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Thursday, April 10, 2008

Three black holes merge in best simulation yet

Two black holes merge quickly in this simulation of a close encounter between three black holes (Courtesy of M Campanelli/L Carlos/Y Zlochower/H-P Bischof; background image: NASA/ESA/Hubble Heritage/STScI/AURA)
A black-hole pair and a third black hole travel on strange, looping paths prior to merging (Illustration: M Campanelli/L Carlos/Y Zlochower/H-P Bischof; background image: NASA/ESA/Hubble Heritage/STScI/AURA)
A black-hole pair and a third black hole travel on strange, looping paths prior to merging (Illustration: M Campanelli/L Carlos/Y Zlochower/H-P Bischof; background image: NASA/ESA/Hubble Heritage/STScI/AURA)

When three black holes get intimate, their relationship is bound to be complex. According to the first full simulation of this cosmic ménage à trois, it is likely to end in sudden violence.

The simulation, performed by researchers at the Rochester Institute of Technology in New York, US, shows that these three-way collisions should send out distinctive pulses of gravitational waves, which might be detected within a decade.

Encounters between three or more black holes have been modelled before using simplified physics. But this is the first time it has been done using full-on general relativity, Einstein's powerful and highly complicated theory of gravity.

That enabled the team to predict what happens when the holes get very close to one another, and even collide. "The only way to see mergers is through a fully relativistic simulation," says Manuela Campanelli, lead author of the study.

To simplify their task, the team chose to model three black holes of equal mass, and with no spin. First they looked at a pair of holes orbiting each other closely, with a third looping around them in the same direction. The third hole swoops in, collides and merges with one of the inner pair, flinging the remaining hole out into a distant, stable orbit.

Head-on collision

Then the simulation was changed, so that the third hole starts out moving in the opposite direction. The outcome is completely different, as two rapid collisions leave all three holes merged into one.

Each collision shakes the fabric of spacetime, sending out a burst of gravitational waves - although it turns out to be a relatively quiet event compared with collisions when only two black holes involved.

A simple pair of orbiting black holes will gradually spiral in towards one another and merge in a relatively prolonged final whirl, radiating gravitational waves all the time. In a three-hole mêlée, however, the end tends to come more quickly and directly.

"These black holes basically approach in a head-on collision, so there's not a lot of time to radiate," Campanelli told New Scientist. Nevertheless, these are still among the most energetic events in the universe, she adds.

Dense clusters

Such complex encounters might be taking place inside large star clusters, where the black-hole remnants of heavy stars are thought to swarm.

They would send out a distinctive gravitational wave signal. Two collisions leading to a merger of all three holes would send two blasts of waves in quick succession, for example.

Multiple mergers of small black holes might be detected within the next few years by the Laser Interferometer Gravitational Wave Observatory.

And if three supermassive black holes decide to collide at the heart of a distant galaxy, that would be picked up by a planned space-based gravitational-wave detector called LISA (Laser Interferometer Space Antenna).

Journal reference: Physical Review D (forthcoming)


Astronomers discover our 'twin' solar system

Astronomers have discovered a distant "twin" solar system which looks very similar to our own.

So far researchers have identified two planets very similar to Jupiter and Saturn, which orbit a star about half the size of the Sun around 5,000 light-years away.

But they believe this could be just the start of an exciting time of discovery which will eventually lead to astronomers finding new planets which could support life.

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Breakthrough: Astronomers say the discovery of a new solar system backs up their belief they will soon discover other habitable planets

Martin Dominik, from St Andrews University, said: ""We found a system with two planets that take the roles of Jupiter and Saturn in our solar system.

"These two planets have a similar mass ratio and similar orbital radius and a similar orbital period.

"It looks like this may have formed in a similar way to our solar system. And if this is the case, it looks like our solar system cannot be unique in the Universe.

"There should be other similar systems out there which could host terrestrial planets."

Dr Dominik presented his new findings to the Royal Astronomical Society's National Astronomy Meeting in Belfast.

So far astronomers have found nearly 300 planets beyond our own solar system.

The new system orbits the star OGLE-2006-BLG-109L which is about 5,000 light-years away.

Researchers say it is unusual as it has more than one planet, a characteristic of only ten per cent of systems found to date.

But according to Dr Dominik, astronomers' investigations are currently hampered by limited techniques.

However, he claimed the technology was improving rapidly - and said that he expected habitable planets would be found in the next few years.

He added: "I think it will happen quite soon. In the next few years, we will see something really exciting."

According to Dr Dominik, it is unlikely his team will be able to detect planets similar to Earth in OGLE-2006-BLG-109L as it is too far away for current technology.

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Space Startup Rocketplane Fails to Launch


Rocketplane's suborbital spacecraft, the XP, glides above Earth in this rendering.
Image courtesy of Rocketplane Global

In the hypercompetitive world of commercial spaceflight, you need deep pockets just to stay in the game.

That's why some customers and investors are losing confidence in Rocketplane, which spent 2007 getting outflanked by better-funded competitors and being buffeted by bad publicity -- instead of launching its first suborbital flight, as the company had promised just a few years earlier.

In October 2004, when Reda Anderson plunked down her deposit and made the first reservation to be flown to the edge of space, she had a reasonable expectation that she'd be the first civilian "pioneer" (she dislikes the term "tourist") to take that ride. She signed up with the company that was then called Rocketplane Limited, which hoped to be the first to market with commercial spaceflights in 2007.

Now Anderson is quietly checking out other companies that could get her off the ground sooner.

"Rocketplane is plan A, absolutely," Anderson told Wired.com. "But there's always a plan B."

Rocketplane has suffered largely from the scope of its ambition: It tackled both the suborbital tourist market and the NASA-servicing orbital market at the same time, and tried to do it all without the benefit of a billionaire backer, like Virgin Galactic's Richard Branson. While all of the companies in the young commercial space industry have experienced delays and setbacks, Rocketplane's current position seems shakier than most.

At the Space Access conference in Phoenix on the last weekend of March, panelists called the rush toward the first space tourism flight a "horse race" with two clear leaders: the well-financed Virgin and the scrappy but impressive Xcor Aerospace, which announced the design for its small suborbital vehicle two weeks ago. Almost as an afterthought, panelists mentioned the other companies in the pack: Rocketplane, Armadillo Aerospace and the secretive Blue Origin.

The CEO of Rocketplane, George French, declined to comment on the challenges faced by his company, or on its progress in raising investment money to build its suborbital vehicle. The company has publicly stated that it still expects to start commercial flights in 2010 or 2011, the same time frame now being quoted by Virgin and Xcor.

