I once read that while he was studying in war college as a young officer, Von Clausewitz was given the assignment of planning an assault on a fortified castle as part of a fictional war between two countries. His immediate response was to ask why the two countries were at war. He was told it didn't matter, just plan the assault. His response was, of course it matters, how can I know what outcome to pursue for the battle if I don't know what the causes of the war were?
Clausewitz understood, you see, that nothing occurs in a vacuum. And that's my biggest gripe with Life After People, a show on the History Channel (or as I've grown to see it, the Aliens/Holy Grail/Nostradamus/FreeMasons/Cryptozoology/2012/Crackpot Theory Channel). The series starts with the premise that overnight, every human on Earth is just... gone. It doesn't explain how, or why, or even try to -- did we die? Get abducted by aliens? spontaneously combust? Evacuate? Phase shift into another dimension? Or did we, in the words of Chekov (Pavel, not Anton), simply "Wanish"? It apparently doesn't matter to the writers of the show. We're gone, and everything on the planet is exactly as we left it, and then we watch over the cours of hours, days, months, years, centuries, and even millenia to see how man-made objects stop functioning, go haywire, fall apart, deteriorate, etc. And in that sense, it does have some interesting and informative points regarding human made structures, devices, systems, and how they must be maintained and the effects of entropy that would take place if they were not. But in terms of giving an accurate general picture of how life on Earth would look without the human race, it doesn't, and really, can't. The two adjectives are mutually exclusive. Because HOW we go and WHY we go really are crucial, aren't they?
I mean, look, there are now almost what, 7 Billion of us? That's a lot of people to haul outta here in one fell swoop. To do it all in one literal 24-hour period would require either a level of technology and infrastructure unimaginable even by all but the most far-fetched of science fiction writers (I mean hell, this makes Greg Bear seem timid), or a natural catasprophe on a scale that would definitely affect far more than the biological entity that is the human race -- we're talking planet killing asteroids, etc. Whatever the cause, the outcome is not going to take us and leave everything else untouched and pristine. And if the exodus takes time, humanity will have reacted to whatever circumstances caused it.
So while, as I've said, it's an informative look at just how things fall apart if the center cannot hold, because it focuses only on what happens after our exit, stage implausible, and not during it, the show falls short for me.