BERKELEY, Calif., Feb. 7 (UPI) -- In the ongoing debate about what killed off the dinosaurs, new evidence suggests a comet or asteroid was the final if not only blow, U.S. scientists say.
A comet or asteroid impact has long been considered a possibility, but others theories have focused on volcanic eruptions or climate change.
Now scientists at the University of California, Berkeley, with British and Dutch colleagues, have determined the most precise dates yet for both the dinosaur extinction around 66 million years ago and for the well-known cosmic impact that occurred around the same time when a 6-mile wide object slammed into the Caribbean off the Yucatan coast.
The dates are so close, the researchers say, they now believe the comet or asteroid, if not wholly responsible for the global extinction, at least dealt the dinosaurs their final death blow.
"The impact was clearly the final straw that pushed Earth past the tipping point," Berkeley earth and planetary science Professor Paul Renne said. "We have shown that these events are synchronous to within a gnat's eyebrow, and therefore the impact clearly played a major role in extinctions, but it probably wasn't just the impact."
The new date for the impact -- 66,038,000 years ago -- is the same within error limits as the date of the extinction, Renne said, suggesting the events were simultaneous.
He cautions this doesn't mean the impact was the sole cause of the extinction.
Dramatic climate variations over the previous million years, possibly made more extreme by volcanic eruptions, probably brought many creatures to the brink of extinction, ready to be kicked over the edge by the asteroid or comet impact, he said.
Warning given on 'trial by Google'
CANTERBURY, England, Feb. 7 (UPI) -- Britain's attorney general says the country's legal system, and particularly its jury system, is threatened by what he termed "trial by Google."
The increasing presence and use of smartphones threatens to undermine the integrity of the British jury system and "offends the principle of open justice," Dominic Grieve said.
"What does the Internet mean for our system of trial by jury?" he asked. "How can we be sure that jurors decide their cases on the basis of the evidence they hear -- and not what they looked up on their smart phones on the bus on the way to court?"
The challenges posed to the legal system by smartphones and their Internet access are becoming more immediate, he said.
Grieve made his comments in a lecture at the University of Kent on Wednesday, The Guardian reported.
"The Internet is a haystack of material, scattered with the odd prejudicial needle, as it were," he said. "Trial by Google allows a juror to locate the haystack, find the needle, pull it out and ascribe significance to it that it simply would never have had otherwise.
"It takes a minor risk and turns it into a major risk," he said, adding jurors searching the Internet, "offends some foundational principles of our legal system."
"If a jury is exposed to prejudicial material which, for whatever reason, is not before the court, the basis on which the defendant is convicted or acquitted will never be known."
Antarctic pond may yield Mars water clues
PROVIDENCE, R.I., Feb. 7 (UPI) -- Earth's most unlikely body of water, in frigid Antarctica, is liquid only because its salt content -- the highest on Earth -- keeps it that way, scientists say.
Don Juan Pond, located in the freezing McMurdo Dry Valleys, one of the coldest and driest places on Earth -- and with similarities to the frozen deserts of Mars -- could have implications for understanding water flow on Mars both in the past and maybe in the present, they said.
A research team led by Brown University geologists has discovered how the pond gets the salty water it needs to exist.
The scientist have determined water sucked out of the atmosphere by parched, salty soil is the source of the saltwater brine that keeps the pond eight times more salty than the Dead Sea and keeps it from freezing, a university release said Thursday.
Antarctica is an excellent model for the cold, dry desert of Mars, and the findings about Don Juan Pond and how it stays liquid at temperatures far below freezing could offer clues about the possibilities for flowing water on Mars, the researchers said.
"Broadly speaking, all the ingredients are there for a Don Juan Pond-type hydrology on Mars," Brown geologist James Dickson said. "It's not likely that there's enough water currently on Mars for the water to form ponds, but stronger flows in Mars's past might have formed plenty of Don Juan Ponds."
East-West divide in social site use found
EAST LANSING, Mich., Feb. 7 (UPI) -- The contrast between U.S. "me-first" culture and China's "collective-good" mentality shows in differing use of social networking sites, a psychologist says.
Michigan State University psychology Professor Linda Jackson said U.S. citizens spend more time on social networking sites, consider them to be more important and have more "friends" on them, while Chinese citizens tend to be more interested in real-world relationships than online friendships and less inclined toward the self-promotion that's popular on sites such as Facebook and Twitter.
"In the United States, it's all about promoting yourself and taking credit for positive outcomes and denying blame for negative outcomes," Jackson said in a university release Thursday. "In China, it's the opposite. If something bad happens, you take the blame and talk about how you can improve. If something good happens, the credit is shared for the good of the group."
Jackson and colleague Jin-Liang Wang of China's Southwest University surveyed more than 400 college-aged residents from each country on their use of social network sites.
They said U.S. study participants spent nearly twice as long on social networking sites, nearly 52 minutes a day, compared with Chinese participants at about 28 minutes daily.
Jackson said she worries about the potential negative effects of spending an increasing amount of time online.
"Because we are essentially social creatures, I cannot see good coming out of social isolation and practices that encourage aloneness and solitary activities," she said. "And a lot of technology does this."