Humanity will never be able to resurrect the creatures of long ago. New research suggests that even under ideal conditions, DNA becomes unreadable after a mere 1.5 million years. Thus all the dino bones and amberized insects in the world are useless for cloning purposes, Scientific American writes:
Palaeogeneticists led by Morten Allentoft in Perth, Australia, examined 158 DNA-containing leg bones belonging to three species of extinct giant birds. By comparing the specimens’ ages and degrees of DNA degradation, the researchers calculated that DNA has a half-life of 521 years. That means that after 521 years, half of the bonds between nucleotides in the backbone of a sample would have broken; after another 521 years half of the remaining bonds would have gone; and so on.
The team predicts that even in a bone at an ideal preservation temperature of −5 ºC, effectively every bond would be destroyed after a maximum of 6.8 million years. The DNA would cease to be readable much earlier — perhaps after roughly 1.5 million years, when the remaining strands would be too short to give meaningful information.