Rotello describes how these factors began to work together in a dynamic way among gay men in the 1960s and 1970s as the previous restrictions on gay life gave way to the era of gay liberation and a culture of casual sex with multiple partners. He describes how similar changes were occurring among young heterosexuals during the same era, but were vastly overshadowed by the gay world's network of bars, cruising areas, sex clubs and bathhouses. Within certain gay core groups, particularly those attending gay bathhouses and sex clubs, many gay men had hundreds of sexual partners per year, setting up a unique sexual ecology.