But Joe Pistritto, one of the Space Access panelists, doesn't seem enthusiastic about Rocketplane's prospects. An angel investor who made his money in the early days of the dot-com boom, Pistritto has a large stake in Xcor, and also owns a small amount of stock in Rocketplane. He said that Virgin and Xcor are viewed as leaders because of two things: money and reputation.

"I don't think anyone worries that Virgin is going to run out of money," Pistritto said. "And Xcor has built up a really good track record, partly because the company has a reputation for underpromising and overdelivering."

While French has served as the company's angel investor, he isn't in the same financial league as Branson or Blue Origin's Jeff Bezos, founder of Amazon.com. French has instead turned to the market, vigorously promoting his company as a sound investment for angel or institutional investors.

Commentators on the emerging commercial space industry, which is often dubbed "NewSpace," say that in contrast to Xcor, Rocketplane's reputation has been hurt by ambitious pronouncements that don't come true. "In the past, they've been good at promoting the sizzle, and not so good at showing they have the steak," said Charles Lurio, a former aerospace engineer who writes a space newsletter, The Lurio Report.

Like many other outside observers, Lurio said he respects French's fundraising abilities, and believes the company has a plausible design for its suborbital tourism vehicle, the XP. "But I would be very cautious if I was an investor," Lurio said. "I would have to see an awful lot of working hardware to be convinced."

Chuck Lauer, Rocketplane's vice president of business development, told a Space Access audience that the XP's development was delayed by more than a year while the company focused on a NASA contract for an orbital vehicle to resupply the space station. Rocketplane lost its contract in September 2007 because it hadn't met milestones in private fundraising.

Many NewSpace observers say the company can't be entirely faulted for that failure. They note that NASA never provided assurance that it would buy a certain number of flights from Rocketplane, and also publicly announced its purchase of future flights on the Russian spacecraft Soyuz, essentially souring Rocketplane's pitch to investors at a crucial moment in May 2007.

Rocketplane's suborbital program, too, has been slowed, as the company announced a new design for the vehicle in October 2007. The previous design would have used a commercially available Learjet as a base; now the company plans to build the airframe from scratch.

Whether or not the company lost credibility in the marketplace because of these developments, the delays killed its momentum, and caused several key players to depart. The former astronaut John Herrington, who was expected to be the XP's pilot, resigned from Rocketplane in January 2008.

"My plan was to be flying by 2007," Herrington said. "The reason it didn't happen was all due to funding. You can only put so much time and effort into something before you decide it's time to move on."

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Before the Big Bang: A Twin Universe?

The new study suggests that the universe that came before our own universe was its identical twin. Image credit: NASA and ESA.
The new study suggests that the universe that came before our own universe was its identical twin. Image credit: NASA and ESA.

Until very recently, asking what happened at or before the Big Bang was considered by physicists to be a religious question. General relativity theory just doesn’t go there – at T=0, it spews out zeros, infinities, and errors – and so the question didn’t make sense from a scientific view.

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But in the past few years, a new theory called Loop Quantum Gravity (LQG) has emerged. The theory suggests the possibility of a “quantum bounce,” where our universe stems from the collapse of a previous universe. Yet what that previous universe looked like was still beyond answering.

Now, physicists Alejandro Corichi from Universidad Nacional Autónoma de México and Parampreet Singh from the Perimeter Institute for Theoretical Physics in Ontario have developed a simplified LQG model that gives an intriguing answer: a pre-Big Bang universe might have looked a lot like ours. Their study will appear in an upcoming issue of Physical Review Letters.

“The significance of this concept is that it answers what happened to the universe before the Big Bang,” Singh told PhysOrg.com. “It has remained a mystery, for models that could resolve the Big Bang singularity, whether it is a quantum foam or a classical space-time on the other side. For instance, if it were a quantum foam, we could not speak about a space-time, a notion of time, etc. Our study shows that the universe on the other side is very classical as ours.”

The finding builds on previous research, with some important differences. Last year, Penn State physicist Martin Bojowald used a simplified version of LQG to show that a universe “on the other side” of the bounce could have existed. However, although that model produced valid math, no observations of our current universe could have lead to any understanding of the state of the pre-bounce universe, as nothing was preserved across the bounce. Bojowald described this as a sort of “cosmic amnesia.”

But Corichi and Singh have modified the simplified LQG theory further by approximating a key equation called the quantum constraint. Using their version, called sLQG, the researchers show that the relative fluctuations of volume and momentum in the pre-bounce universe are conserved across the bounce.

“This means that the twin universe will have the same laws of physics and, in particular, the same notion of time as in ours,” Singh said. “The laws of physics will not change because the evolution is always unitary, which is the nicest way a quantum system can evolve. In our analogy, it will look identical to its twin when seen from afar; one could not distinguish them.”

That means that our universe today, roughly 13.7 billion years after the bounce, would share many of the same properties of the pre-bounce universe at 13.7 billion years before the bounce. In a sense, our universe has a mirror image of itself, with the Big Bang (or bounce) as the line of symmetry.

“In the universe before the bounce, all the general features will be the same,” said Singh. “It will follow the same dynamical equations, the Einstein’s equations when the universe is large. Our model predicts that this happens when the universe becomes of the order 100 times larger than the Planck size. Further, the matter content will be the same, and it will have the same evolution. Since the pre-bounce universe is contracting, it will look as if we were looking at ours backward in time.”

Specifically, Corichi and Singh calculate that the change in relative fluctuations across the bounce is less than 10-56, a number which becomes even smaller for universes that grow larger than 1 megaparsec (our universe is somewhere between 3,000 and 6,000 megaparsecs).

As the researchers explain, having an identical twin universe would not necessarily mean that every single feature of both universes would be identical. For instance, it doesn’t imply that there was another you that existed at some point, a person who has already lived your life.

“If one were able to look at certain microscopic properties with a very strong microscope – a very high-energy experiment probing the Planck scale – one might see differences in some quantities, just as one might see that twins have different fingerprints or one has a mole and the other does not, or a different DNA,” Singh said.

As Singh explained, there are still many questions regarding the details of the possible pre-bounce universe.

“The biggest question is whether these features survive when we consider more complex situations,” he said. “For example, one would like to know whether some structures present in the previous universe – like galaxies – will leave some imprint in the new expanding one that will give rise to identical structure or just 'similar.' For instance, it could happen that, in the previous universe, galaxies formed in a different way, so one might have a different distribution of galaxies on the other side. We will be able to answer this question when we understand these models.”

