This is well-documented in Humankind: A Hopeful History by Rutger Bregman. It's worth a read, as it also dispels other experiments in human behaviour that have subsequently been difficult to replicate (for a variety of reasons).
https://www.goodreads.com/book/show/52879286-humankind
Yep, great book. Also dispels the Lord of the Lies myth that people have taken as gospel.
Yep, great book. Also dispels the Lord of the Lies myth that people have taken as gospel.