Life found deep below Antarctic ice
sciencenews.org
sciencenews.org
> The Dwarves dug too greedily and too deep. You know what they awoke in the darkness of Khazad-dum...
So, the question the Smudge was genuinely asking (and I think it's a clever one) is are the "organisms cut off from the rest of the ecosystem" the microbes in the glacial lake, or are the humans the "organisms cut off from the rest of the ecosystem" for 100,000 years?
I think that the biggest problem of the scientific is to ensure that the bacteria they got come from the lake and are not dew to contamination.
The same applies to pests and their targets. There is a continuous arms race between attacker and victim. Any combination of older variations of same creatures would play out in favor of younger creature/plant.
I read somewhere that it is pretty much the same between sexes. A man of 2000 years ago would possibly be unable to impregnate todays woman (e.g.: www.sciencedaily.com/releases/2009/09/090908125137.htm)
There is no inexorable refinement force in effect in natural selection; simple organisms are selected for their current environment with no plan of building complex defenses against ancient enemies or any such.