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ETpro's avatar

What is the oldest piece of complete DNA yet sequenced?

Asked by ETpro (34552points) February 25th, 2010

Of course, if you are a Creationist then the answer is pretty simple. Nothing is over about 6,600 years old, so there’s a fairly small window of time to evaluate, and you simply throw out all conflicting evidence because you know your time scale is right, so the evidence before your eyes has to be wrong.

But for the more scientifically minded, there are serious hurdles to overcome in researching the answer to this question. Every website that states an oldest DNA age seems to have its own answer. And of course, part of the problem is that newer and newer discoveries keep pushing the date further back in time. What can you cite that seems to give a definitive answer, and why do you feel it is the right answer?

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8 Answers

fireinthepriory's avatar

“There is one problem that DNA studies of population movements within the past 10,000 years do not have: dating of the samples, as radiocarbon dating is considered to be accurate up to 50,000 years. Beyond that, other methods are needed (Hebsgaard et al, 2005), which increases the margin for error. Nevertheless, most researchers in the field accept that the oldest DNA sample sequenced so far is from plant material around 400,000 years old (Willerslev et al, 2003). From animals, sequences at least 70,000 years old have been obtained—Gilbert and others published a sequence of bison DNA that was at least 64,800 years old (Gilbert et al, 2004).”

This is from Ancient DNA Research Goes Nuclear, an article by Philip Hunter, © 2006, published in the European Molecular Biology Organization. It’s on the NCBI (the National Center for Biotechnology Information) web site, which is in conjunction with the National Institute of Health, and their journal database, PubMed is one of the most used in the country. As far as peer-reviewed scientific sources go, this is golden.

The next paragraph is also very interesting, and sheds further light on your question:
“This begs the question of what is the theoretical age limit for recoverable DNA. Various attempts have been made to calculate the theoretical survival rate for DNA at different temperatures, but as Gilbert pointed out, these have been based on simple degradation models that are known to be fairly inaccurate. The generally accepted limit is around 1 million years, certainly no more than 2 million, which makes it impossible to recover, for instance, DNA from dinosaurs. Yet DNA damage occurs in many ways, so it is possible that the absolute limit may be considerably greater, even if a sequence of that age has never been recovered.”

Wow, isn’t this stuff incredible?? :)

ETpro's avatar

@fireinthepriory Fantastic answer. I was reading a book that claimed 120 million years, and that seemed difficult to fathom. I tried looking online, and every reference I found had a different (often wildly different) date.

fireinthepriory's avatar

@ETpro 120 million years? Well that’s definitely not right! I wonder is they were talking about something else, or if they’re just… utterly wrong! Unless you’re using really specific language, talking about the “earliest sequenced DNA” could mean a lot of different things, which is probably why you found so many different answers online. Glad to help you find a legitimate source on the subject!

benjaminlevi's avatar

I dont know if its the oldest but we have dna from bee and termites from 20–45mya.

ETpro's avatar

@benjaminlevi Can you provide a reference to that? The number I read was 40 million years and it was from a termite, I believe.

benjaminlevi's avatar

@ETpro No I don’t sorry, it was just something my professor mentioned briefly in class. (but i meant that bees were more on the 20mya end and termites were more on the 40mya end)

ETpro's avatar

@benjaminlevi The oldest unambiguous termite fossils date to the early Cretaceous (circa 145 million years ago), although structures from the late Triassic have been interpreted as fossilized termite nests.

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