by Arlos » Tue Dec 04, 2007 9:47 pm
There are a whole host of problems with reconstructing DNA from fossilized remains. Honestly, even in cases where we have sequenced the entire genome, we STILL don't k now how things work. For example, in humans, most of our DNA is outside the genes, it apparently doesn't even do anything. Same thing with other organisms. Yet when we've manipulated the DNA of simpler organisms to remove all the "junk" DNA, the creatures in question die almost immediately. So, it's clear that the inter-genomic regions of DNA have some vital function, but what that is we have no idea, since it's the genes where all the proteins and such are made.
As a result, reassembling the DNA of a completely extinct animal is going to be basically impossible. We may get fragments, but with even foreseeable future technology, we would have no idea how to assemble them. Even in the cases of stuff like those frozen wooly mammoths, we're not likely to get useable DNA, and they aren't even fossilized. While you can preserve DNA by freezing cells, it has to be done under specific conditions, or you get ice crystals forming inside the cells. Ice crystals are spiky and sharp, and puncture the cell nuclei and cell membranes as they grow, scrambling the DNA and reducing it to tiny fragments. Still, at least it's POSSIBLE we could get intact DNA from frozen creatures pulled out of the tundra, if exceedingly unlikely. But from fossilized remains? Not likely, especially considering DNA molecules are huge and incredibly fragile as a result.
-Arlos