I don't believe anarchy could work.
If there were no government in any given area, humans would have no difference than animals. They may put down a house or something, but they would have to be totally alone.
To reproduce, a man could mate, leave, and let the woman raise the child alone.
If anyone wants anything done, they would have to do it themselves or run around like a decapitated chicken looking for random people to help, then immediately dismiss them.
If there's a dispute that gets heated enough (or a lot of little disputes), there is nothing to stop a whole population of humans from killing each other off.
People would have to gather their own food. They would have to find or make their own shelter.
Even if it did come about, anarchy is nigh-unsustainable. humans will almost always band together in some form.
---
If one person comes across someone else, becomes good friends, and starts a family, the family will try to stay together and help each other (in most cases.) The family will grow, and eventually become a tribe.
---
If one person starts to get a little cocky and has the strength or firepower to back it up, they will often start ordering people around. They become a form of dictator, and what they desire happens.
---
If there is an issue like a drought or a flood, people will either band together to fix it or die. This removes the anarchy, at least temporarily.
---
If two people live in one shelter, they will fight for dominance and if the result is consistent, the house would no longer be "anarchic" (Kind of stretching it, but keep reading
.) If the shelters get close enough together, people near others will try to establish dominance whenever an occasion to do so arises, and there would be a community.
---
If there gets to be any large-scale dispute, any ensuing fights would result in at least one victor. They would put their foot down, state their word as law, and, in some cases, get sick of fighting and just say "I make the rules now!"
In short, even in the unlikely event that a sustained anarchy was in place, humans would really get nowhere as a species, and have a pretty sucky life. And would probably have to consciously choose to stay that way, as any form of cohesive group would be enough to at least suspend anarchy.