while they were disturbed, even after the perturbations stopped. Ants had switched tasks and positions in the nest, and so the patterns of encounter took a while to shift back to the undisturbed state. No individual ant remembered anything but, in some sense, the colony did.
Sea invertebrate sheds light on evolution of human blood, immune systems -- ScienceDaily"The mammalian and Botryllus blood-forming systems also share hundreds of homologous genes, even though the two species are separated by over 500 million years of evolution," said former postdoctoral scholar Benyamin Rosental, PhD. Rosental shares lead authorship of the study with graduate student Mark Kowarsky. The senior authors are Irving Weissman, MD, the Virginia and D.K. Ludwig Professor for Clinical Innovation in Cancer Research and professor of pathology and of developmental biology; Stephen Quake, PhD, the Lee Otterson Professor in the School of Engineering and professor of bioengineering and of applied physics; and senior research scientist Ayelet Voskoboynik, PhD. The researchers isolated the Botryllus stem cells that are the foundation of its blood and immune system, as well as the progenitor cells they make on their way to becoming adult blood and immune cells. "Out of all the invertebrates, the Botryllus blood stem cells and progenitors are the most similar to vertebrate blood cells, so it is possible, if not likely, that they are the 'missing link' between vertebrates and invertebrates," said Weissman, who also directs the Stanford Institute for Stem Cell Biology and Regenerative Medicine and the Ludwig Cancer Center at Stanford.
New research suggests evolution might favor 'survival of the laziest'"We wondered, 'Could you look at the probability of extinction of a species based on energy uptake by an organism?'" said Luke Strotz, postdoctoral researcher at KU's Biodiversity Institute and Natural History Museum and lead author of the paper. "We found a difference for mollusk species that have gone extinct over the past 5 million years and ones that are still around today. Those that have gone extinct tend to have higher metabolic rates than those that are still living. Those that have lower energy maintenance requirements seem more likely to survive than those organisms with higher metabolic rates."
Luck plays a role in how language evolves, team finds -- ScienceDaily"If you have a phonetic neighborhood with lots of rhyming irregular verbs, it acts like a gravitational force and makes it more likely that the past tense of other rhyming verbs will irregularize," said Clark.
White skin an evolutionary adaption for low sunlight in north latitudes?In the July 2000 issue of the Journal of Human Evolution, California Academy of Sciences anthropologists Nina Jablonski and George Chaplin wrote that because dark skin requires about five to six times more solar exposure than pale skin for equivalent vitamin D photosynthesis, and because the intensity of UVB radiation declines with increasing latitude, one could surmise that skin lightening was an evolutionary adaptation that allowed for optimal survival in low-UVR climes, assuming a traditional diet and outdoor lifestyle.
Wired to Run—and Think 2012"While early hominins were undergoing intense skeletal and metabolic changes, major changes also occurred in their brains," Spedding and Noakes wrote in a recent commentary in Nature. "We propose that these changes have rendered us dependent on mental and physical exercise to maintain brain health. Exercise doesn’t just help muscles—it activates our brains." It is widely believed that bigger brains resulted from a shift in the hominin diet to include more meat, which requires less digestion than vegetables, freeing up energy to feed the brain instead. Anthropologist Richard Wrangham famously proposed that cooking our food made meals even easier to digest, increasing the potential for bigger brains. But recently, studies into a protein called brain derived neurotrophic factor (BDNF) have uncovered a more basic link between running after prey and growing bigger brains—exercise stimulates BDNF production. This led Spedding and Noakes to propose BDNF as a central factor in both the mental and physical advances as humans evolved to run. Carl Cotman first discovered this link between BDNF and exercise in the early 90s when he was studying aging, and realized that more active elderly people experienced slower mental decline. Thinking that increased blood flow to the brain was not sufficient to explain the phenomenon, he began to look for a more fundamental relationship. He discovered a few studies that described BDNF's essential role in neuronal growth and health, and started experimenting with mice. Sure enough, by exercising the animals in wheels, Cotman found that BDNF levels increased in the brain, particularly in the hippocampus. Further study has revealed just how fundamental BDNF is to maintaining brain health. "It controls things from synaptic plasticity to new synapse growth, promotes neurogenesis in the hippocampus, and plays in part in mediating vascularization," said Cotman. "It's basically like brain fertilizer." Spedding and Noakes believe that it's this relationship that drove human brains to develop as our ancestors started to run away from the trees and towards meat on the open plains. Indeed, BDNF appears to play crucial roles in building brain areas associated with the task of tracking prey in organized social groups. "As humans needed more brain power to track prey, increases in BDNF may have helped to build up the hippocampus and prefrontal cortex—key brain areas that are involved in spatial mapping, decision-making and control of context, fear and emotions, including violence," Spedding and Noakes wrote in their commentary. BDNF comes in several forms, created via alternative splicing patterns of the transcribed gene, and although it is found across the animal kingdom, more varieties are found in humans than any other species. Compared to rodents, regulation of the different BDNF forms is more complex and sophisticated in humans, providing more control over a greater number of BDNF varieties. While the majority of these proteins are found in the brain, they are also in muscle and other tissues, where they can increase protein synthesis and fat metabolism. Restricting BDNF in mice induces obesity and type II diabetes, ailments readily coupled with lack of exercise, but diminishing BDNF is also associated with stress and psychiatric disorders. Conversely, exercise has been linked to many cognitive benefits, including helping to treat mild depression, Alzheimer's disease, and schizophrenia. "Putting it all together, we think that exercise increases BDNF in key areas of the brain, which, in turn, has physiological effects that help to protect humans from psychiatric problems," Spedding and Noakes wrote. But while BDNF levels rise in the bloodstream of people as they exercise, the direct influence on brain function isn't clear. While there is mounting evidence from human studies to support the hypothesis that BDNF was crucial to the developing brain, Noakes said, but this has yet to be shown more definitively. Ongoing work by Cotman and others, such as investigations into the effects of exercise on Alzheimer's, could be the nail in the coffin Spedding and Noakes, both competitive athletes themselves, have been waiting for. But even with details left to be worked out, Spedding and Noakes are pushing the idea of exercise as a way to brain health, as well as bodily health. Cotman agrees. "I think it's an important principle that there is something you are physically doing to your brain that we know is good for it," he said. "I know sometimes when I'm working out I think, 'Oh boy, my BDNF levels are getting a boost!'"
