Alexander’s experiments, in the 1970s, have
come to be called the “Rat Park.1 Researchers had already proved that when rats were placed in a cage, all alone, with no other community of rats, and offered two water bottles-one filled with water and the other with heroin or cocaine-the rats would repetitively drink from the drug-laced bottles until they all overdosed and died. Like pigeons pressing a pleasure lever, they were relentless, until their bodies and brains were overcome, and they died.