YUCATAN, Mexico— Bird calls ring from the forest, echoing amid the crumbling ruins whose darkened doorways have long beckoned explorers and scholars.

The Maya ancients who built the ruins of Kiuic (kee-week) here fled those doorways in a hurry, an international archaeology team now realizes. Left behind may be frozen-in-time clues to the fabled collapse of their civilization.

"Why did they leave? That's the question," says archaeologist George Bey of Millsaps College in Jackson, Miss. The ancient Maya fled Kiuic, nestled in the Puuc (pook) foothills of the Yucatan, around 880. "Things were going full-bore, construction was underway. And things stopped," Bey says.

AMATEUR astronomers are enjoying a cat-and-mouse game with the US military in keeping track of its secret space plane, the X-37B.

The X-37B was launched in April amid much publicity, but scant detail about its true use.

Built by Boeing's Phantom Works division, the X-37B program was originally headed by NASA.

It was later turned over to the Pentagon's research and development arm and then to a secretive Air Force unit.

MADISON, Wis. – University of Wisconsin student Leo Burt approached his former journalism instructor at the student union one day in August 1970.

The intense 22-year-old thanked the man for encouraging him to write for a left-wing student newspaper, where he covered the Vietnam War protests raging on campus and where his politics had become radicalized. And he said goodbye because he was planning to live underground in Canada for reasons he wouldn't share.

"Only 10 days later, there he was on television," the instructor, Jack Holzhueter, recalled. "And I was shocked to know that Leo had participated in this event."

Like 10,000 others up and down the California coast, the family was suddenly forced to uproot. At their new place in Salinas, they had to be home by 8 p.m. or face arrest. And when the government seized fishing boats for the war effort, Maiorana's dad, a naturalized U.S. citizen, saw his livelihood go down the drain.

"He was on the skids for the rest of his life," said Maiorana, 75, who owns a boatyard and marina on the harbor where his father's boat — as well as those of his uncles and several dozen other Italian fishermen — were confiscated.

ATLANTA — In February 2007, Alberto R. Gonzales, the attorney general under President George W. Bush, issued a stern warning to those who murdered blacks with impunity during the civil rights era: “You have not gotten away with anything. We are still on your trail.”

He noted that time was short. The window of opportunity to solve racially motivated crimes more than 40 years old was closing. Families of the victims had waited decades for resolution, while suspects and witnesses have died.

More than three years later, they are still waiting.

There have been no federal indictments since Mr. Gonzales’s announcement, which heralded the Civil Rights-Era Cold Case Initiative. Very little of the millions of dollars approved by Congress to finance the initiative has materialized. Though 40-year-old murder cases are incredibly difficult to solve, no Federal Bureau of Investigation field agents are assigned to pursue the cases full time.

BISBEE, Ariz. — Many hotel guests would complain if they were awoken by bumps in the night or if they found their things had mysteriously disappeared from their dressers. But not visitors to the Copper Queen Hotel, a rustic old place that is considered Arizona’s longest continuously operated hotel.

The Copper Queen is haunted, or at least that is what the owners claim and what numerous guests have affirmed over the years with stories about mysterious voices, odd sounds and smells, and even levitating objects. For many, a quiet, uneventful night at the Copper Queen, which dates to 1902, is a dire disappointment.

“Oh, oh!” a non-ghostly woman exclaimed in surprise when she rounded a corner on the fourth floor one recent evening. When she realized she had encountered another non-ghost, she seemed disappointed. “Have you seen anything?” she asked.

When Jerry Campbell became president of California's renowned Claremont School of Theology four years ago, low enrollment and in-the-red books threatened to close the 125-year-old institution. But since Claremont is the only United Methodist seminary west of Denver, Campbell resolved to find a way to stay open.

Drawing from classic American entrepreneurial wisdom — when faced with extinction, innovate — and a commitment to engage today's multi-faith culture, this fall Claremont will commence a first on U.S. soil: a "theological university" to train future pastors, imams, and rabbis under one roof. The experiment to end isolated clerical training brings together Claremont, the Islamic Center of Southern California (ICSC) and the Academy for Jewish Religion California.

