July 18, 2013 | David F. Coppedge

Longevity of DNA Estimated

How long can DNA survive in a fossil?  Claims of ancient DNA can be compared with a new estimate based on a crime scene.

A re-investigation of the 1960’s Boston Strangler case has given researchers a chance to study the condition of the perpetrator after 50 years in the grave, Rachael Rettner of Live Science reported.  Because DNA degrades over time, it has a “half-life” even under ideal conditions of keeping it frozen.  From Slate Magazine‘s article about Richard III’s remains, Rettner writes,

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 million years, after which all the bonds would be broken. But DNA would not be readable after about 1.5 million years, the researchers said.

According to Slate, the DNA of Egyptian mummies has degraded.  Amber is also not a good preserver of DNA.  You can’t tell by outward appearance, the article said.  DNA’s “shelf life” is fairly low:

The decay rate of DNA depends on the conditions of its storage and packaging. Above all, it depends on whether the DNA is exposed to heat, water, sunlight, and oxygen. If a body is left out in the sun and rain, its DNA will be useful for testing for only a few weeks. If it’s buried a few feet below the ground, the DNA will last about 1,000 to 10,000 years. If it’s frozen in Antarctic ice, it could last a few hundred thousand years. For best results, samples should be dried, vacuum-packed, and frozen at about -80 degrees Celsius. Even then, ambient radiation is likely to render DNA unrecognizable before it celebrates its millionth birthday.

Both articles claimed the oldest DNA found so far, in permafrost, is 450,000 to 800,000 years old.  Neanderthal DNA said to be 100,000 years old has been sequenced by paleoanthropologists, but “When it comes to modern humans, the oldest DNA recovered so far has been only about 5,000 to 7,000 years old,” the Slate article said.

Back in 2004, the upper limit was stated to be 400,000 years (1/6/04, see also 9/4/06), but then last month (6/17/13), horse DNA in permafrost said to be 700,000 years old was found.

These claims should be remembered if ancient DNA older than that is confirmed in future finds.  Biblical creationists will deny the ancient ages, of course, saying that they are based on evolutionary assumptions.  But if intact DNA is found in a dinosaur or other fossil older than the upper limit they just stated, it could have the effect of falsifying the evolutionary timescale.  Since evolutionists are such staunch believers, though, most likely the reaction will be, “Well, what do you know; DNA can survive for 65 million years.”  That’s what they have already done with certain proteins and soft tissues that should have been long gone.  The rest of us should remember what they said beforehand about DNA’s upper limit age, and not let them get away with it.

 

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