comment: >
  
  That's not the same. 
  We mostly identify what prehistoric people/animals ate from stuff like remnants of bones/shells, wear patterns on teeth, minerals in their bones and such.
  Organic evidenced is generally from once in a million chance events when stars align and dozens of different conditions are perfectly right. In almost all cases that does not happen and any evidence is gone withing a couple of years.
context: The issue back when this was killing people in the 80s was they were feeding the cows their own byproducts, like brains. That was causing it to spread so I assume this practice has stopped. >
  
  Prions are the cause of mad cow disease, and they are very difficult to destroy. Obviously feeding bovine by-products to cows is a concern, but fertilizing with manure from infected cows that hasn't been properly composted is a huge concern. We see e-coli outbreaks in lettuce from insufficiently composted manure. The spread of mad cow could happen just as easily. >
  
  Are you saying it because you know for sure (from actual studies) or are you just extrapolating from the e-coli stuff.
  Because one thing is a whole bacteria which has an actual cell wall that lets it resist the active chemical and biological agents of the outside environment, a completelly different thing is a random protein from inside an animal that's misfolded.
  I don't thing you can just presume that a protein will last long outside: it might, it might not.
  PS: Not a biologist, might be completelly wrong, would love to hear more about this. >
  
  Prions are extremely resilient... I doubt composting would touch them.
  They even survive basic incineration which was basically unheard of in the pathogen world. 
  Not many things totally freak me out, but prions are one of my actual nightmares. >
  
  That's nuts! I'm a composting nut... but a year for anything that small should tell you all you need to know about how tough they are. 
  Not much lasts a 3 months, let alone a year in a properly managed composting setup.
  It would be fascinating to know what exactly is doing the dirty work at that level (enzyme/bacteria/fungi/worms exc). >
  
  I mean, we can look at prehistorical garbage dumps that are thousands of years old and still identify what people ate and threw away, down to individual species of plants and animals. We can do that because enough organic molecules survive intact over even that time span.
  We've even managed to extract DNA from archaeological and paleontological remains, and DNA is a much more delicate molecule than a prion.