The original question was: I have read and watched Professor Neeland’s material on your site about life spans of various molecules. What does he have to say about scientific claims we can extract detectable DNA from material hundreds of thousands to millions of years old? What is a reliable lifespan for intact DNA? And what happens to it as it degrades. Does it leave unique testable fragments?
Answer by Ed Neeland
Apart from the obvious question for the writer about how he knows that the material is hundreds of thousands to millions of years old, we can state that for DNA, the lifespan depends on the conditions under which it has been preserved. Put DNA in a warm, well lit hydrous (watery) environment and it will hydrolyze (split up) much more quickly than being preserved at minus 100 degrees C in the dark. But one thing is certain: DNA cannot last for millions of years.
However, we do find DNA traces in dinosaur fossils. This is puzzling based on what we know about the half-life of DNA. We have calculated an optimum half-life of DNA to be about 500 years (give or take a few decades). What this means is that x grams of fresh DNA will degrade to x/2 grams after 500 years. Then x/4 g after 1,000 years, and so on. It doesn’t take too many consecutive half-lives before we are beyond the detection limits of our analytical equipment. After twenty half-lives (only 10,000 years) the amount of DNA left would be (1/2)20or 9.5 x 10 -7 of the original concentration of DNA.
As the DNA degrades it leaves a variety of by-products, including some very disagreeable molecules. One of them is called cadaverine, and another putrescine. You get the idea.
Added to that ideal estimate, we must add that it is likely that DNA’s half-life is very much less than 500 years, given the ubiquitous microorganism presence, enzymes released during decomposition of the dead organism, and very fast hydrolysis reactions. You can read all about it in this in Nature News article: DNA has a 521-year half-life. Also, see Creation Research File item: Dino DNA Problem .
To Further Help You Think It Through.
One professional Journal states; “Even when preserved in bone, DNA is completely disintegrated in 22,000 years at 25°C ….or 131,000 years at 15°C.” (Ref. 1)
However, Mary Schweitzer of North Carolina State University found DNA in aTyrannosaurus rex bone dated as 67 million years and Brachylophosaurus bone dated as 80 million years. (Ref. 2) and Scott Woodward and colleagues isolated DNA from a bone dated as 80 million years old in 1994 when the bone was found in the roof of a coal mine in a rock formation where they suggest the temperature had reached 90°C to 95°C. (Ref 3)
Can you see the problem yet?
All of this means if you find DNA traces in dinosaur bones, they have not been dead for vast ages at all. To claim DNA detection past the 10,000 year mark is right at the end of the confidence range. Pushing DNA dates past that is getting to wishful thinking. As for millions, that’s taking crack cocaine and looking at the data.
1. Allentoft, M.E. et al., The half-life of DNA in bone: measuring decay kinetics in 158 dated fossils, Proc. Royal Society B279(1748):4724–4733,7 December 2012.
2. Bone doi: 10.1016/j.bone.2012.10.010, 16 October 2012
3. Science, vol. 266, pp1229-1232, 18 November 1993
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