AMSTERDAM — The monumental chestnut tree that cheered Anne Frank while she was in hiding from the Nazis was toppled by wind and heavy rain on Monday.

The once mighty tree, now diseased and rotted through the trunk, snapped about 3 feet above ground and crashed across several gardens. It damaged a brick wall and several sheds, but nearby buildings — including the Anne Frank House museum — escaped unscathed. No one was injured, authorities said.

"It broke off like a match. It broke off completely about one meter off the ground," the spokesman for the museum told Reuters.

BELFAST, Northern Ireland – The British government and the Roman Catholic church colluded to cover up the suspected involvement of a priest in a 1972 bombing that killed nine people and injured 30, a new report said Tuesday.

The Northern Ireland police ombudsman's report determined that Father James Chesney was the prime suspect in the blast in the village of Claudy, just outside of Londonderry and that the police chose not to pursue him. The Irish Republican Army has been blamed for the attack.

"A senior (police) officer sought the government's assistance in December 1972, through their engagement with senior figures of the Catholic Church, to 'render harmless a dangerous priest,'" the report said.

Researchers at Big Bear Solar Observatory have tuned their adaptive optics array and achieved first light, capturing this image of a sunspot that is now the most detailed ever captured in visible light. The image was captured with Big Bear’s New Solar Telescope (NST), a brand new instrument (as the name implies) with a resolution of just 50 miles on the sun’s surface.

The NST is the precursor to an even-larger telescope, the Advanced Technology Solar Telescope (ATST), which will be constructed over the next decade, allowing Big Bear researchers to build a new kind of adaptive optics system known as multi-conjugate adaptive optics, that should provide them with a clear, distortion-free means of observing the sun from Earth in unrivaled detail.

Darwin is one of my heroes, but I believe he was wrong in seeing human evolution as a result of the same processes that account for other evolution in the biological world - especially when it comes to the size of our cranium.

Darwin had to put large cranial size down to sexual selection, arguing that women found brainy men sexy. But biomechanical factors make this untenable. I call this the smart biped paradox: once you are an upright ape, all natural selection pressures should be in favour of retaining a small cranium. That's because walking upright means having a narrower pelvis, capping babies' head size, and a shorter digestive tract, making it harder to support big, energy-hungry brains. Clearly our big brains did evolve, but I think Darwin had the wrong mechanism. I believe it was technology. We were never fully biological entities. We are and always have been artificial apes.

IT IS a bright spring morning here at Heriot-Watt University in Edinburgh, UK, where I have come to meet my interviewee for this article, Shanwen Tao. Normally when I interview someone, I give them a business card and maybe the latest issue of New Scientist. Today, I give Tao a bottle of my own pee.

Chemist Tao doesn't find this odd. Urine, he believes, could help solve the world's energy problems, powering farms and even office buildings. And he has agreed to use my offering to show me how.

Urine might not pack the punch of rocket fuel, but what it lacks in energy density it makes up for in sheer quantity. It is one of the most abundant waste materials on Earth, with nearly 7 billion people producing roughly 10 billion litres of it every day. Add animals into the mix and this quantity is multiplied several times over.

Surfers, bodyboarders and dolphin-spotters at the English seaside resort of St Ives were mostly unaware of a techno drama being played out about a kilometre beyond the breakers this month. Since 1 August, engineers on the cable ship Nordica have been trying to begin deployment of Wave Hub, an undersea extension cord that could make harnessing wave energy more viable. The first part of the roll-out hasn't gone at all smoothly, however.

So just what is Wave Hub? Essentially, it's a four-way socket that will be installed 50 metres down on the seabed 16 kilometres from shore, where the Atlantic swell is deemed perfect for serious energy capture, and connected via a giant 50-megawatt-capacity cable to an electricity substation in Hayle, on St Ives bay.

A new analysis of a meteorite shows that an inclusion within the carbonaceous stone is older than any known material in the solar system. The finding pushes back the estimated age of the solar system to 4.568 billion years, older than previous estimates by up to 1.9 million years.

