A team of researchers from Murdoch University have published a study which categorically proves that DNA could not survive any longer than 6.8 million years in an optimal environment.

 

While the findings show DNA can exist significantly longer than the currently accepted record of 450,000 to 800,000 years, it has finally put the rest the idea that pre-historical animals might be brought back to life using DNA samples.

 

The researchers came to their conclusions after studying 158 fossilised leg bones belonging to three species of moa, a family of birds that have long since been extinct.

 

“It has been agonisingly difficult to estimate the rate of DNA decay before now because finding a large set of DNA-containing fossils with which to make meaningful comparisons are exceedingly rare,” Dr Mike Bruce from Murdoch University said.

 

“Environmental conditions like temperature, degree of microbial ‘attack’ and oxygenation, can affect the DNA decay process and make it hard to detect a basic rate of degradation.

 

“The moa bones however have allowed us to study the comparative DNA degradation because they come from different ages from a region where they have all experienced the same environmental conditions.”

 

The fossil bone specimens were carbon dated as being between 600 and 8000 years old and looking at the varying degrees of DNA degradation in each specimen, the team were able to calculate a DNA half-life of 521 years. The half-life is the amount of time taken for an amount of DNA to reach 50 per cent of the starting amount.

 

The scientists found that the estimated decay rate in the specimens was almost 400 times slower than predicted from simulation experiments carried out in the lab.

Based on these calculations and other investigations, the team were able to make their predictions of DNA survival deeper into time.

 

“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,” added Dr Bunce.

 

The research team say that much more research into DNA degradation was required because their findings showed that the age of the fossils can account for only 38.6% of the variation in DNA preservation.