Seven Masterpieces Stolen in Dutch Museum Heist

Seven masterpieces, including paintings by Picasso, Matisse, Monet and Gauguin, were stolen in a pre-dawn heist Tuesday at Rotterdam's Kunsthal museum, the biggest such theft in the Netherlands in two decades, police said.

Alerted by an alarm but arriving on the scene after the thief or thieves had fled, police said they had launched a major investigation that includes interviewing possible witnesses and examining closed-circuit television.

"On Tuesday morning seven artworks were stolen from the Kunsthal in Rotterdam," police said in a statement, adding the burglary took place at around 3:00 a.m..

After having initially declined to name the stolen paintings, they said that after consulting with the owners, they can now release photographs of the works.

"A major investigation is under way and forensics are at the scene," Rotterdam police spokeswoman Patricia Wessels said. "We're investigating how they got access, what time it happened and who did it."

Dutch state television showed a police forensic team dusting one of the Kunsthal's outer doors for fingerprints. The museum's director is flying back from Turkey after hearing news of the theft, television said.

The NOS broadcaster said the haul was worth "millions and millions of euros", but the paintings are so famous that it will be difficult to get anything like their real value on the black market.

It is the biggest art theft in The Netherlands since 20 paintings were stolen from Amsterdam's Van Gogh museum in 1991.

The paintings are Pablo Picasso's "Tete d'Arlequin", Henri Matisse's "La Liseuse en Blanc et Jaune", Claude Monet's "Waterloo Bridge, London" and "Charing Cross Bridge, London", Paul Gauguin's "Femme Devant une Fenetre Ouverte, dite La Fiancee", Meyer de Haan's "Autoportrait" and Lucian Freud's "Woman with Eyes Closed".

"We're a bit shocked that something like this happens here and at the same time we have some respect for thieves who got away with something likes this," said student Ibo Bose, disappointed not to be able to visit the museum.

"Police are interviewing possible witnesses and examining closed-circuit video footage," the police statement said. "An initial investigation suggests that the robbery was well prepared."

The police spokeswoman said that police were alerted during the night when an alarm went off but the thief or thieves had made off by the time police arrived at the scene.

A statement on the museum's website quoted director Willem van Hassel as saying that the museum would be closed to the public on Tuesday.

The museum is in Rotterdam's museum park where few people go at night.

The works were among the 150-strong Triton Foundation's collection, which was being shown in its entirety to the public for the first time to mark the museum's 20th anniversary, the Kunsthal's website said.

Read more at Discovery News

Egyptian City Aligns with Sun on King's Birthday

The Egyptian city of Alexandria, home to one of the seven wonders of the ancient world, may have been built to align with the rising sun on the day of Alexander the Great's birth, a new study finds.

The Macedonian king, who commanded an empire that stretched from Greece to Egypt to the Indus River in what is now India, founded the city of Alexandria in 331 B.C. The town would later become hugely prosperous, home to Cleopatra, the magnificent Royal Library of Alexandria and the 450-foot-tall (140 meters) Lighthouse of Alexandria, one of the wonders of the ancient world. Today, more than 4 million people live in modern Alexandria.

Ancient Alexandria was planned around a main east-west thoroughfare called Canopic Road, said Giulio Magli, an archaeoastronomer at the Politecnico of Milan. A study of the ancient route reveals it is not laid out according to topography; for example, it doesn't run quite parallel to the coastline. But on the birthday of Alexander the Great, the rising sun of the fourth century rose "in almost perfect alignment with the road," Magli said.

The results, he added, could help researchers in the hunt for the elusive tomb of Alexander. Ancient texts hold that the king's body was placed in a gold casket in a gold sarcophagus, later replaced with glass. The tomb, located somewhere in Alexandria, has been lost for nearly 2,000 years.

Building by the stars

Magli and his colleague Luisa Ferro used computer software to simulate the sun's position in the fourth century B.C. (Because Earth's orbit isn't perfect, there is some variation in the sun's path through the sky over centuries.) Alexander the Great was born on July 20, 356 B.C. by the Julian calendar, which is slightly different than the modern, Gregorian calendar, because it does not have leap years to account for partial days in the Earth's orbit around the sun. On that day in the fourth century B.C., the researchers found, the sun rose at a spot less than half a degree off of the road's route.

