Washington - The worldwide spread of ancient humans has long been depicted as flowing out of Africa, but tantalizing new evidence suggests it may have been a two-way street.

A long-studied archaeological site in a mountainous region between Europe and Asia was occupied by early humans as long as 1.85 million years ago, much earlier than the previous estimate of 1.7 million years ago, researchers report in Tuesday's edition of Proceedings of the National Academy of Sciences.

Early human Homo erectus is known to have occupied the site at Dmanisi later. Discovering stone tools and materials from a much earlier date raises the possibility that Homo erectus evolved in Eurasia and might have migrated back to Africa, the researchers said - though much study is needed to confirm that idea.

"The accumulating evidence from Eurasia is demonstrating increasingly old and primitive populations," said Reid Ferring of the University of North Texas. Dmanisi is located in the Republic of Georgia.

Innovations in programming are changing archaeologists' perception of how settled life and early agriculture spread through Britain.

The long-lost 'history' of prehistoric Britain, including our island's first wars, is being re-discovered - courtesy of innovations in computer programming as well as archaeology.

Using newly refined computer systems, developed over recent years by programmers at Oxford University, archaeologists from English Heritage and Cardiff University have for the first time been able to fairly accurately date individual prehistoric battles, migrations and building construction projects.

After eight years of research, the team has been able to create a 'historical' chronology for the first 700 years of settled life in Britain.

Analysis of the fossilized teeth of our early ancestors living in southern Africa shows it was the women who ventured out when they came of age, while men tended to remain close to home, researchers say.

Archeologists studied teeth from 19 sets of prehistoric early human remains found in two caves in South Africa's Sterkfontein Valley.

The researchers, whose work was published in the journal Nature, were able to surmise that the females grew up in a different area from where they died, while the men appeared to be local.

Julia Lee-Thorp, co-author of the study, told CTV.ca the research helps provide a rare glimpse into the way human ancestors lived their lives.

"It's exciting because it's the first real hard evidence we have of an ancient social pattern, so it begins to give us much better clues about how they constructed their family groups than we had before," said Lee-Thorp, reached by phone at Oxford University in the U.K., where she is an archeological scientist.

A team of archaeologists from the University of Florida have discovered in St. Augustine the ruins of a church more than 300 years old that belonged to a mission of the Spanish colonial period.

The archaeologists believe it could be the oldest stone building of Spain's colonial period and one of the largest mission churches built during that time in Florida.

Researchers from the Florida Museum of Natural History, located on the UF campus in Gainesville, discovered coquina stones and foundations indicating a structure some 27 meters (90 feet) long by 12 meters (40 feet) high, which would be "the only mission church made of stone," the university said in a communique.

The ruins were found at the place where the first Franciscan mission was built in Florida, called Nombre de Dios (Name of God), which remained active from 1587 until 1760.

It was a monumental project with modest beginnings: a small group of scholars and some index cards. The plan was to explore a long-dead language that would reveal an ancient world of chariots and concubines, royal decrees and diaries - and omens that came from the heavens and sheep livers.

The year: 1921. The place: The University of Chicago. The project: Assembling an Assyrian dictionary based on words recorded on clay or stone tablets unearthed from ruins in Iraq, Iran, Syria and Turkey, written in a language that hadn't been uttered for more than 2,000 years. The scholars knew the project would take a long time. No one quite expected how very long.

Decades passed. The team grew. Scholars arrived from Vienna, Paris, Copenhagen, Jerusalem, Berlin, Helsinki, Baghdad and London, joining others from the U.S. and Canada. One generation gave way to the next, one century faded into the next. Some signed on early in their careers; they were still toiling away at retirement. The work was slow, sometimes frustrating and decidedly low-tech: Typewriters. Mimeograph machines. And index cards. Eventually, nearly 2 million of them.

And now, 90 years later, a finale. The Chicago Assyrian Dictionary is now officially complete - 21 volumes of Akkadian, a Semitic language (with several dialects, including Assyrian) that endured for 2,500 years. The project is more encyclopedia than glossary, offering a window into the ancient society of Mesopotamia, now modern-day Iraq, through every conceivable form of writing: love letters, recipes, tax records, medical prescriptions, astronomical observations, religious texts, contracts, epics, poems and more.

Why is there a need for a dictionary of a language last written around A.D. 100 that only a small number of scholars worldwide know of? Gil Stein, director of the university's Oriental Institute (the dictionary's home), has a ready answer:

"The Assyrian Dictionary gives us the key into the world's first urban civilization," he says. "Virtually everything that we take for granted ... has its origins in Mesopotamia, whether it's the origins of cities, of state societies, the invention of the wheel, the way we measure time, and most important the invention of writing.

