What are the oldest fully intact samples of Human DNA we have? I imagine now that we have sequenced the human genome, the further back we can get samples the more we can learn about the human race’s development over time.
Thanks for all replies,
AllFree
I don’t know if it’s the oldest, but I know that DNA from teeth of over 14k years have been found in the US. I’m sure that older have been found, but not sure about the ‘fully intact’ part of your question.
-XT
About 60,000 years, apparently, although it doesn’t say if they recovered the whole genome - if they did, my guess is they didn’t sequence it. It’s actually not that important that the DNA in the sample be intact - if you think about it, our genome is already broken up into 46 pieces to begin with. When you sequence a long strand of DNA you don’t actually start at one end and read it all the way to the other, you break it up into chunks and do many reads of a few hundred to a thousand base pairs long. You then get a computer to help you align these short reads into one long sequence. So a sample that contained the whole genome in 100,000 little pieces instead of 46 big pieces wouldn’t be as terrible as it sounds. In addition, you wouldn’t necessarily need the entire genome to give you insight into human evolution - tracking changes in just a few genes could tell you a lot, although whole-genome work is a lot sexier these days.
I know a complete sequence isn’t neccesary, as we go back through time in what I guess you could call ‘genetic archeology’ we will get different pieces of the puzzle, however, I would assume the earliest complete sequence would be of some importance in the far future when we really understand DNA, this will be the earliest complete blueprint for an actual individual human being, at least in biological and genetic terms.
You can find other accounts of this discovery on the 'Net, some of which (gasp!) actually indicate what part of the DNA was recovered!
AFAIK, all (or almost all) of the very old DNA recoveries, including Mungo Man, are of mtDNA only, a very tiny portion of total DNA.
I can’t think of an example, but isn’t it true that since a single protein, peptide, miRNA, etc can affect many different biological pathways, some of the most significant evolutionary changes have some of the smallest DNA footprints.
Did that make any sense?
Yeah, I saw a link to a Science article but was too lazy to log in… Mitochondrial DNA does seem to be reported on the most often, but I suspect this is because its usefulness for tracing ancestry leads scientists to look specifically at mtDNA - sequencing is expensive (although rapidly getting cheaper), so they use primers specific to mtDNA genes when they amplify their sample. I can’t see any reason why mtDNA would be any more stable than any other DNA, so I assume much of the genome was present in their original samples - they just didn’t amplify and sequence it.
AllFreedom: It’s funny, we’ve sequenced most of the Neanderthal genome (actually, a composite of three Neanderthals found close to each other), which would have to be at least ~30,000 yo, but I couldn’t find any really old human genomes that have been compiled. Like you said, it would indeed tell us a lot about our species. mtDNA is useful for determining lineage, but it doesn’t really tell us much else.
I know that several Egyptian mummies have had enough DNA isolated to do familial testing at least.