"With a slight displacement of the day, the phenomenon is still enjoyable in our times," Magli told LiveScience.

A second star would have added to the effect, Magli said. The "King's Star" Regulus, which is found on the head of the lion in the constellation Leo, also rose in near-perfect alignment with Canopic Road and became visible after a period of conjunction with the sun near July 20. Earth's orbit has changed enough that this Regulus phenomenon no longer happens, Magli said.

Sun as a symbol

Architecture-by-astronomy was common in the ancient world, Magli said. The Great Pyramid of Giza, for example, is aligned with amazing precision along the compass points, which would have required the use of the stars as reference points. The Egyptians, whom Alexander conquered, had long associated the sun god Ra with their pharaohs.

"Aligning the city (of Alexandria) to the sun in the day of birth of Alexander was a way to embody in the architectural project an explicit reference to his power," Magli said. The King's Star would have only added to the mystique, he said.

Read more at Discovery News

Possible Richard III Body Almost Destroyed in 1800s

Last month, a search for King Richard III's remains turned up a human skeleton beneath a parking lot in England. Researchers have a long way to go in the lab before they can determine whether it belongs to the monarch, but they say they were lucky to have found a body at all. Evidence suggests the grave was almost razed by 19th-century builders.

"It was incredibly lucky," archaeologist Mathew Morris, said in a statement. "If the Victorians had dug down 30 cm (12 inches) more they would have built on top of the remains and destroyed them."

Leicester City Mayor Sir Peter Soulsby added that the head of the body was found "inches from the foundations of a Victorian building."

"They obviously did not discover anything and probably would not have been aware of the importance of the site," Soulsby said of the 19th-century builders. "If their plans had been just a little different, they could have destroyed a most significant historic find."

The remains were hidden within the choir of a medieval church known as Greyfriars, where many thought the English monarch was buried after his death in the Battle of Bosworth Field, part of the War of the Roses. The location of this church had been lost to history, but University of Leicester archaeologists traced the likely location to beneath the parking lot for the Leicester City Council offices.

Archaeologists began excavating the lot on Aug. 25 and soon after found what they believe is the lost church. The excavation also uncovered paving stones that may be part of the garden built by Leicester mayor Robert Herrick on top of the church where Richard III was buried. In 1612, a man named Christopher Wren reported a 3-foot (1-meter) tall stone pillar in the garden that was inscribed, "Here lies the body of Richard III sometime King of England."

Read more at Discovery News

Planet Found in Quadruple Star System

Once again the compulsive real universe upstages science fiction. Imagine Luke Skywalker watching four stars setting in the evening: a white hot globe, its diminutive red companion, and a pair of brilliant stars in the background that look like an apparition of a double Venus.

That’s the view from an obscure system of four co-orbiting stars where a gas giant planet has been found. It sets the record for the first quadruple stars system where a transiting planet – and presumably many more – is known to exist.

The gas giant whirls around a tight binary system consisting of a red dwarf and a star slightly hotter than our sun. The two stars complete an orbit about each other once every 20 days.

The other pair of stars, which are a sun-like star and red dwarf, are separate from the planet’s binary stars by a whopping 800 billion miles (or slightly over 100 solar system diameters as measured out to the radius of Neptune’s orbit).

Volunteers searching the publicly available Kepler data as part of the Planet Hunters citizen science project discovered the planet. The project uses human pattern recognition via the World Wide Web to identify the unique light curves recorded by NASA's Kepler space telescope as an object passes in front of a star. Message boards enable volunteers to discuss and analyze interesting Kepler light curves from numerous observations.

Once the planet was identified it was confirmed by spectroscopic observations at the Keck observatory to measure the stellar wobble induced by the small gravitational pull of the planet. The accompanying binary system was then discovered in residual anomalous stellar motion. This yielded telltale evidence for the pull of the distant binary. The faint duo was then visually found with Keck (photo below of the entire quad system).

