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Old January 26th, 2012, 04:22 PM   #341

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This is an article about abiogenesis, not evolution, yet it is worthy of a spot in this thread, I think.

ScienceDaily (January 24, 2012) "Scientists Discover New Clue to Chemical Origins of Life"

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Organic chemists at the University of York have made a significant advance towards establishing the origin of the carbohydrates (sugars) that form the building blocks of life.

A team led by Dr Paul Clarke in the Department of Chemistry at York has re-created a process which could have occurred in the prebiotic world.

Working with colleagues at the University of Nottingham, they have made the first step towards showing how simple sugars -- threose and erythrose -- developed. The research is published in Organic & Biomolecular Chemistry.

All biological molecules have an ability to exist as left-handed forms or right-handed forms. All sugars in biology are made up of the right-handed form of molecules and yet all the amino acids that make up the peptides and proteins are made up of the left-handed form.

The researchers found using simple left-handed amino acids to catalyse the formation of sugars resulted in the production of predominately right-handed form of sugars. It could explain how carbohydrates originated and why the right-handed form dominates in nature.

Dr Clarke said: "There are a lot of fundamental questions about the origins of life and many people think they are questions about biology. But for life to have evolved, you have to have a moment when non-living things become living -- everything up to that point is chemistry."

. . .

"What we have achieved is the first step on that pathway to show how simple sugars -- threose and erythrose -- originated. We generated these sugars from a very simple set of materials that most scientists believe were around at the time that life began."

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Old January 26th, 2012, 07:02 PM   #342

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Life Beyond Earth? Underwater Caves in Bahamas Could Give Clues

"...Tom Iliffe, professor of marine biology at the Texas A&M-Galveston campus, and graduate student Brett Gonzalez of Trabuco Canyon, Calif., examined three "blue holes" in the Bahamas and found that layers of bacterial microbes exists in all three, but each cave had specialized forms of such life and at different depths, suggesting that microbial life in such caves is continually adapting to changes in available light, water chemistry and food sources...
..."These bacterial forms of life may be similar to microbes that existed on early Earth and thus provide a glimpse of how life evolved on this planet," he adds. "These caves are natural laboratories where we can study life existing under conditions analogous to what was present many millions of years ago..."
Life beyond Earth? Underwater caves in Bahamas could give clues
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Old February 19th, 2012, 03:29 PM   #343

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ScienceDaily (February 16, 2012) "Genes May Travel from Plant to Plant to Fuel Evolution"

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Evolutionary biologists at Brown University and the University of Sheffield have documented for the first time that plants swap genes from plant to plant to fuel their evolutionary development. The researchers found enzymes key to photosynthesis had been shared among plants with only a distant ancestral relationship. The genes were incorporated into the metabolic cycle of the recipient plant, aiding adaptation. Results appear in Current Biology.

The evolution of plants and animals generally has been thought to occur through the passing of genes from parent to offspring and genetic modifications that happen along the way. But evolutionary biologists from Brown University and the University of Sheffield have documented another avenue, through the passing of genes from plant to plant between species with only a distant ancestral kinship.

How this happened is unclear. But the researchers show that not only did a grouping of grasses pass genes multiple times over millions of years, but that some of the genes that were transferred became integral cogs to the plants' photosynthetic machinery, a critical distinguishing feature in C4 plants, which dominate in hot, tropical climes and now make up 20 percent of Earth's vegetational covering.

. . .

"We've long understood how evolutionary adaptations are passed from parents to offspring. Now we've discovered in plants that they can be passed between distant cousins without direct contact between the species," added Colin Osborne, an evolutionary biologist from the University of Sheffield and a corresponding author on the paper.

"What is so exciting here is that these genes are moving from plant to plant in a way we have not seen before," said Erika Edwards, assistant professor of biology at Brown and the second author on the paper. "There is no host-parasite relationship between these plants, which is usually when we see this kind of gene movement."

Scientists call this evolutionary event "lateral gene transfer." The question, then, how are the plants passing their genes? The best guess at this point is that genetic material carried airborne in pollen grains land on a different species and a small subset of genes somehow get taken up by the host plant during fertilization. Such "illegitimate pollination events," as Edwards described it, have been seen in the laboratory. "There are reproductive mishaps that occur. In some cases, these could turn out to be highly advantageous," she said.

Christin, Osborne and Edwards think gene-swapping among plants continues today. "Is it good? Bad? I don't know," Christin said. "It's good for the plants. It means that plants can adapt to new environments by taking genes from others."

"It's like a short cut," Edwards added, "that could present itself as a mechanism for rapid evolution."

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New research shows genes can travel from plant to plant between distant cousins, not just from one generation to the next. This “short cut" could be a mechanism for rapid evolution. Credit: Les Watson and Wikimedia Commons
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Old February 26th, 2012, 09:25 PM   #344

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European Neanderthals were on the verge of extinction even before the arrival of modern humans

"...New findings from an international team of researchers show that most Neanderthals in Europe died off around 50,000 years ago. The previously held view of a Europe populated by a stable Neanderthal population for hundreds of thousands of years up until modern humans arrived must therefore be revised.


