There are lots of examples in the first six chapters of the how the boys are living civilization behind. Here are a few to get you started.
In Chapter 4, Jack and the hunters let the fire go out when they become obsessed with killing the pig. They are beginning to lose sight of getting rescued.
The boys begin to call themselves bigguns and littluns. The twins simply become Samneric instead of two distinct individuals of Sam and Eric.
The boys no longer use the designated latrine area. The littleuns especially are just going to the bathroom wherever they please. The littluns are also pretty much on their own. They're dirty and they have diarrhea all the time because they're are eating fruit from the jungle, but not really picky about if it's not ripe or too ripe.
The boys are naked or near naked a lot of time.
Jack paints his face to blend in with the jungle.
I'm not sure what you mean by Real Life examples. But one example is that younger kids have to be told to take a bath and to use manners. We learn these things, but often people will not use their manners, etc. when there is no one to remind them. For example, when students go off to college for the first time, they often have dirty dorm rooms and bad eating habits because there are no adults to tell them what to do.