Chinese archeologists have identified the route of a 137-km stretch of China's oldest Great Wall in central Henan Province, on which the remnants of 30 km of wall is still standing.

"The wall structure was built no later than 221 B.C. in the Warring States period," said Sun Yingmin, spokesman of the provincial Cultural Relics Bureau, Tuesday.

He said previous to this, only sporadic discoveries of wall remains were found. The actual appearance of the main body of Great Wall of the Chu State was only recorded in historical records.

The primordial soup that gave birth to life on Earth may have had an extra, previously unrecognised ingredient: a "molecular midwife" that played a crucial role in allowing the first large biomolecules to assemble from their building blocks.

The earliest life forms are thought by many to have been based not on DNA but on the closely related molecule RNA, because long strands of RNA can act as rudimentary enzymes. This would have allowed a primitive metabolism to develop before life forms made proteins for this purpose.

New research reveals just how bad an idea it was to colonize Greenland and Iceland more than a millennium ago: average temperatures in Iceland plummeted nearly 6°Celsius in the century that followed the island’s Norse settlement in about A.D. 870, a climate record gleaned from mollusk shells shows.

The record is the most precise year-by-year chronology yet of temperatures experienced by the northern Norse colonies, says William Patterson, an isotope geochemist at the University of Saskatchewan in Saskatoon, Canada, who led the new work. The study will appear online in the Proceedings of the National Academy of Sciences.

“We’re aware from written documents of the kinds of things that people faced in the North Atlantic over the last 1,000 years,” he says. “This is a way to quantify the experiences they had.”

A scientist and a composer are working together to explore a thousand years of human history through soil samples.

The pair have built an installation in Dundee which tells the story of Viking settlers in Greenland going back to the year 900.

Images of soil samples gathered by Dr Paul Adderley have been set to audio by Dr Michael Young.

Add plumbing to the mysterious arts of the ancient Maya, investigators report. In a Journal of Archaeological Science study, anthropologist Kirk French and civil engineer Christopher Duffy of Penn State report on a conduit designed to deliver pressurized water to Palenque, an urban center in southern Mexico, more than 1,400 years ago.

"The ancient Maya are renowned as great builders, but are rarely regarded as great engineers. Their constructions, though often big and impressive, are generally considered unsophisticated," say the study authors.

Researchers have found that eggshells of extinct bird species are a rich source of preserved DNA.

An international team isolated the delicate DNA molecules of species including the massive "elephant birds" of the genus Aepyorni.

The Proceedings of the Royal Society B research demonstrated the approach also on emu, ducks and the extinct moa.

The team says that the technique will enable researchers to learn more about ancient birds and why they died out.

Deforestation has revealed what could be a giant impact crater in Central Africa, scientists say.

The 36-46km-wide feature, identified in DR Congo, may be one of the largest such structures discovered in the last decade.

Italian researchers considered other origins for the ring, but say these are unlikely.

They presented their findings at the recent Lunar and Planetary Science Conference in Texas, US.

The ring shape is clearly visible in the satellite image by TerraMetrics Inc reproduced on this page.

Robots are great for going where humans can't, and the cramped confines of municipal water pipes are the perfect example. A new initiative is working on building robots that can access and repair aging water pipes from the inside.

Old pipes are a pressing issue for many cities. The American Society of Civil Engineers which rates the quality of city infrastructure, including water works, estimates that 6 billion gallons of clean drinking water disappears each day, mostly due to old, leaky pipes and mains. That's enough water to supply all the residents of California for a year.

The Large Hadron Collider (LHC) must close at the end of 2011 for up to a year to address design issues, according to an LHC director.

Dr Steve Myers told BBC News the faults will delay the machine reaching its full potential for two years.

The atom smasher will reach world record collision energies later this month at 7 trillion electron volts.

STOCKHOLM (AFP) – A dozen previously unknown shipwrecks, some of them believed to be up to 1,000 years old, were discovered in the Baltic Sea during a probe of the sea bed to prepare for the installation of a large gas pipeline, the Swedish National Heritage Board said Monday.

"We have manage to identify 12 shipwrecks, and nine of them are considered to be fairly old," Peter Norman, a senior advisor with the heritage board, told AFP.

The binary system consists of two white dwarfs. These are the burnt- out cinders of stars such as our Sun, and contain a highly condensed form of helium, carbon and oxygen. The two white dwarfs in HM Cancri are so close together that mass is flowing from one star to the other. HM Cancri was first noticed as an X-ray source in 1999 showing a 5.4 minutes periodicity but for a long time it has remained unclear whether this period also indicated the actual orbital period of the system. It was so short that astronomers were reluctant to accept the possibility without solid proof.