Ultimately, Corichi and Singh’s model might even tell us what a future universe would look like. Depending on how fast our present universe is accelerating – which will ultimately determine its fate – there’s a possibility that a generalization of the model would predict a re-collapse of our own universe.

“Such a universe will have many bounces from one branch to another,” Singh said. “It is also possible that universes in different branches will be identical.”

Original here

Black hole in funding say scientists

By Susan Watts
BBC Newsnight, science editor

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Watch Jodrell Bank radio telescope in action

The young man at the back of the room got a big clap. "I'm a PhD student in solar physics. Why, in the current climate, should I and other students take the risk of continuing to do research in this area?" he'd asked the panel.

Nicholas Owen, from the solar theory group at St Andrews University, summed up the mood last week of astronomers gathered in Belfast for the annual meeting of the Royal Astronomical Society.

Some, especially the younger ones, were resigned to having to get out of astronomy altogether.

Astronomy and fundamental physics in the UK are in the midst of their worst funding crisis for decades.

These are the scientists trying to make sense of the very big and the very small - the stars and the galaxies of the Universe beyond Earth, and the sub-atomic particles that make up everything on it.

That might seem esoteric, but as another solar physicist pointed out, his work on the activities of the Sun will help us to understand climate change or make communications satellites work better.

Physicists working on huge particle accelerators that smash electrons into each other are trying to create new light sources so focussed they can target cancers deep inside someone's brain - tumours it's too dangerous to treat with today's X-ray techniques. This is the type of science that created the iPod. All this is under threat from cuts.

Brian Cox explains how the funding crisis is hitting UK science

At the Belfast astronomy meeting, it was as if I'd stepped back in time to the 1980s. One of the first articles I ever wrote back then was for a series in New Scientist magazine called "Research in Peril".

The New Labour government vowed to rejuvenate science and put the UK back on track to create a "knowledge-based economy", as Gordon Brown is fond of putting it. And science in general is in relatively good health these days - getting closer to the level of funding it deserves.

Yet since last December, once again, we've seen senior astronomers and senior scientists from fundamental physics having to speak out to defend their subjects. So what's gone wrong?

The crisis has its roots in the merger last year of two of the government quangos that run UK research into one superquango, the Science and Technology Facilities Council, or STFC.

Ministers promised there'd be no reduction in funding, but with the Comprehensive Spending Review of December 2007 came news that although science had done well overall, the STFC was in dire straits.

Professor Martin Rees
The funding of the physical sciences is at a precarious state
Prof Martin Rees

The STFC has so much of its budget tied up in long-term international projects, like Cern, the international particle physics facility in Geneva, and the European Space Agency, that it faces an £80m shortfall in cash over the next three years.

High-profile centres like Jodrell Bank and its radio astronomy Lovell telescope have question marks over their future. For the Astronomer Royal, Professor Martin Rees, the problem is symptomatic of a much bigger and more serious problem.

Professor Rees, who is also president of the UK's national science academy, the Royal Society, told me that the health of the physical sciences in Britain is not good.

He says it's time for a major re-think in the way the physical sciences are funded.

"Issues that have hit the headlines like serious cuts in physics departments and the cutting of high-profile projects like Jodrell Bank, those are the consequence of poor planning within the research council, not at government level. However, overall the funding of the physical sciences is at a precarious state in this country compared to the biomedical sciences.

"We are up against competition not just from the US but also from universities in the Far East. Unless we can compete we will fall behind, and unless in the UK we retain our competitiveness in these areas it's bad for the economy in general."

Cern
Cern's Atlas detector will search for the elusive "God particle"

The government has made much of wanting the UK to be a magnet for mobile talent. The cuts defy that goal.

Professor Swapan Chattopadhyay is director of the Cockcroft Institute at the Daresbury Laboratory near Manchester, where particle physics facilities and jobs are at risk. He was attracted to the UK as part of a reverse brain drain. Now he's thinking of going back.

"I would like government and the research council to take a serious look at how they are generating their future vision for science, and whether the community of scientists at large are participating in it or whether what's coming out is a quick response to a local fiscal problem."

So how does the chief executive of the STFC, Keith Mason, defend what's happening? Many of the scientists whose work is at risk hold him responsible. Some suspect the £80m shortfall is even there more by design than mismanagement, and that he is carrying out an agenda from government to move money away from pure science and emphasize the practical, the money-making. He says that's wrong.

"The mantra is not that we want to do less cutting edge pure science, we want to do more.

"But we need to farm the knowledge that we get more effectively so that we can afford to do more of it because, ultimately, the amount of astronomy and particle physics and pure science we can do depends ultimately on how well our economy is doing - and we should be contributing to that, too."

That may well confirm the worst fears of the astronomers and particle physicists under threat.

If you cared about money you wouldn't be a scientist at all would you
John Womersley
STFC

"It's quite clear to us," he went on, "that we do need to get better economic impact from the stuff that we invest in. It's taxpayers' money, and taxpayers have a right to a return from it. You won't have innovation without the science - but equally people have to face the fact that you won't get pure science unless you also get the value out of it and get the innovation, too."

I'm told by the Astronomer Royal that he thinks Jodrell Bank's Lovell telescope itself was never under serious threat. What was at risk was something called eMerlin, an array of radio telescopes, including the Lovell dish, for sensitive radio mapping of the skies. Now, after all the attention, it seems even eMerlin will be "re-prioritised".

There are even signs that the secretary of state at the Department for Innovation Universities and Skills, John Denham, has woken up to the seriousness of the situation over which he is presiding. Last night, Downing Street responded to the 17,000-plus e-petition over the cuts.

Delegates at the annual National Astronomy Meeting, Belfast (Image: BBC)
A number of scientists said astronomy was not being rewarded properly

The amount of money to be saved is small, and dwarfed by the impact it's having. Senior scientists say the situation is serious enough that the government should step in, and find some extra cash to tide the STFC over. Working out the "nitty gritty" of the finances of the STFC, to really understand what's gone wrong, will take a bit of work. At the Belfast meeting, Keith Mason offered the books up for astronomers to examine. They will surely take him up on this offer.

So what of Nicholas Owen, the student who's wondering if he should carry on?

The answer he got, from John Womersley, director of science programmes at the STFC, was criticised as patronising: "If you cared about money you wouldn't be a scientist at all would you," he told the students in the hall.

