What about the Neanderthal and Denisovan DNA that Pääbo et al have been working with?
Along those lines….
When I was a teenager just starting working, my supervisor had a habit? nervous tic? some thingy anyway. She ate tootsie roll minis, those little rods around an inch long? as a snack all the time. The thing is, she ALWAYS fiddled with their paper wrapper while she was chewing the candy. She’d smooth the waxed paper flat, then fold it in half lengthwise three (maybe four, it’s been decades) times lengthwise. Then she took the resultant strip and twisted it exactly three times along the length, first close to one end, then in the middle, then at the other end. After all that, she’d just throw the resultant ‘sculpture’ out.
Normally you’d just see her do it once in passing, but staff meetings she’d sit there doing it over and over, and by the end of the meeting there would be small stack of them in the closest ash tray. (Yeah, we smoked openly in those days.) Everybody knew she did this, sometimes people joked about it, but it wasn’t a big deal or anything.
Then one day a guy she’d often argued with about some topic or other got up after the meeting, pulled a plastic baggie out of his pocket, and emptied that ashtray into it, and tucked it away ostentatiously into his breast pocket. Everyone stared at him. He gave us a smile. “I’ve always known that someday I will want to murder someone important,” he said. “When I do, I’ll leave these wrappers sprinkled around the site. I wonder how long it will take for the FBI to track them back to Dana?”
We all just looked amused or shook our heads. Dana looked shocked.
But from then on, or at least as long as I worked there, Dana would carefully drop her tortured wrappers into her purse or pocket.”
I read the book some time ago, so from memory: most of it is about where in the fossil record the DNA is best preserved (unsurprisingly: in the inside of teeth, but only in caves that had not been subject to flooding) and how the team extracted small fragments of the total DNA without contaminating them, reproduced them with Polymerase Chain Reaction (PCR), and tried to find bits that overlapped partially to deduce (with some margin of error) what the original DNA looked like. The last part was serious computer work, where parts of the DNA that repeat themselves over and over again being a mess to sort out. It took them years to assemble the bits and pieces into the first prehistoric DNA, now the process is faster, but by no means simple. Svante Pääbo et al do not find DNA and extract it just like that, it is more that they reconstruct it by hard work, many guesses, a lot of try and error, and plenty of computer power starting with small, disjointed traces of DNA.