The team of astronomers, led by Dr Gijs Roelofs of the Harvard-Smithsonian Center of Astrophysics, and including Professor Tom Marsh and Dr Danny Steeghs at the University of Warwick in the UK, have now used the world's largest telescope, the Keck telescope on Hawaii, to prove that the 5.4 minute period is indeed the binary period of the system.

What is death? Over the centuries, the line dividing life and death has moved from the cessation first of breathing, then of the heartbeat, and finally of brain activity. But cryogenic methods first contemplated in science fiction may push the line even further. The idea is to freeze legally dead people in liquid nitrogen in the hope of regenerating them at some future date.

Today’s cryonics scientists believe that this future may be a mere 100 years away. Alcor Life Extension Foundation in Scottsdale, Ariz., the world’s largest cryonics company, charges US $150,000 to freeze and maintain a body and $80,000 for a head, typically paid for with a life insurance policy.

Scientists may have identified the first specks of interstellar dust in material collected by the US space agency's Stardust spacecraft.

A stream of this dust flows through space; the tiny particles are building blocks that go into making stars and planets.

The Nasa spacecraft was primarily sent to catch dust streaming from Comet Wild 2 and return it to Earth for analysis.

But scientists also set out to capture particles of interstellar dust.

Captain Kirk might want to avoid taking the starship Enterprise to warp speed, unless he's ready to shrug off interstellar hydrogen atoms that would deliver a lethal radiation blast to both ship and crew.

There are just two hydrogen atoms per cubic centimeter on average in space, which poses no threat to spaceships traveling at low speeds. But those same lone atoms would transform into deadly galactic space mines for a spaceship that runs into them at near-light speed, according to calculations based on Einstein's special theory of relativity.

Here we are drinking coffee and tweeting and otherwise going about our lives, generally not giving much thought to the protection that the Earth’s magnetic field affords us from the solar wind. But that magnetic field is crucial for our existence. Now, new findings in Science say that this protective shield originated even 200 million years earlier than scientists had previously thought, perhaps protecting the planet’s water from evaporating away and aiding the rise of life on the early Earth.

(AP) The deep space antenna that relayed Neil Armstrong's famous "one giant leap for mankind" declaration from the moon to a rapt American audience will be offline for eight months for repair.

Work begins this week to replace a steel donut-shaped bearing on the aging 230-foot-wide dish at the NASA Deep Space Network site at Goldstone Dry Lake in the Mojave Desert about 150 miles northeast of Los Angeles.

The labor-intensive process, which will involve jacking up 9 million pounds, will keep the antenna out of service until at least November.

When English and Scottish settlers first arrived in what was to become the United States, they encountered literally thousands of abandoned earthen and shell mounds that seemed not to be associated with occupied Indian villages. Typically, the new arrivals assumed that the “savages” were intellectually incapable of carrying out major public works. Therefore, they speculated that Europeans or advanced societies from the Middle East had once lived in the New World until they were exterminated by the Indians. It would not be for another 200 years that the public would become generally aware that about 90-95% of the societies who built those mounds had died of diseases or had been enslaved in the decades following Spanish exploration of the region.

One of the more famous paintings of the medieval Ming dynasty, which ruled China for about three centuries, is that of a court attendant holding a rope around a giraffe. An inscription on the side says the animal dwelled near "the corners of the western sea, in the stagnant waters of a great morass." According to legend, the giraffe was found in Africa, along with zebras and ostriches, and brought back with the grand 15th century expeditions of Zheng He, China's greatest mariner.

Has another mystery in the history of Israel been solved? Prof. Gershon Galil of the Department of Bible Studies at the University of Haifa has identified Khirbet Qeiyafa as “Neta’im”, which is mentioned in the book of Chronicles. “The inhabitants of Neta’im were potters who worked in the king’s service and inhabited an important administrative center near the border with the Philistines,” explains Prof. Galil.

Plzen, West Bohemia, March 5 (CTK) - An expedition of Czech archaeologists has found remains of an about 150,000-year-old prehistoric settlement in Arbil, north Iraq, which has been the so far oldest uncovered in this part of northern Mesopotamia, team head Karel Novacek told reporters Friday.

The archaeologists revealed a high number of items, mainly prehistoric stone tools, about nine metres under the ground in Arbil, capital of the Kurdish autonomous region, said archaeologist Novacek, from the University of West Bohemia in Plzen.