Though the planet is gaseous, at half the mass of Jupiter, it could conceivably have large moons like Saturn's moon Titan. But at oven-roasting surface temperatures of 500 degrees Fahrenheit, any moons would be pretty toasty and waterless. The planet is slightly closer to the binary than Venus is too our Sun.

If anyone lived on such a moon, they would routinely see transits and eclipses of the the red dwarf and its brighter companion. Depending on orbital positions, the second, far distant stellar pair, would illuminate the night.

At an estimated age of no more than 2 billion years, the system is too young for intelligent life to exist. What’s more, the unusually rapidly spinning hot white star will burn out in just a few billion years. The red dwarf will feed off the larger companion as it swells ever bigger in its final years.

If intelligent life were to arise there billions of years from now, long after the stellar fireworks, the beings would behold a brilliant icy white dwarf and red dwarf in the daytime sky.

What makes this stellar grouping the stuff of science fiction is that at some point in the far future it is conceivable there could be at as many as three inhabitable planets or moons scattered in the system. The one binary that has two widely separated stars might posses two independent planetary systems.

If so, it is conceivable that space faring civilizations could each arise around the sun-like star, and red dwarf. Once space travel is achieved, they could physically come in contact with each other, assuming the biologies aren't so different that planet visitation isn’t practical.

Read more at Discovery News

Archaeologists to Mount New Expedition to Troy

The ruins of ancient Troy will be examined by a cross-disciplinary team of scientists in an expedition led by UW-Madison classics professor William Aylward.

Troy, the palatial city of prehistory, sacked by the Greeks through trickery and a fabled wooden horse, will be excavated anew beginning in 2013 by a cross-disciplinary team of archaeologists and other scientists, it was announced today (Monday, Oct. 15).

The new expedition will be led by University of Wisconsin-Madison classics Professor William Aylward, an archaeologist with long experience digging in the ruins of classical antiquity, including Troy itself. The new international project at Troy, to be conducted under the auspices of and in cooperation with Turkey's Çanakkale Onsekiz Mart University, will begin a series of summer-time expeditions beginning in 2013.

"Troy is a touchstone of Western civilization," says Aylward. "Although the site has been excavated in the past, there is much yet to be discovered. Our plan is to extend work to unexplored areas of the site and to systematically employ new technologies to extract even more information about the people who lived here thousands of years ago."

Troy and the Trojan War were immortalized in Homer's epic poem the Iliad centuries after the supposed events of the conflict. The site was occupied almost continuously for about 4,500 years, from the beginning of the Bronze Age to the 13th century A.D., when it was abandoned and consigned to myth. It was rediscovered in the 1870s by the wealthy German businessman and pioneering archaeologist Heinrich Schliemann whose work at Troy laid the foundations for modern archaeology.

"Our goal is to add a new layer of information to what we already know about Troy," says Aylward, who is contributing an international team of archaeologists and scientists to conduct what promises to be the most comprehensive dig since Troy's discovery over 140 years ago. "The archaeological record is rich. If we take a closer look with new scientific tools for study of ancient biological and cultural environments, there is much to be found for telling the story of this world heritage site."

The site of Troy is in modern Turkey and is situated on the Dardanelles, a crossroads between East and West and a flashpoint for conflict in both ancient and modern times. The archaeological site is a complex layer cake of history and prehistory, with 10 cities superimposed one atop the other, some with clear evidence for violent destruction.

Following the demise of Troy at the end of the Bronze Age, the site was re-settled by Greeks, Romans and others, who all claimed Homer's Troy and its cast of characters -- Achilles, Helen, Patroclus, Priam and Ajax -- as their own cultural heritage. The ancient city was visited by the Persian general Xerxes, Alexander the Great, and Roman emperors, including Augustus and Hadrian. Homer's epic poems about a lost age of heroes and the legendary Trojan War have endured as sources of inspiration for art and literature ever since.

Although archaeologists have been digging at Troy for almost 140 years, with the exception of a 50-year hiatus between 1938 and 1988, less than one-fifth of the site has been scientifically excavated. With about 4,500 years of nearly uninterrupted settlement at a crossroads between Europe and Asia, Troy is fundamental for questions about the development of civilization in Europe and the Near East. "Troy deserves a world-class archaeological program," says Aylward.

