Ancient rocks from the eastern shore of Hudson Bay have yielded the first direct evidence that carbon dioxide -- the culprit in modern, man-made global warming -- might have stopped the young Earth from freezing over.
The rocks were discovered by Canadian geologists in northern Quebec in 2001, and a team at the University of Colorado at Boulder -- which included Canadian Nicole Cates -- has now confirmed that they are 3.8 billion years old, among the oldest in the world.
Astrophysicists believe that the sun was 25 per cent fainter back then, and many researchers have theorized that high concentrations of greenhouse gases helped the planet avoid global freezing.
The University of Colorado team, working with researchers from the University of Chicago, found that the rocks contain compounds called iron carbonates, which could have been formed only if the atmosphere contained far more carbon dioxide than today.
"We now have direct evidence that the Earth's atmosphere was loaded with CO{-2} early in its history, which probably kept the planet from freezing and going the way of Mars," University of Colorado geologist Stephen Mojzsis says. Too good no good
Women are suspicious of men who seem too perfect, a study suggests.
Simon Chu, a psychologist at the University of Central Lancashire in Britain, asked 186 female students to rank men on their attractiveness as a long-term partner based on a photograph and basic information about their age and profession.
The men in the photographs had previously been judged by another group of women as highly attractive, attractive or not attractive. The fictional professions were meant to provide a clear indicator of socio-economic status. At the top of the heap were company directors, in the middle were teachers and travel agents and low-status jobs included waiter or gardener.
Women did not go for the hottest, high-status men, but preferred really attractive men of medium status. Why? The researchers say the women may worry that a guy who is handsome and rich will appeal to too many women, and may be more likely to cheat or leave them.
The paper, Too good to be 'true'?, was published in the journal Personality and Individual Differences.
Snakes use toad steroids
Toxic toads produce steroids that can stop the heart of a predator. But one species of snake has learned how to eat the amphibians and use the poison to protect themselves.
The snakes, which live in Japan and other Asian countries, store the toad toxin in glands on their necks. They show off the glands to hawks, salamanders and snakes that come after them and they have been observed neck-butting their attackers.
Deborah Hutchinson, a biologist at Old Dominion University in Virginia, had a hunch that the snakes were not making the steroids themselves. She and her colleagues tested snakes that lived on toad-free islands in Japan and found no trace of the toxin, and these snakes were not so quick to offer their necks to attackers.
