Paleogenetics: Unlocking the secrets from DNA of long ago

Eighth in a series of posts inspired by ten topics in ‘Insights of the Decade’ from the December 17, 2010 special issue of Science Magazine The topics are: Inflammation, climatology, tricks of light, alien planets, the microbiome, cell reprogramming, Martian water, the DNA time machine, cosmology and epigenetics. The original articles are now behind a paywall; they won’t be reproduced here, but their gist is present. I’ll try to put them in context and also within the Impact Areas of SciTechStory.

Jurassic Park it isn’t. Not yet. However, paleogeneticists (yes, that’s yet another new field of study) are hot on the trails of DNA and related molecules from long deceased and in most cases extinct creatures. Unlike the Jurassic Park movie, where scientists recreate dinosaurs from their amber-preserved DNA, real scientists are more modestly trying to recreate the DNA structures. In reality, you couldn’t animate the whole animal because much of the DNA is not preserved; big pieces are damaged or missing. Since it’s not known what a complete DNA from these ancient animals looks like, it’s very difficult just to piece together a reasonable reconstruction, much less reanimate the beastie.

While certainly not as dramatic as a living, breathing, puppy-dog eating Tyrannosaurus Rex in 2008 the entire mitochondrial genome of Neanderthal man was published. It was a triumph of modern genome assay equipment – the now relatively famous process that once cost millions of dollars and is now on its way to billing-out at a few hundred. It is also the triumph of ingenuity, as piecing together DNA sequences taking into account the missing and damaged components is no mean feat.

Collectively, between new techniques for genome sequencing, x-ray scans, STM microscopy, fMRI scans and a full panoply of computer assisted graphics and modeling, scientists are rapidly evolving systems for recreating the paleological past in ways that were beyond dreams only fifty years ago. In just the past ten years cave-bear DNA, wooly mammoth DNA, and the DNA of a hitherto unknown species of human has been sequenced and analyzed. From this it has been learned that mammoths were derived from elephants about six million years ago; that Neanderthals did some hanky-panky interbreeding with our (homo sapiens) ancestors; and the unknown human lived in Central Asia about 40,000 years ago.

Likewise paleobiologists are unlocking the DNA of dinosaurs and other prehistoric animals, not so they can do a Jurassic Park with it, but so that questions about evolution, genetic diversity, and fundamental properties of genetic actions can be studied and understood. And yes, some scientists are messing with taking pieces of paleo-DNA and inserting them into living species – species such as bacteria. (Had you worried there?) This is also not like the movie Splice. Yet.

Actually, while I appreciate the opportunity to tweak the old ‘fear of Frankenstein’ nerve that most people have concerning genetic manipulation, the fact of the matter is that human ignorance of the basic biology is far too great to let us achieve anything spectacular. It’s the job of learning about that basic biology that drives much of the work on paleogenetics. If we can get a better handle on where DNA was, say a few tens of millions of year ago, it will probably help us understand what’s going on with our present-day DNA. For example, all genomes sequences so far contain huge amounts of what used to be called ‘junk DNA’ – large stretches of the genome that didn’t direct the production of proteins and didn’t seem to have any useful function. Gradually it’s become known that much of the ‘junk’ is involved with gene regulation and epigenetic activity (short term adaptation). It would be extremely useful to get a picture of what ‘junk’ DNA looked like in prehistoric animals and to fit that into an overall picture of what functions it may have performed at one time versus what it does now.

At SciTechStory this is called ‘Decoding DNA’ and it is, of course, one of the more fundamental tracks with an impact on every biological science. So the fields of paleobiology and paleogenetics are a cadre of motivated and ambitious scientists and it looks like the next ten years will have even more interesting revelations – dinosaurs with colored feathers indeed.

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