"If we ever want to understand our roots," Stein adds, "we have to understand this first great civilization."

Changing climate observed in the Rocky Mountains

Scientists who study prehistoric remains know they have a huge find at Snowmass, probably the biggest of their careers.

Digging furiously for 18 days last fall as winter closed in, they uncovered the remains of eight to 10 American mastodons, four Columbian mammoths and a Jefferson's ground sloth, the first ever found in Colorado and the highest elevation sample anywhere in North America.

Although a herbivore, the ground sloth was the size of a grizzly bear and "capable of ripping your face off if you got too close to it," said Kirk Johnson, chief curator at the Denver Museum of Nature and Science, at a recent press conference.

That's conjectural, as ground sloths and most other species found at the Snowmass site disappeared 10,000 years ago, soon after the last great ice sheets retreated. Other species remain, such as the camel, whose tooth was found at Snowmass. But scientists aren't sure whether the genus of the extinct Camelops, had a hump, as camels today do, or lacked one, like their modern relative the llama.

On the beaches of southern California you can sometimes find clumps of a sticky black substance with a texture halfway between molasses and rubber. Could these tar balls - collected by humans for thousands of years - provide evidence that our long-standing relationship with hydrocarbons was toxic from the outset?

Long before we started asphalting roads, prehistoric people around the world used bitumen, which seeps from the ground naturally in places. Archaeological finds suggest that California's prehistoric locals, the Chumash people, eagerly collected the tar balls. They used them to caulk the seams of ocean-going craft and waterproof woven baskets to make drinking vessels, as well as for making casts for broken bones and poultices for sore joints. Some Chumash even chewed bitumen like gum.

We now know that bitumen can be a source of polycyclic aromatic hydrocarbons (PAHs) - pollutants that have been linked to a number of health problems (see "Poisonous ingredients"). To find out whether California's tar balls had the potential to damage the Chumash's health, Sebastian Wärmländer of Stockholm University in Sweden and colleagues analysed samples taken from Californian beaches and from the La Brea tar pits in Los Angeles. They found the tar contained 44 PAHs, including many known carcinogens.

An ancient Roman shipwreck nearly 2,000 years old may once have held an aquarium onboard capable of carrying live fish, archaeologists suggest.

The shipwreck, which lay 6 miles (nearly 10 kilometers) off the town of Grado in Italy, was discovered by accident in 1986. Approximately 55 feet (16.5 meters) long, it dated back to the mid-second century and had a cargo of about 600 large vases known as amphoras that contained sardines, salted mackerel and other fish products.

Curiously, its hull possessed a unique feature -- near its keel was a lead pipe at least 2.7 inches (7 cm) wide and 51 inches (1.3 meters) long. Why pierce its bottom with a hole that seawater could rise up?

Scientists now suggest this pipe was connected to a hand-operated pump to suck up water. The aim? To keep a constant supply of flowing, oxygenated water into a fish tank onboard the ship.

A Wiltshire mound where the legendary wizard Merlin was purported to be buried has been found to date back to 2400 BC.

Radiocarbon dating tests were carried out on charcoal samples taken from Marlborough Mound, which lies in Marlborough College's grounds.

The 19m (62ft) high mound had previously mystified historians. Some believed it dated back to about 600 AD.

English Heritage said: "This is a very exciting time for British prehistory."

Dig leader Jim Leary said: "This is an astonishing discovery.

"The Marlborough Mound has been one of the biggest mysteries in the Wessex landscape.

"For centuries people have wondered whether it is Silbury's little sister; and now we have an answer. "

'Dramatic history'

Silbury Hill, an artificial man-made mound about five miles away, also dates back to 2,400 BC.

Marlborough Mound was reused as a castle and became an important fortress for the Norman and Plantagenet kings.

Incan fortresses built some 500 years ago have been discovered along an extinct volcano in northern Ecuador, revealing evidence of a war fought by the Inca just before the Spanish conquistadors arrived in the Andes.

"We're seeing evidence for a pre-Columbian frontier, or borderline, that we think existed between Inca fortresses and Ecuadorian people's fortresses," project director Samuel Connell, of Foothill College in California, told LiveScience.

The team has identified what they think are 20 fortresses built by the Inca and two forts that were built by a people from Ecuador known as the Cayambe. The volcano is called Pambamarca.

The team's research was presented in March at the 76th annual meeting of the Society for American Archaeology (SAA), in Sacramento, Calif.

"We know that there are many, many fortresses throughout northern Ecuador that haven't been identified one way or the other," said Chad Gifford, of Columbia University, who is also a project director.