In its heyday, Troy's citadel, with walls 12 feet thick and more than 30 feet high, was about 6 acres in size. A walled lower town covered an expanse of 50 acres, much of which is unexplored. Mysteries abound. Ancient Troy's royal cemetery, for example, has yet to be discovered and archaeologists are eager to add to the single example of prehistoric writing known from Troy, a small bronze seal from the Bronze Age.

"Major gaps in our knowledge involve the identity of the prehistoric Trojans, the location of their principal cemeteries and the nature of their writing system," says Aylward. "The enduring question of the historicity of the Trojan War is also worthy of further exploration."

In future work at Troy, Aylward plans an array of collaborations in order to deploy powerful new scientific techniques to reveal the hidden record of the ancient city and its inhabitants. New methods to examine chemical residues on pottery from ancient kitchens and banquet halls, for example, may reveal secrets of ancient Trojan culinary proclivities, and genomic analyses of human and animal remains may shed light on diseases and afflictions at a crossroads of civilization.

Much of the new work in the area of "molecular archaeology," which includes DNA sequencing and protein analysis, will be conducted in collaboration with the UW-Madison Biotechnology Center, which has become an active partner in the new Troy project. This past summer, researchers from the center participated in reconnaissance for future studies.

Read more at Science Daily

New Way to Mimic the Color and Texture of Butterfly Wings

The colors of a butterfly's wings are unusually bright and beautiful and are the result of an unusual trait; the way they reflect light is fundamentally different from how color works most of the time.

A team of researchers at the University of Pennsylvania has found a way to generate this kind of "structural color" that has the added benefit of another trait of butterfly wings: super-hydrophobicity, or the ability to strongly repel water.

The research was led by Shu Yang, associate professor in the Department of Materials Science and Engineering at Penn's School of Engineering and Applied Science, and included other members of her group: Jie Li, Guanquan Liang and Xuelian Zhu.

Their research was published in the journal Advanced Functional Materials.

"A lot of research over the last 10 years has gone into trying to create structural colors like those found in nature, in things like butterfly wings and opals," Yang said." People have also been interested in creating superhydrophobic surfaces which is found in things like lotus leaves, and in butterfly wings, too, since they couldn't stay in air with raindrops clinging to them."

The two qualities -- structural color and superhydrophobicity -- are related by structures. Structural color is the result of periodic patterns, while superhydrophobicity is the result of surface roughness

When light strikes the surface of a periodic lattice, it's scattered, interfered or diffracted at a wavelength comparable to the lattice size, producing a particularly bright and intense color that is much stronger than color obtained from pigments or dyes.

When water lands on a hydrophobic surface, its roughness reduces the effective contact area between water and a solid area where it can adhere, resulting in an increase of water contact angle and water droplet mobility on such surface.

While trying to combine these traits, engineers have to go through complicated, multi-step processes, first to create color-providing 3D structures out of a polymer, followed by additional steps to make them rough in the nanoscale. These secondary steps, such as nanoparticle assembly, or plasma etching, must be performed very carefully as to not vary the optical property determined by the 3D periodic lattice created in the first step.

Yang's method begins with a non-conventional photolithography technique, holographic lithography, where a laser creates a cross-linked 3D network from a material called a photoresist. The photoresist material in the regions that are not exposed to the laser light are later removed by a solvent, leaving the "holes" in the 3D lattice that provides structural color.

Instead of using nanoparticles or plasma etching, Yang's team was able to add the desired nano-roughness to the structures by simply changing solvents after washing away the photoresist. The trick was to use a poor solvent; the better a solvent is, the more it tries to maximize the contact with the material. Bad solvents have the opposite effect, which the team used to its advantage at the end of the photolithography step.

"The good solvent causes the structure to swell," Yang said. "Once it has swollen, we put in the poor solvent. Because the polymer hates the poor solvent, it crunches in and shrivels, forming nanospheres within the 3D lattice.

"We found that the worse the solvent we used, the more rough we could make the structures," Yang said.