"You may feel it's a bigger gamble than you want to make, knowing what you do about future funding.

"But if it's not rewarding, and it's not exciting and you don't feel you can make a contribution, then don't do it. If you can, then let's figure out a way that you can. The future budgets make it tough, I can't deny that."

He's a particle physicist not an astronomer. Certainly what he said was insensitive. He badly mis-read just how angry and dismayed that room full of astronomers felt. And it was a desperately sad note to end on.

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Faces give away giveaways - psych profs' amazing claim

In today's pseudoscience news, the quality press is alive with the findings by UK psych researchers that people can fairly reliably tell how slutty someone is merely by looking at a picture of their face.

Psychologists at several UK universities teamed up on the research, which will plainly lead in short order to the betterment of humanity. The link between looking dirty and being a tramp was firmly established for both sexes.

This was done by asking students to fill out questionnaires regarding how likely they were to put out, how often they had done so lately etc. Data from such questionnaires is well known to be solidly grounded in fact. This done, the subjects were photographed.

Other students were then asked to look at the photographed faces and say how easy they reckoned the pictured individual might be. In a staggering 72 per cent of cases, they correctly guessed whether the person in the portrait was or was not a slag. Or at least, whether or not they were likely to admit being a slag on an anonymous questionnaire.

"We may be subtly aware of other people’s attitudes to sex," says Dr Lynda Boothroyd of Durham Uni, lead author of the groundbreaking slapper-spotting research.

"What is far more interesting is that despite the subtlety of the explicit awareness... there is a very strong tendency for women to be attracted to... men who are less interested in casual sex. Men have the opposite preference with female faces; they strongly prefer the [easy] women."

Participants were also asked to rate faces on how masculine/feminine they looked, and the researchers believe this shows a connection between masculine aspect in men and a tendency to be anyone's after a couple of drinks. It seems that the study also supports the idea that "male masculinity" has "negative connotations... for long term partnerships".

In other words, manly men are easy, and women don't like that. Or put another way: "Androgenisation in men is related to less restricted sexual behaviour... women are averse to unrestricted men."

Comfort, then, for any chaps out there who don't look very studly and don't get much action - it seems women are much more attracted to your type. Even if they sometimes have an odd way of showing it.

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Vanished: A Pueblo Mystery

Perched on a lonesome bluff above the dusty San Pedro River, about 30 miles east of Tucson, the ancient stone ruin archaeologists call the Davis Ranch Site doesn’t seem to fit in. Staring back from the opposite bank, the tumbled walls of Reeve Ruin are just as surprising.

Some 700 years ago, as part of a vast migration, a people called the Anasazi, driven by God knows what, wandered from the north to form settlements like these, stamping the land with their own unique style.

“Salado polychrome,” says a visiting archaeologist turning over a shard of broken pottery. Reddish on the outside and patterned black and white on the inside, it stands out from the plainer ware made by the Hohokam, whose territory the wanderers had come to occupy.

These Anasazi newcomers — archaeologists have traced them to the mesas and canyons around Kayenta, Ariz., not far from the Hopi reservation — were distinctive in other ways. They liked to build with stone (the Hohokam used sticks and mud), and their kivas, like those they left in their homeland, are unmistakable: rectangular instead of round, with a stone bench along the inside perimeter, a central hearth and a sipapu, or spirit hole, symbolizing the passage through which the first people emerged from mother earth.

“You could move this up to Hopi and not tell the difference,” said John A. Ware, the archaeologist leading the field trip, as he examined a Davis Ranch kiva. Finding it down here is a little like stumbling across a pagoda on the African veldt.

For five days in late February, Dr. Ware, the director of the Amerind Foundation, an archaeological research center in Dragoon, Ariz., was host to 15 colleagues as they confronted the most vexing and persistent question in Southwestern archaeology: Why, in the late 13th century, did thousands of Anasazi abandon Kayenta, Mesa Verde and the other magnificent settlements of the Colorado Plateau and move south into Arizona and New Mexico?

Scientists once thought the answer lay in impersonal factors like the onset of a great drought or a little ice age. But as evidence accumulates, those explanations have come to seem too pat — and slavishly deterministic. Like people today, the Anasazi (or Ancient Puebloans, as they are increasingly called) were presumably complex beings with the ability to make decisions, good and bad, about how to react to a changing environment. They were not pawns but players in the game.

Looking beyond climate change, some archaeologists are studying the effects of warfare and the increasing complexity of Anasazi society. They are looking deeper into ancient artifacts and finding hints of an ideological struggle, clues to what was going through the Anasazi mind.

“The late 1200s was a time of substantial social, political and religious ferment and experimentation,” said William D. Lipe, an archaeologist at Washington State University.

“You can’t have a situation where it just happens that hundreds of local communities for their own individual, particularistic reasons decide to either die or get up and move,” Dr. Lipe said. “There had to be something general going on.”

When scientists examine the varying width of tree rings, they indeed see a pernicious dry spell gripping the Southwest during the last quarter of the 13th century, around the height of the abandonment. But there had been severe droughts before.

“Over all conditions were pretty darn bad in the 1200s,” said Timothy A. Kohler of Washington State University. “But they were not maybe all that worse than they were in the 900s, and yet some people hung on then.”

Even in the worst of times, major waterways kept flowing. “The Provo River didn’t dry up,” said James Allison, an archaeologist at Brigham Young University. “The San Juan River didn’t dry up.”

“Climate probably explains a lot,” Dr. Allison said. “But there are places where people could have stayed and farmed and chose not to.”

Some inhabitants left the relatively lush climes of what is now southern Colorado for the bone dry Hopi mesas. “Climate makes the most sense for this big pattern change,” Dr. Lipe said. “But then you think, So they went to Hopi to escape this?”

Hopi was far from an anomaly. “The whole abandonment of the Four Corners, at least in Arizona, is people moving to where it’s even worse,” said Jeffrey Dean, an archaeologist at the University of Arizona’s Laboratory of Tree-Ring Research.

Some archaeologists have proposed that colder weather contributed to the downfall. Measurements of the thickness of pollen layers, accumulating over decades on the bottom of lakes and bogs, suggest that growing seasons were becoming shorter. But even when paired with drought, the combination may have been less than a decisive blow.

Soon after the abandonment, the drought lifted. “The tree-ring reconstructions show that at 1300 to 1340 it was exceedingly wet,” said Larry Benson, a paleoclimatologist with the Arid Regions Climate Project of the United States Geological Survey. “If they’d just hung in there . . .”

