Forget rise of the machines!
Just pop a DNA writer into skynets datacentre
Researchers at the University of Washington (UW) and Microsoft have managed to write data directly onto DNA, a format with dramatic storage densities and a very long life. The team wrote 200MB onto strands of synthetic DNA, including video footage of the band OK Go, the Universal Declaration of Human Rights in more than 100 …
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I mean we all have destroyed DNA, for example by cooking food. Ultraviolet radiation also is a problem. Essentially you'd get a storage medium which might hold its data for millions of years, but will quickly degrade when left out in the sun, or at temperatures higher than 40 degrees Celsius. It's also very susceptible to chemicals. Just about the only advantage is that you can make copies very easily. (even without a living being)
So they're writing data via DNA using a heavily error corrected format. If preserved for a million years it would be readable, but unless someone knew the error correction format what you read would be gibberish.
Sort of like our so-called "junk DNA" - that almost certainly isn't "junk", but that fact likely won't stop alien conspiracy theorists from before long claiming our very DNA contains instructions to build a FTL communication device to call home to our "parents"...