Can we get DNA out of fossils? – The Naked Scientists

Thanks to Jack Lovegrove for the answer!

James - Can you extract DNA from fossils? Thanks, Phil. You've struck upon the fabulous field of ancient DNA. To help me answer your question. We put in a call to Jack Lovegrove at the Natural History Museum

Jack - For the majority of fossils, the answer is no. Traditionally, when we think of fossils, we are thinking of things that are many million years old. As the fossil is trapped in the sediment and the sediment is squished down and lithified turned to rock, pore waters get into the fossil and replace the original bone with different minerals, and the bone is remineralised, in effect, turned into stone. However, we now have been able to extract DNA from some of the most recent fossils. So the oldest DNA that's been extracted directly from a fossil comes from just over a million years ago, which was from a mammoth tooth that was found in the permafrost. The actual oldest DNA that's been extracted from anywhere comes not directly from a fossil, but from the sediment itself. And that's from a site in Greenland and about 2 million years old.

James - That's interesting. So some of that biological material preserves for millions of years. Life on Earth though, as we know, has been going on for tens and hundreds of millions of years. What's the limiting factor to DNA hanging around for longer, perhaps? Is it, as Paul suggests on our forum, DNA is strung together by means of phosphate ether bonds, which are not the most stable of chemical bonds.

Jack - Paul is right. I'd say there are two main limiting factors, and one of them is that DNA is not a very robust molecule compared to some other organic molecules and organic components of living things. So for example, there have been some controversial studies that have reported finding tiny traces of organic material from much older fossils. So even up to about 190 million years old. But even then, they're not talking about DNA. They're talking about very degraded remnants of collagen and maybe individual amino acids. It's been suggested, have been found in egg shells, but not DNA because it does fall apart. And the second reason that we don't find DNA is that most fossils have been remineralised. So all the organic material has been replaced with inorganic minerals.

James - Your specialty at the Natural History Museum is dinosaurs. It's bad news for those who are helping one day, we might uncover dinosaur DNA. Or is it?

Jack - In terms of non-bird dinosaurs, I would say it's very unlikely we're going to get DNA from their fossils. Sort of last of the non-bird dinosaurs, things like triceratops, that's about 66 million years ago. And then the stuff I work on, the earliest dinosaurs, you're looking at at least 240 million years ago. So sort of an order of magnitude out.

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Can we get DNA out of fossils? - The Naked Scientists