Both superhydrophobicity and structural color are in high demand for a variety of applications. Materials with structural color could be used in as light-based analogs of semiconductors, for example, for light guiding, lasing and sensing. As they repel liquids, superhydrophobic coatings are self-cleaning and waterproof. Since optical devices are highly dependent on their degree of light transmission, the ability to maintain the device surface's dryness and cleanliness will minimize the energy consumption and negative environmental impact without the use of intensive labors and chemicals. Yang has recently received a grant to develop such coatings for solar panels.

The researchers have ideas for how the two traits could be combined in one application, as well.

"Specifically, we're interested in putting this kind of material on the outside of buildings," Yang said. "The structural color we can produce is bright and highly decorative, and it won't fade away like conventional pigmentation color dies. The introduction of nano-roughness will offer additional benefits, such as energy efficiency and environmental friendliness.

Read more at Science Daily

Evolution Mostly Driven by Brawn, Not Brains, Analysis Finds

The most common measure of intelligence in animals, brain size relative to body size, may not be as dependent on evolutionary selection on the brain as previously thought, according to a new analysis by scientists.

Brain size relative to body size has been used by generations of scientists to predict an animal's intelligence. For example, although the human brain is not the largest in the animal kingdom in terms of volume or mass, it is exceptionally large considering our moderate body mass.

Now, a study by a team of scientists at UCL, the University of Konstanz, and the Max Planck Institute of Ornithology has found that the relationship between the two traits is driven by different evolutionary mechanisms in different animals.

Crucially, researchers have found that the most significant factor in determining relative brain size is often evolutionary pressure on body size, and not brain size. For example, the evolutionary history of bats reveals they decreased body size much faster than brain size, leading to an increase in relative brain size. As a result, small bats were able to evolve improved flying maneuvrability while maintaining the brainpower to handle foraging in cluttered environments.

This shows that relative brain size can not be used unequivocally as evidence of selection for intelligence. The study is published today in the Proceedings of the National Academy of Sciences.

Dr Jeroen Smaers (UCL Anthropology and UCL Genetics, Evolution & Environment), lead author of the study said: "When using brain size relative to body size as a measure of intelligence, the assumption has always been that this measure is primarily driven by changes in brain size. It now appears that the relationship between changes in brain and body size in animals is more complex than has long been assumed.

"Changes in body size often occur independently of changes in brain size and vice versa. Moreover, the nature of these independent changes in brain and body size, are different in different groups of animals."

Researchers at UCL gathered data on brain and body mass for hundreds of modern and extinct bats, carnivorans, and primates. They then charted brain and body size evolution over time for each species. Across millions of years, most animals increased body size faster than brain size, with the exception of bats.

In primate lineages decreases in brain size marginally outpaced those in body size. Carnivoran evolution has taken yet a different course, with changes generally more strongly associated with body size rather than selection on brain size and cognition.

Read more at Science Daily

Moon Made Water From Solar Wind

Blast some particles from the sun onto the seemingly dry moon and what do you get? Water, says a team of researchers who probed 43-year-old samples returned from the moon by Neil Armstrong and other Apollo astronauts.

The finding was not really a surprise, notes lead researcher Yang Liu, with the University of Tennessee in Knoxville, but it was a long time coming.

Analysis of the Apollo moon samples, which began in the 1970s, previously had uncovered the presence of hydrogen inside volcanically produced glass beads in the soil. In 2008, scientists found hydrogen in a phosphate mineral in lunar rocks, and last year found it again inside another mineral, olivine.

Three robotic probes, including NASA's LCROSS experiment, also have found evidence for water ice on the moon. But where the water came from has been a mystery.

Using two new techniques to dig down into chemistry of hydrogen inside lunar soil grains, Liu and colleagues determined that most of it came from the solar wind, a steady stream of charged particles from the sun that permeates and defines the boundaries of the solar system.

"The energy of these particles is enough to cause damage of the surface of a grain, but is low enough to be embedded and bound with oxygen on the surface," Liu wrote in an email to Discovery News.

Later, when asteroids or other bodies smashed into the lunar surface, some of the soil melted, forming glass beads laced with hydroxyl, a seemingly "dry" mineral, comprising one oxygen atom and one hydrogen, that actually can store water.