Vision, not limbs, led fish onto land 385 million years ago -- ScienceDailyNeuroscientist and engineer Malcolm A. MacIver of Northwestern and evolutionary biologist and paleontologist Lars Schmitz of Claremont McKenna, Scripps and Pitzer colleges studied the fossil record and discovered that eyes nearly tripled in size before -- not after -- the water-to-land transition. The tripling coincided with a shift in location of the eyes from the side of the head to the top. The expanded visual range of seeing through air may have eventually led to larger brains in early terrestrial vertebrates and the ability to plan and not merely react, as fish do. "Why did we come up onto land 385 million years ago? We are the first to think that vision might have something to do with it," said MacIver, professor of biomedical engineering and of mechanical engineering in the McCormick School of Engineering. "We found a huge increase in visual capability in vertebrates just before the transition from water to land. Our hypothesis is that maybe it was seeing an unexploited cornucopia of food on land -- millipedes, centipedes, spiders and more -- that drove evolution to come up with limbs from fins," MacIver said. (Invertebrates came onto land 50 million years before our vertebrate ancestors made that transition.)
Human skull evolved along with two-legged walking, study confirms -- ScienceDailyTo make their case, Russo and Kirk compared the position and orientation of the foramen magnum in 77 mammal species including marsupials, rodents and primates. Their findings indicate that bipedal mammals such as humans, kangaroos, springhares and jerboas have a more forward-positioned foramen magnum than their quadrupedal close relatives. "We've now shown that the foramen magnum is forward-shifted across multiple bipedal mammalian clades using multiple metrics from the skull, which I think is convincing evidence that we're capturing a real phenomenon," Russo said. Additionally, the study identifies specific measurements that can be applied to future research to map out the evolution of bipedalism. "Other researchers should feel confident in making use of our data to interpret the human fossil record," Russo said.
Reality is too complex for humansEvolution has shaped us with perceptions that allow us to survive. They guide adaptive behaviors. But part of that involves hiding from us the stuff we don’t need to know. And that’s pretty much all of reality, whatever reality might be. If you had to spend all that time figuring it out, the tiger would eat you.
Even when not threatened, some bacteria specialize as antibiotic resistance"It's costly from a metabolic standpoint for a cell to express the proteins that enable it to be resistant," said Mary Dunlop, assistant professor in the university's College of Engineering and Mathematics Sciences, and the paper's corresponding author. "This strategy allows a colony to hedge its bets by enabling individual cells within a population to assume high levels of resistance while others avoid this extra work." Previous research has demonstrated that, when exposed to some antibiotics, all the cells within a bacterial population will use the protein cascade strategy, activated by a mechanism called MarA, to become resistant. But the new study is among the first to show that colonies use the protein cascade strategy even when they are not under threat. "This transient resistance, distributed in varying degrees among individual cells in a population, may be the norm for many bacterial populations," Dunlop said.
When it came to pass
Researchers such as Steinberg and Casey believe this risk-friendly weighing of cost versus reward has been selected for because, over the course of human evolution, the willingness to take risks during this period of life has granted an adaptive edge. Succeeding often requires moving out of the home and into less secure situations. "The more you seek novelty and take risks," says Baird, "the better you do." This responsiveness to reward thus works like the desire for new sensation: It gets you out of the house and into new turf.
Yes, I know, it's just a simple function to display a window, but it has grown little hairs and stuff on it and nobody knows why. Well, I'll tell you why: those are bug fixes. One of them fixes that bug that Nancy had when she tried to install the thing on a computer that didn't have Internet Explorer. Another one fixes that bug that occurs in low memory conditions. Another one fixes that bug that occurred when the file is on a floppy disk and the user yanks out the disk in the middle. That LoadLibrary call is ugly but it makes the code work on old versions of Windows 95. Each of these bugs took weeks of real-world usage before they were found. The programmer might have spent a couple of days reproducing the bug in the lab and fixing it. If it's like a lot of bugs, the fix might be one line of code, or it might even be a couple of characters, but a lot of work and time went into those two characters. When you throw away code and start from scratch, you are throwing away all that knowledge. All those collected bug fixes. Years of programming work.
In other words, there’s things which are true on the internet — like that letter from a disappointed grandpa, or a video of a failed twerk. The Internet is getting increasingly good at generating such content — so good, indeed, that the bar is getting raised, and the chances of successfully viral content simply emerging naturally from the world are getting ever slimmer. There’s now so much fake content out there, much of it expertly engineered to go viral, that the probability of any given piece of viral content being fake has now become pretty high.