Though the rains returned, the people never did.

“Why didn’t they come back?” said Catherine M. Cameron, an archaeologist at the University of Colorado. “Why didn’t anyone come back to the northern San Juan? It was a fine place, and apparently by 1300 it was very fine.”

In the remains of Sand Canyon Pueblo, in the Mesa Verde region, Kristin A. Kuckelman of the Crow Canyon Archaeological Center in Cortez, Colo., sees the story of a tragic rise and fall. As crops withered, the inhabitants reverted from farming maize and domesticating turkeys to hunting and gathering. Defensive fortifications were erected to resist raiders.

The effort was futile. Villagers were scalped, dismembered, perhaps even eaten. Families were slain inside their dwellings, and the pueblo was burned and abandoned. Curiously, as was true throughout the region, the victors didn’t stay to occupy the conquered lands.

But violence was not always an obvious factor. Throwing a wrench into the theories were those curious wanderers from Kayenta. They thrived in their pueblos until about 1290 — some 15 years after the Great Drought began. And when they finally departed for the San Pedro Valley and other destinations, the evacuation was orderly.

“I don’t see any evidence of violence, cannibalism or even defensive posturing,” Dr. Dean said. “The abandonment seems to be different. You get lots of evidence that people intended to come back.”

At Kiet Siel, a cliff dwelling now part of Navajo National Monument in northeast Arizona, people sealed the openings of granaries with carefully fitted rock slabs, caulking the edges with a collar of clay. Finally the evacuees blocked the entranceway to the settlement with a large wooden beam.

“It’s pretty clear that these people weren’t freaking out or weren’t in a hurry when they left,” Dr. Dean said.

Ultimately the motivation for the abandonments may lie beyond fossils and artifacts, in the realm of ideology. Imagine trying to explain the 19th-century Mormon migration to Utah with only tree rings and pollen counts.

By studying changes in ceremonial architecture and pottery styles, Donna Glowacki, an archaeologist at the University of Notre Dame, is charting the rise of what may have been a new puebloan religion. For more than a century, the established faith was distinguished by multistory “great houses,” with small interior kivas, and by much larger “great kivas” — round, mostly subterranean and covered with a sturdy roof. Originating at Chaco Canyon in northwest New Mexico, the formidable temples seem designed to limit access to all but a priestly few.

Though Chaco declined as a regional religious center during the early 1100s, the same architecture spread to the Mesa Verde area. But by the mid 1200s, a different style was also taking hold, with plazas and kivas that were uncovered like amphitheaters — hints, perhaps, of a new openness. At some sites, serving bowls became larger and were frequently decorated with designs, as though intended for a ritual communion. If the pueblo people had left a written history perhaps we would read of the Anasazi equivalent of the Protestant reformation.

But the analogy can’t be pushed too far. The new architecture also included multiwalled edifices — some round, some D-shaped — that might have been chambers for secret rituals.

Though the dogma may be irrecoverable, Dr. Glowacki argues that it rapidly attracted adherents. A center of the movement, she said, was the McElmo Canyon area, west of Mesa Verde. Excavations indicate that the population burgeoned along with the new architecture. An influx of different pottery designs suggests immigrants from the west were moving in. Then around 1260, long before the drought, the residents began leaving the pueblo, perhaps spreading the new ideology.

Other archaeologists see evidence of an evangelical-like religion — the forerunner, perhaps, of the masked Kachina rituals, which still survive on the Hopi and Zuni reservations — appearing in the south and attracting the rebellious northerners. Salado polychrome pottery may have been emblematic of another, possibly overlapping cult.

In an effort to draw together the skein of causes and effects, Dr. Kohler and members of the Village Ecodynamics Project are collaborating with archaeologists at Crow Canyon on a computer simulation of population changes in southwest Colorado from 600 to around 1300. Juxtaposing data on rainfall, temperature, soil productivity, human metabolic needs and diet, gleaned from an analysis of trash heaps and human waste, the model suggests a sobering conclusion: As Anasazi society became more complex, it also became more fragile.

Corn was domesticated and then wild turkeys, an important protein source. With more to eat, the populations grew and aggregated into villages. Religious and political institutions sprung up.

When crops began dying and violence increased, the inhabitants clustered even closer. By the time the drought of 1275 hit, the Anasazi had become far more dependent on agriculture than during earlier droughts. And they had become more dependent on each other.

“You can’t easily peel off a lineage here and a lineage there and have them go their own way,” Dr. Kohler said. “These parts are no longer redundant. They’re part of an integrated whole.” Pull one thread and the whole culture unwinds.

Amid the swirl of competing explanations, one thing is clear: The pueblo people didn’t just dry up and blow away like so much parched corn. They restructured their societies, tried to adapt and when all else failed they moved on.

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Physicist expects 'God particle' will be found soon

 A large dipole magnet, part of the Large Hadron Collider (LHC) at CERN. The $2 billion accelerator is expected to uncover the so-called 'God particle' predicted by British physicist Peter Higgs.
CERN/AFP/Getty Images
A large dipole magnet, part of the Large Hadron Collider (LHC) at CERN. The $2 billion accelerator is expected to uncover the so-called 'God particle' predicted by British physicist Peter Higgs.

GENEVA — The father of a theoretical subatomic particle dubbed "the God particle" says he's almost sure it will be confirmed in the next year in a race between powerful research equipment in the United States and Europe.

British physicist Peter Higgs, who more than 40 years ago postulated the existence of the particle in the makeup of the atom, said his visit to a new accelerator in Geneva last weekend encouraged him that the Higgs boson will soon be seen.

The $2 billion Large Hadron Collider, under construction since 2003, is expected to start operating by June at the European Laboratory for Particle Physics (known as CERN).

It likely will take several months before the hundreds of scientists from around the world are ready to start smashing together protons to study their composition.

Higgs said Monday the particle may already have been created at the rival Fermi National Accelerator Laboratory outside Chicago, where the Tevatron is currently the world's most powerful particle accelerator.

"The Tevatron has plenty of energy to do it," Higgs said. "It's just the difficulty of analyzing the data which prevents you from knowing quickly what's hiding in the data."

The massive new CERN collider, which has been installed in a 17-mile circular tunnel under the Swiss-French border, will be more powerful still and will be better able to show what particles are created in the collisions of beams of protons traveling at the speed of light.

The new Geneva collider will re-create the rapidly changing conditions in the universe a split second after the Big Bang. It will be the closest that scientists have come to the event that they theorize was the beginning of the universe. They hope the new equipment will enable them to study particles and forces yet unobserved.

