3 ms·

Here's the paper this is summarizing: https://www.nature.com/articles/s41559-023-02056-2 https://www.nature.com/articles/s41559-023-02056-2 In cases where a lo

by jefftk 3y ago

Here's the paper this is summarizing: https://www.nature.com/articles/s41559-023-02056-2 https://www.nature.com/articles/s41559-023-02056-2 In cases where a lot of people are contributing DNA to a sample, which I'd expect for most environmental sampling, it seems like you would need impractically large amounts of sequencing before you could identify anyone specific in sequencing conducted for other purposes: you'd need to get a sequencing read which could have come from only one person, or enough reads each matching a small number of people that you could make an inference about an individual. The paper does have "The long eDNA reads sequenced here suggest that with targeted enrichment of informative genomic locations, one could achieve individual-level identification even from pooled samples" but this is just saying that environmental sampling with the specific goal of identifying individuals could be possible. This is very different from this being something that normal researchers might do by accident in the process of environmental sequencing for a different purpose.

godelski 3y ago
I know very little about DNA and sequencing, so this may be a naive or even bad question. But aren't small sections of DNA unique? Or do you need a bunch of those small sections to actually create said fingerprint? Maybe a better question is asking how many of those chains you'd need to collect (and how long they are). Or how DNA identification even works. While the fingerprinting might not be something normal researchers do, there still is the question about if the information exists. Unfortunately you only need a single bad actor. Most people might not go through the trouble to deanonymize this user account, but it definitely is possible and would also be possible (though quite taxing) purely through processing my words alone.
- chris37879 3y ago
  They're probably unique, but the search space is so large you can't be sure that the specific section you have is the section you're checking for from the target. There's only the 4 base pairs in your DNA, so for any given length of base pairs 4^n combinations that are possible to exist. A complete human genome is 3.2 billion base pairs long. So yeah, it's definitely a length vs information density problem. Though those numbers may seem very very large, they get cut down to size very very quickly. Across all human's, there's very little variation in nearly all of our genome, something like 99.6% of those 3.2b genes are identical between all humans, which leaves 0.4% (around 12m) base pairs of DNA that make you you out of all other humans. We have identified (or at least think we have) some specific regions of those 12m pairs that control certain things, that's what the field of genetics has been up to with things like the Human Genome Project, so, plausibly, if they caught an environmental dna sample that was long enough to identify _which_ gene site they had, and they knew (or could at least guess) what value your genes would have at that site, yeah, they could probably tell whether it was you that was nearby, or at least someone related to you!

by jefftk 3y ago

godelski 3y ago

I know very little about DNA and sequencing, so this may be a naive or even bad question. But aren't small sections of DNA unique? Or do you need a bunch of those small sections to actually create said fingerprint? Maybe a better question is asking how many of those chains you'd need to collect (and how long they are). Or how DNA identification even works. While the fingerprinting might not be something normal researchers do, there still is the question about if the information exists. Unfortunately you only need a single bad actor. Most people might not go through the trouble to deanonymize this user account, but it definitely is possible and would also be possible (though quite taxing) purely through processing my words alone.

chris37879 3y ago
They're probably unique, but the search space is so large you can't be sure that the specific section you have is the section you're checking for from the target. There's only the 4 base pairs in your DNA, so for any given length of base pairs 4^n combinations that are possible to exist. A complete human genome is 3.2 billion base pairs long. So yeah, it's definitely a length vs information density problem. Though those numbers may seem very very large, they get cut down to size very very quickly. Across all human's, there's very little variation in nearly all of our genome, something like 99.6% of those 3.2b genes are identical between all humans, which leaves 0.4% (around 12m) base pairs of DNA that make you you out of all other humans. We have identified (or at least think we have) some specific regions of those 12m pairs that control certain things, that's what the field of genetics has been up to with things like the Human Genome Project, so, plausibly, if they caught an environmental dna sample that was long enough to identify _which_ gene site they had, and they knew (or could at least guess) what value your genes would have at that site, yeah, they could probably tell whether it was you that was nearby, or at least someone related to you!