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> Also from the article: DNA has a half-life of ~521 years so there's no DNA left in the blood. Does this mean that the oldest creature that can be “restored”

> Also from the article: DNA has a half-life of ~521 years so there's no DNA left in the blood. Does this mean that the oldest creature that can be “restored” should be dead for less than 521 years old?

selimthegrim 5y ago
The article they cite says this might not apply in caves or permafrost for example. It gives ~1.5 million years as an endpoint for readability
- ummonk 5y ago
  Yeah we've sampled a full horse genome from 700,000 years ago.
dotancohen 5y ago
It means that half the DNA is gone after 521 years. After another 521 years, half of the remaining DNA is gone too, leaving 1/4 of the original DNA. Figure that rate of decay into your "restoration" technique to know for how long an organism can be "restored" after being dead. Does your technique require 100% of the DNA? Better catch them on asphalt. Is 50% good enough? You could probably restore Newton. You could do Paul with 6% give or take.
- jessriedel 5y ago
  I don't think that analysis is right. From the original Royal Society paper: > The average DNA half-life within this geographically constrained fossil assemblage was estimated to be 521 years for a 242 bp mtDNA sequence, corresponding to a per nucleotide fragmentation rate (k) of 5.50 × 10–6 per year. If there is a 50% chance that a 242 base pair sequence has a break in 500 years, you will be able to recover the full sequence in way more than 50% of 500 year old samples. First, you have many copies of the same DNA fragment in a macroscopic drop of blood, so some will not have a break. Second, even if it's older and all strands have at least one break, you can look at a bunch of half strands or tenth strands and infer the complete sequence. Likewise, if I had a thousand copies of a book where each copy had a few destroyed pages, it would not be hard to reconstitute the entire contents of the books. I think the above rate of decay would allow for recovery of the sequence in a sample after probably tens of thousands of years. This is why mammoths, but not dinosaurs, are typically the targets for brining back extinct mammals.
  - dotancohen 5y ago
    Interesting perspective, thank you. I'd like to see the comments of somebody versed in the field.

selimthegrim 5y ago

The article they cite says this might not apply in caves or permafrost for example. It gives ~1.5 million years as an endpoint for readability

ummonk 5y ago
Yeah we've sampled a full horse genome from 700,000 years ago.

dotancohen 5y ago

It means that half the DNA is gone after 521 years. After another 521 years, half of the remaining DNA is gone too, leaving 1/4 of the original DNA. Figure that rate of decay into your "restoration" technique to know for how long an organism can be "restored" after being dead. Does your technique require 100% of the DNA? Better catch them on asphalt. Is 50% good enough? You could probably restore Newton. You could do Paul with 6% give or take.

jessriedel 5y ago
I don't think that analysis is right. From the original Royal Society paper: > The average DNA half-life within this geographically constrained fossil assemblage was estimated to be 521 years for a 242 bp mtDNA sequence, corresponding to a per nucleotide fragmentation rate (k) of 5.50 × 10–6 per year. If there is a 50% chance that a 242 base pair sequence has a break in 500 years, you will be able to recover the full sequence in way more than 50% of 500 year old samples. First, you have many copies of the same DNA fragment in a macroscopic drop of blood, so some will not have a break. Second, even if it's older and all strands have at least one break, you can look at a bunch of half strands or tenth strands and infer the complete sequence. Likewise, if I had a thousand copies of a book where each copy had a few destroyed pages, it would not be hard to reconstitute the entire contents of the books. I think the above rate of decay would allow for recovery of the sequence in a sample after probably tens of thousands of years. This is why mammoths, but not dinosaurs, are typically the targets for brining back extinct mammals.
- dotancohen 5y ago
  Interesting perspective, thank you. I'd like to see the comments of somebody versed in the field.