Well, the Tongan boys provide the only empirical data on how unsupervised children behave on a desert island.

Everything else written about the idea is speculation, from The Coral Island to The CHildren's Island to Lord of the Flies.

But Golding did observe behavior in a boarding school, and while the Tongan boys did also go to boarding school, they also were being raised in Tongan culture, and that culture, including its behavioral norms, was what helped them survive on a desert island.