People have told me in the course of something I was doing at the time   
   that DNA evidence decays rapidly. But it also depends on where it was found   
   and what kind of purpose it's being put to. 98% of human DNA is random   
   junk. It's left over from our individual human inheritance and   
   some is there from our evolutionary history. It's theorize the historical junk   
   can come in handy every now and then if a part of it can be "re-activated"   
   and protect someone against a virus their family or species saw   
   in the past. Or one that may have just evolved from an old one our DNA saw.   
      
   But I also ran across at least one authoritative estimate of how   
   long DNA lasts "on average" which with a lil math explains why   
   "alien DNA" (presumably if by some freak chance DNA is not just specific   
   to Earth as current evidence suggests) has not been found and   
   why DNA surveys of Loch Ness might find nothing interesting but a bunch of   
   eels.   
      
     Boston Strangler Case: How Long Does DNA Last?   
     Live Science, 12 Jul 2013   
     Last year, researchers estimated that the half-life of DNA - the point at   
     which half the bonds in a DNA molecule backbone would be broken - is 521   
     years. That means that, under ideal conditions, DNA would last about 6.8   
     mn years, after which all the bonds would be broken.   
      
   So the "estimate" is that 1/2 the DNA "links" will be broken after 512y.   
      
   Sounds a long time. Some magazine articles say DNA "can last mns of years".   
   But that is mostly hype.   
      
   Let's see what time does to human DNA. Human DNA contains a surprisingly   
   small number of genes -- about 30k define the structure of our body   
   and brains and enough personality traits to get us into a sh*tload   
   of trouble when we exaggerate on USENET.   
      
   According to the cite after 512y only (on average) pairs of base pairs   
   are left. It turns out to be unlikely any complete genes are left   
   because many are so big.   
   On average "every other link" between base pairs has broken down.   
   This means after 512y there is almost certainly not enough info   
   left to even ID a DNA sample as human. But if you have other information   
   to assume it was human then there still might be enough to ID the sex   
   or hair color from unique relatively short sequences that are normally   
   present. But this procedure will be counfounded by the junk DNA   
   that is 50 times more common than the "real DNA" in our genomes.   
   I.e. there are gunna be a lot of false positives to any test.   
      
   We can make a table to show the situation over time:   
      
   After	How many bp are random bits of DNA   
   512y	-> "every 2nd link broken" -- average length of strand ~2 genes   
   256y	avg len 4 genes   
   128		   8   
   64		   16   
   32		   32   
   16                 64   
   8		   128   
   4		   256   
   2		   512   
   1		   1024   
      
   So just using simple "halflife" definition we can deduce that after 12m   
   DNA has broken into approx 1000 bp chunks. Unfortunately this is   
   on average only 1% of what you need to find a single (average) human gene.   
      
   After, eg ~50y,  chunks are only 16 bp long on average. Only if you have   
   some other information that says the sample is e.g. human might and it's only   
   might be able to find genes that contain unique sequences of 16 bp.   
   And because of junk there are big caveats.   
   Other things you cannot determine "at all".   
      
   The situation is actually much worse than this. First, the "521y"   
   is based on average conditions. If the sample is subject to sunlight,   
   heat, or water (and I presume seawater even more) it will degrade faster.   
      
     DNA degrades over time, and just how long it lasts depends on how well it's   
     preserved. Factors such as exposure to heat, water and sunlight can cause   
     the molecule to degrade faster, according to Slate.   
     -- LiveScience, "Boston Strangler Case...", 12 Jul 2013   
      
   And then there again is the "junk DNA" aspect. Only 2% of human DNA actually   
   code for protein/characteristics. The "junk" can be used to identify family   
   connections because it gets inherited (with noise), but whether the DNA is   
   from a male or female requires correct ID of the X and Y chromosomes.   
   Since there is some much junk we can be much more certain if an   
   individual matches a given family profile than we can in deciding whether   
   the sample comes from a redhead or a male.   
      
   Since a (normal) human has 23 pairs of chromosomes each is around   
   30k/23 = 1300 genes long.   
      
   Unless you get a lucky break you might need as many as ~650 genes to   
   definitely ID some sample as e.g. human.   
      
   There are ~3 bn bp in human DNA so discarding 98% as junk we get an   
   average gene size of .02*3*10^9/30000 = 2000 bp.   
   Meaning 650 genes is around 1.3 mn bp long.   
      
   I.e.  even after 1-2 y it maybe impossible to ID species from   
   "wild dna survey" or random sample.   
      
   If Nessie  is only a sometimes visitor to that Scottish lake then   
   it might leave no findable DNA behind to survey.   
      
      
      
   --   
   Upcoming events:   
   9 Jul 2021		NOAA bn Dollar Disasters Q2   
      
   "Online Haters" Are Psychopaths, Recent Study Finds.   
   The Debrief, 6 Apr 2021   
   Recently published research finds that "online haters" or people who   
   post hateful comments on online forums and social media demonstrate   
   high levels of personality disorder traits associated with psychopathy.   
      
   'I can't imagine they're nice': Sci-fi creators weigh in on aliens,   
   impending UFO report   
   NBC News on MSN.com, 27 May 2021 14:24Z   
   The US govt is finally starting to publicly acknowledge UFOs.   
   The creator of "The X-Files" has been waiting for this ...   
      
   Extraordinary explanations for UFOs look increasingly plausible   
   The Hill, 27 May 2021 21:46Z   
   Any revelation that Russia or China has developed technology capable of   
   defying the laws of physics and aerodynamics would ...   
   [Dont worry. Putin is only 1000 years ahead of US military tech.   
   You can catch up by April]!   
      
   Britain's X Files: Government's UFO hunters may restart their search for   
   alien life   
   The Daily Telegraph, 28 May 2021 18:0Z   
   Dept that once investigated other-worldly sightings in Smethwick and   
   north London could be revived after Pentagon ...   
      
   What the shakeups, legal losses for fossil fuel companies mean for climate   
   change efforts   
   PBS NewsHour, 28 May 2021 0:03Z   
      
     Why a 'crushing' day for Big Oil represents a watershed moment in   
     the climate battle   
     CNBC, 28 May 2021 0:03Z   
     A series of landmark boardroom and courtroom defeats shows the   
     growing pressure on international oil and gas companies to set   
     short-, medium- and long-term ...   
     [In a shock result an AI s/w I run indicates the change in energy   
     tech is behind the sudden "change of heart" on UFO disclosure policy   
     in the US.  Nick Pope mentioned "powerful forces" were at work and   
     it seems this is what might have been between the lines. :) But it   
     also may indicate nothing will really change because some fossil   
     companies are transforming to renewables companies and still won't   
     want to allow or even ack tech 100s of y in advance of theirs].   
      
   Newly released radar footage shows UFOs swarming Navy ship, filmmaker claims   
   New York Post, 28 May 2021 02:56Z   
   The filmmaker who leaked footage of UFOs harassing a warship off the coast   
      
   [continued in next message]   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)