Unfortunately, the helicopter could only lift juvenile and adult female elephants. It could not lift the larger adult bull elephants, so they were left behind. All went well until the rangers at the new park noticed that white rhinos were turning up dead. They found to their surprise that they were being killed by bands of young, hyper- aggressive male elephants who knocked the rhinos down and gored them to death. Such behavior is unheard of in elephants.
Elephants are usually docile creatures and kept in line by the dominant adult bull elephant.
And that turned out to be the problem. The young elephants were missing the civilizing presence of their elders. Once an adult bull elephant was introduced into the herd, the gangland behavior of the young elephants was stopped by the dominant elephant. Now you have to be careful not to immediately extrapolate from elephants to humans. But you can see a striking comparison.