Most of us know the plot. Maverick scientist extracts DNA from blood preserved in the stomachs of mosquitoes trapped in ancient amber and uses it to populate a remote island with real-live dinosaurs, at which point it all starts going horribly wrong.
In 1993, the year the original Jurassic Park movie was released, researchers claimed to have recovered DNA from a weevil fossilised in amber 120-135 million years old. Suddenly, the gulf between science and science fiction didn’t seem so wide.
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It didn’t last long. Subsequent attempts to replicate the results failed and it became clear that the original samples had probably become contaminated with modern DNA. Studies carried out since have found little evidence that DNA embedded in amber can survive more than a few thousand years.
Like other organic material, DNA degrades over time, fragmenting into ever smaller pieces bearing shorter sequences of the genetic code. The oldest high-quality genomes yet recovered from modern humans are about 45,000 years old, for example. Go back to 430,000-year-old hominin remains, however, and the DNA recovered is too fragmented to reconstruct anything close to a complete sequence.
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Low temperatures slow down the rate of decay significantly. Many of the most ancient fragments have been recovered from the Arctic. The oldest DNA extracted from a preserved animal comes from the tooth of a mammoth excavated from Siberian permafrost, where it had been lying for at least 1.2 million years. This yielded fragments large enough to shed light on the species’ evolutionary relationships.
Older - and smaller - fragments have been unearthed from sediment deposited in Greenland about two million years ago. Known as environmental DNA, these originated from cells shed by organisms when they were alive. The DNA then bonded to minerals such as clay and quartz, which helped preserve it. Though very small, the fragments were sufficiently plentiful that researchers were able to identify much of the flora and fauna present in the region at the time, which included mastodons, reindeer, hares, rodents, geese and horseshoe crabs.
The Greenland samples are the oldest DNA found to date. But that’s not to say there aren’t older ones out there somewhere. One place that scientists are looking is eastern Antarctica, where the valleys contain ice formed over eight million years ago.
In which case, it’s not looking good for the idea that we’ll be able to reconstruct dinosaur genomes. But perhaps it’s still too early to write off the possibility completely. Because it might be possible to glean the all-important genetic information DNA encodes long after the molecule itself has decayed.
Researchers have started exploring how genetic sequences can be inferred from ancient proteins. These biological building blocks are made up of chains of amino acids assembled in an order that is determined by the linear instructions carried by the DNA. Work out the order of the amino acids and you can get a good idea of the genetic sequence that coded for them. And crucially, proteins last much longer than DNA does.
In 2025, researchers recovered genetic information from an Arctic rhinoceros that lived 21-24 million years ago by studying the enamel proteins in the animal’s teeth. That’s ten times the age of the oldest DNA sample. Perhaps the gulf between science and science fiction isn’t entirely unbridgeable after all - even without 66-million-year-old DNA to work with.
top image: Dinosaur fossil at exhibition in Edmonton, Canada. Credit: Grant Faint/ Getty Images
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