Re:New human-like species discovered
by colordrops on Thursday September 10, 2015 @02:58PM
(#10199873)
Isn't half-life dependent on temperature? Perhaps 521 is at higher temps. Also, half-life does not imply full destruction. By definition, it's destruction of half of the molecules. With enough copies, and a low temperature, it could last much longer than 521 years.
Re:New human-like species discovered
by jessriedel on Thursday September 10, 2015 @09:50PM
(#10201574)
I believe it's the half-life for each bond. But 10^22 is plenty high enough that essentially all bond are broken, and certainly not enough left to reconstruct the genome. (You need unbroken sections of certain minimal lengths to statistically reconstruct what was there before.)
I think you're right that it's a temperature thing.
> The researchers recovered ancient DNA of Neanderthals by extracting the DNA from the femur bones of three 38,000-year-old female Neanderthal specimens from Vindija Cave, Croatia, and other bones found in Spain, Russia, and Germany.[8] Only about half a gram of the bone samples (or 21 samples each 50–100 mg[1]) was required for the sequencing, but the project faced many difficulties, including the contamination of the samples by the bacteria that had colonized the Neanderthal's body and humans who handled the bones at the excavation site and at the laboratory.
https://en.wikipedia.org/wiki/Neanderthal_genome_project
2^(38000/521)=10^22, so there must be other effects. That Nature article says
> 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.
which I don't know how to square with the 521 year figure. I think maybe 521 years is at the high temp?