“The fact that Neanderthals in Europe were nearly extinct, but then recovered, and that all this took place long before they came into contact with modern humans came as a complete surprise to us. This indicates that the Neanderthals may have been more sensitive to the dramatic climate changes that took place in the last Ice Age than was previously thought”, says Love Dalén, associate professor at the Swedish Museum of Natural History in Stockholm...."
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Old February 27th, 2012, 02:14 AM   #345
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Hello Anna:

The Neanderthal vs Humans has always been fascinating.


The Mysterious Downfall of the Neanderthals: - The Editors ; The Video: Scientific American

The Twilight of the Neanderthals - Kate Wong

lake

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Old April 5th, 2012, 09:02 AM   #346

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ScienceDaily (April 4, 2012) "Analysis of Stickleback Genome Sequence Catches Evolution in Action: Reuse of Key Genes Is Common Theme"

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Three-spine sticklebacks aren't as pretty as many aquarium fish, and anglers don't fantasize about hooking one. But biologists treasure these small fish for what they are revealing about the genetic changes that drive evolution. Now, researchers have sequenced the stickleback genome for the first time, and they have discovered that as fish in different parts of the world adapted to live in fresh water, the same sites in the genome were changed time and again.

Their findings, published April 5, 2012, in the journal Nature, indicate that changes to both genes and, more commonly, stretches of DNA that control gene activity, have driven sticklebacks' adaptation to fresh water environments.

"The cool thing about these fish is that they've colonized a whole series of new environments in the last 10,000 to 20,000 years," says Howard Hughes Medical Institute (HHMI) investigator David Kingsley of Stanford University School of Medicine. As the glaciers melted at the end of the last ice age, marine sticklebacks ventured into fresh water, settling in rivers, lakes, and streams. The fish adapted to their new homes. Compared with their marine relatives, freshwater sticklebacks tend to be smaller and sleeker, with less bony body armor. The challenges of surviving in new habitats also prompted modifications to their teeth, jaws, kidneys, coloration, and numerous other traits. Moreover, this pattern of colonization and adaptation has repeated itself in several areas where sticklebacks live, including the east and west coasts of North America, western Europe, and eastern Asia. "A world-wide collection of lakes and streams became countless natural evolutionary experiments," says Kingsley.

. . .

The stickleback sequences also allowed the researchers to tackle one of the most contentious issues in evolutionary biology. Researchers have battled over what type of genetic changes spur evolution. Some scientists argue for changes to the coding sections of the genome, the portions that cells read to make proteins. More influential, other researchers contend, are alterations to regulatory DNA, which controls the activity of genes. "Here, it isn't either-or," says Kingsley. The team's analysis suggests that both kinds of changes occurred during stickleback evolution, but regulatory changes were about four times as common. "We finally get an idea of the relative contributions of both mechanisms, to a whole range of traits that have evolved in the wild," says Kingsley.

Using genome sequences to analyze the sticklebacks' natural evolutionary experiments "is showing us the genetic mechanism through which animals adapt to different environments," says Kingsley. With this approach, "we can find the key genes that control evolutionary change, helping to bridge the gap between alterations in DNA base pairs and the appearance of new traits in natural populations."

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A model for evolutionary change. Sticklebacks are small migratory fish that have colonized many lakes and streams of the Northern Hemisphere (California stream male shown here). Scientists have recently decoded the genome of 21 populations around the world, making it possible to identify how genes change when organisms adapt over and over again to new environments. (Credit: Tim Howes, Stanford University)
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Old April 5th, 2012, 10:00 AM   #347
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An other side.

Amazon.com: The Greatest Hoax on Earth? Refuting Dawkins on Evolution (9781921643064): Jonathan Sarfati PhD: Books
Amazon.com: The Greatest Hoax on Earth? Refuting Dawkins on Evolution (9781921643064): Jonathan Sarfati PhD: Books


Richard Dawkins is the world's best-known champion of both atheism and its intellectual underpinning, particles-to-people evolution. His latest book, The Greatest Show on Earth: the evidence for evolution is touted as an unanswerable challenge to those who believe in divine creation. In the past, he says, he has assumed evolution; this time he lays out in one major book the evidence for evolution (and its corollary, vast geological ages). Now scientist, chess master and logician Jonathan Sarfati Ph.D. FM goes head to head with Dawkins in this full-on rebuttal, The Greatest Hoax on Earth? Refuting Dawkins on Evolution. Sarfati is no lightweight opponent; his Refuting Evolution at over 500,000 in print is the biggest-selling creationist book ever. In his crisp, highly readable trademark style, Sarfati's sheer competence relentlessly erodes each of Dawkins' claims and in the process, exposes the logical fallacies and even some of the dubious tactics employed. It's precisely those who feel smug in the belief that all the intellectual firepower is on the side of evolution who most need to read Sarfati's book if only to understand better why it is that there are thousands of scientists and intellectuals today who are convinced that biblical creation outguns evolution in a fair science showdown, stripped bare of rhetoric and ideological 'noise'.
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Old April 9th, 2012, 03:57 PM   #348

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Quote:
Originally Posted by Recusant View Post
This is an article about abiogenesis, not evolution, yet it is worthy of a spot in this thread, I think.