But Fermilab still has time to be first if it can show that it has discovered the Higgs boson, Higgs said.

Nobel laureate Leon Lederman has dubbed the theoretical boson "the God particle" because its discovery could unify understanding of particle physics and help humans "know the mind of God."

Higgs told reporters he is hoping to receive confirmation of his theory by the time he turns 80 in May 2009.

If not, he added, "I'll just have to ask my GP to keep me alive a bit longer," referring to his general practitioner, not the God particle, a term he does not embrace because he fears it might offend some people.

Higgs predicted the existence of the boson while working at the University of Edinburgh to explain how atoms — and the objects they make up — have weight.

Without the particle, the basic physics theory — the "standard model" — lacks a crucial element, because it fails to explain how other subatomic particles — such as quarks and electrons — have mass.

The Higgs theory is that the bosons create a field through which the other particles pass.

The particles that encounter difficulty going through the field as though they are passing through molasses pick up more inertia, and mass. Those that pass through more easily are lighter.

Higgs said he would be "very, very puzzled" if the particle is never found because he cannot image what else could explain how particles get mass.

Higgs said initial reaction to his ideas in the early 1960s was skeptical.

"My colleagues thought I was a bit of an idiot," he said, noting that his initial paper explaining how his theory worked was rejected by an editor at CERN.

He said a colleague spent the summer at CERN right after he did his work on the theory.

"He came back and said, 'At CERN they didn't see that what you were talking about had much to do with particle physics.'

"I then added on some additional paragraphs and sent it off across the Atlantic to Physical Review Letters, who accepted it. The mention of what became known as the Higgs-boson was part of the extra which was added on."

Copyright 2008 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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Evolution In The Classroom: 'Evolution Machine' Lets Students See It Happen

Evolution has taken another step away from being dismissed as "a theory" in the classroom, thanks to a new article in PLoS Biology. The research article, by Brian Paegel and Gerald Joyce of The Scripps Research Institute, California, documents the automation of evolution: they have produced a computer-controlled system that can drive the evolution of improved RNA enzymes--biological catalysts--without human input. In the future, this "evolution-machine" could feature in the classroom as well as the lab, allowing students to watch evolution happen in their biology lessons.

The evolution of molecules via scientific experiment is not new. The first RNA enzymes to be "evolved" in the lab were generated in the 1990s. But what is exciting about this work is that the process has been made automatic. Thus evolution is directed by a machine without requiring human intervention-other then providing the initial ingredients and switching the machine on.

As all students of Darwin know, evolution occurs when there is variation in a population; where some variants confer a survival or reproductive advantage to the individual, and where the basis for this advantage can be inherited. Finally, there must be a selection pressure--a reason that not all animals can survive or reproduce--such as a limited supply of food or a predator that must be avoided.

These are the principles that the Paegel/Joyce system uses. The system begins with a population of RNA enzymes, which are the individuals that will evolve, and these enzymes vary slightly from each other. The enzymes are challenged to catalyse a reaction, and those that do catalyse it bind a "promoter" sequence to themselves in the process. Other enzymes in the machine (which act like part of the machine, rather than part of the experiment) cause any RNA enzyme bound to a promoter to be reproduced; therefore, enzymes that are good at reacting with the substrate become more numerous. This is analogous to those animals that are most successful being able to reproduce, both of which lead to the advantageous variation becoming more common.

In their system, Paegel and Joyce establish selection by having the evolution-machine reduce the availability of the reactants as time progresses. Therefore, the only enzymes to be reproduced are those that can bind a promoter when promoters are scarce. Any random mutation that allows an enzyme to bind a promoter more effectively is beneficial and will come to dominate the final population of enzymes. Throughout the process, the evolution-machine can propagate the reaction itself, because whenever the enzyme population size reaches a predetermined level, the machine removes a fraction of the population and replaces the starting chemicals needed for the reaction to continue.

By evolving the RNA enzyme according to this selection regime, the evolution-machine generated an enzyme that was better; it could work quickly with much lower concentrations of reactant then the ancestral enzymes could. The final enzyme at the end of Paegel and Joyce's experiment had 11 mutations which together made it 90 times more efficient at using the starting ingredients.

This beautifully illustrates what about evolution is random and what is not. While the end point is predicted by the selection pressure--i.e., the decreasing concentration of ingredients determines that enzymes will evolve to cope with decreased concentration--the actual mutations that allow this are completely random and cannot be predicted at the outset--i.e., if you bought an "evolution machine" and ran the same experiment, your end product would be an enzyme that could cope with low concentrations too, but the mutations that it acquired to do this might be different.

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Woodpecker with freakish beak photographed

This extraordinary woodpecker - with its freakishly long beak - has been spotted feeding from a domestic garden feeder.

Experts have claimed the beak was the biggest they had ever seen and are surprised it can fly - let alone feed.

Woody', with his extra long beak, using a feeder (right) and a woodpecker with a normal beak (left)

Bird watchers Janet and Bob Morton first spied red-crested male 'Woody' over the winter at their home in Rosedale, near Pickering, North Yorkshire.

Mr Morton, 62, a retired RAF pilot, said: "Woody comes everyday now, you can't miss him. We first noticed the beak at Christmas when he arrived with a female and a baby.

"We just couldn't believe how big it was. Compared to his mate you can see it should be at least half that size."

The woodpecker's beak is used to signal possession of territory to rivals and locate winding tunnels in tree trunks containing grubs and larvae.

Luckily, Woody has no trouble flying, nesting or feeding and has not chopped down any trees so far.

Tony Richardson, from the RSPB in Exeter, said: "The creature does have a serious beak deformity. It's probably 120 per cent bigger than it should be.

"A bird's beak grows much like hair and nails on a human but natural wear and tear should keep it in check, especially on a woodpecker.

"Many birds wouldn't be able to survive with this handicap but luckily woodpeckers have enormous tongues so this one is still able to gather food."

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'Breakthrough' at Stonehenge dig

By Rebecca Morelle
Science reporter, BBC News

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Professor Darvill explains what is happening at the Stonehenge dig

Archaeologists carrying out an excavation at Stonehenge say they have broken through to a layer that may finally explain why the site was built.

The team has reached sockets that once held bluestones - smaller stones, most now missing or uprooted, which formed the site's original structure.

The researchers believe that the bluestones could reveal that Stonehenge was once a place of healing.