Earth's mantle, for example, holds at least one ocean's worth of water in hydroxyl minerals.

"So far, the only generally accepted way of delivering water to the inner solar system is collision with water-rich asteroids or comets that originate from the outer solar system," notes geochemist Marc Chaussidon, with Université de Lorraine in France.

"Liu and colleagues present evidence that the lunar surface contains water that originates from the solar wind -- as well as the water delivered by comets, as previously proposed."

It's too early to say how much of the moon's water can trace its origin to the solar wind.

"We have largely worked with one soil. There is about 80 ppmw (parts per million by weight) water generated by this process. For 3-meter (9-foot) deep soil covering one football field, this (translates) to about 3 metric tons of water if it could be fully extracted," Liu said.

Read more at Discovery News

Complex Logic Circuit Made from Bacterial Genes

By force of habit we tend to assume computers are made of silicon, but there is actually no necessary connection between the machine and the material. All that an engineer needs to do to make a computer is to find a way to build logic gates -- the elementary building blocks of digital computers -- in whatever material is handy.

So logic gates could theoretically be made of pipes of water, channels for billiard balls or even mazes for soldier crabs.

By comparison Tae Seok Moon's ambition, which is to build logic gates out of genes, seems eminently practical. As a postdoctoral fellow in the lab of Christopher Voigt, PhD, a synthetic biologist at the Massachusetts Institute of Technology, he recently made the largest gene (or genetic) circuit yet reported.

Moon, PhD, now an assistant professor of energy, environmental and chemical engineering in the School of Engineering & Applied Science at Washington University in St. Louis is the lead author of an article describing the project in the Oct. 7 issue of Nature. Voigt is the senior author.

The tiny circuits constructed from these gene gates and others like them may one day be components of engineered cells that will monitor and respond to their environments.

The number of tasks they could undertake is limited only by evolution and human ingenuity. Janitor bacteria might clean up pollutants, chemical-engineer bacteria pump out biofuels and miniature infection-control bacteria might bustle about killing pathogens.

How to make an AND gate out of genes

The basis of modern computers is the logic gate, a device that makes simple comparisons between the bits, the 1s and 0s, in which computers encode information. Each logic gate has multiple inputs and one output. The output of the gate depends on the inputs and the operation the gate performs.

An AND gate, for example, turns on only if all of its inputs are on. An OR gate turns on if any of its inputs are on.

Suggestively, genes are turned on or off when a transcription factor binds to a region of DNA adjacent to the gene called a promotor.

To make an AND gate out of genes, however, Moon had to find a gene whose activation is controlled by at least two molecules, not one. So only if both molecule 1 AND molecule 2 are present will the gene be turned on and translated into protein.

Such a genetic circuit had been identified in Salmonella typhimurium, the bacterium that causes food poisoning. In this circuit, the transcription factor can bind to the promotor of a gene only if a molecule called a chaperone is present. This meant the genetic circuit could form the basis of a two-input AND gate.

The circuit Moon eventually built consisted of four sensors for four different molecules that fed into three two-input AND gates. If all four molecules were present, all three AND gates turned on and the last one produced a reporter protein that fluoresced red, so that the operation of the circuit could be easily monitored.

In the future, Moon says, a synthetic bacterium with this circuit might sense four different cancer indicators and, in the presence of all four, release a tumor-killing factor.

Crosstalk and timing faults

There are huge differences, of course, between the floppy molecules that embody biological logic gates and the diodes and transistors that embody electronic ones.

Engineers designing biological circuits worry a great deal about crosstalk, or interference. If a circuit is to work properly, the molecules that make up one gate cannot bind to molecules that are part of another gate.

This is much more of a problem in a biological circuit than in an electronic circuit because the interior of a cell is a kind of soup where molecules mingle freely.

To ensure that there wouldn't be crosstalk among his AND gates, Moon mined parts for his gates from three different strains of bacteria: Shigella flexneri and Pseudomonas aeruginosa, as well as Salmonella.

