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I was chatting with a biologist friend a while back, and one tidbit he dropped in was that any sample of air from anywhere on earth will likely contain the dna of organisms unknown to science, so abundant the tree of life is.
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The immune system destroy all the DNA in unexpected places in case it's a https://en.wikipedia.org/wiki/Viroid or something. Better safe than sorry. One of the important steps in mRNA vaccines was to surround the mRNA with a lipid to ensure it can survive long enough to enter a cell. Naked mRNA would not have worked.
One has to wonder whether destroy is all it does though. Analyzing this as cues about the surroundings seems like it could be pretty useful for successful living, and something evolution could well pick up on. Will we find eventually that some of those nucleic acid fragments were being hauled off for identification in something like an extra inner sense of smell?
I was chatting with a biologist friend a while back, and one tidbit he dropped in was that any sample of air from anywhere on earth will likely contain the dna of organisms unknown to science, so abundant the tree of life is.
DNA is a molecule, not a microorganism or virus.
[stub for offtopicness]
I do often wonder about stories like this in the context of forensic science – my (incomplete!) understanding a lot of the time suspect DNA samples are taken from small areas and amplified significantly with high-cycle count PCR. I'd worry that any jury presented with a statistical argument about a fragment of somebody's DNA being very unlikely ("1 in 100 million") to be different to the sample found at the scene wou…
Air contamination is very unlikely. You aren't going to get air contamination inside the victim's bedroom... And if somehow a whiff of your air travelled a hundred miles into their bedroom and all over their corpse, other evidence would be used to rule you out.
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One has to wonder whether destroy is all it does though. Analyzing this as cues about the surroundings seems like it could be pretty useful for successful living, and something evolution could well pick up on. Will we find eventually that some of those nucleic acid fragments were being hauled off for identification in something like an extra inner sense of smell?
No need to wonder if you study the lymphatic system.
Sure, some samples will be off to antigen presentation, but does that inform more than this is an encountered foreign substance and this is how to bind to it for neutralization ? Seems like in principle you could take the overview picture and have something like olfaction, but for things that hadn't been sufficiently cracked open when they passed the olfactory epithelium. Maybe it's starting to be sorted out, but I'm not up to date on what the neural feedback from the immune system carries.
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Paleontology has been really helped by the ease of sequencing, to the point where many evolutionary arguments are moot. Humans are apes, birds are dinosaurs. Some people still dispute it, but not with evidence on their side.
> birds are dinosaurs Not that I doubt that, but how does DNA help, when we have no DNA samples from dinosaurs?
But you're right, it is the fossil record that provides the strongest evidence.
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four figures these days. fits in your hand. nanopore is a revolution. https://nanoporetech.com/products/sequence/minion there’s youtubers that have videos about doing this in a home wetlab. very achievable. some amateur soil biologists using this to try and sample microdiversity as the planet… humanifies.
Ex-Nanopore employee here. One interesting thing we heard about internally was that OceanX[0] has one of our GridION[1] devices (slightly larger, and built-in compute) that they were using to track whales in the ocean by sequencing DNA found in seawater. Really cool. [0] https://en.wikipedia.org/wiki/OceanX [1] https://nanoporetech.com/products/sequence/gridion
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But we’re they at the scene or did they just bump into someone or something that was there?
That's something that would have to be addressed at the trial by the defense attorney raising challenges. If the DNA is present, it's present - barring any procedural mistakes by the forensics technicians (mislabeled sample, dirty lab equipment, didn't follow manufacturers instructions, etc). Or deceit by one or more members of the forensics team to implicate the suspect.