ScienceDaily (January 24, 2012) "Scientists Discover New Clue to Chemical Origins of Life"
I'm not sure I quite get that. If by "right handed" and "left handed" they mean dextrorotatory and laevorotatory, then they are wrong. Hydrolyse sucrose (dextrorotatory) and you get glucose (also d-rotatory, but less so) and fructose, one of the commonest, most basic sugars, which is strongly l-rotatory.
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Old April 15th, 2012, 08:33 PM   #349

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"...ScienceDaily (Apr. 5, 2012) — Bacteria are the most populous organisms on the planet. They thrive in almost every known environment, adapting to different habitats by means of genetic variations that provide the capabilities essential for survival. These genetic innovations arise from what scientists believe is a random mutation and exchange of genes and other bits of DNA among bacteria that sometimes confers an advantage, and which then becomes an intrinsic part of the genome....

But how an advantageous mutation spreads from a single bacterium to all the other bacteria in a population is an open scientific question. Does the gene containing an advantageous mutation pass from bacterium to bacterium, sweeping through an entire population on its own? Or does a single individual obtain the gene, then replicate its entire genome many times to form a new and better-adapted population of identical clones? Conflicting evidence supports both scenarios.
In a paper appearing in the April 6 issue of Science, researchers in MIT's Department of Civil and Environmental Engineering (CEE) provide evidence that advantageous mutations can sweep through populations on their own. The study reconciles the previously conflicting evidence by showing that after these gene sweeps, recombination becomes less frequent between bacterial strains from different populations, yielding a pattern of genetic diversity resembling that of a clonal population....


This indicates that the process of evolution in bacteria is very similar to that of sexual eukaryotes (which do not pass their entire genome intact to their progeny) and suggests a unified method of evolution for Earth's two major life forms: prokaryotes and eukaryotes...." Study shows unified process of evolution in bacteria and sexual eukaryotes
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Old May 8th, 2012, 08:10 PM   #350

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"...ScienceDaily (May 7, 2012) — One of the world's most important fossils has a story to tell about the brain evolution of modern humans and their ancestors, according to Florida State University evolutionary anthropologist Dean Falk....
The Taung fossil -- the first australopithecine ever discovered -- has two significant features that were analyzed by Falk and a group of anthropological researchers. Their findings, which suggest brain evolution was a result of a complex set of interrelated dynamics in childbirth among new bipeds, were published May 7 in the Proceedings of the National Academy of Sciences.
"These findings are significant because they provide a highly plausible explanation as to why the hominin brain might grow larger and more complex," Falk said.


The first feature is a "persistent metopic suture," or unfused seam, in the frontal bone, which allows a baby's skull to be pliable during childbirth as it squeezes through the birth canal. In great apes -- gorillas, orangutans and chimpanzees -- the metopic suture closes shortly after birth. In humans, it does not fuse until around 2 years of age to accommodate rapid brain growth.
The second feature is the fossil's endocast, or imprint of the outside surface of the brain transferred to the inside of the skull. The endocast allows researchers to examine the brain's form and structure.
After examining the Taung fossil, as well as huge numbers of skulls belonging to apes and humans, as well as corresponding 3-D CT (three-dimensional computed tomographic) scans, and taking into account the fossil record for the past 3 million years, Falk and her colleagues noted three important findings: The persistent metopic suture is an adaptation for giving birth to babies with larger brains; is related to the shift to a rapidly growing brain after birth; and may be related to expansion in the frontal lobes.
"The persistent metopic suture, an advanced trait, probably occurred in conjunction with refining the ability to walk on two legs," Falk said. "The ability to walk upright caused an obstretric dilemma. Childbirth became more difficult because the shape of the birth canal became constricted while the size of the brain increased. The persistent metopic suture contributes to an evolutionary solution to this dilemma."
The later fusion of the metopic suture is most likely an adaptation of hominins who walked upright to be able to more easily give birth to babies with relatively large brains. The unfused seam is also related to the shift to rapidly growing brains after birth, an advanced human-like feature as compared to apes.
"The later fusion was also associated with evolutionary expansion of the frontal lobes, which is evident from the endocasts of australopithecines such as Taung," Falk said.
The Taung fossil, which is estimated to be around 2½ million years old, was discovered in 1924 in Taung, South Africa. It became the "type specimen," or main model, of the genus Australopithecus africanus when it was announced in 1925...."http://www.sciencedaily.com/releases/2012/05/120507154025.htm
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Taung surrounded by a juvenile chimp skull and human skull, the latter having a fontanelle and metopic suture. The metopic suture is visible on the frontal lobe of Taung's endocast. (Credit: CT-based images by M. Ponce de León and Ch. Zollikofer, University of Zurich)
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