Although the parts from the three different strains were already quite dissimilar, he made them even more so by subjecting them to error-prone copying cycles and screening the copies for ones that were even less prone to crosstalk (but still functional).

Another problem Moon faced is that biological circuits, unlike electronic ones, don't have internal clocks that keep the bits moving through the logic gates in lockstep. If signals progress through layers of gates at different speeds, the output of the entire circuit may be wrong, a problem called a timing fault.

Experiments designed to detect such faults in the synthetic circuit showed that they didn't occur, probably because the chaperones for one layer of logic gates degrades before the transcription factors for the next layer are generated, and this forces a kind of rhythm on the circuit.

Hijacking a bacterium's controller

"We're not trying to build a computer out of biological logic gates," Moon says. "You can't build a computer this way. Instead we're trying to make controllers that will allow us to access all the things biological organisms do in simple, programmable ways."

"I see the cell as a system that consists of a sensor, a controller (the logic circuit), and an actuator," he says. "This paper covers work on the controller, but eventually the controller's output will drive an actuator, something that will do work on the cell's surroundings."

Read more at Science Daily

Fly Genomes Show Natural Selection and Return to Africa

When ancestral humans walked out of Africa tens of thousands of years ago, Drosophila melanogaster fruit flies came along with them. Now the fruit flies, widely used for genetics research, are returning to Africa and establishing new populations alongside flies that never left -- offering new insights into the forces that shape genetic variation.

That's one of the findings from two new papers published this month by researchers at the University of California, Davis, and their colleagues that describe the genomes of almost 200 strains of the tiny flies.

The work reveals strong evidence of pervasive natural selection throughout the D. melanogaster genome, said Charles Langley, professor of genetics in the Department of Evolution and Ecology at UC Davis and an author on both papers. That is in striking contrast with what is known of the human genome, which shows comparatively little evidence of adaptation over the last 100,000 years.

The overall aim of the research is to better understand the forces that shape genetic variation, Langley said. Human geneticists are working to sequence a thousand human genomes to get at the same issue. The knowledge from studying fly genetics has and will help in that effort, he said.

"Most of the theory and statistical methods in human genetics were originally motivated by studies of flies, because they're easier and faster to work with," Langley said. "Model organisms like these play a critical role in developing tools and ideas."

The first paper, published Oct. 1 in the journal Genetics, reports the genomes of 37 strains of Drosophila collected in Raleigh, N.C., and six strains from the sub-Saharan nation of Malawi. The other paper, to be published in PLoS Genetics and currently available online as a preprint, describes the genomes of 139 fly strains covering 22 African and one European population.

Drosophila melanogaster, like humans, originated in Africa, and that's where they show the most genetic diversity -- just as humans do. The flies are thought to have appeared in Europe about 50,000 years ago, along with modern humans. On the way, both humans and flies squeezed through genetic bottlenecks that reduced the diversity in the population. Over generations, different fly strains evolved quite specialized niches -- such as a fondness for colonizing breweries, for example.

But the African fly genomes show that just in the past couple of decades, flies similar to those found in Europe or the U.S. have established populations back in Africa, often in new environments such as urban and industrial developments. For example, where modern breweries and bottled beer have displaced traditional African brewing, "Europeanized" brewery flies have followed.

The spread of those "European" genes is more rapid than if it were occurring by random processes, the researchers write.

"It may be that urbanization and development favor the more 'European' flies," Langley said.

UC Davis is internationally recognized for research in evolution, ecology and genetics. Campus researchers have collaborated on efforts to sequence the genomes of a wide variety of plants and animals, including wheat, rice, cucumber, horses, cats and chickens.

Langley's UC Davis-affiliated co-authors on the Genetics paper are researchers Kristian Stevens and Charis Cardeno, graduate students Yuh Chwen Lee, Sasha Langley, Charlyn Suarez and Russell Corbett-Detig, Professor David Begun, and postdoctoral researcher John Pool, all in the Department of Evolution and Ecology. Other co-authors include researchers at Indiana University, Bloomington; Lawrence Berkeley National Laboratory; University of Florida, Gainesville; UCSF; Rutgers University; Academica Sinica, Taiwan; and UC Berkeley.

Read more at Science Daily