Biologists say the way to stop killing sprees by male juvenile delinquents is to bring in older males, at least if you're dealing with elephants.
Until recently, the orphan male elephants in Pilanesberg National Park in South Africa lived in an unnatural, predominantly adolescent world, explains Rob Slotow of the University of Natal in Durban. Starting in 1992, the young males began rampaging, and in 5 years, they had killed more than 40 white rhinos.
Introducing six full-grown bull African elephants in 1998 settled down the youngsters, Slotow says. In the Nov. 30 Nature, he and his colleagues attribute the turnaround to a shortening of the time a young male spends in a testosterone-crazed state called musth.