LONDON, Jan. 30 (UPI) -- An exploding comet did not end the prehistoric culture known as the Clovis people in North America 13,000 years ago as some have theorized, a study concludes.
Researchers from Royal Holloway, University of London, along with European and U.S. colleagues, say they've gathered evidence rebutting the belief a large impact or air burst caused a significant and abrupt change to the Earth's climate and terminated the Clovis culture.
Writing in the journal Geophysical Monograph Series, the researchers argue other explanations must be found for the apparent disappearance of the Clovis people.
Archaeologists have given the Clovis name to the earliest well-established human culture in the North American continent, after the town in New Mexico where stone tools were uncovered in the 1920s and 1930s.
Throwing the comet hypothesis into doubt, the researchers said no appropriately sized impact craters from that time period have ever been discovered and no material or other features usually associated with an impact have been found in sediments.
"The [comet] theory has reached zombie status," Professor Andrew Scott from the Department of Earth Sciences at Royal Holloway said. "Whenever we are able to show flaws and think it is dead, it reappears with new, equally unsatisfactory, arguments.
"Hopefully new versions of the theory will be more carefully examined before they are published."
Veggies grown in space said safe to eat
MOSCOW, Jan. 30 (UPI) -- Russian scientists say vegetables grown on board the International Space Station can be consumed without fear of food poisoning or other adverse effects.
Researchers have been studying "orbital-grown" vegetables such as Japanese cabbage for several years.
"The samples of cabbage have been brought to Earth," a researcher at the Moscow-based Institute of Medical and Biological Problems told RIA Novosti Wednesday. "We have not detected any deviations in their biomass composition compared with cabbage grown on Earth."
"From a microbiological perspective, these samples were absolutely safe to consume," the researcher said.
Because fruits and vegetables cannot be washed with water on board a spacecraft, the researchers said, microbiological safety is a significant factor in determining space travelers' diets.
The results of the orbital growing experiments could help in compiling a list of plants suitable for cultivating during prolonged space missions including manned flights to Mars and beyond, they said.
Study yields new ideas on exit from Africa
OXFORD, England, Jan. 30 (UPI) -- Modern humans left Africa earlier than previously thought in a number of climate-driven waves rather than a single period of movement, a British study suggests.
While previous attempts to date the exit of modern humans from Africa have relied heavily on evidence from genetics and archaeology, the researchers behind the new study said data on climate and environment could unlock new clues as to both how and why humans spread from the continent.
"The consensus view has been that modern humans left Africa around 60,000 years ago by a coastal route, skirting around some very arid places, and spread to Australia very quickly," said Michael Petraglia of the University of Oxford, co-author of the study published in the journal Quaternary International.
"We think that's wrong. We think people left Africa multiple times, probably a long time before, and we think it was terrestrial rather than coastal."
He acknowledged the idea goes against a well-established and widely held consensus, but said climate should be taken into account in any theory of movement out of Africa.
"We know that the climate has shifted a lot of times," he said.
"We think that has acted like a pump out of Africa, pushing waves of people into South Asia."
Winter to hang on in U.S. Northeast
STATE COLLEGE, Pa., Jan. 30 (UPI) -- The U.S. Northeast is likely to experience six more weeks of winter weather lasting into March, long-range forecasters at AccuWeather.com say.
The Northwest is also likely to have winter maintain its grip on the region, regardless of what Punxsutawney Phil has to say on Groundhog Day, forecasters said.
A couple of winter storms may impact the Northeast in February and March, they said.
"I think we could still see some late-season winter storms [in the Northeast]," AccuWeather lead long-range forecaster Paul Pastelok said.
Snow along the Interstate 95 corridor from Washington to New York City and Boston is not unusual, he said; "Typically, February to March is the season on the East Coast."
AccuWeather meteorologists said a stormier pattern, similar to what occurred in early December, is predicted for the Northwest, and snowfall could impact travel through the heavily traveled mountain passes of the region.
For the rest of the country, a near-normal tornado threat may be in store this spring especially across the Mississippi and Tennessee valleys, AccuWeather said, while another warm spring is expected across the Plains and Rockies.
Drought is expected to continue in the hardest-hit areas, it said, with extreme and exceptional drought conditions gripping Colorado, Wyoming, South Dakota, Nebraska, Kansas, Oklahoma and portions of Texas.