A piece of the meteorite, known as Northwest Africa 2364, was purchased in 2004 in Morocco and is now part of a collection at Northern Arizona University in Flagstaff, Ariz. About 150 miles south of Flagstaff, two researchers at the Arizona State University Center for Meteorite Studies in Tempe, Audrey Bouvier and Meenakshi Wadhwa, dated an especially primitive piece of the meteorite known as a calcium-aluminum-rich inclusion, or CAI. Their findings appeared online August 22 in Nature Geoscience.

Hobbits, as Lord of the Rings fans know, sometimes find themselves is some surprisingly big battles.

So perhaps we shouldn't be too surprised that paleontology's "hobbits," otherwise known as Homo floresiensis, have ended up in quite a number of fights too, ever since their 2003 discovery in the Liang Bua cave on the Indonesian island of Flores.

Most of the fights have been over whether hobbits were truly a distinct species given their small size or just diseased humans, or whether creatures with their small brains could have used tools. But the latest skirmish appears in the current J ournal of Human Evolution, where John Trueman of the Australian National University (ANU) drags the puny pre-human species — which stood less than four feet tall and went extinct more than 12,000 years ago — into a fight over whether researchers should depict humanity's origins as a family tree.

MEXICO CITY (Reuters) – The remains of a prehistoric child were removed from an underwater cave in Mexico four years after divers stumbled upon the well-preserved corpse that offers clues to ancient human migration.

The skeletal remains of the boy, dubbed the Young Hol Chan, are more than 10,000 years old and are among the oldest human bones found in the Americas.

The corpse was discovered in 2006 by a pair of German cave divers who were exploring unique flooded sandstone sinkholes, known as cenotes, common to the eastern Mexican state of Quintana Roo.

The new study, which looked at temperatures during the early Eocene period 52 to 53 million years ago, also has implications for the impacts of future climate change as Arctic temperatures continue to rise, said University of Colorado at Boulder Associate Professor Jaelyn Eberle of the department of geological sciences, lead author of the study.

The team used a combination of oxygen isotope ratios from fossil bone and tooth enamel of mammals, fish and turtles that lived together on Ellesmere Island to estimate the average annual Eocene temperature for the site. They also were able to tease out temperature estimates for the warmest and coldest months of the year, critical data that should help scientists better understand past and future biodiversity in the High Arctic as the climate warms, including the geographical ranges and species richness of animals and plants.

The study, scheduled to appear in the December print edition of the Journal of Mammalian Evolution and now available online, describes a new species that evolved to half the size of its ancestors during this period of global warming.

The hyena-like animal, Palaeonictis wingi, evolved from the size of a bear to the size of a coyote during a 200,000-year period when Earth's average temperature increased about 15 degrees Fahrenheit. Following this global warming event, Earth's temperature cooled and the animal evolved to a larger size.

"We know that plant-eating mammals got smaller during the earliest Eocene when global warming occurred, possibly associated with elevated levels of carbon dioxide," said lead author Stephen Chester, a Yale University doctoral student who began the research at UF with Jonathan Bloch, curator of vertebrate paleontology at the Florida Museum of Natural History. "Surprisingly, this study shows that the same thing happened in some carnivores, suggesting that other factors may have played a critical role in their evolution."

Some objects can be moved, while others cannot. Balls can be placed on top of boxes, but boxes cannot be stably stacked on top of balls. A typical one-year-old child can discover this kind of information about its environment very quickly. But it is a massive challenge for a robot - a machine - to learn concepts such as ‘movability’ and ‘stability’, according to Björn Kahl, a researcher at the Bonn-Rhein-Sieg University and a member of the Xpero robotics research project team.

The aim of the Xpero project was to develop a cognitive system for a robot that would enable it to explore the world around it and learn through physical experimentation.

Dr Shostak said current experiments aiming to locate extraterrestrial intelligence all assume it is most likely to be found on "habitable worlds" with liquid surface water and light gaseous atmospheres, in other words, worlds that could support life similar biochemically to that on Earth.

The problem with this assumption is that the development of artificial intelligence may come soon after the invention of communication technologies, as it has for us, which means SETI's targeted searches may be "chasing a very short-lived prey," Dr Shostak said. We have a chance of detecting extraterrestrial intelligences once they invent radio and go on the air, but within a few hundred years they are likely to invent their thinking machine successors.