all the humans were dead or turned into zombies? Would they eventually try to eat each other? Would they just walk around still looking for more humans? Would they try to revert back to what they did as humans? What do you guys think?
There is some research which suggests that they are attracted to the 'life force' in humans. It's been seen that zombies without anything to eat will eventually start to feed on plants and the bark of trees.
Obviously they get just as much value from eating these as they do eating humans so they will still continue to rot at the same rate as they would if they didn't feed on the plants/humans.
Eventually they would eat everything, until almost nothing was alive(i say almost, because zombies don't eat bacteria.(well, they do, but its not killed in the process.)) Then they would eventually rot and stop functioning, and bacteria would eventuall evolve all over again into multicelled organisms, and there would be a new chain that is drastically different from what we know to be life today, because the ozone is different now then when our evolution started, and the soil will be different due to all of the necrotic influence(not to say most soil isn't touched by death, because, I mean, everything is one, so, there's been plenty of dead things in the soil) Interesting concept, I hope it never happens.
If the risen dead were a result of bacterial or viral infection if the infection was not fed a source of energy the host would die once again because the infection would die. Dead flesh would not be great to feed a virus or bacteria for it contains nothing but malignant sources. The flesh of the living contains many energy sources ranging from vitamins and nutrients to the vry flesh itself which contains all a person needs to live. The symbiotic relation between the Undead and the Viral infection would collapse when they could no longer feed and thus after all life died the unlife would fade causing an extinct planet.
Like anything, if there is no food source, the Zombie would eventually wither and die.
The only way to test this is on a caged Zombie and could take several years. The best bet would be to put it into an empty concrete septic tank and seal the tank, then reopen in say, 2 year, 5 year and 10 year intervals.
I don't think Zombies are like Vamps who can "hibernate" indefinately without a blood source (thank you Anne Rice lol)