The dig is the first to take place at Stonehenge for more than 40 years.

The team now needs to extract organic material from these holes to date when the stones first arrived.

Professor Geoff Wainwright explains why the dig is taking place

Professor Tim Darvill, of Bournemouth University, who is leading the work with Professor Geoff Wainwright, president of the Society of Antiquaries, said: "The first week has gone really well. We have broken through to these key features.

"It is a slow process but at the moment everything is going exactly to plan."

The two-week excavation is being funded by the BBC and filmed for a special Timewatch programme to be broadcast in the autumn.

Professors Darvill and Wainwright say that finding out more about the history of the bluestones could be key to solving the mystery of why the 4,500-year-old landmark was erected.

They believe that the bluestones, which were transported 250km (150 miles) from the Preseli Hills in Wales to the Salisbury Plain in Wiltshire, were brought to the site because the ancient people believed they had healing properties.

Professor Geoffrey Wainwright said the site could have been a "Neolithic Lourdes".

The giant sarsen "goal posts", which came from about 20km (12 miles) away, were thought to have arrived much later.

As well as reaching the bluestone sockets, the archaeologists have also unearthed a whole host of other finds as they have peeled back the layers of the 2.5m-by-3.5m (8.2ft-by-11.5ft) trench.

These include a beaker pottery fragment, Roman ceramics and ancient stone hammers.

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Yvette Staelens reveals some of the unearthed treasures

Daily text and video reports on the Stonehenge dig are published at the BBC Timewatch website. A BBC Two documentary will be broadcast in the autumn and will detail the findings of the investigation

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Paging Dr. Freud: 8 Unusual Mental Illnesses

There are only a certain number of ways to go crazy, and you can find most of them listed in the psychologist’s bible, the Diagnostic and Statistical Manual of Mental Disorders, currently in its fourth edition and commonly referred to as DSM-IV. But along with psych-ward greatest hits like schizophrenia and depression, the DSM lists some less-than-common conditions.

1. Trichotillomania

plucking.jpg
Trichotillomania
is a compulsion to pluck one’s hair and often starts around age 12. A triichotillomaniac in Michigan says that she first started plucking her eyelashes in first grade. By fifth grade she had started pulling hair in earnest. She still does it today, although she over the years she has learned to manage the illness. “I now am a sales manager managing ten account executives and 30 of the largest accounts in the state of Michigan,” she writes. “I have not made less then six figures since I was 24. Oh [yeah]. I also suffer from trich[otillomania] and have bald spots and no eyelashes!”

In rare cases, trichotillomaniacs accumulate hairballs in the intestinal tract by chewing and swallowing the hair they pluck. You can see an extreme example at the National Museum of Health and Medicine in Washington, D.C.—a huge hairball molded to the shape of a girl’s stomach. It took six years to form. [Photo courtesy of BattleAgainstBald.com.]

2. Othello Syndrome


Othello syndrome is also known as delusional or morbid jealousy—a conviction that your husband/wife/partner is cheating on you. It often leads sufferers to threaten to attack their spouses or to stalk the imagined lovers of their spouses. In one case, a woman accused her husband of fathering 10,000 children with a 70-year-old mistress.

3. Pyromania

pyromania.jpg
Def Leppard’s breakthrough album is named after this rare fixation with fire. Pyromaniacs don’t set fires to destroy property, collect insurance, or draw attention; they are attracted to fire itself and may feel tense, aggressive, or piqued before lighting up. They may even hang out at fire departments or become firefighters so they can focus on fire all the time. Pyros tend to be men and tend to drink. Some experts argue that pyromania is a myth, a sexy label attached to mentally ill people who happen to set a fire. One infamous arsonist who had many characteristics of a pyromaniac was Paul Keller of Seattle, now serving a 99-year prison sentence. Keller started setting fires as a child and later tried join the fire department. An alcoholic, he set over 70 fires in his career, including one at a nursing home.

4. Folie a deux

Folie a deux is a delusion or psychosis shared by several people. One individual has a genuine mental illness, often schizophrenia, and their otherwise healthy friends or family members take on some of their neuroses. Psychologists have described families that believe they are infested with invisible parasites, includes Matrix-style robotic bugs. In one case, a French woman and her husband tried to kill her doctor, presumably for giving her the parasites. In a similar case, a woman began to see insects crawling her husband. Then the husband began to see them, too—but when doctors told the two to collect the bugs, they brought in a jar containing hair, thread, and bread crumbs. Once the husband was separated from his wife, he stopped seeing the bugs.

5. Caffeine Intoxication

coffee-coffee.jpg
The DSM contains a diagnosis for caffeine intoxication, which occurs when you ingest more than 250 milligrams of the stuff, about the amount in two cups of coffee. Not surprisingly, caffeine intoxication can contribute to panic and anxiety disorders.

6. Internet Addiction

internet-addiction.jpg
Researchers in Israel have proposed a new diagnosis: internet addition. “The Internet provides inexpensive, interesting and comfortable recreation, but sometimes users get hooked. Thus, the computer-internet addiction concept has been proposed as an explanation for uncontrollable and damaging use.” Sound familiar?

The DSM also lists several mental syndromes unique to certain cultures and circumstances.

7. Brain fag

Brain fag is a common complaint among West African students. It’s sort of like “Teacher, my brain hurts,” accompanied by blurred vision and actual pain in the head or neck.

8. Koro

Koro, says the DSM, is a “sudden and intense anxiety that the penis (or, in females, the vulva and nipples) will recede into the body and possibly cause death.” Koro doesn’t just strike one unlucky person; it hits southeast Asia in waves of a mass hysteria in which everybody becomes terrified of death via genital retraction.

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Self-assembling Nanofibers Heal Spinal Cords

Nano fix: An electron-microscope image shows the matrix of cylindrical nanofibers that self-assemble from engineered biological molecules in a solution.
Credit: Journal of Neuroscience

An engineered material that can be injected into damaged spinal cords could help prevent scars and encourage damaged nerve fibers to grow. The liquid material, developed by Northwestern University materials science professor Samuel Stupp, contains molecules that self-assemble into nanofibers, which act as a scaffold on which nerve fibers grow.

Stupp and his colleagues described in a recent paper in the Journal of Neuroscience that treatment with the material restores function to the hind legs of paralyzed mice. Previously, researchers have restored function in the paralyzed hind legs of mice, but those experiments involved surgically implanting various types of material, while the new substance can simply be injected into the animals. The nanofibers break down into nutrients in three to eight weeks, says Stupp.

