Back in the heyday of reality TV not really giving a hoot about ethics, one reality show in the UK placed 10 boys and 10 girls in separate houses to look after themselves, without adult supervision.
The children, all aged 11 or 12, were provided with food, money, toys, and cleaning equipment for the "experiment", but other than that were left to their own devices, with the proviso that the crew would intervene if there were issues of safety. The kids were filmed the whole time, with the footage broadcast in the UK Channel 4 documentary Boys and Girls Alone.
There was a stark difference between how the boys and girls behaved. While the girls cooked, cleaned, and organized a fashion show for entertainment purposes, the boys set about immediately trashing the house, and writing on the walls.
The boys separated after a few days into two groups, sleeping in two different bedrooms, who would then attempt to antagonize each other. One group decided to keep the other group awake after they decided to have an early night, constantly trying to enter the room and make loud noises. An argument broke out between the boys after one of the boy's t-shirts was painted and covered in shaving cream, but beyond a few minor arguments and annoyances, nobody was hurt.
An early moment of tension for the girls came when a neighbor's cat entered the house and they all attempted to take care of it.
That's not to say that the girls lived without their share of drama. Though they moved all the beds into one room and cooked and ate together, the girls did end up mildly bullying each other, and two of the girls ultimately decided to leave the house before the experiment was over.
While interesting to watch, you can't extrapolate a lot from the experiment, given the presence of cameras and nature of the experiment. There have been real-life examples of children becoming isolated, including one in 1965, when six boys attempted to run away and boat to Fiji. Unfortunately, they fell asleep at some point after stealing and getting in a boat, and became stranded on a small island for 15 months.
Before they were rescued, the boys created a schedule for duties around their camp, created musical instruments to entertain themselves, and attempted to make their own raft. One of the boys fell off a cliff and broke his leg during their stay. The boys set his leg using sticks, and took care of him until he recovered.
[H/T: The Feedski]