DNA can survive in fossils longer than previously believed, researchers say. But the period is not long enough for a story like that of Jurassic Park to ever happen in real life.
The oldest DNA samples ever recovered are from insects and plants in ice cores in Greenland up to 800,000 years old, but researchers had not been able to determine the oldest possible DNA they could get from the fossil record because DNA's rate of decay had remained a mystery.
Now scientists in an Australian report have been able to estimate this rate based on a comparison of DNA from 158 fossilised leg bones from three species of the moa, an extinct group of flightless birds that once lived in New Zealand.
Based on this study, Mike Bunce and his team from Murdoch University put DNA's half-life at 521 years, meaning half of the DNA bonds would be broken down 521 years after death, and half of the remaining bonds would be decayed another 521 years after that, and so on.
This rate is 400 times slower than simulation experiments predicted, the researchers said, and it would mean that under ideal conditions, all the DNA bonds would be completely destroyed in bone after about 6.8 million years.
According to Mike Bunce from Murdoch University's Ancient DNA lab in Perth, temperatures, oxygenation and other environmental factors make it difficult to detect a basic rate of degradation.
"If the decay rate is accurate then we predict that DNA fragments of sufficient length will preserve in frozen fossil bone of around one million years in age," Bunce said.
Beating Einstein's speed barrier
Washington: Einstein's theory of special relativity holds that nothing could move faster than the speed of light, but University of Adelaide applied mathematicians have developed new formulas that allow for travel beyond this limit.
"Since the introduction of special relativity, there has been much speculation as to whether or not it might be possible to travel faster than the speed of light, noting that there is no substantial evidence to suggest that this is presently feasible with any existing transportation mechanisms," said Professor Jim Hill, who developed the new formulas with Dr Barry Cox in the University's School of Mathematical Sciences.
Women remember bad news better
Washington: Women who read negative news remember it better than men do, suggesting they have increased sensitivity to stressful situations, researchers say.
They found women exposed to negative news had higher cortisol levels after the psychological stress test exposure than did men.
Marge Simpson tops hair poll
Marge Simpson's blue beehive has been voted one of the most iconic hairdos of the past 50 years.
The cartoon character's famously tall hair came second only to Princess Diana's Sloane Ranger hairstyle. The Shy Di look was made famous in the 1980s.
Rock 'n roll legend Elvis' quiff came third, just ahead of Friends star Jennifer Aniston, 43, in the survey by hair care website Fabriah.com.
"I was surprised to see Marge Simpson rank so highly," the Daily Star quoted spokesman Francesca Davies as saying.
Her hairstyle was inspired by the Bride's in Bride of Frankenstein and the style that Margaret Groening wore in the 1960s.