Right now, there is no cure for the thousands of people who have injuries to the spinal cord, the bundle of long nerve fibers that connect the brain to the limbs and organs of the body. When it is damaged, nerve stem cells form a scar at the point of the injury, which blocks nerve fibers and keeps them from growing, says John Kessler, professor of stem cell biology at Northwestern's Feinberg School of Medicine, who collaborated on the work with Stupp. Nerves can no longer carry signals to and from the brain, causing patients to lose sensation, digestion, and movement. "It is like cutting a telephone cable," Kessler says. "We're thinking of regrowing the nerve fibers and rewiring the cut."

Other researchers have tried to regenerate nerve fibers using various approaches. They have used natural materials such as collagen as well as synthetic biodegradable polymers to make scaffolds that support nerves, helping them to grow. Implanting these materials at the injury requires surgery.

The new material is different because the researchers can inject it as a liquid directly into the spinal cord. Negatively charged molecules in the liquid start clumping together when they come in contact with positively charged particles such as calcium and sodium ions in the body. The molecules self-assemble into hollow, cylindrical nanofibers, which form a scaffold that can trap cells. On the surface of the nanofibers are biological molecules that inhibit scars and encourage nerve fibers to grow. "The idea of using self-assembling nanofibers that can be directly injected into the spinal cord is appealing," says Harvard Medical School professor Yang Teng, who does neural stem cell research for spinal cord injuries.

Nanofibers help nerves: Northwestern University researchers have designed molecules made of biological parts, such as amino acids and fats, that self-assemble into cylindrical nanofibers. The researchers inject a solution of the molecules into the injured spinal cords of mice, where the nanofibers promote the growth of nerve fibers.
Credit: Samuel Stupp, Northwestern University


Stupp and his colleagues have found other uses for the self-assembling molecules in the past. They have designed molecules with slightly different chemistries that promote the growth of blood vessels and that align themselves to mimic bone structure. In a 2004 Science paper, the researchers reported that in a lab culture of brain cells, versions of the material encourage the cells to grow the nerve fibers that extend into the spinal cord. They also found that the material prevents cultured nerve stem cells from growing into scar tissue.

The new work is the first test for the material to heal spinal cord injuries in animals. And Kessler says that it worked better than the researchers expected. The researchers stimulated a spinal cord injury in mice and injected the material 24 hours later. They found that the material reduced the size of scars and stimulated the growth of the nerve fibers through the scars. It promoted the growth of both types of nerve fibers that make up the spinal cord: motor fibers that carry signals from the brain to the limbs, and sensory fibers that carry sense signals to the brain. What is more, the material encouraged the nerve stem cells to mature into cells that create myelin--an insulating layer around nerve fibers that helps them to conduct signals more effectively.

Nine weeks after the injections, the mice that had been treated showed improvements over untreated mice. The animals could support their body weight on their hind legs and lift their lower bodies. "Animals that couldn't use hind legs at all now had improved ability to use their hind legs," Kessler says. "It was certainly not a cure but quite a substantial improvement in function. They're able to navigate around their cages."

Stupp has cofounded a Stokie, IL-based company called Nanotope, which is working on developing the self-assembling nanofiber therapy for human beings. The first step would be making a material that meets Food and Drug Administration standards and then testing it in clinical trials. So far, Kessler says, some basic tests of the material on human cell cultures have so far shown no apparent toxic effects.

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Scientists Find A Fingerprint Of Evolution Across The Human Genome


DNA double helix. Researchers have found signs that evolution rejects some types of mutations even in these regions of the genome. (Credit: NIH/National Human Genome Research Institute)

The Human Genome Project revealed that only a small fraction of the 3 billion “letter” DNA code actually instructs cells to manufacture proteins, the workhorses of most life processes. This has raised the question of what the remaining part of the human genome does. How much of the rest performs other biological functions, and how much is merely residue of prior genetic events?

Scientists from Cold Spring Harbor Laboratory (CSHL) and the University of Chicago now report that one of the steps in turning genetic information into proteins leaves genetic fingerprints, even on regions of the DNA that are not involved in coding for the final protein. They estimate that such fingerprints affect at least a third of the genome, suggesting that while most DNA does not code for proteins, much of it is nonetheless biologically important – important enough, that is, to persist during evolution.

Conservation of genetic information

To gauge how critical a particular stretch of DNA is, biologists often look at the detailed sequence of “letters” it consists of, and compare it with a corresponding stretch in related creatures like mice. If the stretch serves no purpose, the thinking goes, the two sequences will differ because of numerous mutations since the two species last shared an ancestor. In contrast, it’s believed that the sequences of important genes will be similar, or “conserved,” in different species, because animals with mutations in these genes did not survive. Biologists therefore regard conserved sequences as a sign of biological importance.

To test for conservation, researchers need to find matching stretches in the two species. This is relatively easy for stretches that “code” for proteins, where scientists long ago learned the meaning of the sequence. For “noncoding” regions, however, the comparison is often ambiguous. Even within a gene, stretches of DNA that code for pieces of the target protein are usually interspersed with much larger noncoding stretches, called introns, that are removed from the RNA working copy of the DNA before the protein is made.

Signs of splicing

Previous researchers assumed that mutations in the middle of introns do not affect the final protein, so they simply accumulate. In the new work, however, the researchers found signs that evolution rejects some types of mutations even in these regions of the genome. Although the selection is weak, “introns are not neutral,” in their effect on survival, says CSHL professor Michael Zhang, a bioinformatics expert who headed the research team.

To look for selection, CSHL researcher Chaolin Zhang, a doctoral candidate at Stony Brook University, looked in the human genome for a subtle statistical imbalance in how often various “letters” appear. The researchers attribute this imbalance to special short stretches of DNA that mark regions to be removed. Unless these signal sequences are sprinkled throughout an intron, the data suggest, it may not be properly spliced out, with potentially fatal consequences. Other sequences must likewise be preserved in the regions to be retained.

The scientists found a preference for some “letters” across intron regions, and the opposite preference in coding regions. Together, these regions make up at least a third of the genome, which is thus under selective pressure during evolution. The result supports other recent studies that suggest that, although most DNA does not code for proteins, much of it is nonetheless biologically important.

In addition to demonstrating how splicing affects genetic evolution, the statistical analysis identified possible signaling sequences, some that were already known and others that are new. According to co-author Adrian Krainer, a CSHL professor and splicing expert, “the exciting thing will be to experimentally test whether these predicted elements are really true.”

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