The other day, I had a little bit of a chuckle when eccentric Australian billionaire, Clive Palmer, made international headlines when rumours came out that he wanted to clone dinosaurs, ala Jurassic Park. He instead opted to purchase a replica, though he is quoted as saying “he liked the idea”.
To stress such a point, Nature reports on a new study published in the Proceedings of the Royal Society on DNA decay in the extinct New Zealand moa. They gathered a large sample of 158 bones preserved in three swamps in the South Island of New Zealand. Each bone was radiocarbon dated, and biological material was extracted to determine the quality of the DNA molecules.
The results of the study indicate that in the conditions of the preservation in the swamps, with an average temperature of 13.1 C, half of the DNA molecules have damaged bonds within 521 years. This means that after several thousands of years, there is little useful genetic material left intact. The decay rate is strongly dependent on the the temperature conditions. The authors calculated the decay rate using various temperatures, and found that at -5C, DNA might survive for upwards of 1 million years. This is good news for those who want to clone a mammoth, where remains have been frozen for thousands of years, but certainly quashes any possibility of a billionaire fulfilling his wish for a pet Tyrannosaurus. I think they say it best in the article:
(T)he results indicate that under the right conditions of preservation, short fragments of DNA should
be retrievable from very old bone (e.g. greater than 1 Myr). However, even under the best preservation conditions at -5C, our model predicts that no intact bonds will remain in the DNA ‘strand’ after 6.8 Myr. This displays the extreme improbability of being able to amplify a 174 bp DNA fragment from an 80-85 Myr old Cretaceous bone.