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Why is H5N1, or bird flu, a concern, how does it spread, and is there a vaccine? Here are the answers to some frequently asked questions about avian influenza.
Fossilized footprints discovered in New Mexico indicate that early humans were walking across North America around 23,000 years ago, researchers reported Thursday.
The first footprints were found in a dry lake bed in White Sands National Park in 2009. Scientists at the U.S. Geological Survey recently analyzed seeds stuck in the footprints to determine their approximate age, ranging from around 22,800 and 21,130 years ago.
The findings may shed light on a mystery that has long intrigued scientists: When did people first arrive in the Americas, after dispersing from Africa and Asia?
Most scientists believe ancient migration came by way of a now-submerged land bridge that connected Asia to Alaska. Based on various evidence -- including stone tools, fossil bones and genetic analysis -- other researchers have offered a range of possible dates for human arrival in the Americas, from 13,000 to 26,000 years ago or more.
The current study provides a more solid baseline for when humans definitely were in North America, although they could have arrived even earlier, the authors say. Fossil footprints are more indisputable and direct evidence than "cultural artifacts, modified bones, or other more conventional fossils," they wrote in the journal Science, which published the study Thursday.
"What we present here is evidence of a firm time and location," they said.
Based on the size of the footprints, researchers believe that at least some were made by children and teenagers who lived during the last ice age.
David Bustos, the park's resource program manager, spotted the first footprints in ancient wetlands in 2009. He and others found more in the park over the years.
"We knew they were old, but we had no way to date the prints before we discovered some with (seeds) on top," he said Thursday.
Made of fine silt and clay, the footprints are fragile, so the researchers had to work quickly to gather samples, Bustos said.
"The only way we can save them is to record them -- to take a lot of photos and make 3D models," he said.
Earlier excavations in White Sands National Park have uncovered fossilized tracks left by a saber-toothed cat, dire wolf, Columbian mammoth and other ice age animals.
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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute's Department of Science Education. The AP is solely responsible for all content.
Why is H5N1, or bird flu, a concern, how does it spread, and is there a vaccine? Here are the answers to some frequently asked questions about avian influenza.
An Ontario man who took out a loan to pay for auto repairs said his car was repossessed after he missed two payments.
Royal commentator Afua Hagan writes that when King Charles recently admitted Catherine to the Order of the Companions of Honour, it not only made history, but it reinforced the strong bond between the King and his beloved daughter-in-law.
A Massachusetts man who told police he was exorcising a demon and performing a baptism when he shoved his father's head under water multiple times has been convicted of involuntary manslaughter in his death.
American troops will be spending more time training in the Far North, the new commander of Norad says, a strategy that fits 'hand-in-glove' with Canada's renewed focus on Arctic defence.
During a special winner celebration near their hometown, Doug and Enid shared the story of how they discovered they were holding a Lotto Max ticket worth $70 million and how they kept this huge secret for so long.
A new survey by Dalhousie University's Agri-Food Analytics Lab asked Canadians about their food consumption habits amid rising prices.
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Charlie Woods failed to advance in a U.S. Open local qualifying event Thursday, shooting a 9-over 81 at Legacy Golf & Tennis Club.
Mounties in Nanaimo, B.C., say two late-night revellers are lucky their allegedly drunken antics weren't reported to police after security cameras captured the men trying to steal a heavy sign from a downtown business.
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When identical twin sisters Kim and Michelle Krezonoski were invited to compete against some of the world’s most elite female runners at last week’s Boston Marathon, they were in disbelief.
The giant stone statues guarding the Lions Gate Bridge have been dressed in custom Vancouver Canucks jerseys as the NHL playoffs get underway.
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A former educational assistant is calling attention to the rising violence in Alberta's classrooms.
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At 6'8" and 350 pounds, there is nothing typical about UBC offensive lineman Giovanni Manu, who was born in Tonga and went to high school in Pitt Meadows.